Risques possibles des végéta*ismes

L’évolution humaine ayant reposé durant plusieurs millions d’année sur une consommation significative de produits d’origine animale (voir études ici et article ici), il est possible qu’une alimentation trop exclusivement végétale ne parviennent pas toujours à couvrir les besoins nutritionnels d’Homo sapiens. Avec un engouement de plus en plus important pour ces types d’alimentation, des études plus précises et plus nombreuses commencent à être publiées, identifiant certains risques qui avaient possiblement été sous-estimés jusque-là.

D’autres études sont plus favorables, mais il convient de préciser les biais méthodologiques possibles de ces études, qui restent soit des études de cohorte avec un gros risque de mauvais échantillonnage, soit des études d’intervention de courte durée.

 


 


Dépression, troubles mentaux

Plusieurs études récentes associent une plus forte prévalence de troubles dépressifs et éventuellement d’autres troubles mentaux à une alimentation végétarienne. Il ne s’agit que de corrélations pour l’instant, il faudrait évaluer les causalités, et d’éventuels mécanismes si l’alimentation est responsable (on peut aussi penser que le mécanisme soit inverse : les personnes dépressives peuvent avoir tendance à se diriger vers des comportements alternatifs).
Parmi les mécanismes possibles, on pense à la vitamine D, au niveau plus bas en B12 possible malgré supplémentation, aux oméga 3 à chaîne longue dont la conversion est difficile depuis les sources végétales, et très variable selon les individus (voir cette page pour la conversion ALA vers DHA).

 

Vegetarian or gluten-free diets in patients with inflammatory bowel disease are associated with lower psychological well-being and a different gut microbiota, but no beneficial effects on the course of the disease
Philipp Schreiner et al.
United european gastroenterology journal, 2019
https://journals.sagepub.com/doi/full/10.1177/2050640619841249

Although we did not identify a relevant impact of a specific diet on the course of the disease, there was a significant association with lower psychological well-being in Vegetarian diet and Gluten free diet patients.

Relationships between vegetarian dietary habits and daily well-being
John B. Nezlek et al.
Ecology of food and nutrition, 2018.
https://www.tandfonline.com/doi/abs/10.1080/03670244.2018.1536657

Multilevel modeling analyses (days nested within persons) found that vegetarians (individuals who avoided all meat and fish, n = 24) reported lower self-esteem, lower psychological adjustment, less meaning in life, and more negative moods than semi-vegetarians (individuals who ate some meat and/or fish, n = 56) and omnivores (individuals who did not restrict their intake of meat or fish, n = 323). Vegetarians also reported more negative social experiences than omnivores and semi-vegetarians.

Depressive Symptoms and Vegetarian Diets: Results from the Constances Cohort.
Matta J et al, 2018
https://www.ncbi.nlm.nih.gov/pubmed/30404246

Depressive symptoms were associated with pesco-vegetarian and lacto-ovo-vegetarian diets in multivariable analyses (Odds-Ratio [95% confidence interval]: 1.43 [1.19⁻1.72] and 1.36 [1.09⁻1.70], respectively), especially in case of low legumes intake (p for interaction < 0.0001), as well as with the exclusion of any food group (e.g., 1.37 [1.24⁻1.52], 1.40 [1.31⁻1.50], 1.71 [1.49⁻1.97] for meat, fish and vegetables exclusion, respectively). Regardless of food type, the Odds-Ratio of depressive symptoms gradually increased with the number of excluded food groups (p for trend < 0.0001). Depressive symptoms are associated with the exclusion of any food group from the diet, including but not restricted to animal products.

Vegetarian diets and depressive symptoms among men
JR Hibbeln, K Northstone, J Evans, J Golding – Journal of affective …, 2018 – Elsevier
https://www.sciencedirect.com/science/article/pii/S0165032716323916

Vegetarians [n = 350 (3.6% of sample)], had higher depression scores on average than non-vegetarians (mean difference 0.96 points [95%CI + 0.53, + 1.40]) and a greater risk for EPDS scores above 10 (adjusted OR = 1.67 [95% CI: 1.14,2.44]) than non-vegetarians after adjustment for potential confounding factors.

Vegetarianism, depression, and the five factor model of personality *
Catherine A. Forestell & John B. Nezlek
Pages 246-259 | Published online: 29 Mar 2018
https://www.tandfonline.com/doi/abs/10.1080/03670244.2018.1455675

Although vegetarians and semi-vegetarians were more open to new experiences, they were more neurotic and depressed than omnivores.

Adhering to a vegetarian diet may create a greater risk of depressive symptoms in the elderly male Chinese population
LI Xiu-de, H CAO, S XIE, K LI, F TAO, L YANG… – Journal of affective disorders, 2018 – Elsevier
https://www.sciencedirect.com/science/article/pii/S0165032718309911

The elderly participants who had a vegetable-based diet had the highest GDS scores of 8.78 ± 6.894 (p = 0.001) and the highest rate of depression (32.9%, p = 0.003). After adjustment for the potential confounders, elderly men who had a vegetable-based diet had a higher rate of depression (OR[95%CI]: 1.62[1.07-2.46], 4.71[1.38-16.03]), more severe symptoms of depression (OR[95%CI]: 8.85[2.94-34.12]), and higher GDS scores (β[95%CI]: 1.46[0.70-2.22], 2.97[1.28-4.67]) than male participants who had a meat-based diet, but this was not the case in women.

Vegetarian diet as a risk factor for depression *
Azize Asanova, 2017
https://e-medjournal.com/index.php/psp/article/view/90

The study enrolled 9668 men, 350 (3.6%) of them reported being vegetarians or vegans (311 vegetarians, 39 vegans). The duration of adherence to vegetarian diet ranged from 1 to 41 years (2/3 of men at the moment of evaluation had been vegetarians for more than 10 years). The study found that male vegetarians had more severe depressive symptoms according to EDPS and had a greater risk of depression. On average vegetarians more often received more than 10 points, than non-vegetarians (p<0.0001). This was also confirmed after adjusting to socio-demographic variables. Vegetarians had a 67% higher depression risk (> 10 points) than those who did not follow this diet.

Meat Consumption During Pregnancy and Substance Misuse Among Adolescent Offspring: Stratification of TCN2 Genetic Variants
Joseph R. Hibbeln et al., 2017
https://onlinelibrary.wiley.com/doi/abs/10.1111/acer.13494

Lower prenatal meat consumption was associated with increased risks of adolescent substance misuse. Interactions between TCN2 variant status and meat intake implicate cobalamin deficiencies.

Nutrition and Health – The Association between Eating Behavior and Various Health Parameters: A Matched sample study
Nathalie T. Burkert et al.
Institute of Social Medicine and Epidemiology, Medical University Graz, 2014
https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0088278&type=printable
our results showed that a vegetarian diet is associated with poorer health (higher incidences of cancer, allergies, and mental health disorders), a higher need for health care, and poorer quality of life

Vegetarian diet and mental disorders: results from a representative community survey
Johannes Michalak, Xiao Chi Zhang, Frank Jacobi, 2012
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3466124/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3466124/pdf/1479-5868-9-67.pdf

Vegetarians displayed elevated prevalence rates for depressive disorders, anxiety disorders and somatoform disorders. Due to the matching procedure, the findings cannot be explained by socio-demographic characteristics of vegetarians (e.g. higher rates of females, predominant residency in urban areas, high proportion of singles). The analysis of the respective ages at adoption of a vegetarian diet and onset of a mental disorder showed that the adoption of the vegetarian diet tends to follow the onset of mental disorders.

How does the health and well-being of young Australian vegetarian and semi-vegetarian women compare with non-vegetarians?
Baines S1, Powers J, Brown WJ., 2007
https://www.ncbi.nlm.nih.gov/pubmed/17411462

Ici, malgré des indicateurs indirects plutôt favorables (plus minces et plus d’activité physique), problèmes menstruels et moins bonne santé mentale :

Semi-vegetarians and vegetarians had poorer mental health, with 21-22% reporting depression compared with 15% of non-vegetarians (P < 0.001). Low iron levels and menstrual symptoms were also more common in both vegetarian groups. Vegetarian and semi-vegetarian women were more likely to consult alternative health practitioners and semi-vegetarians reported taking more prescription and non-prescription medications. Compared with non-vegetarians, semi-vegetarians were less likely and vegetarians much less likely to be taking the oral contraceptive pill.
CONCLUSION:

The levels of physical activity and body mass indices of the vegetarian and semi-vegetarian women suggest they are healthier than non-vegetarians. However, the greater reports of menstrual problems and the poorer mental health of these young women may be of clinical significance.

The state of mind of vegetarians: Psychological well-being or distress.
Lindeman, M.
Ecology of Food and Nutrition, 2002
https://www.tandfonline.com/doi/abs/10.1080/03670240212533

The results showed that vegetarian and semivegetarian women had a lower self-esteem and more symptoms of depression and eating disorders than omnivorous women. In addition, vegetarian women had a more negative view of the world than semivegetarian or omnivorous women did. The results suggest that although vegetarians may be healthier, they may be less happy than other individuals.

Characteristics of vegetarian adolescents in a multiethnic urban population
Perry CL1, Mcguire MT, Neumark-Sztainer D, Story M.

The vegetarians were more likely than nonvegetarians to be female, not black, weight- and body-conscious, dissatisfied with their bodies, and involved in a variety of healthy and unhealthy weight control behaviors. Vegetarians more often reported having been told by a physician that they had an eating disorder and were more likely to have contemplated and attempted suicide. Vegetarian males were found to be an especially high risk group for unhealthy weight control practices. Few ethnic group differences among vegetarians were noted. Adolescents who did not eat chicken and fish were at lower risk than those who also ate chicken and fish.
CONCLUSIONS:

Adolescent vegetarians are at greater risk than others for involvement in unhealthy and extreme weight control behaviors. Vegetarian males are at particularly high risk. Vegetarianism among adolescents may therefore be a signal for preventive intervention. Adolescents who choose to become vegetarians may also need to learn how to healthfully do so.

Plus de dépression chez les consommateur d’une alimentation à l’occidentale que chez les consommateur d’une alimentation « traditionnelle » (et donc on aurait dépression végés > dépression occidental > dépression traditionnel ?), le risque de dépression serait plus fort chez les végés que chez les consommateurs d’une alimentation déjà pas optimale :

Association of Western and traditional diets with depression and anxiety in women.
Jacka FN1, Pasco JA, Mykletun A, Williams LJ, Hodge AM, O’Reilly SL, Nicholson GC, Kotowicz MA, Berk M., 2010
https://www.ncbi.nlm.nih.gov/pubmed/20048020

After adjustments for age, socioeconomic status, education, and health behaviors, a « traditional » dietary pattern characterized by vegetables, fruit, meat, fish, and whole grains was associated with lower odds for major depression or dysthymia and for anxiety disorders. A « western » diet of processed or fried foods, refined grains, sugary products, and beer was associated with a higher GHQ-12 score. There was also an inverse association between diet quality score and GHQ-12 score that was not confounded by age, socioeconomic status, education, or other health behaviors.

The Connection Between Anxiety, Depression + Omega Fats
https://thechalkboardmag.com/australian-study-on-meat-consumption-and-mood-disorders

 


 


Squelette et santé dentaire

Veganism, vegetarianism, bone mineral density, and fracture risk: a systematic review and meta-analysis *
Iguacel I et al., 2018
https://www.researchgate.net/publication/328584228_Veganism_vegetarianism_bone_mineral_density_and_fracture_risk_a_systematic_review_and_meta-analysis

Two investigators evaluated 275 studies against the inclusion criteria (original studies in humans, written in English or Spanish and including vegetarian or vegan diets and omnivorous diets as factors with BMD values for the whole body, lumbar spine, or femoral neck and/or the number of fractures as the outcome) and exclusion criteria (articles that did not include imaging or studies that included participants who had suffered a fracture before starting the vegetarian or vegan diet). The quality assessment tool for observational cohort and cross-sectional studies was used to assess the quality of the studies.

Results:

Twenty studies including 37 134 participants met the inclusion criteria. Compared with omnivores, vegetarians and vegans had lower BMD at the femoral neck and lumbar spine and vegans also had higher fracture rates.

Bone turnover, calcium homeostasis, and vitamin D status in Danish vegans.
Hansent TH et al., 2018
https://www.ncbi.nlm.nih.gov/pubmed/29362456

When adjusting for seasonality and constitutional covariates (age, sex, and body fat percentage) vegans had higher concentrations of PINP (32 [95% CI: 7, 64]%, P = 0.01) and BAP (58 [95% CI: 27, 97]%, P < 0.001) compared to omnivores, whereas CTX (30 [95% CI: -1, 72]%, P = 0.06) and osteocalcin (21.8 [95% CI: -9.3, 63.7]%, P = 0.2) concentrations did not differ between the two groups. Vegans had higher serum PTH concentration (38 [95% CI: 19, 60]%; P < 0.001) and lower 25(OH)-D serum concentration (-33 [95% CI: -45, -19]%; P < 0.001), but similar serum calcium concentration (-1 [95% CI: -3, 1]%, P = 0.18 compared to omnivores.

CONCLUSIONS:

Vegans have higher levels of circulating bone turnover markers compared to omnivores, which may in the long-term lead to poorer bone health. Differences in dietary habits including intake of vitamin D and calcium may, at least partly, explain the observed differences.

Ici, le critère est d’être végan depuis plus d’un an (vraiment minimal en termes de durée) et d’être un adulte :
Diet-Dependent Net Endogenous Acid Load of Vegan Diets in Relation to Food Groups and Bone Health-Related Nutrients: Results from the German Vegan Study
Ströhle A. · Waldmann A. · Koschizke J.· Leitzmann C.· Hahn A, 2011
https://www.karger.com/Article/Pdf/331572

Data from healthy men (n = 67) and women (n = 87), aged 21–75 years, who fulfilled the study criteria (vegan diet for ≧1 year prior to study start; age ≧18 years, and no pregnancy/childbirth during the last 12 months) were included in the analysis. NEAP values were calculated from diet composition using two models: one based on the protein/potassium quotient and another taking into account an anthropometry-based loss of urinary organic anions. Results:Mean daily intakes of phosphorus, potassium, sodium, magnesium and vitamin C were above, and vitamin D and calcium below Dietary Reference Intake (DRI).

The influence of vegan diet on bone mineral density and biochemical bone turnover markers.
Jadwiga Ambroszkiewicz et al.
Pediatric Endocrinology, Diabetes and Metabolism 2010
https://www.researchgate.net/profile/Jadwiga_Ambroszkiewicz/publication/49623957_The_influence_of_vegan_diet_on_bone_mineral_density_and_biochemical_bone_turnover_markers/links/0f31753bf94bedc784000000/The-influence-of-vegan-diet-on-bone-mineral-density-and-biochemical-bone-turnover-markers.pdf

Our results suggest that an inadequate dietary intake of calcium and vitamin D may impair the bone turnover rate and cause a de
crease in
bone mineral density in vegans. The parameters of bone density and bone metabolism should be monitored in vegans, especially ch
ildren, in order to
prevent bone abnormalities.

Oral implication of the vegan diet : observational study
L. Laffranchi et al., 2010
https://www.researchgate.net/profile/Domenico_Dalessandri/publication/49739421_Oral_implications_of_the_vegan_diet_observational_study/links/0c96051b484ae6396f000000.pdf

The study revealed greater incidence of demineralization and white spots in vegan subjects compared to the omnivorous ones

Comparative fracture risk in vegetarians and nonvegetarians in EPIC-Oxford
P Appleby, A Roddam, N Allen & T Key, 2007
https://www.nature.com/articles/1602659

Over an average of 5.2 years of follow-up, 343 men and 1555 women reported one or more fractures. Compared with meat eaters, fracture incidence rate ratios in men and women combined adjusted for sex, age and non-dietary factors were 1.01 (95% CI 0.88–1.17) for fish eaters, 1.00 (0.89–1.13) for vegetarians and 1.30 (1.02–1.66) for vegans. After further adjustment for dietary energy and calcium intake the incidence rate ratio among vegans compared with meat eaters was 1.15 (0.89–1.49). Among subjects consuming at least 525 mg/day calcium the corresponding incidence rate ratios were 1.05 (0.90–1.21) for fish eaters, 1.02 (0.90–1.15) for vegetarians and 1.00 (0.69–1.44) for vegans.

Ici, on est sur des crudivoristes :

Low Bone Mass in Subjects on a Long-term Raw Vegetarian Diet
Luigi Fontana et al.

Archives of internal medicine, 2005
https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/486478

A RF vegetarian diet is associated with low bone mass at clinically important skeletal regions but is without evidence of increased bone turnover or impaired vitamin D status.

Protein intake and bone health: the influence of belief systems on the conduct of nutritional science
Robert P Heaney, 2001
https://academic.oup.com/ajcn/article/73/1/5/4729610

Since our study was reported, an impressive body of literature has proven that protein tends to have a positive effect on bone overall. Two randomized controlled trials showed that increased protein intake dramatically improved outcomes after hip fracture (3, 4), and subsequent work showed that protein supplements reduce bone loss at the contralateral hip in patients with upper femoral fracture (5, 6). The most likely explanation is a protein-induced increase in insulin-like growth factor I (7), which is known to be osteotrophic.

Long-Term Vegetarian Diet and Bone Mineral Density in Postmenopausal Taiwanese Women
JF Chiu et al., 1997
https://link.springer.com/article/10.1007/PL00005812

Long-term practitioners of vegan vegetarian were found to be at a higher risk of exceeding lumbar spine fracture threshold (adjusted odds ratio = 2.48, 95% confidence interval = 1.03–5.96) and of being classified as having osteopenia of the femoral neck (3.94, 1.21–12.82). Identification of effective nutrition supplements may be necessary to improve BMD levels and to reduce the risk of osteoporosis among long-term female vegetarians.


 


Troubles digestifs et troubles associés

Association between self-reported vegetarian diet and the irritable bowel syndrome in the French NutriNet cohort
Camille Buscail et al.
Plos one, 2017
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0183039

Among these individuals, 2,264 (5.4%) presented an IBS, and 805 (1.9%) reported a VD. Overall, VD was not associated with IBS or subtypes. A stable VD (i.e. self-declared at least three times) was associated with IBS (aOR 2.60 95%CI [1.37–4.91]), IBS mixed (aOR 2.97 95%CI [1.20–7.36]) and IBS diarrhoea (aOR 2.77 95%CI [1.01–7.59]).

Frequency and risk factors of functional gastro-intestinal disorders in a rural Indian population.
Ghoshal UC, Singh R, 2017
https://www.ncbi.nlm.nih.gov/pubmed/27262283

Functional gastrointestinal disorders, particularly dyspepsia-IBS overlap, are common in rural Indian population; the risk factors included chewing tobacco, aerated soft drink, tea/coffee, vegetarian diet, disturbed sleep, anxiety, and dyspepsia predicting occurrence of IBS.

 


 


Troubles alimentaires

Increased prevalence of vegetarianism among women with eating pathology
Kelly L. Zuromski et al.
Eating behaviors, 2015
https://www.sciencedirect.com/science/article/pii/S1471015315000860

Endorsement of vegetarianism was highest among females with severe eating pathology. Future research should use longitudinal data to examine the temporal relationship between these variables, or other underlying factors that may contribute to the co-occurrence of eating pathology and vegetarianism. Clinically, endorsement of vegetarianism may also be an important variable to consider in treatment disordered eating.

The Inter-relationships between Vegetarianism and Eating Disorders among FemalesAnna M. Bardone-Cone et al.
Journal of the Academy of Nutrition and Dietetics, 2012
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3402905/

Compared to controls, individuals with an eating disorder history were significantly more likely to ever have been vegetarian (52% vs. 12%), to be currently vegetarian (24% vs. 6%), and to be primarily motivated by weight-related reasons (42% vs. 0%). The three recovery status groups (fully recovered, partially recovered, active eating disorder) did not differ significantly in percentiles endorsing a history of vegetarianism or weight-related reasons as primary, but they differed significantly in current vegetarianism (33% of active cases, 13% of partially recovered, 5% of fully recovered). Most perceived that their vegetarianism was related to their eating disorder (68%) and emerged after its onset. Results shed light on the vegetarianism-eating disorders relation and suggest intervention considerations for clinicians (e.g., investigating motives for vegetarianism).

Vegetarianism and eating disorders: Association between eating attitudes and other psychological factors among Turkish adolescents.
Bas, M., Karabudak, E., & Kiziltan, G.
Appetite, 2005.
https://www.researchgate.net/publication/7813871_Vegetarianism_and_eating_disorders_Association_between_eating_attitudes_and_other_psychological_factors_among_Turkish_adolescents

As a conclusion, the present study indicated abnormal eating attitudes, low self-esteem, high social physique anxiety, and high trait anxiety in Turkish vegetarian adolescents. The vegetarian adolescents may be more likely to display disordered eating attitudes and behaviors than nonvegetarians.

Links between meat avoidance, negative eating attitudes, and disordered eating behaviors.
Hormes, J. M., Catanese, D., Bauer, R, & Rozin, P.
Poster session presented at the annual meeting of the American Psychological Association, 2006.

Self-reported vegetarianism may be a marker for college women at risk for disordered eating.

Klopp, S. A., Heiss, C. J., & Smith, H. S.

Journal of the American Dietetic Association, 2003
https://pdfs.semanticscholar.org/4c35/02820abdb307fd8e8056e8437fac35e4cb15.pdf

Although many people follow a vege-tarian diet as part of a healthy lifestyle, the results from this study indicate that the practice of vegetarianism may be a marker for college female students at risk for weight preoccupation and eating disorder tendencies. Clinicians need to be aware of subpopulations at increased risk for eating disorder tendencies to aid in the early detection of those with true eating disorders.

Vegetarianism and eating-disordered thinking.
Lindeman, M., Stark, K., & Latvala, K.
Eating Disorders, 2000

https://www.researchgate.net/publication/233482788_Vegetarianism_and_Eating-Disordered_Thinking

The results indicate that vegetarianism and eating disorders are not independent but rather are intertwined phenomena. The potential common links, for example the possibility that vegetarianism is being used as a smokescreen for more severe eating pathology, are discussed.
(PDF) Vegetarianism and Eating-Disordered Thinking. Available from: https://www.researchgate.net/publication/233482788_Vegetarianism_and_Eating-Disordered_Thinking [accessed Dec 07 2018].

Adolescent vegetarians. A behavioral profile of a school-based population in Minnesota.
Neumark-Sztainer, D., Story, M., Resnick, M., & Blum, R.
Archives of Pediatrics and Adolescent Medicine, 1997
https://www.ncbi.nlm.nih.gov/pubmed/9265888

Vegetarians were almost twice as likely to report frequent dieting (P < .001), 4 times as likely to report intentional vomiting (P < .001), and 8 times as likely to report laxative use (P < .001) than nonvegetarians. Overall, associations with other health-compromising and health-promoting behaviors were not apparent.

Vegetarianism in anorexia nervosa? A review of 116 consecutive cases.
O’Connor, M. A., Touyz, S. W., Dunn, S. M., & Beumont, P. J.
The Medical Journal of Australia, 1987
https://www.researchgate.net/publication/19465975_Vegetarianism_in_anorexia_nervosa_A_review_of_116_consecutive_cases

A retrospective study was carried out of 116 consecutive patients with anorexia nervosa to ascertain the extent and nature of vegetarianism in this population. Sixty-three (54.3%) patients were found to be avoiding red meat. In only four (6.3%) of these did meat avoidance predate the onset of their anorexia nervosa. Of the remaining 59 patients (best termed pseudovegetarians), 25 (42.4%) patients continued to avoid red meat by the end of treatment. Pseudovegetarianism was associated with a longer duration of anorexia nervosa, a lower weight during the course of their illness, and living away from the parental home. The reintroduction of red meat into the diet was more likely if vegetarianism were of a short duration.


 


Divers

Factors associated with anemia among female adult vegetarians in Malaysia
Zi Fei Chai et al.
Nutrition research and practice, 2019
https://synapse.koreamed.org/search.php?where=aview&id=10.4162/nrp.2019.13.1.23&code=0161NRP&vmode=FULL

A total of 177 female vegetarians were recruited from a Buddhist and Hindu organization in Selangor, Malaysia.[…]
The findings revealed 28.2% of the participants to be anemic. The age group (AOR = 2.46, 95% CI = 1.19–5.05), marital status (AOR = 2.69, 95% CI = 1.27–5.71), and percentage of energy from protein (AOR = 5.52, 95% CI = 1.41–21.65) were the significant predictors of anemia.

Is a vegetarian diet safe to follow during pregnancy? A systematic review and meta-analysis of observational studies
Chang Tan & al.
Critical reviews in food science and nutrition, 2019
https://www.tandfonline.com/doi/abs/10.1080/10408398.2018.1461062?fbclid=IwAR1pAuFe7QoUii8mDCXr2at53ghzddO3bsKRaDNojyAdvq59IuiCRhpm4_M

The overall estimated relation between vegetarian pregnancy and low birth weight (LBW) was marginally significant (1.27 (0.98, 1.65), P = 0.07, I2=0%). Asian (India/Nepal) vegetarian mothers exhibited increased risks to deliver a baby with LBW (1.33 (1.01, 1.76), P = 0.04, I2=0%). However, the WMD of neonatal birth weight in five studies suggested no difference between vegetarians and omnivores. Given the high heterogeneity of the included studies, lack of high-quality evidence, and limited studies included for each category, we failed to reach conclusive results regarding the risks of hypospadias, intrauterine growth retardation, maternal anemia, and gestational diabetes mellitus.

Which Is a Good Diet—Veg or Non-veg ? Faith-Based Vegetarianism for Protection From Obesity—a Myth or Actuality ?
Sanjay Borude
Obesity surgery, 2019
https://link.springer.com/article/10.1007/s11695-018-03658-7

 

In an Asian Indian cohort, we found that vegetarian dietary patterns were associated with a higher incidence of morbid obesity culminating in bariatric surgery. Our study is a myth breaker that all vegetarian diets are healthy diets. Our findings can be utilized to discourage refined and processed food consumption and promote healthy vegetarian food choices.

Effect of restriction vegan diet’s on muscle mass, oxidative status, and myocytes differentiation: A pilot study
Daniela Vanacore et al.
Journal of celular physiology, 2018
https://onlinelibrary.wiley.com/doi/full/10.1002/jcp.26427

We enrolled three groups of healthy men (omnivores, vegetarians, and vegans) with similar age, weight and BMI, and we observed a significant decrease in muscle mass index and lean body mass in vegan compared to vegetarian and omnivore groups, and higher serum homocysteine levels in vegetarians and vegans compared to omnivores. We studied whether serum from omnivore, vegetarian, and vegan subjects affected oxidative stress, growth and differentiation of both cardiomyoblast cell line H9c2 and H‐H9c2 (H9c2 treated with H2O2 to induce oxidative damage). We demonstrated that vegan sera treatment of both H9c2 and H‐H9c2 cells induced an increase of TBARS values and cell death and a decrease of free NO2− compared to vegetarian and omnivorous sera. Afterwards, we investigated the protective effects of vegan, vegetarian, and omnivore sera on the morphological changes induced by H2O2 in H9c2 cell line. We showed that the omnivorous sera had major antioxidant and differentiation properties compared to vegetarian and vegan sera. Finally, we evaluated the influence of the three different groups of sera on MAPKs pathway and our data suggested that ERK expression increased in H‐H9c2 cells treated with vegetarian and vegan sera and could promote cell death. The results obtained in this study demonstrated that restrictive vegan diet could not prevent the onset of metabolic and cardiovascular diseases nor protect by oxidative damage.

Anthropometric and physiologic characteristics in white and British Indian vegetarians and nonvegetarians in the UK Biobank.
Tong TY et al., 2018
https://www.ncbi.nlm.nih.gov/pubmed/29868910

In white women, after adjustment for age and compared with regular meat eaters, non-red meat eaters had lower adiposity (e.g., 4.5% lower body fat in vegan women) and lower systolic and diastolic blood pressure (-4.2 and -3.3 mm Hg, respectively), and generally lower heel bone mineral density t-score (-0.26). Patterns of differences by diet group were similar in white men. In the Indian population, compared with meat eaters, vegetarian women were shorter (-1.1 cm) and had lower lean mass (-0.5 kg), and both vegetarian women and men had lower grip strength (-1.3 and -1.4 kg, respectively). No significant differences in the other characteristics were observed.

When veggies aren’t enough
Yvette van Schie
Professional beauty, 2018
https://search.informit.com.au/documentSummary;dn=562484894378004;res=IELHSS;type=pdf

Etude peu significative, mais sujet à creuser en lien avec les possibles manques de collagènes liés aux alimentations purement végétales.

Although vegetarians and vegan diets are healthy for the body, they can have detrimental effects on the skin, says Yvette van Schie, but supplements can help.

What evidence is there that diets help people with rmds?
A Linauskas
Annals of the rheumatics diseases, 2018
https://ard.bmj.com/content/77/Suppl_2/39.4

Mediterranean diet intervention studies have shown tendency to pain reduction and improvement of physical function after 3–6 months.

An intervention study, comparing 7–10 days fasting followed by 13 months vegetarian diet and the ordinary diet, showed significant pain reduction in the intervention group. Though, there was no significant difference in physical function or morning stiffness compared to RA patients adhered to an ordinary diet.

Vegan diet intervention studies did not report statistical significant difference in pain, physical activity or morning stiffness compared to an ordinary diet.

 

Vegan diet: utilization of dietary supplements and fortified foods
An internet-based survey

Irina Vollmer, Markus Keller, Anja Kroke
Ernaehrungs Umschau international, 2017
https://www.ernaehrungs-umschau.de/fileadmin/Ernaehrungs-Umschau/pdfs/pdf_2018/09_18/EU09_2018_WuF_Vollmer_Englisch.pdf

Vegan diets: practical advice for athletes and exercisers.
Rogerson, D, 2017
https://www.ncbi.nlm.nih.gov/pubmed/28924423

[…] veganism creates challenges that need to be accounted for when designing a nutritious diet. This included the sufficiency of energy and protein; the adequacy of vitamin B12, iron, zinc, calcium, iodine and vitamin D; and the lack of the long-chain n-3 fatty acids EPA and DHA in most plant-based sources. However, via the strategic management of food and appropriate supplementation, it is the contention of this article that a nutritive vegan diet can be designed to achieve the dietary needs of most athletes satisfactorily. Further, it was suggested here that creatine and β-alanine supplementation might be of particular use to vegan athletes, owing to vegetarian diets promoting lower muscle creatine and lower muscle carnosine levels in consumers. Empirical research is needed to examine the effects of vegan diets in athletic populations however, especially if this movement grows in popularity […]


Il est ici souligné que l’on a besoin de beaucoup plus de recherche, particulièrement sur la santé à long terme des végans (dont on sait en fait assez peu à ce jour, le recul est faible).

The long-term health of vegetarians and vegans.
Appleby, PN, Key TJ, 2016
https://www.ncbi.nlm.nih.gov/pubmed/26707634

The long-term health of vegetarians appears to be generally good, and for some diseases and medical conditions it may be better than that of comparable omnivores. Much more research is needed, particularly on the long-term health of vegans.

Food intake diet and sperm characteristics in a blue zone: a Loma Linda Study.
Eliza M. Orzylowska et al.
European journal of obstetrics, gynecology and reproductive biology, 2016
https://www.researchgate.net/publication/303692674_Food_intake_diet_and_sperm_characteristics_in_the_Blue_Zones_a_Loma_Linda_Study

Lacto-ovo vegetarians had lower sperm concentration (50.7±7.4M/mL versus non-vegetarians 69.6±3.2M/mL, mean±S.E.M.). Total motility was lower in the lacto-ovo and vegan groups (33.2±3.8% and 51.8±13.4% respectively) versus non-vegetarians (58.2±1.0%). Vegans had lowest hyperactive motility (0.8±0.7% versus lacto-ovo 5.2±1.2 and non-vegetarians 4.8±0.3%). Sperm strict morphologies were similar for the 3 groups. There were no differences in rapid progression and chromatin integrity. Conclusions: The study showed that the vegetables-based food intake decreased sperm quality. In particular, a reduction in sperm quality in male factor patients would be clinically significant and would require review. Furthermore, inadequate sperm hyperactivation in vegans suggested compromised membrane calcium selective channels. However, the study results are cautiously interpreted and more corroborative studies are needed.

A maternal vegetarian diet in pregnancy is associated with hypospadias
K. North, J. Golding
British Journal of Urology International, 2000, 2008
https://onlinelibrary.wiley.com/doi/full/10.1046/j.1464-410x.2000.00436.x


 


Troubles alimentaires

Orthorexic and restrained eating behaviour in vegans, vegetarians, and individuals on a diet
Friederike Barthels et al.
Eating and weight disorder, 2018
https://link.springer.com/article/10.1007/s40519-018-0479-0

Conclusion
In general, the results imply that orthorexic eating behaviour varies with the amount of dietary restrictions people display. Food selection strategies like veganism, vegetarianism, and dieting behaviour are accompanied by more
pronounced orthorexic eating behaviour, indicating that cognitive control and restrictions of food intake play a role in orthorexia, too. Further research is needed to investigate whether these food selection strategies serve as risk factors regarding the development of orthorexic eating behaviour.

 

Discussion
The first objective of the present study was to assess the
orthorexic dietary patterns and eating behaviours among
individuals with differential food preferences. Our results
suggested that individuals who followed a special diet (vegetarian
and vegan diet) reported more orthorexic behaviours

Cette étude trouve une association entre orthorexie et végétarisme :

Prevalence of orthorexia nervosa among ashtanga yoga practitioners: a pilot study
Jesus Herranz Valera
Eating and weight disorders, 2014
https://link.springer.com/article/10.1007/s40519-014-0131-6
When we analyzed the differential distribution of orthorexia in our cohort, we only found an association between the ORTO-15 score and vegetarianism (Table 4), i.e., the ORTO-15 score was lower among vegetarians.

Vegetarianism and eating disorders: Association between eating attitudes and other psychological factors among Turkish adolescents.
Bas, M., Karabudak, E., & Kiziltan, G.
Appetite, 2005.
https://www.researchgate.net/publication/7813871_Vegetarianism_and_eating_disorders_Association_between_eating_attitudes_and_other_psychological_factors_among_Turkish_adolescents

As a conclusion, the present study indicated abnormal eating attitudes, low self-esteem, high social physique anxiety, and high trait anxiety in Turkish vegetarian adolescents. The vegetarian adolescents may be more likely to display disordered eating attitudes and behaviors than nonvegetarians.

Links between meat avoidance, negative eating attitudes, and disordered eating behaviors.
Hormes, J. M., Catanese, D., Bauer, R, & Rozin, P.
Poster session presented at the annual meeting of the American Psychological Association, 2006.

Self-reported vegetarianism may be a marker for college women at risk for disordered eating.

Klopp, S. A., Heiss, C. J., & Smith, H. S.

Journal of the American Dietetic Association, 2003
https://pdfs.semanticscholar.org/4c35/02820abdb307fd8e8056e8437fac35e4cb15.pdf

Although many people follow a vege-tarian diet as part of a healthy lifestyle, the results from this study indicate that the practice of vegetarianism may be a marker for college female students at risk for weight preoccupation and eating disorder tendencies. Clinicians need to be aware of subpopulations at increased risk for eating disorder tendencies to aid in the early detection of those with true eating disorders.

Vegetarianism and eating-disordered thinking.
Lindeman, M., Stark, K., & Latvala, K.
Eating Disorders, 2000

https://www.researchgate.net/publication/233482788_Vegetarianism_and_Eating-Disordered_Thinking

The results indicate that vegetarianism and eating disorders are not independent but rather are intertwined phenomena. The potential common links, for example the possibility that vegetarianism is being used as a smokescreen for more severe eating pathology, are discussed.
(PDF) Vegetarianism and Eating-Disordered Thinking. Available from: https://www.researchgate.net/publication/233482788_Vegetarianism_and_Eating-Disordered_Thinking [accessed Dec 07 2018].

Adolescent vegetarians. A behavioral profile of a school-based population in Minnesota.
Neumark-Sztainer, D., Story, M., Resnick, M., & Blum, R.
Archives of Pediatrics and Adolescent Medicine, 1997
https://www.ncbi.nlm.nih.gov/pubmed/9265888

Vegetarians were almost twice as likely to report frequent dieting (P < .001), 4 times as likely to report intentional vomiting (P < .001), and 8 times as likely to report laxative use (P < .001) than nonvegetarians. Overall, associations with other health-compromising and health-promoting behaviors were not apparent.

Vegetarianism in anorexia nervosa? A review of 116 consecutive cases.
O’Connor, M. A., Touyz, S. W., Dunn, S. M., & Beumont, P. J.
The Medical Journal of Australia, 1987
https://www.researchgate.net/publication/19465975_Vegetarianism_in_anorexia_nervosa_A_review_of_116_consecutive_cases

A retrospective study was carried out of 116 consecutive patients with anorexia nervosa to ascertain the extent and nature of vegetarianism in this population. Sixty-three (54.3%) patients were found to be avoiding red meat. In only four (6.3%) of these did meat avoidance predate the onset of their anorexia nervosa. Of the remaining 59 patients (best termed pseudovegetarians), 25 (42.4%) patients continued to avoid red meat by the end of treatment. Pseudovegetarianism was associated with a longer duration of anorexia nervosa, a lower weight during the course of their illness, and living away from the parental home. The reintroduction of red meat into the diet was more likely if vegetarianism were of a short duration.


 



Adaptations génétiques

Natural selection on HFE in Asian populations contributes to enhanced non-heme iron absorption
Kaixiong Ye et al.
BMC genetics, 2015
https://bmcgenet.biomedcentral.com/articles/10.1186/s12863-015-0223-y

Voir aussi page sur la conversion de l’ALA pour les aspects génétiques liés aux gène FADS.

 

Single nucleotide polymorphisms upstream from the β-carotene 15,15′-monoxygenase gene influence provitamin A conversion efficiency in female volunteers.
Lietz G1, Oxley A, Leung W, Hesketh J.
https://www.ncbi.nlm.nih.gov/pubmed/22113863

β-Carotene, the most abundant provitamin A carotenoid in the diet, is converted to retinal by β-carotene 15,15′-monoxygenase (BCMO1). However, β-carotene absorption and conversion into retinal is extremely variable among individuals, with proportions of low responders to dietary β-carotene as high as 45%. Recently, 2 common nonsynonymous single nucleotide polymorphisms (SNPs) within the BCMO1 coding region (R267S; rs12934922 and A379V; rs7501331) revealed reduced catalytic activity, confirming that genetic variations contribute to the low responder phenotype. Because 4 SNPs 5′ upstream from the BCMO1 gene were recently shown to affect circulating carotenoid concentrations, the current study aimed to investigate the effects of these SNPs on β-carotene conversion efficiency. Three of the 4 polymorphisms (rs6420424, rs11645428, and rs6564851) reduced the catalytic activity of BCMO1 in female volunteers by 59, 51, and 48%, respectively. The TG-rich lipoprotein fraction retinyl palmitate:β-carotene ratio was negatively correlated with the G allele of rs11645428 (r = -0.44; P = 0.018), whereas it was positively correlated with the G allele of rs6420424 (r = 0.53; P = 0.004) and the T allele of rs6564851 (r = 0.41; P = 0.028). Furthermore, large inter-ethnic variations in frequency of affected alleles were detected, with frequencies varying from 43 to 84% (rs6420424), 52 to 100% (rs11645428), and 19 to 67% (rs6564851). In summary, a range of SNPs can influence the effectiveness of using plant-based provitamin A carotenoids to increase vitamin A status in at-risk population groups and this effect may vary depending on ethnic origin.


 


Etudes de cas

 

Recognising the return of nutritional deficiencies: a modern pellagra puzzle
Ng & Neff
British medical journal, 2018
https://www.ncbi.nlm.nih.gov/pubmed/30567139

Dietetic consultation led to the diagnosis of severe protein-energy malnutrition, consequent to a severely restricted, primarily vegan, diet. Analysis of the patient’s reported diet with nutritional software revealed grossly suboptimal caloric intake with risk of inadequacy for most micronutrients, vitamins and minerals, including niacin. Oral thiamine, multivitamin, iron supplementation and vitamin B complex were started, and a single intramuscular vitamin B12 dose was administered. Marked improvement was seen after 6 weeks, with near-complete resolution of skin changes. These findings supported a diagnosis of pellagra.

Veganism as a cause of iodine deficient hypothyroidism.
Yelosof & Silverman
Journal of pediatric endocrinology and metabolism, 2018

https://www.ncbi.nlm.nih.gov/pubmed/29303778?fbclid=IwAR0_e6iPu8zNU3QNJcVEAk1VifriUl432RFs7akL2bY_xb-BfrRMwNP8byk

B12 Deficiency in a Breastfed Infant Due to Maternal B12 Deficiency: A Case Report.
Kamath et al.
Journal of Clinical & Diagnostic Research, 2018
https://web.a.ebscohost.com/abstract?direct=true&profile=ehost&scope=site&authtype=crawler&jrnl=0973709X&AN=128099144&h=MnooFTQzvrwBvRPC9RAfTc9javlCHnbZmtsobuSj1gw1bhLSM6M05ENQggfeaLIleziPIi3VFOU%2fMJunTftufg%3d%3d&crl=c&resultNs=AdminWebAuth&resultLocal=ErrCrlNotAuth&crlhashurl=login.aspx%3fdirect%3dtrue%26profile%3dehost%26scope%3dsite%26authtype%3dcrawler%26jrnl%3d0973709X%26AN%3d128099144

 

Impact of iodine deficiency on thyroid function in vegan siblings
Agnieszka Brandt, Michal Ajzensztejn, Sophia Sakka, Moira Cheung & Tony Hulse, 2018
https://www.endocrine-abstracts.org/ea/0058/ea0058p042

Veganism as a cause of iodine deficient hypothyroidism
Yeliosof O, Silverman LA, 2018
https://www.ncbi.nlm.nih.gov/pubmed/29303778

Toddler’s Paralysis: An Acute Case of Leg Stiffening in a Previously Healthy 2-Year-Old
Kahne, Kimberly Renee, MD; Tay, Ee Tein, MD, 2018
https://journals.lww.com/pec-online/Abstract/2018/06000/Toddler_s_Paralysis__An_Acute_Case_of_Leg.22.aspx?fbclid=IwAR2M661HV2Al024a4SNpnLw9dZw0JvJCJSZehQ0JMO5fNRElw-sxSnyVChQ

We describe a case of a 2-year-old previously healthy child consuming a vegan diet who presented to the pediatric emergency department with an acute inability to move her legs. Ionized calcium was found to be 0.89 mmol/L, and symptoms completely resolved within 2 hours of calcium gluconate infusion.

Acute small bowel obstruction in a child with a strict raw vegan diet
Stefano Amoroso et al., 2018
https://adc.bmj.com/content/early/2018/05/13/archdischild-2018-314910

Unusual cause of glomerular deposition disease: Collagenofibrotic glomerulopathy
S. Nimmagadda
Indian journal of nephrology, 2017
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5255993/

A 63-year-old man, hypertensive for ten years, nondiabetic, a vegan, and with no significant past or family history,

Reticulate pigmentation associated with vitamin B12 deficiency
Amanjot K. Arora et al., 2016
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4886604/

Rare association of thin corpus callosum with infantile tremor syndrome in a 5.5-month-old infant
Chandra Madhur Sharma et al, 2015
[url]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4611903/[/url]

Among various theories, the nutritional theory is the most accepted. Vitamin B12 deficiency has been found to be associated with ITS in many studies.[1] It is usually seen in children who are exclusively breast-fed for prolonged periods by vegetarian mothers.

Neuroregression in an infant: A rare cause
P Subramani, CG Saranya, GM Chand, RS Narayani, S James, PN Vinoth, 2015
https://www.ajol.info/index.php/sajchh/article/view/120204

Neuroregression in infants has diverse aetiologies, and vitamin B12 deficiency is a rare one. Infantile vitamin B12 deficiency is usually secondary to maternal pernicious anaemia or maternal vegetarian diet. We report a 10-month-old infant with developmental regression secondary to vitamin B12 deficiency. Her mother was a strict vegetarian and the patient was exclusively breastfed. Clinical symptoms normalised after vitamin B12 supplementation.

Case Series of Megaloblastic Anemia due to Vitamin B12 Deficiency in Exclusively Breastfed Infants Born to Vegan Mothers in a Rural Area.
Singh, V.; Nigwekar, P.; Dhyabar, A.; Garg, A.; Vaidya, S.; Lonare, N., 2015
http://eds.b.ebscohost.com/abstract?site=eds&scope=site&jrnl=09750533&AN=103581342&h=zDqMwa3ZaL%2bRa6FHp%2fMvVE4p5%2flX8e5wn9FEGQcXvGYnkNEDSTk31iI7nebTyQlMJzWlKCjhagg5EY0xY9ifjQ%3d%3d&crl=c&resultLocal=ErrCrlNoResults&resultNs=Ehost&crlhashurl=login.aspx%3fdirect%3dtrue%26profile%3dehost%26scope%3dsite%26authtype%3dcrawler%26jrnl%3d09750533%26AN%3d103581342

Cerebral Atrophy in a Vitamin B12-deficient Infant of a Vegetarian Mother
Celebi Kocaoglu et al., 2014
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4216972/

Hematological and neurological compromise due to vitamin B12 deficit in infant of a vegetarian mother: case report
PJ Bravo et al., 2014
https://europepmc.org/abstract/med/25697251

Vitamin B12 deficiency with intrinsic factor antibodies in an infant with poor growth and developmental delay
Kathleen McNeil et al., 2014
https://academic.oup.com/pch/article/19/2/84/2647189

A Case of Nutritional Osteomalacia in Young Adult Male
Choong-Kyun Noh et al., 2013
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3780826/?fbclid=IwAR2xC7QucZMiMIebDXfDnTLjxKzdDRniveKN6lTmPLtaXGGuSFsrYdypp7E

Vitamin D is an important hormone that can be a role of bone and calcium metabolism in the human organ. Thus, vitamin D deficiency could contribute to the severity of metabolic bone disease. The osteomalacia, one of the metabolic bone diseases, is the softening of the bones caused by defective bone mineralization secondary to inadequate amounts of available phosphorus and calcium. We experienced a case of osteomalacia presented with walking disturbance, 30 year-old young aged man, caused by vitamin D deficiency due to strict vegetarian diet and lack of sunlight exposures.

Vitamin B12 deficiency presenting as acute ataxia
Crawford JR1, Say D.
BMJ, 2013
https://www.ncbi.nlm.nih.gov/pubmed/23536622

A dietary history revealed the child subscribed to a restrictive vegan diet with little to no intake of animal products or other fortified foods.

Severe vitamin B12 deficiency in an exclusively breastfed 5-month-old Italian infant born to a mother receiving multivitamin supplementation during pregnancy
Sophie Guezet al.
BMC Pediatrics, 2012
https://doi.org/10.1186/1471-2431-12-85

Consequences of exclusive breast-feeding in vegan mother newborn–case report
Mariani et al.
Archives de pédiatrie, 2009
https://europepmc.org/abstract/med/19748244

We report on the case of an infant who was hospitalized because of failure to thrive, megaloblastic anemia, and delayed psychomotor development. He was 10 months old and had been exclusively breast-fed by his vegan mother. Investigations showed vitamin B(12) deficiency with hematocytopenia and pervasive developmental disorders as well as vitamin K and vitamin D deficiencies. The infant’s mother presented the same deficiencies. Introduction of vitamin supplementation normalized the biological disorders, and the infant showed weight gain and neurological improvement. This case highlights that a vegan diet during pregnancy followed by exclusive breast-feeding can induce nutritional deficiencies in the newborn, with clinical consequences. Detecting mother and child vitamin deficiencies and preventing them is essential.

 

Irreversible subacute sclerotic combined degeneration of the spinal cord in a vegan subject
Filippo Brocadello et al., 2007
https://www.sciencedirect.com/science/article/pii/S089990070700175X

Despite rehabilitative treatment, the patient developed spastic hypertonia with mild improvement of paresthesias. Six months later, vitamin B12 plasma levels and hematological analysis were normal. One year later, spastic paraplegia was still present and the patient was unable to walk despite improvement on magnetic resonance imaging.

Floppy baby with macrocytic anemia and vegan mother
Schlapbach LJ et al, 2007
https://www.ncbi.nlm.nih.gov/pubmed/18293883

We report the case of a 7 month-old girl that presented with acute anemia, generalized muscular hypotonia and failure to thrive. Laboratory evaluation revealed cobalamin deficiency, due to a vegan diet of the mother. The clinical triad of an acquired floppy baby syndrome with megaloblastic anemia and failure to thrive is pathognomic for infantile cobalamin deficiency. Neurological abnormalities are often irreversible and may be associated with delayed myelinization in the MRI. A normal cobalamin level in maternal serum and absence of anemia do not exclude subclinical deficiency. If cobalamin deficiency is suspected, e.g. in pregnant women on vegan diet, urinary methylmalonic acid excretion and plasma homocysteine levels should be determined and cobalamin substitution should be started at an early stage to avoid potentially irreversible damage of the fetus.

Severe nutritional vitamin deficiency in a breast-fed infant of a vegan mother
Baatenburg de Jong et al.
European journal of pediatrics, 2005
https://link.springer.com/article/10.1007/s00431-004-1613-8

Failure to thrive combined with severe anaemia can be a sign of nutritional vitamin deficiency. Here, we report a case of severe nutritional vitamin deficiency in a breast-fed infant of a strict vegan mother.

 

 


Coma and respiratory failure in a child with severe vitamin B(12) deficiency
Codazzi D, Sala F, Parini R, Langer M., 2005

The baby had been exclusively breast-fed, but his mother had been a strict vegan for 10 yrs. Chronic dietary vitamin B(12) deprivation was confirmed by blood and urinary samples. Treatment with vitamin B(12) led in 2 wks to rapid and complete hematological improvement and to partial regression of neurologic symptoms. During the following 3 yrs the boy had normal vitamin intake and underwent intensive rehabilitative treatment. The brain atrophy regressed, but linguistic and psychomotor delay persisted.

Breastfeeding and vegan diet
Wagnon et al.
Journal de gynécologie, obstétrique et biologie de la reproduction, 2005
https://europepmc.org/abstract/med/16208206

 

Vegan diet in lactating women can induce vitamin B12 deficiency for their children with risk of an impaired neurological development. A 9.5-month-old girl presented with impaired growth and severe hypotonia. She had a macrocytic anemia secondary to vitamin B12 deficiency. MRI showed cerebral atrophy. She was exclusively breastfed. Her mother was also vitamin B12 deficient, secondary to a vegan diet. She had a macrocytic anemia when discharged from the maternity. Vegan diet is a totally inadequate regimen for pregnant and lactating women, especially for their children. Prevention is based on screening, information and vitamin supplementation.

 

Reversible Subacute Combined Degeneration of the Spinal Cord in a 14-Year-Old Due to a Strict Vegan Diet

Anémie et boiterie chez un adolescent végétalien / Anemia and lameness in a vegan adolescent

Anemia and limping in a vegetarian adolescent
Chiron, R et al.
Archives de pédiatrie, 2001
https://europepmc.org/abstract/med/11218586

A 15-year-old adolescent was hospitalized because of lameness and pallor. The lameness was explained by femoral epiphysiolysis caused by rickets with severe hypocalcemia. The pallor, jaundice and splenomegalia were due to cobalamin-deficiency megaloblastic anemia. A prolonged supplemental diet with calcium, vitamins D and B12 as well as orthopedic treatment stabilized the bone lesions. The megaloblastic anemia was cured by parenteral cobalamin. The adolescent and his brother were victims of a diet imposed by a cult and a lack of care due to their parents refusing that a vegan diet was the cause of the deficient pathology. Penal proceedings led to the incarceration of the parents and to the placement of the children.

Blindness in a strict vegan
Dan Milea et al.
The new england journal of medicine, 2000
https://www.nejm.org/doi/full/10.1056/NEJM200003233421217

The optic neuropathy in our patient was apparently related to deficiencies of vitamins B12 and B1, but other associated deficiencies mtaiway have had a role. Vitamin supplementation is essential in persons who adhere to a strict vegetarian diet, especially because vitamin deficiencies may cause severe, irreversible optic neuropathy.

Maternal vegan diet causing a serious infantile neurological disorder due to vitamin B12 deficiency
T. Kühne, R. Bubl, R. Baumgartner, 1991
https://link.springer.com/article/10.1007/BF01963568

Nutritional Vitamin B12 Deficiency in a Breast-fed Infant of a Vegan-diet Mother
Ronald Sklar.
Clinical pediatrics, 1986
https://journals.sagepub.com/doi/abs/10.1177/000992288602500409?casa_token=gCaZbK0e1UgAAAAA:cNiicQObveO_xJYcpIGu87Dc0KSsRSSE3872odpAo8fb8Kdsx03V8srkn3C6nys4_O7gDywsaGv1

 

Subtle Cobalamin Malabsorption in a Vegan PatientEvolution Into Classic Pernicious Anemia With Anti-intrinsic Factor Antibody
Ralph Carmel
Journal of internal medicine, 1982
https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/602617

 

Megaloblastic Anemia in an Adult Vegan
John D. Hines.
The american journal of clinical nutrition , 1966
https://academic.oup.com/ajcn/article-abstract/19/4/260/4787636


 


 

Risques liés aux supplémentations

Des cas d’allergies ou de problèmes cutanés liés à certaines supplémentations en vitamine B12 sont rapportés. Difficile d’évaluer leur fréquence.

P484 Cobalt as the culprit: vitamin B12 supplementation as a trigger for chronic pruritis
S. Vakaljan, J. Ohayon
Annals of allergy, asthma and immunology, 2017
https://www.annallergy.org/article/S1081-1206(17)31045-1/pdf?fbclid=IwAR0go61fhvaXXW6oZ6sAq8EyNqLXqdoQ2-m5aKYt6T28k1WbgVX171dMi0o

Cobalt-Induced Contact Urticaria Presenting as Chronic Urticaria Due to Intramuscular Vitamin B12 Injections

Jordan Huber et al.
Dermatitis, 2016
https://journals.lww.com/dermatitis/Citation/2016/09000/Cobalt_Induced_Contact_Urticaria_Presenting_as.13.aspx

VItamin B12 supplementation has been reported to cause a variety of cutaneous reactions ranging from urticaria to anaphylaxis

A Review of Vitamin B12 in Dermatology
Jennifer Brescoll, Steven Daveluy
American journal of clinical dermatology, 2015
https://link.springer.com/article/10.1007/s40257-014-0107-3

several dermatologic conditions, including vitiligo, aphthous stomatitis, atopic dermatitis, and acne are related to cobalamin excess or deficiency. The cutaneous complications of cobalamin therapy include acne, rosacea, and allergic site reactions, or anaphylaxis with cobalamin injections. As cobalt is a component of cobalamin, patients with cobalt sensitivity have been reported to have cutaneous manifestations when receiving cobalamin replacement therapy.

 

 

 


Soja

Parmi les aliments retrouvés de manière importante dans les alimentations végétales, le soja a été soupçonné de pouvoir induire des perturbations hormonales. Si peu des risques supposés semblent être supportés par des études, il en existe tout de même quelques-unes liant notamment un allaitement avec des formules à base de soja et des troubles à l’âge adulte. Une question de dose ?

Soy-based infant formula feeding and menstrual pain in a cohort of women aged 23–35 years
Kristen Upson et al.
Human reproduction, 2018
https://academic.oup.com/humrep/advance-article/doi/10.1093/humrep/dey303/5146638

Women ever fed soy formula as infants were more likely than unexposed women to report ever use of hormonal contraception for menstrual pain (RR 1.4, CI: 1.1–1.9) and moderate/severe menstrual discomfort/pain with ‘most periods’, but not ‘every period’, during early adulthood (ages 18–22 when not using hormonal contraception) (RR 1.5, CI: 1.1–2.0).

Soy-based infant formula feeding and ultrasound-detected uterine fibroids among young african-american women with no prior clinical diagnosis of fibroids
Kristen Upson et al.
Environmental health perspective, 2018
https://ehp.niehs.nih.gov/doi/abs/10.1289/ehp.1510082

Results:

We did not observe an association between soy formula feeding and fibroid prevalence [adjusted prevalence ratio (aPR) 0.9, 95% CI: 0.7, 1.3]. Nor were exposed women with fibroids more likely to have ≥ 2 tumors than unexposed women with fibroids (aPR 1.0, 95% CI: 0.7, 1.6). However, exposed women with fibroids had significantly larger fibroids than unexposed women with fibroids. On average, soy formula feeding was associated with a 32% increase in the diameter of the largest fibroid (95% CI: 6%, 65%) and a 127% increase in total tumor volume (95% CI: 12%, 358%).

Conclusions:

Our observation that women fed soy formula as infants have larger fibroids than unexposed women provides further support for persistent effects of early life phytoestrogen exposure on the uterus.

The effects of dietary levels of genistein on ovarian follicle number and gene expression
Payel Kundu et al.
Reproductive toxicology, 2018

The present study investigated the effects of adult genistein exposure on follicle number and gene expression in the ovaries of CD-1 mice. We found that exposure to genistein had no effect on follicle number, but it did affect the expression of apoptotic regulatory genes (Bax, Bcl-2, Bid, and Dffa) in the ovary.

Soy-based infant formula feeding and heavy menstrual bleeding among young African American women
Kristen Upson et al.
Epidemiology, 2016.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5425950/

We observed associations between soy formula feeding and variables indicating a history of heavy menstrual bleeding, including ever experiencing heavy, gushing-type bleeding (RR 1.2, 95% CI: 1.0-1.4), ever use of non-steroidal anti-inflammatory drugs for heavy bleeding (RR 1.3, 95% CI: 1.0-1.6), and ever use of a contraceptive method for heavy bleeding (RR 1.2, 95% CI: 0.9-1.6).

Early-life factors and endometriosis risk
Kristen Upson et al.
Fertility and sterility, volume 101, Issue 4, 2015
https://www.sciencedirect.com/science/article/pii/S0015028215004690

We observed that women who were regularly fed soy formula as infants had more than twice the risk of endometriosis compared with unexposed women (aOR 2.4, 95% CI 1.2–4.9). Our data also suggested increased endometriosis risk with prematurity (aOR 1.7, 95% CI 0.9–3.1) and maternal use of DES (OR 2.0, 95% CI 0.8–4.9, adjusting only for frequency matching variables), although these confidence intervals included the null.

Un doute sur cette étude publiée dans une revue open acces. Serait à évaluer.

Soy Infant Formula may be Associated with Autistic Behaviors
Cara J. Westmark; 2013
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4229689/?fbclid=IwAR0Eoc0JK63SK7Y0k8lS5RAworClb6K3drxUZQKCE-urnOkf55McEs_dDX0

This study provides preliminary data that the use of soy-based infant formula may be associated with specific autistic behaviors.

From one womb to another : early estrogenic exposures and later fibroid risk
M. Nathaniel Mead
Environmental health perspective, 2010
https://ehp.niehs.nih.gov/doi/full/10.1289/ehp.118-a131a

The authors report a 25% increase in early fibroid diagnoses for women who had been fed soy formula compared with those who had not. Although the authors postulated the first 2 months of life may include a period more sensitive to isoflavone exposure, they were unable to demonstrate an association with soy formula intake during this time period specifically.

Soy infant formula and phytoestrogens
PG Tuohy
Journal of paediatrics and child health, 2003
https://onlinelibrary.wiley.com/doi/abs/10.1046/j.1440-1754.2003.00178.x

Against this generally positive view there is an increasing number of recent reports that suggest that in experimental animals, phytoestrogens have adverse effects with respect to carcinogenesis, reproductive function, immune function, and thyroid disease. Despite the absence of adequate scientific research that quantifies the level of risk to infants, most would argue for a precautionary approach to be taken in situations where there are potential developmental effects from the consumption of pharmacologically active compounds in infancy and childhood.

Soy Diets Containing Varying Amounts of Genistein Stimulate Growth of Estrogen-dependent (MCF-7) Tumors in a Dose-dependent Manner
Clinton D. Allred, Kimberly F. Allred, Young H. Ju, Suzanne M. Virant and William G. Helferich
Cancer research, 2001.
http://cancerres.aacrjournals.org/content/61/13/5045.short

Soy protein diets containing varying amounts of genistein increased estrogen-dependent tumor growth in a dose-dependent manner. Cell proliferation was greatest in tumors of animals given estrogen or dietary genistein (150 and 300 ppm). Expression of pS2 was increased in tumors from animals consuming dietary genistein (150 and 300 ppm). Here we present new information that soy protein isolates containing increasing concentrations of genistein stimulate the growth of estrogen-dependent breast cancer cells in vivo in a dose-dependent manner.



 

Avis divers

Plusieurs agences et association ont émis des avis favorables aux alimentations végétariennes et végétaliennes bien planifiées, précisant parfois « à tous les âges de la vie » (une liste ici). Certains avis sont cependant plus prudents, notamment en ce qui concerne l’adoption de tels types d’alimentation pour les enfants.

La COFA  (Commission Fédérale de l’Alimentation (Suisse)), remarque qu’entre la théorie des tables nutritionnelles et la réalité du terrain, il y a de sérieuses différences, et ne conseille un régime végétalien qu’à des personnes hautement motivées.

Régimes végétaliens: analyse des avantages et des inconvénients sur le plan nutritionnel et pour la santé (2018)
https://www.eek.admin.ch/eek/fr/home/pub/dieteveganeavantagesetinconvenients.html

Un régime végétalien bien planifié et supplémenté pourrait en théorie couvrir les besoins nutritionnels, mais les résultats montrent qu’en réalité, les carences sont fréquentes pour certains nutriments. Si des sujets hautement motivés veulent adopter ou conserver un régime végétalien, ils devraient être informés des directives alimentaires, des besoins en supplémentation et des précautions de suivi possibles.

[Vegetarian Diets in Children? – An Assessment from Pediatrics and Nutrition Science]
Kersting et al, 2018
https://europepmc.org/abstract/med/29471576

 

Vegetarian diets as the lacto-ovo-vegetarian diet (exclusion of meat, fish) and the vegan diet (exclusion of all food groups of animal origin) need to be evaluated for their potential to safely meet the high and specific requirements for growth and development. In this regard, high-quality studies are needed. In individuals on lacto-ovo-vegetarian diets, the safe supply with critical nutrients should be checked by thorough dietary history, possibly additional laboratory tests in risk situations like pregnancy, infancy and toddlerhood. Children on pure vegan diet need ongoing elaborate dietary strategies and continuous supplementation at any age, similar to nutritional management in children with metabolic disorders. A vegan diet is disadvised during all periods with intense growth and development.

Is vegetarianism healthy for children?
Nathan Cofnas.
Critical review of food science and nutrition, 2018.
https://www.tandfonline.com/doi/full/10.1080/10408398.2018.1437024

The present paper argues that the Academy of Nutrition and Dietetics ignores or gives short shrift to direct and indirect evidence that vegetarianism may be associated with serious risks for brain and body development in fetuses and children. Regular supplementation with iron, zinc, and B12 will not mitigate all of these risks. Consequently, we cannot say decisively that vegetarianism or veganism is safe for children.


Cette publication souligne l’hétérogénéité des échantillons, les biais en faveur des classes supérieures, la rareté des études récentes… et conclut que l’on ne peut pas tirer de conclusions solides sur les risques ou bénéfices d’une alimentation de type végétarienne pour les enfants et les adolescents.

Vegetarian diets in children: a systematic review
Schürmann S, Kersting M, Alexy U, 2017
https://www.ncbi.nlm.nih.gov/pubmed/28299420

Due to the study heterogeneity, the small samples, the bias towards upper social classes, and the scarcity of recent studies, the existing data do not allow us to draw firm conclusions on health benefits or risks of present-day vegetarian type diets on the nutritional or health status of children and adolescents in industrialized countries.

Complementary Feeding: A Position Paper by the European Society for Paediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN) Committee on
Nutrition
Mary Fewtrell et al., 2017
https://journals.lww.com/jpgn/fulltext/2017/01000/Complementary_Feeding___A_Position_Paper_by_the.21.aspx

Although theoretically a vegan diet can meet nutrient requirements when mother and infant follow medical and dietary advice regarding supplementation, the risks of failing to follow advice are severe, including irreversible cognitive damage from vitamin B12 deficiency, and death. If a parent chooses to wean an infant onto a vegan diet this should be done under regular medical and expert dietetic supervision and mothers should receive and follow nutritional advice (115). Mothers who are consuming a vegan diet need to ensure an adequate nutrient supply, especially of vitamins B12, B2, A, and D, during pregnancy and lactation either from fortified foods or supplements. Careful attention is required to provide the infant with sufficient vitamin B12 (0.4mg/day from birth, 0.5mg/day from 6 months) and vitamin D, and iron, zinc, folate, n-3 fatty acids (especially DHA), protein, and calcium, and to ensure adequate energy density of the diet.

La société allemande de nutrition considère qu’avec une alimentation purement végétale, il est difficile ou impossible de parvenir à un apport adéquat en certains nutriments. Elle ne recommande pas une alimentation végétalienne aux femmes enceintes, femmes allaitantes, nourrissons, enfants et adolescents. Elle recommande à ceux qui voudraient le faire supplémentation et suivi nutritionnel régulier.

Vegan Diet
Position of the German Nutrition Society (DGE)
Margrit Richter et al., 2016
https://www.ernaehrungs-umschau.de/fileadmin/Ernaehrungs-Umschau/pdfs/pdf_2016/04_16/EU04_2016_Special_DGE_eng_final.pdf

On the basis of current scientific literature, the German Nutrition Society (DGE) has developed a position on the vegan diet. With a pure plant-based diet, it is difficult or impossible to attain an adequate supply of some nutrients. The most critical nutrient is vitamin B12. Other potentially critical nutrients in a vegan diet include protein resp. indispensable amino acids, long-chain n-3 fatty acids, other vitamins (riboflavin, vitamin D) and minerals (calcium, iron, iodine, zinc and selenium). The DGE does not recommend a vegan diet for pregnant women, lactating women, infants, children or adolescents. Persons who nevertheless wish to follow a vegan diet should permanently take a vitamin B12 supplement, pay attention to an adequate intake of nutrients, especially critical nutrients, and possibly use fortified foods or dietary supplements. They should receive advice from a nutrition counsellor and their supply of critical nutrients should be regularly checked by a physician.

Ici on souligne le manque d’études randomisées (voir une liste de biais possibles des études non-randomisées plus bas dans la page). La conclusion n’est pas très claire, soulignant encore une fois ces faiblesses mais supposant que le végéta*isme est acceptable s’il n’est pas contraint financièrement.

Vegan–vegetarian diets in pregnancy: danger or panacea? A systematic narrative review
GB Piccoli et al.
BJOG, 2015
https://obgyn.onlinelibrary.wiley.com/doi/full/10.1111/1471-0528.13280

The evidence on vegan–vegetarian diets in pregnancy is heterogeneous and scant. The lack of randomised studies prevents us from distinguishing the effects of diet from confounding factors. Within these limits, vegan–vegetarian diets may be considered safe in pregnancy, provided that attention is paid to vitamin and trace element requirements.[…]
Considering only those who choose vegan–vegetarian diets without financial constraints, and within the limits of highly heterogeneous, often low‐quality or old information (when the reporting and research standards were remarkably different), the available data support the safety of vegan–vegetarian diets in pregnancy, provided attention is paid to compensating for the nutritional deficiencies (mainly of vitamin B12 and iron).

Is a vegetarian diet safe to follow during pregnancy? A systematic review and meta-analysis of observational studies
Tan et al.
Critical studies in food science and nutrition, 2019
https://www.tandfonline.com/doi/abs/10.1080/10408398.2018.1461062

 

The overall estimated relation between vegetarian pregnancy and low birth weight (LBW) was marginally significant (1.27 (0.98, 1.65), P = 0.07, I2=0%). Asian (India/Nepal) vegetarian mothers exhibited increased risks to deliver a baby with LBW (1.33 (1.01, 1.76), P = 0.04, I2=0%). However, the WMD of neonatal birth weight in five studies suggested no difference between vegetarians and omnivores. Given the high heterogeneity of the included studies, lack of high-quality evidence, and limited studies included for each category, we failed to reach conclusive results regarding the risks of hypospadias, intrauterine growth retardation, maternal anemia, and gestational diabetes mellitus.



Biais possibles des études de nutrition en général et des études sur les végétariens et les végans en particulier

 

Biais d’échantillonnage

Étant donné qu’une part importante de végétariens et végans abandonnent assez rapidement leur régime pour redevenir omnivores (suggéré : 80 à 85%, études à retrouver), on peut craindre un fort biais du survivant (seules les personnes à qui cette alimentation convient bien sont prises en compte par les études, qui ne sont généralement pas randomisées).

Une étude allemande récente relève des durées d’adhésion à une alimentation végétalienne très courtes. Environ 88% sont végans depuis moins de 5 an :

Vegan diet : motives, approach and duration. Initial results of a quantitative sociological study
Pamela Kerschke-Risch
kerschke-risc 2015 abandon d'une alimentation végane

Une étude du Human Research Council rapportée par Psychology Today trouve un chiffre très proche de 84% d’abandons pour les régimes végétariens. 29% d’entre eux invoquant des raisons de santé, 43% la difficulté d’avoir une alimentation « pure ».

Un autre biais d’échantillon est lié au fait que les femmes sont nettement plus nombreuses à être végétariennes ou végétaliennes que les hommes.

Biais de déclaration

On peut avoir des doutes aussi sur la réalité du régime déclaré, et les végans ne sont pas toujours évalués spécifiquement. Par exemple, dans cet article de la série EPIC, on apprend qu’on ne distingue pas végans et végétariens, et que 23% des « végétariens » consomment soit occasionnellement de la viande, soit éventuellement plus régulièrement du poisson.

The Oxford Vegetarian Study: an overview
Paul N Appleby, Margaret Thorogood, Jim I Mann, and Timothy JA Key, 1999
http://ajcn.nutrition.org/content/70/3/525s.full.pdf

Mortality in the Oxford Vegetarian Study was first studied after an average of 12 y of follow-up (10). Subjects were divided into meat eaters (who ate meat at least once a week) and non-meat-eaters (all others). Most of the non-meat-eaters were vegetarian or vegan, although 23% of the non-meat-eaters ate meat occasionally but less than once a week, or ate fish, or both.

Dans cette étude de 2018, on apprend c’est cette fois plus de la moitié des personnes se déclarant végétariennes qui consomment en réalité du poisson maigre et du poisson gras (on pense aussi à Novak Djokovic qui se déclarait végan en 2016 mais disait aussi consommer du poisson gras quotidiennement).

Vegetarian diets and depressive symptoms among men
JR Hibbeln, K Northstone, J Evans, J Golding – Journal of affective …, 2018 – Elsevier
https://www.sciencedirect.com/science/article/pii/S0165032716323916

Vegetariens qui mangent du poisson et de la viande, Hibbeln, 2018

Ici, ce sont les 3/4 des personnes qui déclarent consommer moins de viande, qui en fait en consomment toujours autant :

Current Attitudes and Future Influence on Meat Consumption in the U.K.
Richardson et al.
Appetite, 1993
https://www.sciencedirect.com/science/article/pii/S0195666383710354

En 2002, un sondage Time/CNN mené par téléphone auprès de 10 000 américains a recensé 6% de personnes déclarées comme végétariennes. Ces personnes ont été rappelées une semaine plus tard avec une question différente, leur demandant de déclarer ce qu’ils avaient mangé dans les 24 heures précédentes. 60% des végétariens ont alors déclaré avoir mangé de la chair animale durant ces 24 heures.

Une étude scientifique trouvait à peu près les mêmes résultats en 2003, à savoir que seuls un tiers des jeunes se définissant comme végétariens ne mangeaient en réalité pas de chair animale :

What do vegetarians in the United States eat?
Ella h. Haddad, Jay S. Tanzmann.
The american journal of clinical nutrition, 2003
https://academic.oup.com/ajcn/article/78/3/626S/4690004

Also, only about one-third of self-defined vegetarians in the CSFII reported no meat, poultry, or fish on recall days.

Self defined vegetarians Addad 2003

Food Intake Patterns of Self-identified Vegetarians among the U.S. Population, 2007-2010
WenYen Juan et al.
Procedia food science, 2015
https://core.ac.uk/download/pdf/82713837.pdf

Compared to non-vegetarians, vegetarians consumed significantly fewer calories (1862 kcal vs. 2058 kcal; p<0.05) with the same number of food items (n=16) per day, and they consumed significantly less meat, poultry, solid fats and added sugars, and more soy, legumes, and whole grains than non-vegetarians. Both groups consumed about the same amounts of eggs, dairy, seafood, fruits, and vegetables. After energy adjustment, vegetarians consumed significantly more fruits, vegetables, whole grains, and total grains than non-vegetarians per 1000 kcal. Although a large proportion of self-identified vegetarians report consuming some type of animal products, such as meat, poultry and/or seafood, their dietary patterns contain more plant-based foods and whole grains with less solid fats and added sugars. Caution is needed in interpreting the term “vegetarian” from self-reports.

Self defined vegetarians Juan 2015

 

Comparison of Sociodemographic and NutritionalCharacteristics between Self-Reported Vegetarians,Vegans, and Meat-Eaters from the NutriNet-Santé Study
Benjamin Allès et al.
Nutrients, 2017
https://hal.archives-ouvertes.fr/hal-01592223/document

Self defined vegetarians Alles 2017 Nutrinet

 

Certaines publications ironisent carrément sur la difficulté de trouver de véritables végétariens dans les études de nutrition :

Will the real vegetarian please stand up? An investigation of dietary restraintand eating disorder symptoms in vegetarians versus non-vegetarians
C. Alix Timko et al.
Appetite, 2012
https://foodethics.univie.ac.at/fileadmin/user_upload/p_foodethik/Timko__C.__2012._Will_the_real_vegetarian_please_stand_up.pdf

’ In the majority of studies investigating meatrestriction, vegetarianism is defined as eliminating red meat;however, this does not reflect a true vegetarian diet (which wouldalso eliminate all fish and poultry) but rather what is moreaccurately described as asemi-vegetarian diet (Gilbody et al.,1999; Kadambari et al., 1986; Klopp et al., 2003; O’Connor et al.,1987; Trautman et al., 2008; Worsley & Skrzypiec, 1998). Fewstudies have looked at true vegetarianism or even veganism, withthe largest published true vegetarian sample consisting of twentyindividuals (Curtis & Comer, 2006), and the largest vegan sampleof a mere eight participants (Janelle & Barr, 1995). In most studiesvegetarians and semi-vegetarians are combined in the ‘‘vegetarian’’group due to low sample sizes (e.g.,Fisak et al., 2006). Thus, themajority of research reports that find differences between‘‘vegetarians’’ and non-vegetarians use a mixed sample of semi-vegetarians and true vegetarians.

 

Il est en réalité très difficile d’évaluer le nombre de véritables végans, possiblement nettement inférieur à celui des végans déclarés. Une autre étude suggère qu’ils n’étaient en 2005 que 0,1% de la population aux Etats-Unis, mais l’étude ne porte pas spécifiquement sur ce dénombrement.

Our findings indicate that strict vegetarians and vegans, who comprise probably less than 0.1% of the US population, have higher education, higher incomes, and healthier lifestyles than the general population.

Très souvent, les études sont sur de très petits échantillons, surtout pour les végétaliens. Cet aspect, ajouté au problème sus-cité du biais du survivant rend très difficile toute généralisation de résultats obtenus.

On trouve aussi parfois des extrapolations abusives. Ainsi, des études ayant montré un bénéfice à consommer plus de végétaux, ou plus de protéines végétales pour des personnes mangeant au départ beaucoup de viande, sont extrapolées à « ces études ont montré qu’il faut être végétarien ou végan ».
Une autre extrapolation abusive est sur la durée. Des études portant sur des personnes végétariennes ou végétaliennes depuis quelques années, ayant eu une alimentation omnivore une nette majorité de leur vie, sont extrapolées à « on peut être ou il est favorable d’être végétarien ou végétalien toute sa vie ».
Une autre extrapolation fréquente porte sur les dangers de la viande transformée ou de la viande rouge, souvent généralisés à l’ensemble de la viande, voire des produits animaux.

L’étude de Dinu de 2016, parfois citée par des sites végétariens, a été contestée pour ses nombreux biais :

Plant-based diets do not prevent most chronic diseases
Tanis Fenton & Chelsia Gillis
Critical Reviews in Food Science and Nutrition, 2017
https://www.tandfonline.com/doi/pdf/10.1080/10408398.2017.1389692
We are concerned about the selective reporting, over-stated cause-and-effect statements and lack of mentioning the 10 results of no associations between vegetarian and vegan diets and chronic diseases in the recent paper (Dinu et al. 2017).

Autres biais possible : les végétariens consomment moins d’aliments raffinés, de junk food, sont plus attentifs à leur santé en général, sont d’un niveau social plus élevé, et ont un QI plus élevé à l’origine. Tous éléments généralement corrélés à une meilleure santé, une moindre mortalité, une meilleure espérance de vie. « Effet cigogne » possible.

Higher Cognitive Performance Is Prospectively Associated with Healthy Dietary Choices: The Maine Syracuse Longitudinal Study.
G.E. Crichton et al.
The Journal  of Prevention of Alzheimer’s Disease, mars 2015.
https://digitalcommons.library.umaine.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpsredir=1&article=1029&context=longitudinal_papers

Higher WAIS Scores at baseline were prospectively associated with higher intakes
of vegetables, meats, nuts and legumes, and fish, but inversely associated with consumption of total grains and carbonated soft drinks.

Cet article souligne la faiblesse gérérale des associations en épidémiologie de la nutrition.

Research gaps in evaluating the relationship of meat and health.
DM Klurfeld
Meat science, 2015

The observational studies are heterogeneous and do not fulfill many of the points proposed by AB Hill in 1965 for inferring causality; his most important factor was strength of the association which in dietary studies is usually <1.5 but is not considered adequate in virtually all other areas of epidemiology outside nutrition. Accepting small, statistically significant risks as « real » from observational associations, the field of nutrition has a long list of failures including beta-carotene and lung cancer, low-fat diets and breast cancer or heart disease that have not been confirmed in randomized trials.

 

Des études sont parfois citées par des sites végétariens, présentées explicitement comme favorables au végétarisme, ou parmi des études favorables au végétarisme, alors qu’elles ne parlent pas de cela.

 

L’étude de Harvard sur 130 000 professionnels de santé est souvent citée à l’appui de l’argumentaire végétarien. Pourtant, elle ne parle pas de cela. Elle conclut seulement que remplacer des protéines animales par des protéines végétales à hauteur de 3% de l’apport calorique a un effet bénéfique, et les personnes consommant le moins de viande on moins de risques seulement chez les personnes ayant des facteurs de risque par ailleurs. L’étude insiste aussi sur la qualité des sources animales, différenciant clairement viande transformée, viande rouge, viandes blanches et poisson.
Association of animal and plant protein intake with all-cause and cause-specific mortality
Mingyang Song et al.
JAMA internal medecine, 2016
https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2540540
L’étude Farm, porte sur une communauté très particulière, qui prend pas mal de compléments alimentaires (Vitamine B12, A et D, plus d’autres vitamines et minéraux, dit la publi), qui est d’un excellent niveau de compétence nutritionnelle, qui produit elle-même une part de sa nourriture. L’étude n’investigue rien d’autre que la taille et le poids des enfants, ne fait aucune recherche supplémentaire. Elle trouve une taille et un poids un peu inférieurs à la normale, mais sans que ce soit significatif.
Une telle étude ne peut en aucun cas être extrapolée aux personnes ne se complémentant qu’en B12, à la population générale moins compétente en nutrition, aux personnes consommant une nourriture industrielle. Elle ne conclut par ailleurs rien sur d’éventuels autres aspects que le poids et la taille, et ne peut en aucun cas conclure à une absence de problèmes sanitaires des enfants étudiés, puisqu’elle ne les investigue pas.
Farm Study

Cherry-Picking

Les études portant sur le végétarisme sont parfois positives, et parfois négatives. Dans de nombreux avis favorables aux végéta*ismes, les études négatives, comme celles citées sur cette page, sont purement et simplement oubliées.

Is There a Lack of Support for Whole-Food, Plant-Based Diets in the Medical Community?
Maximilian Andreas Storz, MD
The permanente journal, 2019
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6307547/

Threads de Frédéric Leroy (@fleroy1974) avec notamment beaucoup d’études de cas :
https://twitter.com/fleroy1974/status/1036366992654184453
Sur les biais et l’idée que la viande soit dangereuse :
https://twitter.com/fleroy1974/status/1037456501596725249