TV food expert Nikki Hart says she's "not the poster girl" for controversial chemical aspartame, despite being paid to promote it by Diet Coke.
The nutritionist and presenter of Eat Yourself Whole and The Fat Chance has been criticised over her efforts to ease fears about the alternative sweetener.
"There has been a lot of scaremongering about aspartame so Diet Coke asked me to provide knowledge about it," she said.
"I will promote wholefoods, I will promote anything that I believe is safe, which aspartame has proven to be."
Aspartame is found in an array of food and drinks and is often labelled 951 on products in New Zealand.
Hart agreed to join forces with Coca-Cola Oceania to dispel claims it has adverse side-effects but refused to reveal how much she was being paid.
"I am there to advise about all sweeteners and because they know that I am on the Low Calorie Advisory Sweeteners Board, they felt I had the most up-to-date information about it.
"I wish people would see that I'm not out there to get paid gazillions of dollars by a company to prove a topic.
"I'm not the poster girl for anybody. I am not in anyone's pocket."
Aspartame, which is 200 times sweeter than sugar, has been the subject of controversy for years but has been found to be safe for human consumption by more than 90 countries worldwide.
The Italian-based Ramazzini Foundation of Oncology and Environmental Sciences has released two reports since 2005, each claiming to have found a significant increase in lymphomas and leukaemias in rats exposed to a diet containing aspartame.
After assessing the study, the European Food Safety Authority concluded there was no need to further review aspartame's safety or revise the acceptable daily intake.
A study of drink consumption by almost half a million Americans carried out by the US National Cancer Institute found no relationship between aspartame use and cancer in humans.
Hart said aspartame was a "very emotive" subject and until she found conclusive evidence it was unsafe she would not advise people to avoid it.
"This is the price you pay when you are asked for an opinion. Let's try and base it on current factual evidence."
New Zealand nutritionists and dietitians spoken to by the Herald on Sunday agreed aspartame was safe, but recommended a natural sweetener instead.
Frances Pitsillis, health expert on TV One's Breakfast show, said people should avoid "anything processed or artificial" if they could help it.
"We all know that big companies will pay someone a lot of money to say what they want to say.
"I personally wouldn't recommend aspartame. If you have to have an artificial sweetener in your [drink], Stevia is a natural sweetener so go for the natural one."
Angela Berrill, of ABC Nutrition in Auckland, said people should try to reduce their preference for sweet foods and drinks rather than take artificial sweeteners.
"Ideally, people need to be steered away from sugary drinks regardless whether it is artificially or naturally sweetened."
The Soil and Health Association of New Zealand has been campaigning against the use of aspartame and claims its efforts helped reduce Diet Coke sales last year.
"Aspartame is not doing us any good at all, but there are some people who are particularly sensitive to it," said spokesman Steffan Browning.