VITAMIN/MINERAL SUPPLEMENT USERS DO NOT SHOW DECREASED MORTALITY RISK
This article was originally published in The Tan Sheet
VITAMIN/MINERAL SUPPLEMENT USERS DO NOT SHOW DECREASED MORTALITY RISK in a study published in the April edition of the American Journal of Public Health. Conducted by Insun Kim, DrPH, et al., Centers for Disease Control and Prevention's National Center for Chronic Disease Prevention and Health Promotion, the study "found no evidence of increased longevity among vitamin and mineral supplement users in the United States." The researchers used data through 1987 on individuals who were part of the NHANES I Epidemiologic Follow-Up Study, a prospective study of adults originally examined in the First National Health and Nutrition Examination Survey (NHANES I), which took place from 1971-1975. Between 1982 and 1984, 10,523 surviving members of the NHANES I cohort were reinterviewed. Participants, aged 25 to 74, were followed for an average of 13 years. Both before and after adjusting for potential confounding factors, Kim, et al. discovered that "the risk of all-cause mortality for regular [supplement] users was not significantly different from that for nonusers." Similarly, the risk of cancer mortality for regular users of supplements "was not significantly different from that for nonusers." In addition, "no consistent mortality benefits or risks of supplement use were found across a number of population subgroups," the CDC group observed. Regular use of supplements was defined as daily. The study defined irregular use as "at least once a week but not daily." Nonusers were defined people who took supplements less than once a week. The study authors concluded that "although there may be some reasons why people take vitamin and mineral supplements apart from life-extension, the cost-effectiveness of the annual $ 3 bil. expenditure on nutritional supplements and the safety issues of self-supplementation should be more carefully considered." The researchers also noted that although vitamin and mineral supplement use is a "widely practiced health behavior" in the U.S., "there are reasons to be concerned about the risks of toxicities associated with overdose among those who ingest certain nutrients in potentially harmful amounts." Questions related to potential benefits and risks associated with long-term supplement use "have not been well addressed by large-scale epidemiologic studies," the study adds. A study by Badi Boulos, MD/PhD, University of Illinois-Chicago School of Public Health, presented at the recent Federation of American Societies for Experimental Biology meeting looked at the potential risks from calcium supplements and antacids containing trace metals including lead, arsenic, aluminum and cadmium. Boulos found that these products can pose health hazards at certain levels, particularly in older people due to decreased rate of metabolism, kidney function, and decreased rate of elimination from the body. Boulos added that trace metals are a potential danger for anyone with kidney or gastrointestinal disease who cannot excrete substances adequately. Boulos urged FDA and "the pharmaceutical industry to discourage the chronic, continual use of such [dietary] supplements even at low doses and provide lay educational materials about the dangers of such trace metals," according to an abstract of the presentation. "Even if made by a well-known pharmaceutical manufacturer with the ingredients as well as contaminants listed on the label, the consumers are unaware of the health hazards of these contaminants," the abstract says. The Kim, et al. study and Boulos' report at FASEB seem to buck the trend of recent studies showing benefits of dietary supplements. Recent reports include a statement by the Consensus Development Conference in Hong Kong that calcium supplement intake has been shown to increase bone mass in children and adolescents and reduce bone loss associated with increasing age ("The Tan Sheet" April 5, In Brief). A group of Boston University researchers also discovered that use of folic acid supplements decreases the risk of first-time neural tube defects by 60% ("The Tan Sheet" March 15, p. 15). Another study, presented by Erika Trainer, University of California-Davis, in an April 1 poster session at FASEB, observed that high doses of zinc monomethionine complex (InterHealth's OptiZinc) improved zinc status among diabetics, a population whose zinc metabolism is altered. In the study, 14 diabetics were given 30 mgs of OptiZinc for 30 days. OptiZinc increased plasma zinc levels by 20%, Trainer found, but did not affect copper plasma levels, a concern for users of zinc supplements that are above the Recommended Daily Allowance. Additional reports touting the benefits of dietary supplements were heard at the American Heart Association's Epidemiology Conference in March. For instance, a study by JoAnn Manson, MD, Brigham and Women's Hospital, Boston, et al., found that "higher antioxidant vitamin consumption is associated with a reduced risk of ischemic stroke in women." Based on a semiquantitative food frequency questionnaire and eight-year follow-up, Manson, et al. determined that "carotene intake was the predominant contributor to the reduced risk, with modest contributions from vitamins C and E," according to an abstract of the presentation.
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