Consumer Knowledge of Dietary Supplements

Although most consumers believe they have adequate knowledge about dietary supplements, a significant number would like more information about health benefits and think additional information would help them avoid potentially harmful adverse reactions. Other knowledge gaps pertain to specific nutrients, relationships between dietary supplements and disease, and outcomes of taking dietary supplements. In one survey, almost 60 percent of consumers incorrectly answered that it is more important for postmenopausal women to consume the recommended amount of calcium than for people of other ages. (In fact, after age 9, both males and females should consume approximately 1300 mg of calcium daily.) More than 40 percent incorrectly answered that iron supplements provide more energy (only 13 percent of consumers surveyed understood the role of iron, that is, as the oxygen-carrying component of hemoglobin). Twenty-one percent of consumers thought that noticeable effects of dietary supplements can be appreciated after one week, while 12 percent said they did not know how long it would take to see the effects.

According to the 2001 “Dietary Supplement Barometer Survey,” 91 percent of consumers said it was important to comply with recommended dosages for prescription drugs, whereas only 71 percent shared this view on dietary supplements. Those surveyed also had surprising opinions about the comparison between dietary supplements and conventional prescription and over-the-counter drugs. About half believed that some supplements are superior to drugs, and about half believed dietary supplements were equivalent to conventional drugs but threatened fewer adverse effects. All of those beliefs are false.

Information from the Natural Marketing Institute showed that more than 70 percent of consumers believed dietary supplements can prevent and treat certain health conditions. While most consumers still choose prescription drugs before dietary supplements to treat a disease or condition, about 40 percent said they would use a combination of prescription drugs, over-the-counter therapies, and dietary supplements as their first choice. About 30 percent of consumers said they would first use only dietary supplements.

A 2002 Harris Poll found that 59 percent thought that dietary supplements must be approved by a government agency before they can be sold to the public. Sixty-eight percent believed that the government required warning labels on supplements with potential adverse effects or dangers, and 55 percent believed that supplement manufacturers cannot make safety claims without solid scientific support. None of these statements is true.

Only half of dietary supplement users tell their doctors about the supplements they are taking. It is unclear whether this is because doctors don’t ask or because patients don’t tell. What is clear, however, is that this lack of communication prevents doctors and patients from making informed decisions about which dietary supplements, drugs, and behaviors are appropriate and safe.

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