L-ascorbic acid improves the serum folate response to an oral dose of [6S]-5-methyltetrahydrofolic acid in healthy men

Objective: To investigate the effect of simultaneous administration of [6S]-5-methyltetrahydrofolic acid ([6S]-5-CH(3)H(4)PteGlu) with L-ascorbic acid (L-AA) on serum folate concentrations in healthy male subjects. Subjects and methods: A total of nine healthy male volunteers were recruited. Serum folate concentrations were measured before and up to 8 h after administration of each treatment (1) placebo, (2) 343 mu g [6S]-5-CH(3)H(4)PteGlu), (3) 343 mu g [6S]5-CH(3)H(4)PteGlu) with 289.4 mg L-AA and (4) 343 mu g [6S]-5-CH(3)H(4)PteGlu) with 973.8 mg L-AA (n = 10 samples per treatment). Results: Serum folate concentrations significantly increased compared with baseline values, starting from 30 min after [6S]5-CH(3)H(4)PteGlu administration and remained significantly higher than baseline values during the first 6 h for treatments 3 and 4, and during the first 4 h for treatment 2. Maximal serum folate responses were observed between 0.5 and 1.5 h after [6S]5-CH(3)H(4)PteGlu consumption and significantly differed between treatments 2 and 4 (P<0.05). When [6S]-5-CH(3)H(4)PteGlu was concurrently administered with 289.4 or 973.8 mg L-AA, the total serum folate response, calculated as the area under the curve (AUC), was significantly improved (46.5 +/- 4.0 and 53.0 +/- 4.0 vs 34.3 +/- 3.8 h nmol/l, P<0.05). No significant difference in AUC was found between the 289.4 and the 973.8 mg L-AA treatments. Conclusions: Administration of a physiological dose of [6S]-5-CH(3)H(4)PteGlu with L-AA significantly improved the measured serum folate response in folate saturated healthy men.