There was a time when all we had to remember when it came to fats was that saturated ’animal’ fats were the bad guys because they clogged our arteries and increased the risk of heart disease, while unsaturated fats, ’vegetable oils’, were the good guys. But now it seems there’s a new kid on the block - trans fats, which according to health experts are bad news for our hearts.

Trans fats occur naturally in small amounts in meat and dairy products, but they are also produced artificially as the result of a chemical process called hydrogenation, which is used to convert vegetable oils into semi solid fats. Hydrogenating vegetables oils helps extend their shelf life but by changing the nature of the fat they also change the way it behaves in the body. Although chemically trans fats are still unsaturated in the body they behave as if they were saturated fats.

In fact, research suggests they are even worse than saturated fat. Not only do they increase levels of LDL ’bad’ cholesterol but they also reduce levels of HDL ’good’ cholesterol.

greater risk

One study, which tracked the diet of over 80,000 female nurses, found that those who ate foods high in trans fats were over 50% more likely to suffer from heart disease compared with women who rarely ate these fats.

Although trans fats are found naturally in small amounts in meat and dairy products, over 70% of the trans fats in our diet are artificially created. The main source of these fats are processed foods like biscuits, cakes, pastries, meat pies and some confectionery.

Because trans fats are less likely to turn rancid, hydrogenated oils are also often used for deep-frying in fast-food restaurants. And some products that might seem healthy, such as cereal bars, also contain a hefty dose of trans fats.

Labelling law

From January 2006, all packaged foods sold in the US must, by law, list levels of trans fats on the nutrition panel on the label. Many people would like to see the same law in the UK but at the moment there is no legal requirement to provide information about trans fats.

The rules regarding the content and format of nutrition labels on foods sold in the UK and other EU countries are laid down by a European Directive.

At the moment this directive does not specify the labelling of trans fats. But it is due to be revised in 2007 and a spokesperson for the Food Standards Agency said it would be pressing for the revised regulations to include information on trans fats.

The good news is that many retailers and manufacturers have committed to removing hydrogenated oil from their products and nutrition surveys suggest that our average intake of trans fats in the UK is well below the maximum safe target of no more than 2% of our total energy. But many experts feel that the only safe intake of trans fats is zero. n