AHPA Challenges Kelp Case

SILVERSPRING, Md.—The American Herbal Products Association (AHPA) countered a recently published case report involving kelp toxicity. The report, published in the journal Environmental Health Perspectives (115, 4:606-8, 2007) concluded a kelp supplement may have caused arsenic poisoning; however, AHPA noted the subject ignored a specific label caution and suggested iodine overdose was no less plausible an explanation for the observed symptoms.

The subject, a 54-year-old woman with a two-year history of worsening hair loss, memory loss and fatigue “initially took two tablets,” and later increased to “at least four pills per day,” even though the product was labeled to “not exceed” one tablet daily.

According to AHPA, “The authors fail to report that the product was used at two- to ‘at least’ four-times the suggested amount; [this is] of potential significance due to the naturally occurring presence of iodine in kelp.” Each tablet of the product was labeled to contain 225 mg of iodine (Food and Drug Administration, 21, 1, Sec. 172.365, 2006). Federal regulations limits daily ingestion of kelp to an amount that provides no more than 225 mcg of iodine. “Taking iodine ‘at least’ four times this product’s recommended dose must be considered in evaluating the observed symptoms,” AHPA continued. The letter also observed that most of the woman’s symptoms — weakness, nausea, vomiting, and possibly erythema, as well as headache and diarrhea — are associated with iodine toxicity, although usually at higher doses, and that cause should also be considered.

The AHPA letter also stated, “This report did not differentiate between organic and inorganic arsenic.” Arsenic, commonly found in seaweeds used as food and, with the exception of hijiki (Hizikia fusiformis), is generally the organic form, recognized as less toxic than the inorganic form (Food Chem Tox; 45:1263-7, 2007). The European Pharmacopoeia allows up to 90 ppm arsenic in kelp used in medicinal products (European Pharmacopoeia 5: 1869-1870, 2006), while food regulators have advised that consumption of hijiki —but not kelp or other seaweeds—be avoided due to arsenic concentrations in this species, according to the Food Standards Agency of London.