The popular view that supplements contribute to nutrition got a boost from a study published by the American Dietetic Association. In the March issue of the ADA's journal, scientists based in Seattle, Atlanta and Minneapolis found that supplements help middle-aged and older Americans meet their daily intake requirements. Results varied by population group, the study found.

Specifically, the research found that many adults do not meet the daily required intake guidelines even with the help of dietary supplements, and the effect of supplementation can vary according to ethnicity and sex. Also, high-dose supplement use is associated with intakes above upper limits for intake levels for calcium, magnesium, and vitamin C.

The study looked at 6,814 subjects aged 45 to 84 in six regions spanning the nation from Forsyth County, North Carolina, to Los Angeles County. About 38% of participants were white, 28% African American, 22% Hispanic, and 12% Asian American. Participants were classified based on whether they were users or nonusers of supplements and again based on whether they used multivitamins or high-dose supplements.

The results:

• Overall, median dietary intake of calcium, magnesium, and vitamin C was similar between supplement users and nonusers among both men and women.
• In men, calcium supplementation increased median calcium intake by 56% and for magnesium supplementation by 42%.
• Vitamin C supplementation had the largest effect on median intake in men, ranging from a 160% increase in Chinese men to 235% in African-American men.
• For all women, magnesium supplementation increased median magnesium intake by 61% and vitamin C supplementation by 181%.
• Calcium supplementation produced a 101% increase in median calcium intake among Hispanic women and a 151% increase in Chinese women.

The benefits of increased intake came with a warning from the study's authors: those who consumed high-dose supplements were more likely than nonusers to exceed upper intake limits. The overage could lead to health problems, such as kidney stones from too much calcium.