How bad are trans fats for your health?

According to recent reports in the media, trans fats (such as margarine and vegetable shortening)are very dangerous to your health. So much so, that the New York health department is requiring restaurants to eliminate their use in the food they serve. To find out how dangerous trans fats really are, I did a Google Scholar" search, and found a detailed review paper titled "Types of Dietary Fat and risk of Coronary Heart Disease: A Critical Review", published in the Journal of the American College of Nutrition, vol. 20, p5, 2001. The authors, who are associated with the Harvard School of Public Health, cite two previous studies: a European ("EURAMIC") study where those with the highest intake of trans fats had a 1.44 times larger risk of heart disease compared to those with the lowest intake, and the (U.S.) Nurses Health Study, where those with the highest intake had a 1.53 larger risk, compared to those with the lowest intake. So one might be tempted to conclude that trans fats really are dangerous, increasing the risk of heart disease by about 50%.

However - the Margin of Error is very large in both studies! The EURAMIC relative risk spans the region between 0.94 (reduced risk!) and 2.20, and the Nurses Health Study spans the range between 1.16 to 2.02. So it is possible, within the margin of error, that trans fats have almost no impact on heart disease!

There are other reasons that may indicate that trans fats enhance the danger of heart disease:

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