A study of 21 health food stores and 21 pharmacies found health food stores were more likely to recommend products that could react with a prescribed medication.

Although pharmacies did better than health stores, a third of pharmacies gave inappropriate advice.

In the study, co-authored by researchers at the Medical Research Institute of New Zealand, University of Otago, and Capital and Coast District Health Board, a mystery shopper visited the stores and complained of tiredness. The shopper also explained to staff that he’d been taking warfarin over the previous two months for treatment of a pulmonary embolus (a blockage in the lung).

The study found the health food stores recommended more products than the pharmacies – and that they were more likely than the pharmacies to recommend products that could interact with warfarin.

Only four of the health food stores (and 13 of the pharmacies) either recommended a product that wouldn’t interact with the warfarin, or made no product recommendation.

The study's authors say the results highlight the need for formal training of retail staff in health food stores and pharmacies, and better regulation of natural health products.

Revised proposals to tighten controls on these products were released in 2010 with legislation expected to be introduced this year. But little progress has been made.

More from consumer.org.nz

• Natural health products - our July 2010 look at plans to regulate natural health products.

Got a question or comment on this topic? Share your views and experiences with other Consumer members...