Interest in and use of dietary supplements have grown considerably in the past two decades. Consumers state that their primary reason for using herbal supplements is to promote overall health and wellness, but they also report using supplements to improve performance and energy, to treat and prevent illnesses (e.g., colds and flu), and to alleviate depression. According to a 2002 national survey on Americans' use of CAM, use of supplements may be more frequent among Americans who have one or more health problems, who have specific diseases such as breast cancer, who consume high amounts of alcohol, or who are obese.4 Supplement use differs by ethnicity and across income strata. On average, users tend to be women, older, better educated; live in one- or two-person households; have slightly higher incomes; and live in metropolitan areas.
Use of vitamin and mineral supplements, a subset of dietary supplements, by the U.S. population has been a growing trend since the 1970s. National surveys--such as the Third National Health and Nutrition Examination Survey (NHANES III, 1988-1994); NHANES, 1999-2000; and the 1987 and 1992 National Health Interview Surveys--indicate that 40 to 46 percent of Americans reported taking at least one vitamin or mineral supplement at some time within the month surveyed.5-8 Data from national surveys collected before the enactment of DSHEA in 1994, however, may not reflect current supplement consumption patterns.
In 2002, sales of dietary supplements increased to an estimated $18.7 billion per year, with herbs/botanical supplements accounting for an estimated $4.3 billion in sales.9 Consumers consider the proposed benefits of herbal supplements less believable than those of vitamins and minerals. From 2001 to 2003, sales of herbs experienced negative growth. This was attributed to consumers' withering confidence and confusion. Within the herbal category, however, formulas led single herbs in sales; products became increasingly condition-specific; and sales of women's products actually increased by approximately 25 percent.10
In contrast to dietary supplements, functional foods are components of the usual diet that may have biologically active components (e.g., polyphenols, phytoestrogens, fish oils, carotenoids) that may provide health benefits beyond basic nutrition. Examples of functional foods include soy, nuts, chocolate, and cranberries. These foods' bioactive constituents are appearing with increasing frequency as ingredients in dietary supplements. Functional foods are marketed directly to consumers. Sales increased from $11.3 billion in 1995 to about $16.2 billion in 1999. Unlike dietary supplements, functional foods may claim specific health benefits.11 The Nutrition Labeling and Education Act (NLEA) of 1990 delineates the permissible labeling of these foods for health claims.aa
Information on NLEA and the scientific review of health claims for conventional foods and dietary supplements is available at vm.cfsan.fda.gov/~dms/ssaguide.html#foot1.