Interesterified Oils – Are They the New Trans Fat?

by Aviva Natural Health Solutions September 18, 2008

Dr. Kristie Leong

Just when you thought you could breathe a sigh of relief that trans fats had been eliminated from your favorite food products, along comes another nutritional concern in the form of interesterified oils. Food manufacturers are now using these chemically modified oils to replace the partially hydrogenated oils that have been the focus of such recent health scrutiny. Interesterified oils are meant to be a replacement for the old trans fats, allowing food products to have a longer shelf life and increased stability when exposed to heat. Unfortunately, the health effects of interesterified oils are no better and may actually be worse than the trans fats they replaced. What are the possible health effects of the interesterified oils?

A study published in the Journal of Nutrition and Metabolism in 2007 demonstrated that the addition of interesterified oils to the diet of test subjects caused negative effects on both glucose metabolism and metabolism of blood lipoproteins when compared to an unmodified saturated fat. The result could be elevations in blood sugar levels which would not only increase the risk for diabetes in normal subjects but have adverse effects on the blood sugar levels of established diabetics. Interestingly, the trans fats these modified oils are meant to replace, had similar effects including negative effects on lipid metabolism, raising blood levels of LDL and lowering levels of HDL, the good cholesterol. Trans fats also appeared to have a slight negative effect on blood sugar levels. It appears that this replacement for trans fats may be no better and may in actuality have a more negative impact on blood sugar levels than even the trans fats themselves.

What types of food products contain the new interesterified oils? You'll mostly find these modified oils in food products such as margarines and baked goods. You can find these oils already on the shelves of your local supermarket. This presents a problem for consumers who may have blissfully returned to the products they had abandoned believing they are now safe since the trans fats have been removed.

How can you recognize the presence of interesterified oils in the products you buy at the supermarket? In most cases, they'll be listed on the label as "interesterified oils" or "fully hydrogenated oils". This illustrates the importance of carefully reading the ingredient list of items before purchasing them since these products will typically state that they have zero grams of trans fats which can give a false sense of security.

Since interesterified oils are relatively new, it will take further testing to determine what the long term consequences of their use will be. Until then, proceed with caution when you grocery shop. One of the best ways to avoid interesterified oils is to stay away from processed foods entirely.