You are what you eat

If deep-fried foods and baked goods made with solid, hydrogenated fats have not yet given you indigestion, recent scary and sometimes conflicting news

September 11, 2005 14:52

If deep-fried foods and baked goods made with solid, hydrogenated fats have not yet given you indigestion, recent scary and sometimes conflicting news reports of the alleged cancer and heart-disease dangers they pose probably have. With the scandal of mad-cow disease out of the headlines, acrylamide and trans fats (TF) have been the most prominent food scares in the past year. During the past month alone, New York City health commissioner Dr. Thomas Frieden compared TF to toxic substances such as asbestos and lead, and asked restaurants to stop serving foods made with these solidified fats. A few weeks ago, the Israel Cancer Association advised minimizing consumption, especially by young girls, of french fries, after researchers at Brigham and Women's Hospital and Harvard Medical School published a paper on the subject in the International Journal of Cancer. Frequent consumption of french fries whose starch is heated to high temperatures by girls aged three to five was found to increase the risk of breast cancer after they grew up. It was not perfect research, as it was not a prospective study but a retrospective one with mothers of adult women recalling what their daughters ate as preschoolers but it still lit warning lights. The ICA said the results "strengthen previous knowledge proving that diet has a deciding influence on the development of cancer, and that obesity causes a variety of cancers such as colon, breast, prostate and kidney." Previously, the World Health Organization stated that 35 percent of all cancers were due to high-fat diets and being overweight. Our first course for discussion is trans fats, which are a byproduct of the conversion of oils or fats to more solid stable forms through hydrogenation. Unsaturated fats, such as those derived from olives, avocados, corn and canola (rapeseed) are healthful, but when exposed to the air, after a while they can go rancid by absorbing oxygen and then decompose. To increase product shelf life, food manufacturers can stop this process by bubbling hydrogen through the fat at a high temperature in the presence of a catalyst like nickel and in the absence of oxygen. The process raises the fat's melting point, turning liquid vegetable oil into products ranging from soft margarine to solid shortening. When the healthful unsaturated fats are partially hydrogenated, the double chemical bonds are rearranged, converting some to the trans configuration and shifting the double bonds along the chain. Unfortunately, TFs are artery-cloggers that have been found in numerous studies to be partly responsible for the formation of calcified ridges that can block the flow of blood in coronary arteries and to raise blood cholesterol and triglyceride levels. The more solid the form, the more trans fatty acids, thus softer margarines contain lower amounts of TFs than harder spreads. In packaged goods, they are listed among the ingredients as "partially hydrogenated" oils. In 2006, the US Food and Drug Administration (FDA) will require them to be listed on food labels as trans fats, and this may become mandatory next year as well by our own Health Ministry's Food and Nutrition Service. When you eat in restaurants and fast-food joints, you can't know what fats are used, but the more junk food you consume, the more likely you are to consume a lot of TFs. TFs are most common in pastries, doughnuts, pizza, potato chips, french fries, margarine, cookies, crackers and bread. You can reduce your consumption when you cook at home by using substitutes, but most cookies and pastries will not turn out well if made with oil. Most processed foods prepared with trans fats are made with flours low in vitamins B6 and B12 and magnesium; the combination of TF and vitamin and mineral deficiency is partly responsible for the formation of calcified ridges in the arteries, experts say. But if you avoid margarine and other hydrogenated spreads, what are the alternatives? Butter is high in saturated fats, which are not heart-healthy either. The American Heart Association's nutrition committee advises that mono- or polyunsaturated cooking oils in their natural state, such as canola, olive or corn oil, should be substituted for hydrogenated oils or saturated fats. For spreads, low-fat white cheese, avocado, tehina (made from sesame seeds) and peanut butter are preferable to margarine, but if you have to use margarine, softer versions are preferable to harder ones. If you're going to melt semi-solid fat, you might as well start off with a liquid. Nili Arbel, a clinical dietitian and acting head of the nutrition department in the ministry's Food and Nutrition Service, says she is convinced that TFs are harmful and should be minimized in the diet, especially if you already have high levels of cholesterol and triglycerides. There is still no regulation on the books that requires food companies to list trans fats. Such a decision has been taken in Denmark, the US and France. "We are discussing it now, having studied all the relevant material here and abroad, Arbel says. "We expect during the next month to decide whether companies will have to list it. The problem is we don't have labs that can check for it, and if we had, it would cost money to check whether figures printed on labels are correct. But it is an important aim. Just putting trans fats on labels will increase consumer pressure on food companies to reduce their TFs, as happened here with artificial colors and other additives. We take this issue seriously." Arbel says that she and colleagues have already met with food companies and asked them to decrease the amount of TFs in processed foods, but more healthful fats are more expensive. Some US firms, such as PepsiCo's Frito Lay, have already eliminated TFs from some of their products, and others have promised to explore ways of replacing the fat. Dr. Kathleen Koehler, an epidemiologist at the FDA's Center for Food Safety and Applied Nutrition in Washington, calculates that just removing trans fats from all margarine would prevent approximately 6,300 heart attacks and 2,100 deaths in the US each year; additionally, removing trans fats from just 3 percent of breads and cakes and 15% of cookies and crackers would prevent an estimated 17,100 heart attacks, including 5,600 deaths. Our second course for discussion is acrylamide, a probable human carcinogen that has been found in a variety of fried and starch-based foods, including fried potatoes. The polymer (chain of molecules), which is used in the manufacture of plastics, is formed when starchy food is cooked at temperatures well above 100 Centigrade. It is believed that when a naturally occurring amino acid, asparagine, is heated with certain sugars, such as glucose, acrylamide is created. However, boiled starchy foods do not show an increase in acrylamide. Two years ago, the Journal of the [US] National Cancer Institute reported that acrylamide can produce changes that interfere with the DNA replication process and lead to mutations and, in theory, to tumor formation. Rodent studies show that exposure to large amounts of acrylamide increases the incidence of a variety of cancers, but this link has not yet been proven in humans. Researchers note that questions still remain about the levels and extent of acrylamide in food products, the mechanisms by which it is formed in fried foods, and whether the body can efficiently absorb and process it. Until there are more answers, a special joint consultation on acrylamide set up by the UN's Food and Agriculture Organization and World Health Organization recommends that people avoid overcooking foods (but undercooking is also dangerous because of the risk of surviving pathogens). It said more research on the matter is needed, and that of the limited range and number of foods analyzed so far, "acrylamide levels are highest in potato and cereal-based products subjected to heat processing such as frying, grilling or baking." The Snack Food Association, an international trade association of more than 700 member companies that manufacture potato chips, tortilla chips, corn chips, pretzels, popcorn, crackers and other snacks with $32 billion of annual sales in the US alone, reacted to this by saying that while large amounts of acrylamide have caused cancers in rodents, "there is no evidence it does the same in people. In fact, a different model could predict the actual theoretical risk to consumers is zero. What is important here is that it is far too early to draw any definitive conclusions from the limited data that has been made available to the scientific community." But some environmental and health advocates are already taking legal action. Ben Yeroushalmi, a Los Angeles lawyer specializing in carcinogenic chemicals known to the State of California to cause cancer and reproductive toxicity, told The Jerusalem Post that his firm recently filed suit against several major corporations that do business in that state "for failing to warn consumers that french fries and potato chips can cause cancer." Over the past decade, he said, he has successfully pursued scores of cases against corporations that expose consumers to chemicals that cause cancer and are toxic to the reproductive system without proper warnings and disclosures. He claims that "french fries cause cancer to everyone, and not just females who consumed them in childhood. I believe this is something grave that the Israeli public should be made aware of." Arbel of the Health Ministry says that since evidence on the risks of trans fats have been conclusive, it has focused its attention on them. It is collecting material on acrylamide, but hasn't reached conclusions or issued recommendations, unlike the cancer association, which suggests minimizing consumption of fried and grilled foods and increasing consumption of fresh vegetables and fruits. Arbel notes that despite the plethora of fast-food restaurants here, Israeli culinary habits are still "much better than in the US. We eat much more home-cooked meals and less processed food, especially on weekends, than Americans do." While health risks of specific foods should be investigated, nutrition and metabolism expert Prof. Elliot Berry advises keeping your eyes on the big picture. "Food is an important issue, because too much leads to obesity, which is very harmful to health," says Berry, the dean of the Hebrew University-Hadassah Braun School for Public Health and Community Medicine in Jerusalem. "But that doesn't mean you can never eat french fries or potato chips. One should observe the advice of the great sage Maimonides, who urged moderation in all things. An informed population becomes concerned about their own and their family's health and empowered to take responsibility, rather than just leaving their health just to their doctors. The big picture is exercising regularly by walking 10,000 steps a day and not smoking."

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