Laboratory analysis by the California Animal Health & Food Safety Laboratory found detectable
levels of arsenic in eight of the nine kelp herbal supplements, ranging from 1.59 ppm to 65.5
ppm by dry weight. The arsenic concentrations of the eight supplements with detectable levels
were 1.59, 2.28, 9.55, 9.97, 10.5, 24.1, 34.8, 65.5; median value was 10.23 ppm. One of the nine
samples was below the method detection limit of 0.010 ppm. The 3 samples from the kelp
supplement consumed by our patient throughout the duration of her symptoms showed arsenic
concentrations of 34.8, 2.28, and 1.59 ppm.
A recent analysis of ayurvedic herbal medicine products showed 20% of products tested
contained heavy metals. Detectable arsenic levels in six of seventy samples ranged in
concentrations from 37 ppm to 8,130 ppm (Saper et al. 2004). While the kelp samples we
analyzed were consistently elevated, the concentration of arsenic in our samples was
considerably lower than previously documented concentrations in herbal remedies (Mitchell-
Heggs et al. 1990, Saper et al. 2004, Tay and Seah 1975). This raises the concern that chronic
exposure to contaminated supplements even with moderately elevated arsenic concentrations
could still be toxic. None of the supplements contained labeling information regarding the
possibility of arsenic or other heavy metal contamination.
The FDA has set tolerance levels for arsenic in food products. These permissible levels range
from 0.5 ppm in eggs and uncooked edible tissues of chickens and turkeys, to 2 ppm in certain
uncooked edible by-products of swine. The concentration of arsenic found in seven of the nine
supplements exceeded the FDA tolerance level of 2 ppm.
Regulation and Standards of Homeopathic Remedies:
In 1998, the California Department of Health reported that 32% of traditional Asian medicines
sold in the state contained heavy metals (including lead, mercury and arsenic) or undeclared
pharmaceuticals (Ko 1998). While this case report focuses on the potential for arsenic
contamination in herbal supplements, lead exposure from supplements is also of increasing
concern (Mattos 2006). Labeling information provides little warning; two-thirds of homeopathic
medicines sampled contained arsenic levels higher than indicated on the label (Kerr and Saryan
Commenting on DSHEA, former FDA Commissioner David A. Kessler, MD, JD, stated that “the
Act does not require that dietary supplements be shown to be safe or effective before they are
marketed. The FDA does not scrutinize a dietary supplement before it enters the marketplace”
(Kessler 2000). Instead, Kessler noted, the FDA must rely on adverse event reports to determine
product safety and efficaciousness. As a result, dietary supplements such as herbal therapies are
now subject to lower safety standards than food additives
. A review of current regulation of
botanical medicines warns that “consumers are provided with more information about the
composition and nutritional value of a loaf of bread than about the ingredients and potential
hazards of botanical medicines” (Mitchell-Heggs et al. 1990).
Heavy metal intoxication should be suspected in a patient presenting with idiopathic neuropathy.
When neuropathy is accompanied by an elevated urinary arsenic level, it is crucial that the
physician determine the source of the arsenic (Walkiw and Douglas 1975). Our patient, Ms. KB,
had complete resolution of her symptoms and was able to return to work within weeks of
discontinuing her kelp supplements. Her urine arsenic levels returned to normal within two
months of the initial diagnosis. Given the nature of her symptoms and the temporal association
of her kelp ingestion with the occurrence and resolution of the symptom (an association
supported by urinary arsenic levels which were elevated as her kelp ingestion increased), we
believe that there was a causal association between her ingestion and symptoms. There was also
clear biological plausibility in this case; arsenic is known to cause the symptoms observed in our
patient, and previous studies have demonstrated toxicity from intake of dietary herbal
supplements. We were unable to identify any other probable dietary or environmental exposure.
We recognize, however, that the estimated dose of her exposure in this case was based on limited
analyses, and was therefore approximate.
Our finding that eight of the nine commercially available kelp supplements contained detectable
levels of arsenic is a cause for concern. It appears from our results that there is little consistency
in the arsenic content of the kelp supplements from batch to batch. Three samples, all from the
same bottle, showed variability in contamination ranging from 1.59 ppm to 34.8 ppm of arsenic.
It is unlikely that people are aware of the potential exposures they receive from herbal
supplements. Not one of these products had labels indicating the possibility of arsenic and other
heavy metals in the kelp. It is unfortunate that a therapy which is advertised as contributing to
“vital living and well-being” would have potentially unsafe levels of arsenic.
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-medication
in the general public, it is prudent that companies demonstrate safety and efficacy before their
products are placed on the market. Concentrations of materials contained in the preparations, as
well as expected benefits and potential side-effects, should be studied, standardized, monitored
and accurately labeled.
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