Herbal :: High arsenic levels in herbal kelp supplements

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 HealthPerspectives (http://www.ehponline.org/) was prompted by the case of a54-year-old woman who was seen at the UC Davis Occupational Medicine Clinicfollowing a two-year history of worsening alopecia (hair loss), fatigue andmemory loss.

The woman’s symptoms had begun with minor memory loss and fatigue. Herprimary care physician initially found nothing wrong with the woman andthought the symptoms were related to menopause. With no specific diagnosisor treatment recommendations, the patient started taking a variety ofherbal therapies, including a kelp supplement, fish oil, ginkgo biloba andgrape seed extract. The kelp supplement was the only herbal therapy shetook regularly throughout the course of her illness.

Over a period of several months the woman’s short- and long-term memorybecame so impaired that she could no longer remember her home address. Shealso reported having a rash, nausea and vomiting, which made it verydifficult to work and forced her to leave a full-time job. The womanactually increased her dosage of kelp from two to four pills a day afterher doctors still could not find a clear diagnosis.

Subsequent laboratory tests finally revealed arsenic in the patient’s bloodand urine. At her physician’s suggestion, the patient discontinued the kelpsupplement. Within weeks, her symptoms disappeared, and within severalmonths arsenic was no longer detected in her urine and its levels haddropped significantly in her blood. She later was referred to the UC DavisOccupational Medicine Clinic as a follow-up to her primary care.

“It’s unfortunate that a therapy that’s advertised as contributing to’vital living and well-being’ would contain potentially unsafe levels ofarsenic,” said Schenker, who is a professor of Public Health Sciences and aleading authority on occupational and environmental diseases andrespiratory illness. “Concentrations of materials contained in herbalsupplements, including both the expected benefits and potential sideeffects, should be studied, standardized, monitored and accuratelylabeled.”

To assess the concentration of arsenic present in commercially availablekelp supplements, the UC Davis investigators purchased nineover-the-counter kelp samples from local health food stores. Included weresamples from three different batches of the product consumed by thepatient.

The researchers sent the samples to the California Animal Health & FoodSafety Laboratory in Davis, which operates in partnership with UC Davis,the California Department of Food and Agriculture and others to providespecialized testing that helps protect both human and animal health.Investigators found detectable levels of arsenic in eight of the nine kelpsupplements by using a hydride vapor generation method with an inductivelycoupled argon plasma spectrometer. Seven of the supplements exceeded thetolerance levels for food products set by the U.S. Food and DrugAdministration (FDA).

“Part of the problem,” said Schenker, “is that the FDA has limited controlover dietary supplements. It can’t scrutinize products like herbal kelpbefore they enter the market, so it has to rely on adverse reports todetermine product safety.”

He noted that none of the kelp products in the study had labels indicatingthe presence of arsenic, nor were there any warnings about the potentialdangers of ingesting large quantities of the supplement.

Arsenic is a heavy metal that occurs naturally in the environment and as aby-product of some agricultural and industrial activities. Due to higharsenic concentrations in algae and marine micro-organisms, seafood is thehighest dietary source of arsenic for consumers. While long-term humanexposure to arsenic from food sources such as fish does occur, it isusually significantly lower than anything approaching toxic levels.How-ever, dietary supplements, which are largely unregulated, have raisedhealth concerns.

There have been a number of published studies highlighting cases in whichthe uses of homeopathic remedies to relieve everything from asthma torheumatoid arthritis have caused arsenic poisoning. Schenker’s findingsoffer a cautionary tale for consumers who use herbal treatments and dietarysupplements. The kelp samples analyzed in the study had consistentlyelevated levels of arsenic, but they were considerably lower thanpreviously documented concentrations found in other herbal remedies.

“What concerns me,” said Schenker, “is that chronic exposure tocontaminated herbal supplements, even those with moderately elevatedconcentrations of arsenic, can still be toxic. Consumers won’t find suchlabel information on these products, so they could end up like that womanin our study who consumed dangerously high amounts of a toxic substancewithout realizing it.”

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