The products: At a time when heavy metals are showing up in tuna steaks and toy cabooses, it's only natural to worry about the metals in our bodies. The good news: Americans have much less lead in their blood than they did a couple of decades ago, back in the days of leaded house paint and gasoline. And though mercury levels seem to be slowly climbing, cases of acute poisoning severe enough to cause symptoms (such as upset stomach and breathing troubles) are still very rare.
If you're worried about a metal overload, you might be tempted to try one of many over-the-counter chelation agents that promise to bind heavy metals and flush them out of the body. Chelation products come in many guises, including DMSA (dimercaptosuccinic acid) and EDTA (ethylene diamine tetra-acetic acid).
DMSA and EDTA are mainstream medications. A prescription version of DMSA -- brand name Chemet -- is used (rarely) to treat severe overdoses of lead. Some poisoning centers treat metal poisoning by giving EDTA through an IV.
The compounds have also made their way to heath-food stores, vitamin aisles and websites. A company called Vitamin Research Products offers 45 100-milligram capsules of DMSA for about $40. Users are instructed to take two or three capsules each day. (The company also sells a low-dose, 25-milligram version "with children in mind.")
FoodScience of Vermont sells a product called Chelation Factors that combines DMSA with cilantro, garlic, chlorella (a type of alga) and other ingredients. A one-month supply costs about $30. A company called Vibrant Life sells a one-month supply of Life Glow Basic capsules containing 400 mg of EDTA and other compounds for about $60. Phoenician Herbals sells 120 1,350-milligram EDTA capsules -- a two-month supply -- for about $20.
The claims: Chelation products claim to rid the body of heavy metals and the illnesses that supposedly go along with them. A website selling DMSA from Vitamin Research Products says that the product can help treat autism, the childhood developmental disorder that, according to the site, is linked to mercury in childhood vaccines. The Vibrant Life website claims that EDTA "reduces iron and heavy metal stores in the body" and helps treat clotting problems and "vascular disease."
The bottom line: Chelation is sometimes necessary to treat severe cases of metal poisoning, but it's "shocking and worrisome" that such products are sold over the counter, says Dr. Michael Shannon, chief of emergency medicine at Children's Hospital in Boston and a specialist in lead poisoning.
According to Shannon, chelation agents have several drawbacks that make them too risky to use without close guidance from a physician. Compounds such as DMSA and EDTA aren't very choosy when it comes to binding to metals, so they'll wash out important metals such as iron, calcium and manganese along with mercury and lead. Chelation agents can also be toxic to the liver. And if a person really does have an overload of lead or mercury, Shannon says the top priority should be removing the source of the metal, not taking a pill. If chelation is necessary, it should be done by a doctor who specializes in treatment for poisoning.
EDTA capsules have another shortcoming, Shannon says. Unlike DMSA, the compound isn't easily absorbed through the digestive system, which is why doctors deliver it through an IV. "There's no evidence that it works when taken orally," he says.
"This whole chelation therapy craze is one of my pet peeves," says Hilary Godwin, chair of environmental health sciences at UCLA. "It's not something you should be doing on your own." Because of its risks, doctors would never consider using chelation except in the most dire cases of metal poisoning, she says. "I can't even imagine how many fish you'd have to eat in order to need chelation [for mercury]."
Even when properly used, chelation has its limits. Godwin points to a 2004 study in the journal Pediatrics that found treatment with oral DMSA didn't improve the thinking skills or behavior of children with moderate to high levels of lead in their blood.
Godwin, mother of an autistic son, says she is especially irked by claims that chelation can treat autism, claims that aren't supported by evidence, she adds. "Parental anxiety drives people to try anything."
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