Effects of multivitamin/mineral supplementation on plasma levels of nutrients.Report No. 4 of the Italian-American Clinical Trial of Nutritional Supplements and Age-related Cataract

摘要

The use of multivitamin-mineral supplements has become increasingly common, butwhether the use of such supplements improves micronutrient status remains still unclear. The objec-tive of this report is to investigate how a long-term vitamin-mineral supplementation following the USRecommended Daily Intake (RDI) affected the plasma levels of selected nutrients in a subset (No. =407) of participants in the Italian-American Clinical Trial of Nutritional Supplements and Age-re-lated Cataract (CTNS). The CTNS was a double-blind, single centre, controlled clinical trial of 1020participants aged 55-75 years randomized to a daily tablet of Centrum or placebo. A representativesample of 40% of the 1020 subjects, whom plasma level of selected vitamins was determined at thebaseline, was retested throughout the treatment period that averaged 9.0 ± 2.4 years. Participants as-signed to Centrum showed a significant increase (p < 0.005) in mean/median plasma levels of vita-min E, beta-carotene, folate, andvitamin B12, and an improved riboflavin status when compared withparticipants assigned to placebo. Differences concerning vitamin C were statistically less relevant andthose concerning vitamin A were at a borderline level. In the treated group the effect of supplementa-tion on plasma levels of vitamins A, E, and C, and on the glutathione red uctase activation coefficientwas significantly higher in participants with lower nutritional status at baseline.