UC Davis Study Finds High Arsenic Levels In Herbal Kelp Supplements
Main Category: Complementary Medicine / Alternative Medicine News
Article Date: 10 Apr 2007 - 14:00 PDT
A study of herbal kelp supplements led by UC Davis public health expert Marc Schenker concludes that its medicinal use may cause inadvertent arsenic poisoning and health dangers for consumers, especially when overused. Schenker and two researchers evaluated nine over-the-counter herbal kelp products and found higher than acceptable arsenic levels in eight of them.
The new study, published in the April issue of Environmental Health Perspectives (http://www.ehponline.org/
) was prompted by the case of a 54-year-old woman who was seen at the UC Davis Occupational Medicine Clinic following a two-year history of worsening alopecia (hair loss), fatigue and memory loss.
The woman's symptoms had begun with minor memory loss and fatigue. Her primary care physician initially found nothing wrong with the woman and thought the symptoms were related to menopause. With no specific diagnosis or treatment recommendations, the patient started taking a variety of herbal therapies, including a kelp supplement, fish oil, ginkgo biloba and grape seed extract. The kelp supplement was the only herbal therapy she took regularly throughout the course of her illness.
To assess the concentration of arsenic present in commercially available kelp supplements, the UC Davis investigators purchased nine over-the-counter kelp samples from local health food stores. Included were samples from three different batches of the product consumed by the patient.
The researchers sent the samples to the California Animal Health & Food Safety Laboratory in Davis, which operates in partnership with UC Davis, the California Department of Food and Agriculture and others to provide specialized testing that helps protect both human and animal health. Investigators found detectable levels of arsenic in eight of the nine kelp supplements by using a hydride vapor generation method with an inductively coupled argon plasma spectrometer. Seven of the supplements exceeded the tolerance levels for food products set by the U.S. Food and Drug Administration (FDA).
"Part of the problem," said Schenker, "is that the FDA has limited control over dietary supplements. It can't scrutinize products like herbal kelp before they enter the market, so it has to rely on adverse reports to determine product safety."
He noted that none of the kelp products in the study had labels indicating the presence of arsenic, nor were there any warnings about the potential dangers of ingesting large quantities of the supplement.
Arsenic is a heavy metal that occurs naturally in the environment and as a by-product of some agricultural and industrial activities. Due to high arsenic concentrations in algae and marine micro-organisms, seafood is the highest dietary source of arsenic for consumers. While long-term human exposure to arsenic from food sources such as fish does occur, it is usually significantly lower than anything approaching toxic levels. How-ever, dietary supplements, which are largely unregulated, have raised health concerns.