There is evidence indicating that a vegan diet could be beneficial in the prevention of neurodegenerative disorders, including Alzheimer's disease (AD). The purpose of this review is to summarize the current knowledge on the positive and negative aspects of a vegan diet regarding the risk of AD. Regarding AD prevention, a vegan diet includes low levels of saturated fats and cholesterol, contributing to a healthy blood lipid profile. Furthermore, it is rich in phytonutrients, such as vitamins, antioxidants, and dietary fiber, that may help prevent cognitive decline. Moreover, a vegan diet contributes to the assumption of quercetin, a natural inhibitor of monoamine oxidase (MAO), which can contribute to maintaining mental health and reducing AD risk. Nonetheless, the data available do not allow an assessment of whether strict veganism is beneficial for AD prevention compared with vegetarianism or other diets. A vegan diet lacks specific vitamins and micronutrients and may result in nutritional deficiencies. Vegans not supplementing micronutrients are more prone to vitamin B12, vitamin D, and DHA deficiencies, which have been linked to AD. Thus, an evaluation of the net effect of a vegan diet on AD prevention and/or progression should be ascertained by taking into account all the positive and negative effects described here.

• Keywords
• Alzheimer’s disease, cognition, vegan diet,
• MeSH
• Alzheimer Disease * etiology   prevention & control   MeSH
• Diet, Vegan * MeSH
• Diet, Vegetarian MeSH
• Diet MeSH
• Humans MeSH
• Micronutrients MeSH
• Vegans MeSH
• Vitamins MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Micronutrients MeSH
• Vitamins MeSH

Vegetarian (VG) and vegan (VN) diets in childhood are of growing interest due to their perceived health and environmental benefits. Concerns remain due to the possible disruption of healthy growth and development of children because of the scarcity of evidence-based studies. Among the nutrients of special concern is vitamin B12. Therefore, the Czech Vegan Children Study (CAROTS) decided to examine the relationship between B12 metabolism parameters and B12 intake through diet and supplementation. We analyzed laboratory parameters within n = 79 VG, n = 69 VN, and n = 52 omnivores (OM) children (0−18 years old). There were no significant differences in levels of holotranscobalamin (aB12), folate, homocysteine (hcys), or mean corpuscular volume. However, there was a significant difference in levels of cyanocobalamin (B12) (p = 0.018), even though we identified only n = 1 VG and n = 2 VN children as B12 deficient. On the other hand, we identified n = 35 VG, n = 28 VN, and n = 9 OM children with vitamin B12 hypervitaminosis (p = 0.004). This finding was related to a high prevalence of over-supplementation in the group (mean dose for VG 178.19 ± 238.5 µg per day; VN 278.35 ± 394.63 µg per day). Additionally, we found a significant (p < 0.05) difference between B12, aB12, and hcys levels of supplemented vs. non-supplemented VG/VN children. This can show that the intake of vitamin B12 via diet in the VG group might not be sufficient. Secondly, we analyzed a relation between supplement use in pregnancy and breastfeeding and its impact on vitamin B12 levels of children aged 0−3 years. Out of n = 46 mothers, only n = 3 (e.g., 6.5%) were not supplemented at all. We have not identified any clinical manifestation of B12 deficiency and only n = 1 child with low serum cobalamin, a child who did not receive vitamin B12 supplementation and whose mother took only low doses of vitamin B12 (25/µg/day).To conclude, we did not observe any life-threatening or severe consequences of laboratory-stated vitamin B12 deficiency; thus, our group was well supplemented. On the other hand, we have identified many subjects with vitamin B12 hypervitaminosis of unknown impact on their health. Further research and new guidelines for B12 supplementation among VG and VN children are needed.

• Keywords
• B12 supplementation, children, deficiency, vegan, vegetarian, vitamin B12,
• MeSH
• Child MeSH
• Infant MeSH
• Humans MeSH
• Adolescent MeSH
• Vitamin B 12 Deficiency * epidemiology   MeSH
• Infant, Newborn MeSH
• Dietary Supplements MeSH
• Child, Preschool MeSH
• Prevalence MeSH
• Cross-Sectional Studies MeSH
• Pregnancy MeSH
• Vegans MeSH
• Vegetarians MeSH
• Vitamin B 12 * MeSH
• Habits MeSH
• Check Tag
• Child MeSH
• Infant MeSH
• Humans MeSH
• Adolescent MeSH
• Infant, Newborn MeSH
• Child, Preschool MeSH
• Pregnancy MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Vitamin B 12 * MeSH