The Dangers of Trans Fats

Manufactured hydrogenated oils, which your body cannot digest, are a serious risk to heart health.

Many Americans are still unaware that the one of the most harmful heart-health trends of the last century was the gradual replacement of healthy natural fats with foods such as margarine. Many margarines were formed by hydrogenating or partially hydrogenating oil, forming fats never found in nature. Called trans fats—they are manufactured by heating vegetable oils at a high temperature and treating them with hydrogen gas to form more stable oils. The process creates trans fats constructed of twisted, unnatural molecules that the body cannot process. For years the food industry has put these hydrogenated and partially hydrogenated oils in packaged goods to increase shelf life.

The reasons are economic ones. Unlike butter, olive oil or other natural fats, trans fats have a much longer shelf life. Walter Willett, M.D., chairman of the department of nutrition at the Harvard School of Public Health, was coauthor of a 1993 report on the 75,521 women who were tracked in the Harvard Nurses Study. Women with a high intake of trans fats were 1½ times more likely to develop coronary heart disease than women with a low intake of these so-called “foods." For many people, the real shocker in this study was the statistic that women who ate the equivalent of four or more teaspoons of margarine per day had a 66 percent greater risk of heart disease than women who ate little or no margarine. But when it comes to butter, this vast study found no association between its consumption (in any amount) and the probability of contracting heart disease1.

Willett's report is shocking only if you have not had an eye on the research. Other scientists have demonstrated that while fats that are solid at room temperature, such as butter has both good and bad effects on cholesterol levels, the effects of trans fatty acids are purely negative. Research also has shown that lipoprotein (a), one of the more damaging forms of chemical substances in cholesterol, consistently increases as a result of eating trans fatty acids2.

The Food and Drug Administration has mandated trans fats be listed on the Nutrition Facts panel of all food labels by January 2006. Then, although foods may still contain these dangerous fats, you could choose to not purchase them. If enough consumers reject these foods, manufacturers will have to change their formulations.

Butter, olive oil, coconut oil and lard worked very well for our heart-healthy ancestors. Or if you prefer, use olive, canola or grape seed oil.

Selected References:

1. Willett, W.C., Stampfer, M.J., Manson, J.E., et al., "Intake of Trans Fatty Acids and Risk of Coronary Heart Disease Among Women," Lancet, 341(8845), 1993, pages 581-585.

2. Mensink, R.P., Zock, P.L., Katan, M.B. et al., " Effects of Dietary Cis and Trans Fatty Acids on Serum Lipoprotein [A] Levels in Humans," Journal of Lipid Research, 33(10), 1992, pages 1493-1501.