Essential Roles of Nutrient Factors in Learning and Memory.

Essential nutrient factors, including water- and fat-soluble vitamins, minerals, and essential amino acids, play an important role in brain function. We have investigated the roles of these nutrients in learning and memory in mice. Interestingly, we found that dietary deficiency of vitamin B1 or magnesium, inhibition of the vitamin A signaling pathway, and restricted intake of tryptophan impair hippocampus-dependent memory. Furthermore, magnesium deficiency causes neuroinflammation in the hippocampus. Conversely, dietary heat-killed Lactobacillus species enhance hippocampus-dependent memory. These results suggest that the nutrient factors investigated in our studies have strong influences on hippocampus-dependent memory performance.