Does published research affect supplement sales?

It depends on what’s being reported.

Researchers from the National Institutes of Health and Mayo Clinic reviewed sales of 5 popular supplements in light of emerging negative evidence.

First, the details.

• Supplements that were the subject of at least 1 study published in a major US medical journal (The New England Journal of Medicine, Annals of Internal Medicine, or JAMA) from 2001 to early 2006 were included.
  • Vitamin E
  • St. John’s Wort
  • Echinacea
  • Saw palmetto
  • Glucosamine/chondroitin
• Annual sales through 2006 from the Nutrition Business Journal, which tracks industry sales trends in the US were recorded.
• US news and wire stories for each study for 1 week prior to publication through 2 months after publication were tallied.

And, the results.
Vitamin E (alpha-tocopherol)

• First, a review of vitamin E studies raised concerns about higher death rates in those taking more than 800 IU of Vitamin E per day.
• Then, 2 more studies reported little or no effect of vitamin E in preventing cancer and cardiovascular disease.
• There were 178 news stories on these studies.
• Annual sales dropped sharply (down 33%) from previous sales levels and continued to decline at an accelerated pace the following year.

St. John’s wort

• 2 large studies on major depression cast doubt on its effectiveness.
• There were 130 new stories.
• No evidence that sales were affected.

Echinacea

• 2 studies, 1 with Echinacea purpurea and the other with Echinacea angustafolia showed no benefit in treating and preventing colds.
• There were 94 news stories.
• No significant decline in sales.

Saw palmetto plant (Serenoa repens)

• A study reported that saw palmetto was no better than placebo for improving symptoms of benign prostatic hyperplasia (BPH).
• The results were covered in 45 news stories, but no change in sales.

Glucosamine and chondroitin

• A study showed that glucosamine alone or with chondroitin did not improve osteoarthritis symptoms more than placebo.
• This was countered by a secondary analysis showing that the combination was more beneficial than placebo in people with moderate-to-severe osteoarthritis.
• There were 58 news story, but no change in sales.

The bottom line?
The authors concluded, that their findings “illustrate some of the challenges in translating research evidence into public health impact.”

It appears that only in the face of potential harm, as reported for vitamin E, are people motivated to rethink their use of a supplement.

By comparison, evidence that a supplement is not effective creates barely a divot in sales.

12/17/08 21:10 JR