Fall 2008

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Putting science behind botanical supplements

Diane F. Birt is a Mary B. Welch Distinguished Professor in the Department of Food Science and Human Nurtition and director of the Iowa Botanical Center. Mark Widrlechner is a horticulturist with the U.S. Department of Agriculture-Agricultural Research Service's North Central Regional Plant Introduction Station.

The number of U.S. consumers who said they used botanical dietary supplements dramatically rose from 2.5 percent to 20 percent from 1990 to 2002. While this increase is evidence of Americans seeking to take more control of their health, there's little firm evidence showing that these supplements have clear health benefits.

That's why scientists from Iowa State University and the University of Iowa joined forces in 2002 to establish the Center for Research on Botanical Dietary Supplements (referred to as the Iowa Botanical Center). The center, funded by the National Institutes of Health, conducts research to understand the range of bioactvities and toxicities of medicinal herbs and to learn more about their positive or negative effects on human health.

Currently, the Iowa Botanical Center focuses on three plant genera, Echinacea, Hypericum (St. John's wort) and Prunella (self-heal). Previous research demonstrated the potential of these plants for important health applications, particularly related to infection, inflammation and pain receptivity. The center's objectives are to:

The USDA-ARS North Central Regional Plant Introduction Station on the ISU campus is a key resource for the center's success because of the station's extensive experience collecting and growing Echinacea, Hypericum and Prunella and because of its role in conserving these germplasm collections within the U.S. National Plant Germplasm System.

A key focus of our research has been on botanical supplements and infection. With the emergence of new infectious agents and increased resistance to conventional drug therapies, this issue takes on added importance.

Both Echinacea and Hypericum have been studied clinically for potential health benefits, and, in general, the studies have yielded mixed results, with some suggesting a health benefit but others reporting no measurable impact on the indicators of infectious disease. It is our Center's objective to identify chemical profiles and the key compounds that define their bioactivity, and to provide a context that can be used to reinterpret past studies and serve as a foundation for future research.

What's important for consumers to know right now:

Continued research on the effectiveness of herbal medicines is timely and important, given the trend toward increased consumer self-selection of complementary and alternative medicine, including dietary botanical supplements.

Stay tuned. Once scientists better define the active chemicals in botanical supplements, recommendations will change and hopefully become more clear. The aim is to provide consumers with science-based recommendations to guide whether and how they supplement their diets to enhance their health.