Natural health products should have labels outlining the level of evidence of any health claims, Sir Peter Gluckman says.

The prime minister's chief science advisor today told Parliament's health committee consumers have ''a right know what evidence exists'' to support any claims, whether it was based on science or traditional use.

Gluckman expressed his ''personal views'' in his submission on the Natural Health Products Bill.

The bill, which was one of the shared policy initiatives agreed by National and the Greens, aimed at giving the public assurances about safety and efficiency of natural health products.

It would provide a list of prohibited ingredients and an open-ended list of ingredients that could be used.

The bill would also require sponsors to declare that they hold evidence to support the health benefits claimed for their products and provide the evidence if requested by the regulatory authority.

But Gluckman said the evidence summary should be made publicly available through a database.

If there was scientific evidence, which should also be defined in the bill, it would be ''ideal'' for the label to state the quality of proof with a scale from low to high.

''The quality of the regulations prescribing the standards for evidence required to support a health benefit claim is absolutely key to providing the public with confidence in purchasing these products,'' Gluckman said.

''Without clarity as to the standards to be used, there is the potential for New Zealand's reputation to be harmed.''

He said health products regulations in Australia and Canada were highly prescriptive about acceptable levels of evidence.

''I would strongly recommend that regulations in New Zealand are equally robust.''

Gluckman told the committee he was also concerned about the bill's name.

''It is unfortunate that the bill has progressed so far with such a misleading title,'' he said.

''The use of 'natural' draws on the naturalistic fallacy that what is found in nature is somehow better - even though many 'natural' products are highly toxic.''

He said the bill also covered ''synthetic'' equivalents.

But he was more concerned with the use of the word ''health''.

He said it carried the presumption of proof of effect, which may not exist for many of the products.

When asked what he would call the bill however, Gluckman said: ''I don't know what a better name is, to be honest''.