Vegan diet in young children remodels metabolism and challenges the statuses of essential nutrients
Authors: Liisa Korkalo
Pirjo Isohanni
Topi Hovinen
Essi Skaffari
Riitta Freese
Helena Gylling
Mikko Niemi
Nicola Zamboni
Jaakko Nevalainen
Maijaliisa Erkkola
Anu Suomalainen
Journal: EMBO Molecular Medicine (2021)
Discipline: CLINICAL MEDICINE
Keywords: development; metabolism; nutrition; vegan; vitamin.
Affiliations: Research Programs Unit, Stem Cells and Metabolism, University of Helsinki, Helsinki, Finland., Department of Food and Nutrition, University of Helsinki, Helsinki, Finland., Department of Pediatric Neurology, Children's Hospital, University of Helsinki and Helsinki University Hospital, Helsinki, Finland., Individualized Drug Therapy Research Program, University of Helsinki, Helsinki, Finland., HUSLAB, Helsinki University Hospital, Helsinki, Finland., Health Sciences, Faculty of Social Sciences, Tampere University, Tampere, Finland., Department of Medicine, Division of Internal Medicine, University of Helsinki, Helsinki, Finland., Institute of Molecular Systems Biology, ETH Z√ºrich, Z√ºrich, Switzerland., Neuroscience Center, HiLife, University of Helsinki, Helsinki, Finland.

Abstract:  Vegan diets are gaining popularity, also in families with young children. However, the effects of strict plant-based diets on metabolism and micronutrient status of children are unknown. We recruited 40 Finnish children with a median age 3.5 years-vegans, vegetarians, or omnivores from same daycare centers-for a cross-sectional study. They enjoyed nutritionist-planned vegan or omnivore meals in daycare, and the full diets were analyzed with questionnaires and food records. Detailed analysis of serum metabolomics and biomarkers indicated vitamin A insufficiency and border-line sufficient vitamin D in all vegan participants. Their serum total, HDL and LDL cholesterol, essential amino acid, and docosahexaenoic n-3 fatty acid (DHA) levels were markedly low and primary bile acid biosynthesis, and phospholipid balance was distinct from omnivores. Possible combination of low vitamin A and DHA status raise concern for their visual health. Our evidence indicates that (i) vitamin A and D status of vegan children requires special attention; (ii) dietary recommendations for children cannot be extrapolated from adult vegan studies; and (iii) longitudinal studies on infant-onset vegan diets are warranted. 

Retracted: No

PubPeer comments:
 **Can we draw conclusions from a study with a sample of six vegan children?** EMBO Molecular Medicine published a Finnish study about the nutritional status and metabolism of six vegan children (Hovinen et al. 2021). The tiny number of vegans raises a question, can we make some conclusions about this study? If so, conclusions should be made with caution. The lower levels of vitamin D and vitamin A in vegan children was one finding in this study. But how much does a vegan diet really challenge the intake of these essential nutrients? The intake of both vitamins A and D in vegan children was adequate and in line with the recommendations. In fact the average vitamin D intake of vegan children was almost twice (18.2 u00b5g day) as much as the Finnish recommendation, 10 u00b5g day for children. Omnivore peers received exactly the same amount of vitamin D from their diet. One of the shortcomings of the study was the missing information whether the vitamin D supplement received by vegan children was D2 or D3. At the time of the measurement, in July-October 2017, and slightly before, there was a transition from D2 supplements to vegan D3 supplements in Finland. Vitamin D levels in vegan children varied from 53 to 67 nmol l. According to Finnish nutrition recommendations 50 nmol l is considered sufficient. None of the vegan children were below this border. Absent prevalence of vitamin D deficiency is rare in Europe (Lips et al. 2019). Deficiency has been varied from one percentage in toddlers to 19,5 % in older children in Finland (Rosendahl J et al 2018, Soininen et al. 2016). RBP (Retinol binding protein) was used as a measure of vitamin A status in this study. According to RBP all vegan children had vitamin A levels below the limit considered adequate. However, as authors note, RBP is considered reliable in group level analysis and its assessment on individual level has some pitfalls. One of the three referees of this study pointed out, that the RBP is not sufficient to evaluate whether the children were insufficient or deficient in vitamin A. The referee also argues why serum retinol concentrations were not evaluated or reported, which is the standard method for evaluating vitamin A deficiency in children. However, vitamin A status was also measured by calculating RBP, transthyretin, and CRP. The vitamin A status showed no deficiency in any of the vegan children. The intake of essential fatty acids from food was higher in vegan children, but DHA levels were lower, a result consistent with previous vegan studies (Elorinne et al. 2016, Sarter et al. 2015, Sanders 2014, Rosell et al. 2005.) However, the clinical significance of the observed differences in DHA levels remains unclear. Although vegans have lower DHA levels, no adverse effects on vision, cognition or health have been observed. **Growth was normal** The vegan children grew normally and their weight and height did not differ from the other children studied. There was no difference in energy intake between the groups. The protein intake of vegan children was as recommended, 13.5% of total daily energy intake. Hence, are the observed lower levels of essential amino acids in serum in vegan children of any clinical significance? Omnivore diets typically contain excess protein. Vitamin B12 intake and blood levels, as well as iodine levels in urine, were adequate in vegan children and did not differ between groups. Fatty acid quality was better in vegan children: they received more unsaturated and less saturated fat than their omnivorous peers. Fiber and folate intake as well as folate levels in serum were higher in vegan children. Folate levels were above reference values in some vegan children. Their cholesterol levels were also significantly lower, yet normal. All of these results are consistent with previous studies in vegan children and adults. There were no differences in calcium intake between groups. The zinc and iron intake was significantly higher in vegans, and there was no difference in ferritin, hemoglobin or zinc levels between groups. Authors did not discuss whether the effects of vegan diet on metabolism seen in this study were positive or negative. The cholesterol levels of the vegan children were normal, but half of the vegetarians and most omnivores exceeded the total cholesterol level of 4.0 mmol l, which is considered the upper limit in children. Generally the growth, as well as nutritional intake and status was normal and adequate in the six vegan children studied. References: Elorinne A-L, Alfthan G, Erlund I, Kivimu00e4ki H, Paju A, Salminen I ym. Food and nutrient intake and nutritional status of Finnish vegans and non-vegetarians. 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