The FDA-funded Health and Diet Survey involved telephone interviews with 2,743 participants in 2002. Seventy three percent of respondents said they had used dietary supplements in the past 12 months, and 4 percent said they had experienced some adverse event that they attributed to supplements.
Eight-five percent of supplement users said they took multivitamins/multiminerals, and 13.3 percent of reported events were attributed to these products.
Although authors say the results should be "interpreted with caution"since the information provided was self-reported and the intention was not to attribute adverse events to a particular ingredient within a multi-ingredient formulation, the survey provides gives an indication of associations drawn by consumers.
Adverse events reporting is a very current topic for the North American dietary supplements industry - especially since the herbal ephedra, linked to serious cardiovascular problems, was banned in 2004.
The US industry is regulated by the 1994 Dietary Supplement Health and Education Act. Although upheld by the industry associations as a good law, it does not make the reporting of adverse events mandatory by companies - an omission that has opened it up to criticism from those who believe products should be subject to the same pre-market testing as prescription drugs.
Earlier this year a bill was introduced that would make the reporting of serious adverse events mandatory. The bill is supported by much of the industry; it sends out a clear message that it is a responsible industry for which safety is paramount.
However while the bill relates only to serious adverse events, the survey includes the whole spectrum, from heart problem and chest pain to nausea, rash, and other less reported minor symptoms. The published data does not indicate whether or not the supplements were used according to instructions.
Ninety percent of respondents stopped taking the supplement product on experiencing an adverse event; 48 per cent saw a doctor; 25 per cent reported the incident to a health authority; 12 percent went to an emergency room, and 9 percent complained to the manufacturer.
The survey also asked about consumer usage patterns. Seventy-four percent of users reporting an adverse event said they were taking a supplement while also taking a prescription drug.
Although the survey was not designed to collect data on specific interactions, the researchers concluded: "Food and nutrition professionals and other health care professionals should take special care to learn about their patients' multivitamins/multiminerals use".
Source: Journal of the American Dietetic Association December 2006. doi: 10.1016/j.jada.2006.09.002 "Dietary Supplements in a National Survey: Prevalence of Use and Reports of Adverse Events Authors: B.B. Timbo, M. Ross, P. McCarthy, Chung-Tung J. Lin