A store worker walks past rows of herbal, vitamin and mineral pill products at a suburban pharmacy in Sydney in a 2003 file photo. Credit: Reuters/David Gray

In 2008, users of Total Body Formula and Total Body Mega Formula started losing their hair and began suffering from fatigue, diarrhea, nausea and other symptoms; some doubled their dose of the liquid supplement in response.

But the symptoms, first reported by patients of a Florida chiropractor who was selling the products in his office, were subsequently traced to a batch of the supplements carrying up to 200 times the amount of selenium stated on the label. Further investigation found 201 people in ten states who had been sickened by the supplement.

While small amounts of selenium are essential for proper nutrition -- and people usually get plenty in their diet -- excess amounts are toxic, and the effects can persist for months, Dr. Timothy F. Jones of Vanderbilt University School of Medicine in Nashville, a co-author of the case report, told Reuters Health. He and his colleagues found that the median dose of selenium people had consumed was nearly 42,000 micrograms per day; the recommended daily allowance of selenium is 55 micrograms.

These heavy metals stay in your system, it just takes time for them to sort of get flushed out, he explained. Even once you take the product away, you're still going to have to deal with it for weeks or months.

In their report, published in the Archives of Internal Medicine, Jones and his team point out that the product had been on the market for 12 years with no reports of problems. The Food and Drug Administration determined that a human error by one of the company's suppliers was behind the selenium overage. Phone numbers listed for the maker of the products, Woodstock, Georgia-based Total Body Essential Nutrition, were out of service.

This is more of a rarity than the usual thing, says Dr. William Obermeyer, vice president of research at Consumerlab.com, an independent company that tests the quality of health and nutritional products.

Still, at the time of the 2008 poisonings, the FDA was phasing in rules requiring supplement makers to use good manufacturing practices, said Obermeyer, who previously worked at the FDA. Good manufacturing practices mean a company must have systems in place to ensure that the identity, purity, strength, and composition of their products are consistent, according to the FDA Web site; the rules also require companies to test any ingredients that they obtain from other sources.

Whether those rules would have helped prevent the selenium poisonings is unclear, Obermeyer said. Because the FDA doesn't specify the types of tests companies need to do, Consumerlab.com president Dr. Tod Cooperman said, there are still plenty of holes in the process that can allow contaminated or adulterated products to make it onto the market. The FDA certainly doesn't have the manpower to check on many companies, he added. It's doing spot checking now.

And there is currently no easy way for consumers to make sure that the supplements they see on health food store shelves are safe, Cooperman added; in a recent survey, Consumerlab customers reported using 1,100 different brands of supplements. I think it's hard for anyone to keep track of all the brands and products out there, he said. They don't have to register anywhere to sell these products.