The study, published in the recent issue of the Canadian Medical Association Journal (November 25, 2003) was carried out last year, to assess the impact of Health Canada's advisory in February and again after the August 2002 ban on the sale of herbal kava.
One month after the advisory, 22 (67 per cent) of 33 health food stores approached were selling kava. Two months after the stop-sale order, 17 (57 per cent) of 30 stores continued to sell kava, reported Edward Mills and colleagues from the Canadian College of Naturopathic Medicine.
Kava is used to treat anxiety symptoms but it has been banned in a number of countries worldwide after its use was associated with fatal liver toxicity. In Europe industry members are campaigning to restore sales of the product as they claim that scientific evidence backing its ban is flawed.
In the study, trained simulated customers were instructed to ask an employee of the identified health food stores for a treatment for anxiety one month after the federal advisory. The simulated customer inquired about the possibility of interactions between the recommended treatment and other drugs.
The customers also inquired about the employee's training in complementary and alternative medicine.
In November 2002, more than two months after the federal ban, the simulated customers revisited their respective health food stores to determine whether kava could still be purchased. They then asked employees if they knew about the product's safety record. Among the 17 stores still selling kava after the ban, six (35 per cent) said that they knew about the federal ban.
While the authors acknowledged that one or two months may have been insufficient time to allow health food stores to respond to the advisory or ban, they added that health food stores may need to be better informed about the sale of restricted natural health products.
In a commentary on the study, Heather Boon and Albert Wong from the University of Toronto write that it raises questions of "how Health Canada can enforce its position on natural health products and what the impact on the health of Canadians might be if stop-sale orders are ignored.
"Kava represents an important test case with respect to Health Canada's approach to natural health products," write the authors.
Canadian law currently requires kava to be registered as a drug.However, in January 2004 new natural health product regulations come into effect under the auspices of the Natural Health Products Directorate of Health Canada. Kava could then return to the market, provided the safety concerns can be mitigated through appropriate use of warning labels or other measures.
But Boon and Wong write that the sale of kava in health food stores two months after a stop-sale order, reflects the confusion surrounding the regulation of herbs and its enforcement and suggests the need for regulation not only of the products themselves, but also at the point of sale.
"Informing consumers of the potential risks of nonprescription pharmaceuticals through product labelling is a good idea, but the differing opinions on the evidence of kava toxicity demonstrate that the assessment of risks and benefits can be complex, and it might be a considerable challenge to adequately equip the public to make informed decisions about whether or not to use such products," they argue.
More than 35 per cent of Canadians take nutrient supplements and 15 per cent use herbal products, according to figures cited by Mills and colleagues.