Three years into an extensive revamp of the Heart-Foundation's Pick the Tick scheme, it has come under fire from experts who say it is confusing, ineffective, too commercially driven, and needs to go.

Under the scheme, products that meet guidelines for healthy ingredients receive a Heart Foundation tick.

The foundation is re-evaluating the programme, toughening the criteria products must meet to gain the tick of approval.

The foundation claims 69 per cent of shoppers are swayed by the tick and says the programme has eradicated thousands of tonnes of fat, sugar and salt from New Zealanders' diets.

But even before the giant task of toughening up the tick is finished next year, setting new levels to further restrict the amount of harmful substances in food, the scheme is earning a big cross from disgruntled anti-obesity groups and dietitians.

They have long challenged it for the way it gives a tick to foods that seem healthy but which still contain what they believe are unhealthy levels of fat, salt or sugar.

Anti-obesity groups have pitched the idea of a traffic-light system, already launched in Britain, to a health select committee inquiry into obesity and Type 2 diabetes.

The red-orange-green sticker system would be mandatory and would show consumers which foods to eat often, sometimes or only very occasionally.

The Heart Foundation tick is currently awarded to 900 "healthier" products in particular food categories. Under the scheme, companies must submit their products for testing and, if ticked, pay 0.25 per cent of sales to the foundation.

It's costly - three years ago Sanitarium refused to pay a $60,000 tick fee for top-selling Kiwi stalwart Weetbix and reported no drop in sales.

But critics also say confusion sets in when a tick gives the impression that a product is healthy, but means only that it is among the healthiest products in that food group.

They also point out that many companies are choosing not to take the tick and that even companies with obviously healthy products have chosen not to embrace it.

In 2003, George Weston Foods went tick-less on its Ploughmans bread range - a smart business decision, marketing general manager Andrew Atkinson later told a reporter.

"It is expensive and [the Heart Foundation] are making it more and more difficult [to qualify]."

Dietitians grumble about the tick appearing on foods such as pies, icecream, flavoured milk, oven fries and chicken nuggets.

Auckland dietitian Elizabeth Carnachan said people still viewed the tick as a go-ahead to eat unhealthy food and it was confusing that ticks were on foods such as icecream and pies.

"They think, 'Oh, yeah, that's great, I can eat as much as I like'. It's a fallacy. I think it's wrong. We need the Heart Foundation to explain more clearly exactly what the tick means."

Dr Robyn Toomath, of the Fight the Obesity Epidemic group, said until recently she did not realise the tick was for "healthy in a particular category" rather than generally healthy.

She worried that other consumers had the same impression - for example, a shopper spotting a tick on a packet of wedges could easily assume they were healthy enough to eat every day.

"The problems with Pick the Tick are that producers have to pay to be part of the programme. And they compare within categories - so they tick the best form of, for example, butter chicken. It gives a more reassuring picture than it should do for some foods."

Dr Toomath liked the idea of consumers being able to identify healthy foods, but said the tick information was "incredibly incomplete" and "could be vastly improved".

Dr Gay Keating, director of the Public Health Association, said the tick had been a brilliant concept that had taught the industry three things: people recognised a symbol; the categories system was too complex; and food labelling needed to be compulsory.

She believed the traffic-light and tick systems could work well alongside one another on packaging.

Ian Mathieson, divisional manager of the tick programme, said it was too early to comment on the proposed traffic-light scheme as it had been used only in workplace cafeterias, university and school tuck shops - not supermarkets or the wider food environment.

"It is also unclear how a traffic-light system would encourage the food industry to improve the food supply or how it would positively change consumer purchasing behaviour as the tick has done," he said.

He cited Calci-Yum dairy food as an example, saying under the new, stricter criteria it had halved fat and saturated fat levels, removing eight tonnes of fat annually from across its product range.

Since the review began, 14 new cereal bars had been developed, all with one-third less energy than the market average.

In one year, 33 tonnes of salt had been removed from our bread, cereal and margarine.

Mr Mathieson said pies provided one example of the importance of signposting healthier choices. Kiwis down 60 million pies each year. Those that earned the tick had shed about half their saturated fat and salt.