This article explores the ways in which a vegan diet affects the brain, both positively and negatively. A vegan diet high in nutrient-dense whole foods can have positive effects on the brain, such as improved cognitive function and reduced risk of cognitive decline. However, vegans need to be mindful of potential nutrient deficiencies, particularly with regard to vitamin B12, protein, and iron. Consultation with a healthcare provider is recommended for those considering a vegan diet.