What do you know about industrially produced trans fatty acids? Unless you are actually a nutritionist or a doctor, the answer is most likely to be: nothing at all. And why should you? One survey a few years ago found that of the sample asked, 15 per cent thought trans fats were good for your love life.

Trans fats are a lethal side effect of boiling vegetable oil. Why boil vegetable oil? That all goes back to a pharmacist called Wilhelm Norman in 1903. Mr Norman was trying to find a way of making a substitute for tallow, which was very expensive at the time. Mr Norman discovered that if he boiled cotton seed oil up to 260 degrees Centigrade in the presence of a catalyst such as nickel, that when it cooled, it went hard. He had produced cheap candle wax by “hydrogenating vegetable oil”. The thick, greyish-white slabs produced were great candles but Mr Norman did not anticipate human beings eating them.

Food giant, Proctor & Gamble, saw the potential and bought the patent from Mr Norman. They were soon producing Crisco in America, a hard vegetable fat that was great for baking and had a long shelf life. Along came a whole series of Crisco cookery books for Japanese, Jewish or Philippine households. Titles included: A Cookery Course in 13 Chapters; 24 Pies Men Like; and Crisco Recipes for the Jewish Housewife. That Crisco contained no animal fat made it ideal for vegetarian, Kosher and Halal households.

But there was a problem: this industrial processing of vegetable oil into hydrogenated fat (HVO or PHVO) turned out to be killing people. It was not really until a big clinical trial, The Nurses' Health Study, which ran for about 10 years in the 1970s and 1980s that the damage really surfaced.

By carefully detailing just what kinds of fat were being consumed, the researchers identified this hydrogenated or partially hydrogenated vegetable oil as the queen of fast food. It was more of a killer than saturated fats. They discovered that you would need to increase your intake of saturates by about 900 per cent to have the same harmful impact that you would have from the same amount of trans fat. Just small amounts of trans fat - say two grammes a day - increases your risk of heart disease by 23 per cent.

There is no use looking for cartons of trans fat to avoid on the supermarket shelves. What you need to look for is hydrogenated-anything on the ingredients panel, very possibly in a text so small that unless you have a magnifying glass, you will find it hard to read. Even so, you may still innocently purchase commercially baked produce containing trans fats - because the ingredients do not have to be declared on in-store bakery goods.

So surely the European Food Safety Authority would ban it immediately? Not so. It is far too useful in the catering trade. Apparently, it gives great “mouth feel” - what you get with a nice sticky doughnut or a moist Danish pastry. It lengthens shelf life too. One man lobbying against trans fats in America appears on television with a cup cake made more than 20 years ago. It still looks perfect and has retained the soft springiness associated with such confections.

Like so many of the dangerous substances we consume, trans fats appear in everything from stock cubes to sweets, children's cereals to vitamin tablets, Danish pastries to doughnuts, deep-fried foods in restaurants, lunchtime snacks like sausage rolls and other produce from takeaways. They were in lots of the Easter eggs we gorged on a few weeks ago, they are even in some of the so-called “energy” or “health” bars on the supermarket shelves.

It is ironic that so many Danish pastries contain trans fat because Denmark was the first country to ban them in 2000. Nowhere there can hydrogenated vegetable oil be used, including within the catering and restaurant industries as well as the food producers. On April 1 this year, Switzerland followed Denmark and introduced similar legislation. In the rest of Europe, we continue to gorge our way through mountains of dangerous products.

When I came to writemy book on the subject, it was this deception that really annoyed me. How dare the Food Standards Agency, our elected politicians, the consumer outlets and the catering and restaurant industries not tell us that we are eating candle wax.

All of them have known full well about how trans fats are associated not only with a five-fold increase in heart disease but also with Type 2 diabetes, some cancers, infertility, inflammatory diseases, obesity and insulin resistance.

Eight of the big supermarkets said in January 2007 that they would remove all trans fats from their “own brand” ranges within the year. Some managed it. Others did not. There is nothing the law can do because this was a voluntary agreement. Besides, how much of what you buy in the supermarket is “own brand” produce? If you shop at Sainsbury or Tesco, then it is likely to be no more than 10 per cent.

Professor Steen Stender is the cardiologist in Denmark who became the driving force behind the decision to ban trans fats there. He says: "Between the introduction of the ban in 2000 and 2005, we saw heart disease rates in this country decline by 20 per cent. What more proof does the EU need before it dispenses with ineffective food labelling ideas and voluntary codes and introduces a level playing field for the food industry throughout the EU where no trans fats are used anywhere?"

Maggie Stanfield is the author of Trans Fat: The Time Bomb in Your Food (Souvenir Press £8.99),

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