Fat is a villain; but some fat is good, even essential. In our confusion about what is healthy and what is not, we risk coronaries, cancers and rheumatism. Only a Campaign for Real Oil will set us straight.
Last week one of the health scare stories was that fat people were discriminated against. And what advice do we have for fat people? Eat a low-fat diet. A couple of weeks before that it was the nutritional value of school meals. And what should our kids be eating? Why, a low- fat diet of course.

Demonising fat people may not be quite acceptable - even Vogue has plump models - but fat as a food is out, out, out. This, however, is a bad mistake. What we need is not less fat but better fat. By getting our nutritional knickers in such a twist over fats, we are actually doing ourselves considerable harm. The whole low-fat fad has been a total disaster. Not only have we not lost weight but all sorts of diseases such as rheumatism, coronaries and cancers have been linked to not getting the right kind of fats.

In fact, fats and oils should lie at the heart of any healthy diet alongside fresh vegetables and whole foods. The problem is that the oils we are sold at the moment are the nutritional equivalent of white bread and canned fruit. Extensively treated to increase their shelf-life and profitability, they are at best inert, and at worst actually toxic. What we desperately need is a Real Oil campaign.

Given the conflicting messages over the past decade most people are, not surprisingly, very confused about the rights and wrongs of fats. Is it safe to go back to butter? Do those polyunsaturated spreads protect against heart disease or do they give you cancer? Is lots of olive oil and the Mediterranean diet the key to healthy living? What have been almost totally ignored in the popular coverage of this are the two fats that are essential: Omega 3 and Omega 6. Our bodies can't make them so we have to get them from our diet.

When the link between saturated fats - those that are hard at room temperature, such as butter, animal fat, coconut - and heart disease was made about 25 years ago the answer was to use polyunsaturates. Most of the polyunsaturates that we have been so conscientiously ingesting since then come from oils like sunflower, which are full of Omega 6. However, most of us are dreadfully short of the other one, Omega 3, which comes from oily fish and some vegetable oils.

This is disastrous, according to Professor Michael Crawford, director of the Institute of Brain Chemistry and Human Nutrition at the University of North London, because humans evolved on a diet which provided equal amounts of both. In fact, he believes that it was our high fish diet at one time that crucially enabled our brain to grow. Now, because of many factors to do with modern food production, most of us are getting about 20 times more 6 than 3.

Until about 15 years ago nobody even knew Omega 3 was essential. Surveys still don't check people's consumption, health committees rarely recommend it. But Omega 3, sometimes described as supersaturated, is the new super- hero of the fats saga. It is vital to the use of oxygen in our body, it is involved in governing our metabolic rate and it keeps our blood "unsticky". It builds cell walls, lowers triglyceride fats in the blood and is used by the brain and the hormone system.

We can get Omega 3 in small amounts from many different sources. It is found in animals, particularly in the eyeball, testes and brains. Horse meat has lots. The best source is flax oil. Along with hemp - which just happens to have Omega 6 and Omega 3 in exactly the right proportions - flax looks set to take over from virgin olive oil in the fashion stakes. Other good plant sources include evening primrose, dark green vegetables and walnuts, while another good animal source is snake.

Much of this information comes from an American book, Fats that Heal, Fats that Kill by Udo Erasmus, published here last month, a clear and passionate revisionist account of our most maligned food. It turns out that, like most villains, fat has been misunderstood. To take just one example, a lack of Omega 3 could be involved in heart disease and rheumatism. Both Omega 3 and Omega 6 are also involved in making a family of hormones known as the prostaglandins, which comes in several types. One of them, PG1, reduces inflammation or swellings, thins the blood and lowers blood pressure. This is made by Omega 3, while Omega 6 makes PG2, which does the opposite - clots to deal with wounds and produces inflammation to deal with infection. It's not hard to see how a lack of Omega 3 can make rheumatism and heart conditions far worse.

When Omega 3 fatty acids are used in the body, they naturally produce chemicals called free radicals which, if left to their own devices, damage cells and have been linked with heart disease and cancer. In a healthy body, however, they need not be a problem since other chemicals, known as anti-oxidants, mop them up before they can do any harm. Among the most potent anti-oxidants are vitamins C and E, and it just so happens that they come already packaged in unrefined oil seeds such as flax and hemp.

Modern oil manufacturing techniques, however, destroy this natural balance. It is precisely the quality that makes Omega 3 so valuable in the body - its ability to react easily with other molecules - that manufacturers find inconvenient. Omega 3 also reacts with light and oxygen in the air, which means it goes off easily, which in turn means it has a short shelf life. So it is removed. This is why we need a campaign for Real Oil.

Our health, Erasmus claims, will improve dramatically if we put an end to all this tinkering, which is not only dangerous but unnecessary. Just as unrefined rice and wheat are much better for us, so oil seeds come with all sorts of beneficial extras like vitamin E - now removed and then sold back to the customer. The only oil that isn't put through this particular mill is olive oil, which is one reason why it is so healthy.

A sticking point for some in embracing a Real Oil campaign is that it entails a ban on frying. No more pan-seared tuna steak, says Erasmus: "If you want to eat healthily don't fry". Frying heats oils above the point where dangerous transfatty acids are created: transfats are more "sticky" than essential fatty acids and they have been associated with an increase in cholesterol; they also seem to interfere with the working of the liver and can stop Omega 3 and Omega 6 doing their job. If you must have the occasional fry-up, use saturated vegetable oils like palm, since they are less chemically volatile, or butter.

Already there are signs that the real oil message is attracting devotees. At the ultra trendy health food shop Planet Organic in Westbourne Grove, west London, sales of unrefined oils have doubled in the last year. "We're now doing 20 cases a week," says Troy Smith. But it's still very expensive. Unrefined sunflower is about pounds 2 a litre, as against 99p, while flax is pounds 8 for 500ml." The reason flax and hemp are so expensive is that elaborate precautions have to be taken to prevent the highly reactive Omega 3 from going rancid.

But while the big manufacturers get round this by removing it, a number of new small presses now press it in the dark, and then seal it in opaque bottles that have had any oxygen flushed out with an inert gas. It has to be refrigerated and will go off in about four to six weeks.

Flax seed oil and others made to Udo Erasmus's specifications can be obtained from Savant Distribution in Leeds, tel: 0113 230 1993.