Health benefits and natural products

The Natural Health and Supplementary Products Bill is back from the Health Committee. From the Principles section of the Bill:

(c) that natural health and supplementary products should be accompanied by information that—

   (i)is accurate; and

   (ii)tells consumers about any risks, side-effects, or benefits of using the product:

(d)that health benefit claims made for natural health and supplementary products should be supported by scientific or traditional evidence.

There’s an unfortunate tension between (c)(i) and (d), especially since (for the purposes of the Bill) the bar for ‘traditional evidence’ is set very low: evidence of traditional use is enough.

Now, traditional use obviously does convey some evidence as to safety and effectiveness. If you wanted a herbal toothache remedy, you’d be better off looking in Ngā Tipu Whakaoranga and noting traditional Māori use of kawakawa, rather than deciding to chew ongaonga.

For some traditional herbal medicines there is even good scientific evidence of a health benefit. Foxglove, opium poppy, pyrethrum, and willowbark are all traditional herbal products that really are effective. Extracts from two of them are on the WHO essential medicines list, as are synthetic adaptions of the other two. On the other hand, these are the rare exceptions — these are the  ones where a vendor wouldn’t have to rely only on traditional evidence.

It’s hard to say how much belief in a herbal medicine is warranted by traditional use, and different people would have different views. It would have been much better to allow the fact of traditional use to be advertised itself, rather than allowing it to substitute for evidence of benefit.  Some people will find “traditional Māori use” a good reason to buy a product, others might be more persuaded by “based on Ayurvedic principles”.  We can leave that evaluation up to the consumer, and reserve claims of ‘health benefit’ for when we really have evidence of health benefit.

This isn’t treating science as privileged, but it is treating science as distinguished. There are some questions you really can answer by empirical study and repeatable experiment (as the Bill puts it), and one of them is whether a specific treatment does or does not have (on average) a specific health benefit in a specific group of people.