Effect of folic acid by mouth on cerebrospinal fluid homovanillic acid and 5-hydroxyindoleacetic acid concentration

Abstract

SUMMARY Administration of 30 mg folic acid by mouth caused a significant fall in cerebrospinal fluid homovanillic acid concentration in 11 subjects. There was no significant change of 5-hydroxyindoleacetic acid concentration. The fall was less marked in five patients on anticonvulsant medication and failed to reach statistical significance. Neither homovanillic acid nor 5-hydroxyindoleacetic acid concentrations changed significantly when 15 mg folic acid was given in divided dosage for one, two, and four weeks. The effect appeared to be related to the height of serum-folate levels reached and to be independent of cerebrospinal fluid-folate levels, which did not change significantly. Possible mechanisms and their potential therapeutic application are discussed.

Reply to Folate Supplementation

“…28 L-Methylfolate has not been studied in reducing morbidity associated with cardiovascular disease, but it has demonstrated a significant improvement in endothelial function and vasodilation. [29][30][31][32] Regarding the potential association between folate and decline in cognition, folic acid dosed at 800 µg or greater leads to unmetabolized folic acid in the serum, 33,34 which can reduce the amount of L-methylfolate that reaches the brain, thus leading to toxic complications, 35,36 reduction in monoamines, 37 and a potential increase in depression. 38 L-Methylfolate is able to cross the blood-brain barrier [39][40][41] and may therefore be safer in elderly populations in whom cognition decline may be a concern; it may also be less likely to result in other toxic complications such as the reduction of natural killer cell cytotoxicity in postmenopausal women.…”