Trans fats are formed during the partial hydrogenation of vegetable oils by a process that converts these oils and to semi-solid fats for use in margarines, commercial cooking, and the manufacturing processes. From the perspective of the food industry, trans fats have been particularly attractive because of the long shelf life, the stability during deep-frying, and their semi-solidity, which then can be customized to enhance the palatability of baked items and sweets. The average consumption of industrially produced trans fatty acids in the United States is 2-3% of the total calories consumed. Trans fats do occur naturally in meats and dairy products from cows, sheep, and other ruminants. They are produced by the action of bacteria in the ruminant’s stomach, however, consumed in very small amounts.
In 2006 the Food and Drug Administration ruled that the nutrient labels on conventional foods and supplements must indicate the contents of trans fatty acids. This was prompted by evidence that the consumption of trans fats increases the risk of coronary heart disease. Trans fats appear to increase the risk of coronary heart disease more than any other macronutrient. In the meta-analysis of four prospective cohort studies involving nearly 140,000 subjects, a 2% increase in energy intake from trans fats was associated with a 23% increase in the incidence of coronary heart disease. It is interesting to learn that of the prospective studies, which evaluated the relationship between the intake of trans fatty acids from ruminants and the risk of coronary heart disease, none identified a significant association. Some people in the food industry disseminate false information that somehow this lack of association between naturally occurring trans fats with coronary heart disease somehow provides evidence that the risk of industrially produced trans fats and coronary heart disease is not valid. This statement is not only false but also extremely harmful to the public in that any justification to encourage one to eat any food item loaded with trans fats is unethical and reprehensible. The truth is that the intake of naturally occurring trans-fats is an exceedingly small fraction in one’s diet. Also the chemical structure of industrially produced and naturally occurring trans-fats is not identical. The propaganda from the food industry simply cannot be is totally unacceptable.
I have written previously in other articles about what is considered the gold standard in terms of a clinical study. What is called “level one” evidence is based on prospective, randomized, long-term trials that are often difficult to undertake. Given the known increase risk of eating trans-fats on coronary heart disease, it is unethical to conduct randomize long-term trials to test the effects of trans fat intake on the incidence of cardiovascular events such as heart attacks and strokes. The food industry likes to use the fact that this type of study does not exist to further their claim that the trans fats are not harmful. On the basis of evidence from laboratory experimental studies, dietary trials, and prospective observational studies, it is known now that the consumption of trans fatty acids from partially hydrogenation oils has absolutely no nutritional benefit and has considerable potential for harm. As we strive to eliminate trans fats from foods, the claim is often made that this is extremely challenging and costly for restaurants and food manufacturers in the United States. The experience in other countries, however, indicates that these fats can largely be replaced by what is called “cis unsaturated fats” without increasing the cost or reducing the quality or availability of foods. The avoidance of trans fatty acid consumption will result in substantial health benefits by lowering the incidence of obesity and diabetes and will undoubtedly avert thousands of heart attacks and strokes in each year in the United States.