Végétarisme

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.

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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]).

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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.

Squelette

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.

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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.

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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).

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The influence of vegan diet on bone mineral density and biochemical bone turnover markers.
Jadwiga Ambroszkiewicz et al.
Pediatric Endocrinology, Diabetes and Metabolism 2010

Cliquer pour accéder à 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.

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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.

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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.

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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.

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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 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.

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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).

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.

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].

Etudes de cas

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

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

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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.

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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

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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,

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

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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.

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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.

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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

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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/

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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

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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

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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.

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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.

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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

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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.

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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.

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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.

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Anémie et boiterie chez un adolescent végétalien / Anemia and lameness in a vegan adolescent
R Chiron et al., 2001
https://www.sciencedirect.com/science/article/pii/S0929693X00001688

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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.

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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

Soja

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).

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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.

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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.

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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).

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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.

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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.

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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.

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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.

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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.

Adaptations génétiques

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.

Divers

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.

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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.

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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.

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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.

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Oral implication of the vegan diet : observational study
L. Laffranchi et al., 2010

Cliquer pour accéder à 0c96051b484ae6396f000000.pdf

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

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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

Avis divers

COFA : Comission Fédérale de l’Alimentation (Suisse)

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.

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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.

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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.

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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.

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Vegan Diet
Position of the German Nutrition Society (DGE)
Margrit Richter et al., 2016

Cliquer pour accéder à 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.

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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).

Possibilités de biais

(à compléter et étayer)

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).

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

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

Cliquer pour accéder à 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.

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.

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.

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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 :

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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.

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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.

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.