Folate profile in frontal cortex from male human infant decedents.

Information on tissue folate profiles in human tissues is limited to colon mucosa, epidermis and dermis. Recently, infant rhesus macaques fed folic acid (FA) were reported to have unmetabolized FA (UMFA) in each of 7 brain regions tested. We hypothesized that human infant brain would also contain UMFA. Therefore, we sought to analyze the folate profile in frontal cortex from 5 human infant decedents. Archived frontal cortex samples from 5 male human infant decedents aged 5 to 273 days, without brain abnormalities or systemic pathologies were analyzed for tetrahydrofolate (THF), 5-methyltetrahydrofolate (5-MTHF) and UMFA by LC-MS/MS. All 3 folates were detected in each frontal cortex sample. THF was the most abundant folate in each sample with a mean concentration of 202 pmol/g tissue. Mean concentrations of 5-MTHF (30.3 pmol/g tissue) and UMFA (20.8 pmol/g tissue) were significantly lower (P < .0001) than THF and were not different from each other. Two decedents had UMFA concentrations that were 2-fold higher than those of 5-MTHF. In conclusion, THF, 5-MTHF, and UMFA were found in each frontal cortex sample with the order of mean values being THF > 5-MTHF = UMFA. In 2 of the 5 decedents we observed UMFA concentrations that were double those of 5-MTHF. These findings merit further research into folate metabolism and status in infants.