Last week, we reviewed the evidence on how well the Mediterranean, DASH, and MIND diets promote brain health. Now we investigate the benefits of diets that leave something out, such as meat or milk. How does eliminating animal-based products from your diet affect your brain health?
The vegetarian diet is plant-based, excluding the consumption of meat and sometimes animal by-products. There are many variations, including the ovo- and lacto-vegetarian diets (those that include eggs and dairy, respectively). Evidence suggests that the vegetarian diet can lower blood pressure and improve blood lipid profiles. Whether it can promote brain health, however, is up for debate. Many vegetarians consume high amounts of nutrient-rich fruits and vegetables, and they avoid the processed meats rich in nitrates and nitrites that have been suggested to increase the risk of dementia in preliminary studies. On the other hand, vegetarians have a higher risk of vitamin B-12 deficiency that, if undetected and left untreated, can cause cognitive problems and even dementia. Few studies have looked carefully at the risk of dementia in vegetarians versus other people, and the data is contradictory. One small study of California residents found that meat eaters were more likely to become demented than their vegetarian counterparts. Another study in Alzheimer’s patients, however, found that adhering to a strict vegetarian diet resulted in lower cognition compared to a pescatarian diet (i.e., a diet that includes fish). Additional information about vegetarian diets can be found at MedlinePlus.
The vegan diet is a stricter form of the vegetarian diet. It excludes all meat and animal-derived products (e.g., eggs and dairy). Most vegan diet studies report weight loss and improved blood lipid profiles. No current studies have investigated whether the vegan diet may promote cognition or prevent Alzheimer's disease. Because of the similarities of the vegan diet to the vegetarian diet, the evidence discussed above would likely apply to vegan diets. Additional information can be found at Dietitians of Canada.
Few studies have examined the vegetarian and vegan diets for brain health, but that should not be taken as an indication they will not promote cognitive vitality. These diets have much in common with the Mediterranean, DASH and MIND diets, including high intakes of nutrient-rich fruits and vegetables. They do, however, eliminate food groups that contain important nutrients such as B-12 and omega-3 fatty acids. If these foods are avoided, it is important to find vegetarian and vegan options to consume the vitamins and nutrients that might be missing.
Nick McKeehan is a member of the ADDF's Aging and Alzheimer's Prevention program. He evaluates the scientific evidence for and against therapies to promote brain health and/or prevent Alzheimer's disease at our website CognitiveVitality.org and contributes regularly to the site's blog. Mr. McKeehan previously served as Chief Intern at Mid Atlantic Bio Angels (MABA) and was a research technician at Albert Einstein College of Medicine investigating repair capabilities of the brain. Mr. McKeehan received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. He also writes about the biotechnology industry for 1st Pitch Life Science.
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