Characteristics of vitamin and mineral supplement products in the United States.

A 1986 nationwide survey of 11,775 adults 18 y or older and 1877 children 2-6 y old identified approximately 3400 different (unique) vitamin and mineral supplement products being taken. The most commonly included nutrient listed on the product labels was vitamin C, which was present in 50% of the unique products examined. Calcium and iron were the most commonly included minerals and were present in 25% of the unique products examined. Prenatal and children's chewable products came in a relatively narrow potency range and generally contained nutrients in amounts approximating or less than the US recommended daily allowances. These products also contained significant minimum amounts of nutrients. Potencies of products not targeted for use by these special groups, particularly those products that were self-prescribed, varied widely and ranged from insignificant to extremely large amounts of nutrients. Units used to declare product potency or to prescribe the dosage varied.