Trans Fats and Cardiovascular Health

Testimony submitted at October 30, 2006 hearing before the New York City Board of Health by Dariush Mozaffarian, M.D., Dr.P.H., F.A.C.C.. F.A.H.A., Harvard Medical School and Harvard School of Public Health

I am a cardiologist at Harvard Medical School and an epidemiologist at the Harvard School of Public Health. I would like to thank the New York City Department of Health for the opportunity to speak at this hearing.

Harmful effects of trans fats on blood cholesterol levels are clearly established: Trans fats increase the "bad" LDL cholesterol and decrease the "good" HDL cholesterol. Trans fats also affect other important risk factors for cardiovascular disease. Studies in humans demonstrate that trans fats increase inflammation in the body, a potent risk factor for cardiovascular disease, diabetes, and other diseases. Trans fats also decrease the health of the endothelium, the cells lining the arteries of the body which are essential to cardiovascular health. Studies in primates demonstrate that trans fats cause weight gain, especially increasing abdominal fat which has the greatest metabolic consequences, and worsen insulin resistance, the precursor to diabetes.

Based on these powerful adverse effects of trans fats on risk factors, one would expect powerful harmful effects on disease outcomes. Indeed, this is exactly what is seen. In large studies involving over 140,000 participants, trans fat consumption is consistently associated with increased risk of coronary heart disease. Importantly, the risk is seen at very low levels of trans fat consumption. These studies have spanned a range of populations and cultures, including studies in the U.S., Europe, Australia, and Central America.

When we combined the evidence, there was 23% higher risk of coronary heart disease for each 2% of calories from trans fat. This is staggering. 2% of calories represents 40 calories for an average 2,000 calorie per day diet – calorie-for-calorie, trans fats are the most harmful nutrient in our diet. Some of the most powerful heart medications we have, cholesterol-lowering statin drugs, lower coronary heart disease risk by approximately 25%. So, 40 calories of trans fat nearly cancels out the benefits of some of the most powerful medications we have, and many people eat much higher levels of trans fats. This level of risk is much higher – much higher – per calorie than for saturated fat.
Based on this evidence, we calculated estimates of the impact of artificial trans fat consumption on coronary heart disease events in the U.S. By the most conservative estimates, based only on the effects of trans fats on blood total cholesterol and HDL cholesterol levels, 6% of heart attacks in the U.S. are due to the consumption of artificial trans fats. In New York City, this corresponds to approximately 1,400 deaths from heart attacks each year. This is a remarkably high percentage, given that heart attacks are the number one cause of death in the U.S.

Importantly, this is likely an underestimate, given the harmful effects of trans fats on many other risk factors beyond total cholesterol and HDL cholesterol levels. Based on the relationship between trans fat consumption and coronary heart disease risk seen in human studies, which may better account for the total harmful effects, up to 22% of heart attacks may be due to consumption of artificial trans fats.

Whether the true effect is 6% or as high as 22%, artificial trans fats are a dangerous additive in our food supply. Artificial trans fats have no nutritional value, have great potential for harm, and can be easily replaced by natural fats and oils without compromising food taste, price, or availability.

The strength of the evidence, and the magnitude of the health risks, for artificial trans fats are greater than for other food contaminants or pesticide residues which are already appropriately regulated to very low levels. As a matter of food safety, I strongly support the New York City initiative to eliminate the use of artificial trans fats by restaurants.

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