University alumna Liz Johnson works at Magus Books in Dinkytown, where more than 450 herbal products are sold.

She has her own thoughts on why herbal supplements such as ginseng or ginkgo biloba are gaining popularity.

“People are concerned about their general health,” Johnson said. “It’s a way to treat themselves, but with a greater sense of control.”

But consumers taking herbal supplements might not be getting all they pay for, according to a recent University study.

The study, published in the October issue of the Archives of Internal Medicine, found some products of the same herb contained different plant parts and strength levels, as well as different recommended dosages. However, some question the study’s validity.

The study analyzed products containing 10 top-selling herbs, including ginseng, St. John’s wort and echinacea, said Judith Garrard, one of the study’s authors and a University professor of health services research and policy.

Using a textbook of herbal supplement research, researchers determined common guidelines for ingredients and dosage levels.

Researchers found 880 products containing the 10 herbs in stores throughout the Twin Cities.

Thirty-seven percent of those products were labeled unclearly, Garrard said. The poorly labeled products either did not contain enough details to determine the ingredients or had recommended dosages inconsistent with the pharmacy textbook’s guidelines.

Unclear ingredient labels can mislead consumers because different parts and species of some herbs vary in their effectiveness, said study co-author Susan Harms, senior research associate in the School of Public Health’s Division of Health Services Research and Policy.

Harms said certain plant parts and varieties of the echinacea species are beneficial, while others are not.

“All they say is ‘echinacea,’ ” Garrard said of some ingredient labels. “Echinacea what? What kind and what part of the plant?”

Recommended daily dosages also varied for the same herbs in different products, Harms said.

Garrard said she was astonished at the number of different products for each herb.

“Given this vast array of products, you’d expect them to have the same ingredients,” she said. “But there are no standards.”

The study exclusively focused on what was on the labels, Harms said. It did not address how well these supplements work or if the ingredients listed are what is actually in the supplement.

“We are not saying these herbs are good or bad, we’re saying look at the variations,” Harms said.

“It’s kind of like a crapshoot,” Garrard said. “You don’t know what you are getting.”

Mark Blumenthal, founder and executive director of the American Botanical Council, said he had reservations about the study. The American Botanical Council is an independent, nonprofit research and educational organization that specializes in herbal and medicinal plant information.

The study could be based on faulty product data, Blumenthal said. The study used products collected in 2000 that might no longer represent the range of herbal supplements.

“Many products may have already revised their labeling,” Blumenthal said.

Herbs and other dietary supplements are also categorized as foods by the U.S. government, and are not required under the law to list specific dosage levels on labels, he said.

While no extensive federal regulation exists regarding herbal supplements, Blumenthal said responsible elements within the industry are moving toward more thorough ingredient labeling.

The council created a voluntary ingredient labeling program in 2001 to provide manufacturers with safety information, he said.

Tending the counter of the General Nutrition Center store in Stadium Village, sales representative and University architecture senior Kurt Peterson said customers need to study up on supplements before buying them.

He said making an informed decision is the best way for customers to make sure they are buying a supplement that works.

“It’s really just common sense,” he said.