In November 2019 researchers from the USA published their review on the role of plant-based dietary patterns and polyphenol-rich plant foods in reducing the risk of age-related cognitive decline and/or improving cognitive function. Currently there is no direct evidence to support the benefits of a vegetarian diet in preventing cognitive decline although there is emerging evidence that plant foods rich in polyphenols, anti-inflammatory dietary patterns, and plant-based dietary patterns, such as the Mediterranean diet, that include a variety of fruits, vegetables, legumes, nuts, and whole grains have brain-health-promoting effects. The compounds present in these dietary patterns include antioxidant vitamins, polyphenols, other phytochemicals, and unsaturated fatty acids. In addition, clinical trials have revealed that plant foods (citrus fruits, grapes, berries, cocoa, nuts, green tea, and coffee) are able to improve specific areas of cognition. Further research is required to assess whether plant-exclusive diets have an added cognitive advantage compared with plant-centered diets with fish and/or small amounts of animal foods.
Rajaram S et al. Plant-Based Dietary Patterns, Plant Foods, and Age-Related Cognitive Decline.Adv Nutr. 2019 Nov 1;10(Supplement 4):S422-S436.