I Don't Hear You...

How does the public respond when a published scientific report shows that a dietary supplement is ineffective, or even worse, potentially harmful? To find out, scientists at the National Institutes of Health examined the sales trends of five different dietary supplements before and after the publication of negative research results. There were no significant declines in sales for four of the five supplements (saw palmetto, Echinacea, glucosamine, and St. John’s wort) after published reports that the supplement was ineffective. But sales of the fifth supplement (Vitamin E) declined about 33% after a report suggested that high doses of Vitamin E might actually be harmful.

Why did consumers ignore the reports that supplements just didn’t work, but responded to a report of potential harm? Researchers speculate that reports of harm might have higher impact because of greater news coverage, or that some supplements (such as Vitamin E) might be recommended more often by physicians who are more likely to read and understand scientific reports, or even that it depends on the type of person who takes a particular kind of supplement, the purpose of the supplement, and the availability of alternatives.

Still, it must be discouraging for public health officials to learn that consumers aren’t getting the message, don’t believe the message, or just don’t care whether their supplements work or not.