[6S]5-Methyltetrahydrofolate or folic acid supplementation and absorption and initial elimination of folate in young and middle-aged adults

de Meer K., Smulders Y. M., Dainty J. R., Smith D. E. C., Kok R. M., Stehouwer C. D. A., Finglas P. M., Jacobs C.. (2005)

European Journal of Clinical Nutrition, 59, 1409-1416