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Weighty research on diet supplements

PHS, Bastyr researchers discover certain dietary supplements help prevent weight gain

Jan. 19, 2006
Dr. M.C. Nachtigal seated in front of vitamin containers

Dr. M.C. Nachtigal and colleagues in the Public Health Sciences Division and at Bastyr University found that long-term use of multivitamins, vitamins B6, B12 and chromium may help fight middle-age spread.

Photo by Todd McNaught

After the holidays, when gym memberships surge and people's thoughts turn from eggnog to egg-white omelets, they also may turn to over-the-counter supplements that promise to rev up metabolism and boost weight-loss efforts. But do weight-loss supplements really work?

In a study conducted by Public Health Sciences Division and Bastyr University, researchers found that long-term use of multivitamins, vitamins B6, B12 and chromium among obese or overweight middle-aged people may help prevent additional weight gain. The research was published in the October issue of the Journal of Alternative and Complementary Medicine.

VITAL study

"While watching calories and exercising are the main elements of weight control, we were surprised to learn that some supplements might help," said lead author Dr. M.C. Nachtigal, who has a doctorate in naturopathic medicine and conducted the research in collaboration with former Center scientist Dr. Ruth Patterson and other PHS investigators. Nachtigal currently works as a training grant specialist in the Center's Basic Sciences Division.

Among the 15,655 western Washington residents surveyed about their supplement use over a 10-year period, researchers found that obese or overweight consumers who took the four supplements experienced less weight gain than those who did not use the supplements. Factors such as race or ethnicity, education, calorie intake and physical activity were accounted for in the data analysis.

The data came from participants in the Vitamins and Lifestyle (VITAL) study, led by PHS researcher Dr. Emily White, which looked at the effects of supplement use on cancer risk.

The chromium connection

Nachtigal's analysis also examined 10 other common supplements sometimes marketed for weight control or loss: coenzyme Q10, dehydroepiandrosterone, essential fatty acids, fiber, garlic, ginkgo, ginseng, melatonin, soy and St. John's wort. None had a significant impact on weight control.

But in the case of chromium — which seemed to most help weight control — the researchers found that obese or overweight men who took more than 150 micrograms daily for 10 years lost 3 pounds, while those who didn't take the supplement gained 11 pounds over the same period. Among obese women, the trend was similar: those who took high levels of the supplement daily gained only 3 pounds in 10 years, as compared to those who did not, who gained 14 pounds on average.

Nachtigal and her colleagues are not sure whether the B vitamins, multivitamins and chromium actually prevented weight gain or aided weight loss. More research is needed to explore that question, they said. Previous, smaller studies have also suggested chromium might help keep off the pounds. It helps regulate blood-sugar levels, which keeps appetite in check. Vitamins help control the use of calories and energy.

Nachtigal cautioned about applying the results to normal-weight or other age groups. "We don't know what impact these supplements would have on 25- or 30-year-olds since their bodies are in a different state than 45-year-olds," she said.

While these findings give direction for further research, Nachtigal said she wouldn't recommend people take high doses of the supplements without a randomized clinical trial being done first. "I'm sure there were factors we didn't ask about and couldn't control for, including why the respondents began taking the supplements in the first place. Who told them it was good for what? Maybe there's some other factor we don't know about," she said.

Diet, exercise works best

"It's still really important for people not to take a quick fix or an easy out. Ultimately, weight control is about diet and exercise," Nachtigal said. "But what interests me is understanding these everyday substances are important to a lot of different body systems and even have effects that we didn't expect."

Nachtigal presented the findings at the American Association of Naturopathic Physicians annual conference. White, Dr. Ann Shattuck and Kayla Stratton of the PHS Cancer Prevention Program co-authored the paper, along with Bastyr researcher Dr. Lizbeth Adams.

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