B Vitamins and n-3 Fatty Acids for Brain Development and Function: Review of Human Studies

Background: Nutrition is one of many factors that affect brain development and functioning, and in recent years the role of certain nutrients has been investigated. B vitamins and n-3 polyunsaturated fatty acids (PUFA) are two of the most promising and widely studied nutritional factors. Methods: In this review, we provide an overview of human studies published before August 2011 on how vitamin B-6, folate, vitamin B-12 and n-3 PUFA may affect the brain, their nutrient status and the existing evidence for an association between these nutrients and brain development, brain functioning and depression during different stages of the life cycle. Results: No recommendation can be given regarding a role of B vitamins, either because the number of studies on B vitamins is too limited (pregnant and lactating women and children) or the studies are not consistent (adults and elderly). For n-3 PUFA, observational evidence may be suggestive of a beneficial effect; however, this has not yet been sufficiently replicated in randomized controlled trials (RCTs). Conclusions: We found that the existing evidence from observational studies as well as RCTs is generally too limited and contradictory to draw firm conclusions. More research is needed, particularly a combination of good-quality long-term prospective studies and well-designed RCTs.