Study reports arsenic in kelp supplements

The risk assessment, published in this month's journal of Environmental Health Perspectives , posited from the outset that dietary herbal supplements can cause inadvertent arsenic toxicosis.

This was based on the case of a 54-year-old woman who was found to have a higher than normal arsenic intake, which UC Davis attributed to her kelp supplements.

Even though the sample size tested is small, the study does not present a reliable face of the industry and could serve to persuade formulators to more clearly label or test herbal ingredients for traces of contaminants.

"Given the numerous studies demonstrating unsafe levels of heavy metals in dietary herbal preparations, the growing number of case reports connecting heavy metal toxicities to ingestion of herbal dietary supplements, and the growing popularity of herbal remedies for self-mediation in the general public, it is prudent that companies demonstrate safety and efficacy before their products are placed on the market," concludes the case report.

The UC Davis researchers tested samples from three different batches of the nine supplements selected from local health food outlets.

They determined the arsenic content by means of inductively coupled argon plasma (ICP) using the identical hydride vapour generation method.

According to the report, the arsenic content found in the supplements ranged from 1.59ppm to 65.5ppm by dry weight, and the median value was set at 10.23ppm.

While the case report fails to clearly define the level of arsenic content at which a dietary supplement may considered harmful, it does indicate the US Food & Drug Administration (FDA)'s tolerance range for arsenic in various foods.

This diverges from 0.5ppm for eggs and raw poultry meat, to 2ppm for edible swine by-products.

According to the researchers, the three samples of the brand of kelp supplements consumed by the woman throughout the progression of her symptoms revealed arsenic concentrations of 34.8, 2.28, and 1.59ppm.

"It is unlikely that people are aware of the potential exposure they receive from herbal supplements," states the report.

"Not one of these products had labels indicating the possibility of arsenic or other heavy metals in the kelp."

The report does not reveal the product names.

The issue of high levels of contaminants in supplements has dogged the dietary supplement industry who has defended itself as a whole by denouncing testing methods used, sourcing of materials, or the influence of heavy metals consumed from other sources.

In January, ConsumerLab.com reported 11 out of 21 dietary supplement it had tested had high lead content.

The companies involved defended that neither test methods were not revealed, nor was the selection process for the products.

In addition, they pinpointed ConsumerLab's use of California's particularly stringent regulations as a benchmark for the results.