The chemical structure of the fat that you eat is more important than you think. Everyone needs some fat in their diet, but too much and too much of the wrong types of fat can be bad for your health. A Dutch group of researchers has recently reported that trans fat (more correctly trans fatty acids) are more detrimental to cardiovascular health than saturated fats.
Generally speaking polyunsaturated fats like those found in most vegetable oils and monounsaturated fats that are found in olive and canola oil are considered good fats to have in the diet. Saturated fats, most abundant in animal products such as meat and milk, are usually considered bad. Nutritionists have been advising us for some time now to eat more salads with olive oil dressing and less marbled steak.
Trans fatty acids do occur in milk naturally, but are more commonly produced during food processing. However, because we eat so much processed food now, in countries like the United States and the Netherlands, trans fat can make up to 7% of our total fat intake.
According to the Dutch research, trans fat in the diet can cause even more health problems than saturated fats. Using a “cross over” design in which healthy subjects ate a diet containing trans fat or saturated fat for 4 weeks and then switched to the opposite diet for 4 weeks, several cardiovascular events were affected. When the subjects ate the trans diet their blood vessels dilated 29% less efficiently, and blood levels of HDL or “good cholesterol” was lowered by 20% compared to when subjects ate the diet rich in saturated fats. Trans fat has also been shown in other studies to raise the levels of LDL or “bad cholesterol” and may also increase total serum cholesterol.
Avoiding trans fats may be difficult for the average consumer because the amount of trans fat in foods is not identified on their labels. It is included however in the total fat reported. The French fries, fried chicken, and doughnuts from fast food outlets all contain high levels of trans fat. But soft margarines, especially those that are non-hydrogenated, are the choice to make to spread on your toast.
- Other Reported Effects of Trans Fatty Acids that May be Detrimental to Health
- Increases blood insulin levels in humans in response to glucose load
- Affects immune response
- Decreases the response of the red blood cell to insulin
- Inhibits the function of membrane-related enzymes
- Causes alterations in physiological properties of biological membranes
- Causes alterations in adipose cell size, cell number, lipid class, and fatty acid composition
- Journal of the American Heart Association Atherosclerosis, Thrombosis and Vascular Biology 21:1233-1237.