With new restrictions on their use, trans fats are fast on their way out of favor with the American public. But are replacements for trans fats any healthier?
Artificial trans fats, which are used to extend foods' shelf life and enhance their flavor, have been removed from many products and are even to be banned in New York City restaurants because of increasing concerns about their cholesterol raising abilities.
But one type of fat that is becoming a go-to replacement for trans fats may not be much better. New research has shown that while trans fats raises levels of low-density lipoprotein (LDL) cholesterol, so-called bad-cholesterol, their common replacement, interesterified fats, lower levels of heart-healthy high-density lipoprotein (HDL) cholesterol and raise blood sugar levels.
Trans fats exist naturally in small amounts in dairy products and meat. Artery-clogging artificial trans fats used in deep-frying, baked goods and other foods are made by adding hydrogen to vegetable oil, causing the oil to solidify.
Interesterified fats are also manufactured, but this process changes the chemical makeup of liquid oils to make a solid polyunsaturated fat. These fats seem to be a suitable replacement for trans fats in many cases as they have similar properties. However, though interesterified fats do not increase LDL cholesterol, they may have other serious consequences.
In one study, researchers looked at 30 healthy volunteers who agreed to follow three different diets for four weeks each. Each of the three diets emphasized a different type of fat: trans fats, interesterified soybean oil and a natural, saturated fat. The participants' cholesterol and blood sugar levels were measured before beginning eat diet and at the end of each four-week period.
While on the diet with trans fats, the participants' LDL levels rose, as expected. However, when the participants ate the diet featuring interesterified fat, their blood sugar rose 20 percent and their HDL levels dropped as compared to when they ate the diet featuring the saturated fat.
Health
Hayes believes that interesterified fats change the levels of insulin in the body. This hormone helps regulate blood sugar levels, and if it is not working right, people are at risk for diabetes.
"There is very strong evidence of the association between trans fats and diabetes, but now we have some evidence that interesterified fats also increase your risk," said Dr. K. C. Hayes, study author from Brandeis University in Waltham, Massachusetts.
While more work needs to be done to determine their true health risk, interesterified are currently being used to replace trans fats. To avoid both trans fats and interesterified fats, Hayes recommends closely looking at nutrition labels. Just because a box of cookies says it's "trans-fat free" does not mean it's healthy.
Hayes recommends that consumers look to see if a fat is listed with any words in front of it. Words like "partially hydrogenated oil" signal the use of trans fats, and "fully hydrogenated oil" on the ingredients list is another word for interesterified fats.
The best bet is to look for food that just lists the oil used as it is found in nature: olive oil, canola oil, vegetable oil.
