The food industry is not doing enough to cut levels of dangerous fats in foods, consumer experts have warned.
The fats can affect heart health
An investigation by Health Which? magazine says trans fats, or trans fatty acids, are found in many different kinds of foods.
Doctors have found even a small reduction in trans fats can cut coronary heart disease by a quarter.
But Health Which? said the food industry was not doing enough to minimise the risk.
Trans fats are created in the process of making hydrogenated fats and oils, formed when hydrogen is bubbled through vegetable oil.
Hydrogenated fats are used to extend the shelf life of products.
However, they have no nutritional benefits, and many health experts believe they are more harmful than the better-known saturated fats.
Health Which? says the range of products that trans fats can be found in include those aimed at the "healthy" market, as well as a wide variety of biscuits, cakes, crackers, packet soups and pies.
Many takeaway fast foods also contain hydrogenated fats.
Research published in The Lancet two years ago showed reducing consumption of trans fats by 2.4% of total calorie intake can cut deaths from coronary heart disease by a quarter.
Health Which? contacted three supermarket chains to ask about their use of hydrogenated fats in their own-brand products.
Safeway said its policy is to limit the use of hydrogenated fats wherever possible, and that hydrogenated oil is always listed in ingredients lists.
But Health Which? criticised the company for not including the information in nutrition labelling. Safeway stated that its research shows consumers are more interested in other information.
Waitrose said it includes hydrogenated oil in its ingredients lists and is guided by government advice.
The company said it may take steps to limit hydrogenated fats in its own-brand products, should government guidelines change or technology provide suitable alternatives.
Sainsbury's said that products in its 'health food selection' must not contain hydrogenated fats. However, they are used in some own-brand products and are always included in ingredients lists.
On its website, the Food Standards Agency warns: "The trans fats found in food containing hydrogenated vegetable oil are harmful and have no known nutritional benefits.
"They raise the type of cholesterol in the blood that increases the risk of coronary heart disease. Some evidence suggests that the effects of trans fats may be worse than saturated fats."
It said it has no plans to review its policy as there is no customer demand or government requirement to do so.
Sue Freeman, acting editor of Health Which? said: "There is now strong evidence that trans fats are harmful and that cutting down on them, together with saturated fats, could help reduce your risk of heart disease.
"While it may be difficult to eat a diet totally free of trans fats, where possible consumers should try to replace hydrogenated fats with unsaturated fats and oils."
She added: "Our research suggests that the food industry isn't taking the issue seriously enough.
"Labelling must be improved to provide consumers with more information about trans fats.
"But it is also important that the food industry makes greater efforts to reduce the levels found in foods, particularly as they have no known nutritional benefits whatsoever."
'We don't know'
Professor Daan Kromhout, who led the Lancet study, said: "I would say there are currently two crucial issues facing countries like the UK and the Netherlands.
"One is to increase the consumption of omega 3 fatty acids. The other is to get the intake of trans fats as close to zero as possible."
But Dr Rudolph Riemersma, of the Cardiovascular Research Unit at the University of Edinburgh, pointed out that a major study in eight European countries showed no significant links between trans fats and the risk of having
a heart attack.
He told Health Which?: "Some studies show an association between trans fats and heart disease, others don't. We should tell the public we don't know."
Belinda Linden of the British Heart Foundation told BBC News Online: "Although it is important to manage trans fat intake, it is the reduction of saturated fat in the diet that will have the main effect on lowering blood cholesterol - one of the main risk factors for coronary heart disease."
She added: "Food labelling is crucial in enabling people to manage their trans fats intake. Hydrogenated fats are included in ingrediants lists on products and the lower down the list they appear, the smaller their content."