Vitamin and mineral status in physically active men: effects of a high-potency supplement

Changes in nutritional status during supplementation with a high-potency multivitamin-mineral supplement were examined in 22 physically active men randomly assigned to take a supplement (n = 11) or placebo (n = 11) for approximately 12 wk. Four-day dietary intakes, blood concentrations, and urinary excretions of selected vitamins and minerals were measured before, during (approximately 6 and 12 wk), and after supplementation. No changes were observed in blood concentrations of vitamins A and C and measures of zinc, magnesium, and calcium status; the supplement provided less than 300% of the recommended dietary allowance (RDA) of these nutrients. In contrast, blood concentrations of thiamin, riboflavin, vitamins B-6 and B-12, pantothenate, and biotin increased significantly (P less than 0.05) by 6 wk to values that were maintained until the end of the supplementation. These vitamins were provided in amounts that ranged from 396% (biotin) to 6250% (vitamin B-6) of the RDA. Urinary excretions of these vitamins also increased during supplementation and both blood and urine values returned to presupplementation concentrations at approximately 13.5 wk postsupplementation.