MY SISTER, her husband and their two children, aged 14 and 18, eat out at a food court or cafeteria every weekday. They’re not unusual, according to the 2010 National Nutrition Survey, which found that one in two residents in Singapore eats at a coffee shop, hawker centre or food court almost every day. As a result, the average resident – Singaporean or permanent resident – takes in too much saturated fats – up to 40 per cent of total fats, or 10 per cent over what the Health Promotion Board (HPB) recommends.
Eating out so often exposes people to a very special type of saturated fat called trans fats. These clog up arteries badly. That’s because such fats contain extra hydrogen atoms which are added to liquid plant oils to solidify them. The process prevents the oil from spoiling too fast. Such oils can then be repeatedly heated without their chemicals breaking down or tasting bad.
Trans fats are also cheaper than animal fats, like butter, which have no trans fats. Little wonder then that restaurateurs and hawkers love using them. Compared to animal fats, plant oils are always liquid at room temperature and go bad faster. They can’t withstand the high temperatures used in deep frying or on griddles and they make batter or dough runny. In frying the dough to make doughnuts, liquid plant oils cause glazes to crack because they don’t solidify the same way that animal fats do. Whereas only animal fats can harden at room temperature into, say, butter or ghee, plant oils will not do so unless they have some added hydrogen atoms. This is achieved by boiling plant oils in the presence of a metal catalyst and hydrogen. This process of hydrogenation produces margarine, plant shortening and others generically called “partially hydrogenated plant oils”.
In the process, trans fats are created which harden and can then be used in baking to give pastry its fluffy texture that otherwise can be produced only with butter, ghee, lard or tallow. Trans fats give baked products like cakes or breads their kou gan (Chinese for “mouth feel” or texture) by adding moisture, lubricity, pliability, flakiness and airiness. They also help products remain fresh and look better longer, for example, by keeping the oil from separating out of peanut butter in the bottle. But trans fats block up the arteries feeding the heart and brain, resulting in heart attacks or strokes. Not only do they increase the bad (LDL) cholesterol but they also reduce the good (HDL) cholesterol that scours the insides of our arteries clean. The latter is a side-effect that even the much maligned saturated (animal) fats, which do clog arteries, don’t have.
From May, new limits on trans fats in food items are mandated for all supermarkets, cooked food outlets and food makers here. All margarine, shortening and cooking oil will be allowed to contain only 2g of trans fats per 100g, or 2 per cent, the limit recommended by the World Health Organisation. According to HPB, three in 10 persons here consume over the 2g daily limit. These folks eat out a lot and snack more often on commercially baked and fried foods. With the change, a curry puff with 4g of trans fats now will have under 0.5g of them. You would also want to avoid too much of pastry, cake, doughnut, prata, pie, pizza, crispies or biscuits, say. The epidemic of heart disease that began in the mid-20th century may not have been caused, as is popularly believed, by a modern diet too high in saturated (animal) fats. The culprit was likely trans fats being introduced into the food chain. In 1999, the famous Framingham Study which had followed 832 men for 21 years reported that margarine intake significantly increased the risk of heart attacks in men.
Next, the huge Nurses’ Health Study showed that trans fats doubled the risk of heart disease in women. Other large studies indicate that a given amount of trans fats causes more heart disease than the same amount of saturated (animal) fats. The Institute of Medicine, which advises the US government, concluded in 2002 that the only safe level of trans fat in the diet was zero. Fast-food chain McDonald’s says it already uses no trans fats in all its outlets here. Actually, the HPB defines foods cooked in oil with less than 0.5g trans fats per 100g oil as having zero trans fats. This is what is reflected on the “Nutrition Information” label or “Nutrition Facts” panel on the box or wrapping. That is, if the label or panel says zero trans fats but “partially hydrogenated” or “hydrogenated” plant oils are found in the ingredients list, then that item actually has trans fats but under 0.5g of them.
Also from May, retailers and manufacturers may be expected to use special signs such as “trans-free”, “virtually trans-free”, or “trans-reduced” and so on. This would be in addition to the listing of the amount of trans fats as a line item on the nutrition information panel. However, such “no trans fats” signs may bamboozle consumers into thinking that the food item concerned now has less fats and thus fewer calories than before. Yet whatever the replacement fats may be, they will also carry the same amount of calories as well. It is always bad to consume too many calories, so while going trans fats free is good, remember to watch the calories to