Herbal kelp supplements may cause inadvertent arsenic poisoning, say University of California, Davis (UC) researchers. UC's Marc Schenker and co-researchers evaluated nine over-the-counter herbal kelp products and found higher than acceptable arsenic levels in seven of them.
Schenker's study 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.
The woman's short- and long-term memory gradually became so impaired that she could no longer remember her home address. She also reported having a rash, nausea and vomiting, which forced her to leave a full-time job. The woman actually increased her dosage of kelp from two to four pills a day after her doctors still could not find a clear diagnosis.
Finally, tests revealed arsenic in the patient's blood and urine. At her physician's suggestion, the patient discontinued the kelp supplement. Within weeks, her symptoms disappeared, and within several months arsenic was no longer detected in her urine and its levels had dropped significantly in her blood.
In the new study, Schenker assessed 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. They found detectable levels of arsenic in eight of the nine kelp supplements. Seven of the supplements exceeded the tolerance levels for food products set by the 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. It's unfortunate that a therapy that's advertised as contributing to 'vital living and well-being' would contain potentially unsafe levels of arsenic. Consumers won't find such label information on these products, so they could end up like that woman in our study who consumed dangerously high amounts of a toxic substance without realizing it."
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Source: University of California, Davis - Health System