The truth about.. olive oil

The place: somewhere in Southern Italy. The people: one family, spanning five generations, from great great-grandpapa to the latest bambino, all looking as though they might live for ever. The product (pictured in the foreground): a certain olive oil spread. The message: olive oil promotes longevity. Do as the Italians do and eat lots of it.

It is not only the manufacturers of this particular spread who are pushing the health benefits of a product which until recently most Brits kept in the medicine cupboard. The European Community is financing a campaign (which includes the setting up of a panel of eminent scientists) to promote its consumption, particularly its role in preventing heart disease.

Our obsession with types of fats began two decades ago when we were urged to cut down on total fat intake and on animal fats, because they contain large amounts of the saturated fatty acids associated with coronary heart disease. Instead, it was said, we should eat more of the unsaturated fats found in vegetable oils, particularly poly-unsaturated. Studies had shown that these fats, found in large amounts in soya bean, sunflower and safflower oils, reduce cholesterol, a risk factor for heart disease.

But the polyunsaturates have a down-side. In animal experiments, very high intakes were linked to clotting disorders, impairment of the immune function and the production of harmful free radicals.

So scientists are no longer quite so gung-ho about polyunsaturates as some once were, which is where olive oil comes in. It is a rich source of oleic acid, a monounsaturated fat which, when substituted in the diet for saturated fats, has also been found to lower blood cholesterol levels. Doctors at Munster University involved in the EU campaign point out that olive oil has been used for centuries in the Mediterranean countries and unlike the polyunsaturates its safety in high intakes is proven.

So should those of us who are not doing so already sprinkle it liberally on our rocket salad and mop it up with our crust of ciabatta?

Although useful as a substitute for animal fat (as well as being delicious), olive oil is not the elixir which some of the hype has made it out to be. It is still a fat and too much will make you fat. It has long been known that for those with atherosclerosis, or furred-up arteries, it can take one high-fat meal to bring on a fatal heart attack and research in Britain has found olive oil to be no exception. Nor is it superior in health benefits. Unlike polyunsaturates, it lacks linoleic and linolenic acids, essential nutrients which prevent abnormalities, particularly skin disorders. Unlike fish oils, it lacks EPA and DHA, other fatty acids which can reduce the tendency of the blood to clot. Unlike butter and fortified margarines it does not contain the valuable A and D vitamins.

So experts recommend a balance of poly- and monounsaturated fats. Current recommendations are that fat should provide no more than 35 per cent of our energy, with saturated fats providing no more than 10 per cent, polyunsaturated 6-8 per cent and monounsaturates 10-15 per cent.

Whether you use a spread made from poly- or monounsaturated, make sure it contains no hydrogenated oils or transfatty acids. These are the result of a process called partial hydrogenation, sometimes used to harden fats, which studies suggest may increase the tendency of the blood to clot.