One of the biggest health stories of recent times is the moves to ban heart-stopping trans fatty acids (also known as trans fats) from foods served in restaurants and fast food outlets in New York City. Apparently, a voluntary plan for the removal of these fats from food has not worked out well, and now the city's health commissioner, Thomas Frieden, is reigniting the initiative with a series of public hearings, which may lead to trans fats disappearing off NYC menus in all but minute amounts.
Trans fats have been firmly locked in the sights of health campaigners in the U.S. for some time, but they've only relatively recently hit the radar in Britain. So, what is it about trans fats that some find so unpalatable? To understand that we need to look at where these fats come from.
Most trans fats start out as vegetable oils, including sunflower, soy or safflower oil. In food processing, these oils are heated to a high temperature and then reacted with hydrogen to produce partially hydrogenated fats. The hydrogenation of fats allows vegetable oils to be solidified, which is obviously critical in the manufacturing of solid fats such as margarine. Hydrogenation makes fats less liable to turn rancid, which extends their shelf life. The partial hydrogenation of fat results in the formation of trans fats. Trans refers to shape of these molecules. These fats are straighter than their counterparts naturally found in nature, which are called cis fats, and have a more angular shape.
Small amounts of trans fats are found naturally in food such as butter, pork, lamb and meat. Larger amounts of trans fats are found in a wide range of processed foods including fast food, such as French fries, burgers and chicken nuggets, margarine, biscuits, bread, cakes, pastries, pizza and crackers.
One of my personal beliefs is that we need to be very wary about any food or foodstuff that is a relatively recent addition to the diet. The chances are that we are not well adapted to such foods, and they therefore will tend to have considerable potential for adverse effects on our health. The evidence suggests this is true for industrially-produced trans fats.
In one study, individuals who had suffered a heart attack were found to have significantly higher levels of trans fats in their bodies compared to healthy individuals [1]. Those with the highest concentrations of trans fats were found to be, on average, over two and a half times more likely to suffer from a heart attack than those with the lowest levels. A number of other studies also support the concept that trans fats are bad for the heart. Of four studies that have examined this potential association over time, three found that consuming just two per cent of our calories from trans fats is associated with an increased risk of heart disease of 28-93 percent [2,3,4]. Other evidence links the consumption of trans fats with an increased risk of cancer, diabetes and lower birth weight.
The evidence suggests that trans fats are thoroughly unhealthy. In the U.K., we consume an average of about two and a half to three grams of trans fats per person each day. This may not sound like much; except that studies show even very small amounts of these fats are associated with an increased risk of disease. In 2002, the Food and Nutrition Board of the Institute of Medicine (U.S.) published a report on the role of trans fats on health and made recommendations regarding safe levels of intake [5]. In the summary of this report, its authors suggest the "tolerable upper intake level of zero."
I applaud the seemingly draconian measures that are planned in New York City. In the light of this and despite the evidence regarding the corrosive effects trans fats can have on health, in the U.K. there is not even a legal obligation for food manufacturers to declare the presence of trans fats in their products. The generally laissez-faire attitude regulatory agencies have to potential poisons in the diet is, no doubt, connected to not only the short-term mentality that pervades politics, but also is a testament to the power food companies wield at the highest level. Individuals wanting to avoid trans fat need to look out for foods listing partially hydrogenated fat, partially hydrogenated oil or partially hydrogenated vegetable oil in the ingredients. Take-away and fast foods, which are notorious harborers of trans fats, generally need to be given a wide berth too.
References:
1. Pedersen JI, et al. Adipose tissue fatty acids and risk of myocardial infarction - A case-control study. European Journal of Clinical Nutrition 2000:54:618-625
2. Ascherio A, et al. Dietary fat and risk of coronary heart disease in men: Cohort follow up study in the United States. British Medical Journal 1996:313:84-90
3. Hu FB, et al. Dietary fat intake and the risk of coronary heart disease in women. New England Journal of Medicine 1997:337:1491-1499
4. Oomen CM, et al. Association between trans fatty acid intake and 10-year risk of coronary heart disease in the Zutphen Elderly Study: A prospective population-based study. Lancet 2001357:746-751
5. Letter Report on Dietary Reference Intakes for Trans Fatty Acids Food and Nutrition Board, Institute of Medicine 10th July 2002
Dr John Briffa is a London-based doctor, author and health writer with a special interest in nutrition and natural medicine. His website is www.drbriffa.com
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