With vegan diets on the rise, it is important to discuss the nutritional implications of a plant-based diet on brain health. Because this dietary pattern is relatively new, research is limited when it comes to assessing the long-term effects of a vegan diet on brain development.
However, people who consume a vegan diet are usually deficient in vitamin B12, vitamin D, omega 3, choline and sometimes iron (1). All of which play important roles in brain health. Another concern is the genetic component of nutrient absorption. Various genes have been identified that relate to absorb and utilizing these nutrients (2). All the nutrients listed above have at least one gene related to its availability.
How do potential micronutrient deficiencies affect the brain?
Vitamin B12 is an essential vitamin that helps keep nerves and blood cells healthy. It is also a crucial co-factor in the creation of new DNA. A review conducted in 2018 identified 19 genes that relate to B12 absorption and utilization (3).
A deficiency in B12 is associated with some cancers, neuropsychiatric disorders and cardiovascular disease. While vitamin B12 can be supplemented, it is extremely important to understand your genetic capabilities. It is also important to note that folic acid, which vegans usually have a high intake of, can mask a B12 deficiency. B12 analogues found in nutritional yeast and spirulina are not biologically active and can actually increase B12 deficiency by attaching to receptors without producing any effects on the body (4).
EPA + DHA
Omega 3’s (EPA and DHA) are commonly studied because of the bodies poor conversion rate of turning ALA (plant-based source) into EPA & DHA (animal source). DHA is particularly important for brain health because it comprises key structures like phospholipid membranes. DHA is implicated in various brain disorders like alzheimers, depression, schizophrenia and more (5).
While vegans can receive their DHA from algal oil, the form found in this supplement is in free-DHA form which may be problematic for individuals who carry a copy of the ApoE4 variant in their genes. Research suggests that DHA in phospholipid form, which is only found in fish sources, is more beneficial for individuals who carry an ApoE4 variant (6). Consuming fish can be much more effective, perhaps life saving, when it comes to reducing Alzheimer’s risk in individuals who carry this variant.
Choline is an essential nutrient that needs to be obtained from the diet. Choline is not only required to make the neurotransmitter acetylcholine, but it is needed to make betaine which is responsible for donating a methyl group to make S-adenosylmethionine in the liver and kidneys. Methylation is critical to make neurotransmitters, create new DNA and regulate gene expression (7).
A 2016 review evaluating choline intakes of 17,000 people in the US found that most people do not meet the adequate intake (8). A peer-reviewed article published in 2009 found that at least 50% of the population has genetic polymorphisms that require higher choline intakes than the recommended level (9).
One of the best sources of choline is beef liver and egg yolks. While plants do contain choline, the amount is low and may be harder to absorb from plants alone. A study conducted on healthy adults found that when these adults were deprived of dietary choline, 78% of the adults developed fatty liver and muscle damage. The damage was reversed when the researchers added high amounts of dietary choline back into their diet (10).
Vitamin D is involved in skeletal integrity, immune system regulation and many other functions. People that have darker skin, are older, overweight or wear sunscreen will have greater risk of vitamin D deficiency (11). The primary source of vitamin D3 (cholecalciferol) comes sunlight and animal foods while plant sources have the D2 form (ergocalciferol).
A study published in 2012 found that the D3 form was significantly better at raising serum levels than D2. The researchers explained that this difference was due to the extra methyl group on carbon 24 which greatly affects the conversion of D2 into the active form, as well as its affinity to the vitamin D binding protein (12).
Vitamin D is strongly influenced by genetic variations. A meta-analysis found strong associations between VDR gene variants and cancer outcomes. Individuals who carried TT variants at rs1544410 were 40% more likely to die from specific cancers like breast, haematological and skin cancer (13). Vitamin D also has important implications for brain health. A study conducted by Dr. Patrick and Dr. Ames found that vitamin D activates the gene for tryptophan hydroxylase, which is responsible for converting tryptophan into serotonin (14). A literature review published in 2018 found that vitamin D has very important roles in brain function. Vitamin D deficiency is linked to higher levels of amyloid plaque, increased risk of depression, and in expecting mothers it is linked to higher rates of autism and schizophrenia (15).
Benefits of going plant based?
Eating a plant-based diet has many benefits for the entire body, including the brain. Eating more fiber, vitamins, antioxidants and phytonutrients will definitely promote a healthier lifestyle. However, the strict removal of all animal products is not supported by research.
Studies also show that vegan diets have a low adherence rate, meaning very few people can actually stick to a vegan diet long-term. Strict diets like veganism can promote disordered eating behaviors and lead to unhealthier food choices by people choosing refined grains and high-glycemic foods more often. Dietary changes should be focused on including more fatty fish and nutrient-dense organ meats.
1. Hever J. Plant-Based Diets: A Physician’s Guide. Perm J. 2016;20(3):15–082. doi:10.7812/TPP/15-082
2. Stover PJ, Caudill MA. Genetic and epigenetic contributions to human nutrition and health: managing genome-diet interactions. J Am Diet Assoc. 2008;108(9):1480–1487. doi:10.1016/j.jada.2008.06.430
3. Surendran S, Adaikalakoteswari A, Saravanan P, Shatwaan IA, Lovegrove JA, Vimaleswaran KS. An update on vitamin B12-related gene polymorphisms and B12 status. Genes Nutr. 2018;13:2. Published 2018 Feb 6. doi:10.1186/s12263-018-0591-9
4. Palmer, S. (2018, April). Vitamin B12 and the Vegan Diet – Today’s Dietitian Magazine. Retrieved from https://www.todaysdietitian.com/newarchives/0418p38.shtml.
5. Lauritzen L, Brambilla P, Mazzocchi A, Harsløf LB, Ciappolino V, Agostoni C. DHA Effects in Brain Development and Function. Nutrients. 2016;8(1):6. Published 2016 Jan 4. doi:10.3390/nu8010006
6. Patrick, Rhonda P. Role of phosphatidylcholine-DHA in preventing APOE4-associated Alzheimer’s disease The FASEB Journal 33, no. 2 (February 2019): 1554–64. https://doi.org/10.1096/fj.201801412r
7. Derbyshire E Could we be overlooking a potential choline crisis in the United Kingdom? BMJ Nutrition, Prevention & Health 2019; bmjnph-2019-000037. doi: 10.1136/bmjnph-2019-000037
8. Taylor C. Wallace & Victor L. Fulgoni III (2016) Assessment of Total Choline Intakes in the United States, Journal of the American College of Nutrition, 35:2, 108-112, DOI: 10.1080/07315724.2015.1080127
9. Zeisel SH, da Costa KA. Choline: an essential nutrient for public health. Nutr Rev. 2009;67(11):615–623. doi:10.1111/j.1753-4887.2009.00246.x
10. Fischer LM, daCosta KA, Kwock L, et al. Sex and menopausal status influence human dietary requirements for the nutrient choline. Am J Clin Nutr. 2007;85(5):1275–1285. doi:10.1093/ajcn/85.5.1275
11. Harvard. (2019, July 2). Vitamin D. Retrieved from https://www.hsph.harvard.edu/nutritionsource/vitamin-d/.
12. Tripkovic L, Lambert H, Hart K, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Am J Clin Nutr. 2012;95(6):1357–1364. doi:10.3945/ajcn.111.031070
13. Vaughan-Shaw PG, O’Sullivan F, Farrington SM, et al. The impact of vitamin D pathway genetic variation and circulating 25-hydroxyvitamin D on cancer outcome: systematic review and meta-analysis. Br J Cancer. 2017;116(8):1092–1110. doi:10.1038/bjc.2017.44
14. Children’s Hospital & Research Center Oakland. “Causal link found between vitamin D, serotonin synthesis and autism in new study.” ScienceDaily. ScienceDaily, 26 February 2014.
15.Anjum I, Jaffery SS, Fayyaz M, Samoo Z, Anjum S. The Role of Vitamin D in Brain Health: A Mini Literature Review. Cureus. 2018;10(7):e2960. Published 2018 Jul 10. doi:10.7759/cureus.2960