We have been chomping on a semi secret killer for many years now. Even those vegetarians who were looking at the ingredients of processed foods for signs of animal products were duped. What is this unseen health hazard that lurks in all types of food? They are called trans fatty acids, but go under a variety of other names, just to confuse us.

It has taken a very long time to identify this terrible substance as a killer. It has been with us since around 1911, when Proctor & Gamble bought the rights to the Normann process, which was a way of pumping hydrogen into oils to make them solid, and produced a new shortening called Crisco, made primarily from cotton seed oil. This process also made it possible to use whale oil as a human food, although given the taste of some of the early margarine, it might not have been considered food, which also helped the whales towards extinction.

Trans fats nowadays are almost exclusively made from plant sources such as soya bean oil, palm oil, sunflower oil etc., and are widely used in food manufacturing because not only do they increase the shelf life but food made with trans fats can also be stored at a higher temperature, thus reducing the cost o

During the last thirty years, there has been an increase in the number of vegetarians which meant that foods using animal fats were avoided leading to a further growth in the use of trans fats, other dietary requirements such as Kosher, Halal, etc., could also be catered for by the use of these types of shortenings.

It was thought to be better than the saturated animal fats which were then said to be responsible for most of the bad cholesterol. and it was a lot cheaper so that manufacturing costs were brought down.

The CSPI (the Centre for Science in the Public Interest) even ran a campaign to stop the fast food chains using saturated fats in favour of trans fats, a stance that it was to change some eight years later.

It wasn't until around 1988 that the first medical papers started to appear, suggesting that trans fats were responsible for coronary heart disease, since then the evidence has grown and the governmental agencies are now issuing warnings about trans fats.

One of the major landmarks was when in May 2003 in America, a concerned organization called BanTransFat Inc which is a not for profit company, sued the food giant Kraft Foods over the amount of trans fat used in Oreo cookies, which are a very popular American biscuit. This prompted Kraft to decide to use alternatives for trans fat and the suit was withdrawn, but it did shine a spotlight on the trans fat issue.

Since then, governments around the world have had a very patchy record on the control of these substances, with Denmark which has strict laws against the use of trans fats to Canada which only has recommendations on the permissible amounts. Despite this lack of legislation there is a groundswell of opinion that is having an effect on the amount of trans fat being pumped into our diet. There is a town in California which has declared its self 'Trans Fat Free', in New York City restaurants were ask to eliminate trans fats from their menus which was followed up by the Health Board banning the use of artificial trans fats in cooking.

Companies are now policing themselves as many fast food chains are either reducing trans fats or eliminating them altogether, whilst in the U.K., a number of supermarket chains are not only banning the use of trans fats in their own brand products but asking their suppliers to do the same. The large multi nationals like Kraft and Nestle are responding but care should be taken, just because trans fat may be eliminated or reduced in a product in one country, it does not always follow that it will be the same in other countries.

It may be the legislators have some problems because trans fats are also found in meat and dairy products, albeit in very small proportions. These naturally occurring trans fats are not thought to cause any of the problems associated with the artificially made ones because of the amounts involved.

The trouble with trans fats is that not only do they increase harmful LDL cholesterol, which blocks the arteries, it also actively reduces HDL, the good cholesterol, this in turn will lead to an increase risk of heart attacks or strokes. There are other studies showing an increased risk of diabetes, Alzheimers and a tendency of the body to put more fat on around the stomach and although these studies are still ongoing, should be taken into account.

Children are quite vulnerable, starting with babies because trans fats can also be passed on to infants via the mothers milk so breast feeding mothers should be watching their diet. Children, of course, love fast food, popcorn, biscuits/cookies, cakes and a whole host of things that have trans fats in them. This means that they will be taking on a heavy burden of trans fats, leading to problems later on in life. Certainly in the UK there is an increase in the number of diabetic and obese children.

When shopping, care must be taken and food labels should be read carefully. If you see vegetable shortening, hydrogenated or partially hydrogenated vegetable oils they will have trans fat in them and if they are listed in the top four to five of the ingredients then there will be a larger amount used. It is amazing just how many different types of food it can get into, even youghurt and your choice of margarine should be looked at.

Trans fats do not always occur in the ingredients, they can also be present in your cooking oil if you do not frequently change it, this means that although your favourite fast food outlet may proclaim its self trans fat free, if they do not change their cooking oil a regular basis, you may still be eating trans fats.

You need to be vigilant to be sure that this stealthy killer doesn't creep into your diet on a regular basis but the improvement in your bodys' wellbeing is well worth the effort.