What's the story with trans fats?

It sounds pretty harmless, but hydrogenated vegetable oil is perhaps the most controversial and potentially the most dangerous ingredient to be commonly used in the making of many of the foods stacked on our supermarket shelves today.

A decade ago it sat largely unnoticed on ingredient lists while all the negative attention was directed towards the E numbers which were said to cause everything from cancer to attention deficit disorder. But now hydrogenated vegetable oils, or trans fats, are taking centre stage after being linked to 30,000 fatal heart attacks annually in the US and accused of making a significant contribution to the dramatic increases in the level of obesity in the US and elsewhere.

Industrially produced trans fats, which are devoid of any nutritional value, are to be outlawed in New York restaurants this summer, while the sale of products containing more than 2 per cent of the fats has been banned in Denmark for three years. Certain retailers in Ireland have started removing them from their product lines and fast food chains are falling over themselves to make it clear they no long fry their food in the artery clogging gunk.

Industrially produced trans fats - small quantities naturally occur in meat and dairy products - were, for many years, considered to be a marvel that allowed producers to cheaply extend food's shelf life. For nearly 50 years the fats, made by mixing liquid vegetable oils with hydrogen and heating it in a process called partial hydrogenation, were added to an astonishing array of processed foods.

Then, in the 1990s, scientists made the link between them and heart disease. It was found that not only did trans fats increase the levels of LDL - the "bad" cholesterol which attaches itself to arteries causing atherosclerosis and heart disease. They also reduced the HDL cholesterol - the "good" cholesterol which keeps arteries clear.

The presence of high levels of trans fats in many processed foods features high on the the Irish Heart Foundation's (IHF) agenda. "We feel that the trans fats are a serious concern. As a nation we are eating more processed foods then ever now and there can be a high level of trans fats present in such foods," says IHF dietician Janis Morrissey. "Evidence clearly links these fats with an increased incidence of heart disease." She says that consumer awareness of the problem is low at present, but is optimistic the issue can be shifted higher up the agenda.

With that in mind, the IHF recently issued new guidelines on the amount of trans fats we should be consuming. It recommends a daily allowance of no more than 2 per cent or 50 calories of the daily energy intake - a long way short of the more than 300 calories of trans-fat-heavy foods we are estimated to consume daily. In the US the American Heart Association is even stricter and has lowered its recommended amount of trans fats to less than 1 per cent of total daily calories consumed.

These guideline recommendations are all well and good, but seeing as how the labelling of food products in Ireland can be ludicrously vague and the fats can be hidden in everything from ready meals to ice creams to chocolate bars, it is very difficult for consumers to tell with any degree of accuracy exactly how much of the stuff they are consuming.

One thing is clear, it's probably way too much. According to a study completed in 1996, the average Irish person consumes 5.4g of trans fats every day.

However, some volunteers surveyed consumed as much as 26g a day. The biggest source of trans fats was margarine spreads. Milk and meat were also a significant contributor for men, while women consumed significantly larger amounts through confectionery.

While there is no up-to-date information available, it is reasonable to suspect that, with the increased prevalence of ready meals and convenience food in our diet, the amount of trans fats we consume has increased.

WITH THIS LEVEL of consumption, it is unsurprising that the Department of Health has expressed concern that people may be unknowingly eating excessive amounts of trans fats. It has made a submission to the EU in conjunction with the Irish Food Safety Authority supporting a move to make listing trans fat content on food labels mandatory. It is, at least, a start.

Further baby steps have been taken by Fine Gael MEP Jim Higgins who has launched a campaign in Strasbourg aimed at getting trans fats labelled on food. Earlier this year he reminded the European Parliament, "Heart disease accounts for 1.9 million deaths in the European Union each year.

"Trans fatty acids are proven to increase LDL cholesterol while decreasing HDL cholesterol, increasing the risk of developing coronary heart disease, thus contributing to diseases of the heart and circulatory system . . . The replacement of trans fatty acids with alternatives in food production can lead to increasing levels of HDL cholesterol that helps to reduce the risk of coronary heart disease." The EU is to issue new guidelines on food labelling later this year. "The level of trans fats present in a product should be clearly listed so consumers can make an informed choice about what they are eating," says Morrissey.

Industry is already taking steps to phase the fats out of the production line. KFC fast food chain last month announced it was cutting trans fats from the products it sells in Ireland and is to phase in a "low trans" blend of cooking oil at its 713 stores across Ireland and Britain beginning this month. McDonald's also uses non-hydrogenated cooking oil in its restaurants here.

While trans fats are considered to be twice as dangerous as the saturated fats found in animal products, consumed in moderation they will do no harm, particularly if recommended guidelines are adhered to. Unfortunately for the lazy and sugar-addicted, this will mean a significant reduction in confectionery and processed food consumption, no matter how much labelling and manufacturing processes are improved.