Effect of a two-year supplementation with low doses of antioxidant vitamins and/or minerals in elderly subjects on levels of nutrients and antioxidant defense parameters

Abstract

Background: Eighty-one elderly hospitalized subjects (> 65 years) were recruited for a double-blind placebo-controlled study to examine low dose supplementation of antioxidant vitamins and minerals on biological and functional parameters of free radical metabolism. Subjects were randomly assigned to one of the four treatment groups, daily receiving for 2 years: placebo group; mineral group: 20 mg zinc, 100 micrograms selenium; vitamin group: 120 mg vitamin C (Vit C), 6 mg beta-carotene (beta CA), 15 mg vitamin E (Vit E); mineral and vitamin group: Zn 20 mg, Se 100 micrograms, Vit C 120 mg, beta CA 6 mg, Vit E 15 mg.

Results: Fifty-seven subjects completed the study. A large frequency of Vit C, Zn and Se deficiencies were observed at baseline. As early as 6 months of treatment, a significant increase in vitamin and mineral serum levels was observed in the corresponding groups. The increases ranged from 1.1-4.0 fold depending on the nutrient. Antioxidant defense, studied in vitro with a test using red blood cells in presence of 2,2'-azo-bis (2-amidinopropane) by hydrochloride, showed an increase of cell resistance in patients receiving vitamins (p = 0.002); it was positively correlated with serum Vit C (p < 0.0001), alpha-tocopherol/cholesterol (p = 0.06), beta CA (p = 0.0014), serum Cu and Se (p < 0.05). Moreover, red blood cell antioxidant defense was reduced in elderly compared with young control subjects (50% hemolysis time: 69 +/- 14 mn and 109 +/- 12 mn, respectively). Erythrocyte glutathione peroxidase activity was enhanced in groups receiving minerals, whereas no significant change was observed for other indicators of oxidative stress (erythrocyte superoxide dismutase activity, thiobarbituric acid-reactive substances, total glutathione, reduced and oxidized forms).

Discussion: Our results provide experimental evidence that a low dose supplementation with vitamins and minerals was able to normalize biological nutrient status as early as 6 months of treatment. In addition, our data indicate that antioxidant defense in elderly subjects was improved with low doses of vit C, vit E and beta CA as studied by means of a functional test utilizing red blood cells challenged in vitro with free radicals.