Tate & Lyle, the maker of the big-selling artificial sweetener sucralose, has alleged a consumer health campaign against the product is being orchestrated by rivals in the sugar industry.
The company's claim comes as a campaign group in the US asked regulators to pull sucralose off the market and investigate whether it causes stomach pains and other side effects.
Tate & Lyle shares fell 11p to 564.5p yesterday on news that Citizens for Health, a group which promotes alternative medicines and natural health foods, has lodged its petition with the Food & Drug Administration.
Citizens for Health's chairman, Jim Turner, said the organisation had been contacted by consumers who claimed sucralose was causing them gastrointestinal problems, headaches and rashes. The organisation had been further alarmed to see that hundreds of people were talking about similar problems on anti-sucralose websites.
Sales of the sweetener have exploded in the past few years, and it is used widely as an ingredient in low-calorie drinks by Coca-Cola and Pepsi and in foods. Tate & Lyle's ingredients business sells the product in industrial quantities, and it is also sold to consumers under the brand name Splenda by the company's US partner, Johnson & Johnson.
Tate & Lyle made profits of £33m from sucralose in the six months to last September, according to its most recent results, up 10 per cent and accounting for about a fifth of group profit.
Tate & Lyle said 100 studies over 20 years had shown sucralose to be safe, and the concerns are being stoked by a website - truthaboutsplenda.com - which is paid for by the Sugar Association. Sugar producers are losing market share to sucralose, which has a flavour particularly close to sugar but with virtually no calories.
The company pointed out that a press conference to launch Citizens for Health's petition had been promoted by Qorvis, the public relations firm hired by the Sugar Association to set up the website and to run the anti-sucralose campaign. The petition is "another tactic in a long chain of orchestrated events led by organisations representing bodies with clear commercial interests", a Tate & Lyle spokesman said.
Mr Turner said Citizens for Health had not been funded by the Sugar Association, although it did support the use of sugar and other natural products in preference to artificial sweeteners. The FDA said it would review Citizens for Health's petition, which opens up a regulatory front in the increasingly bitter marketing battle over sucralose.