Feb 12, 2007

Oil Changes: Part 1

Amy Campbell

Years ago, when I was a new dietitian, I remember counseling my patients to use what were then considered to be the most “heart-healthy” oils: corn oil, safflower oil, and vegetable (soybean) oil. These oils are known as polyunsaturated fats, due to the presence of double bonds in their chemical makeup (I’ll spare you the chemistry lesson, however). Then, monounsaturated fats came into favor, and the “polys” took a back seat. Monounsaturated fats include canola oil, olive oil, and peanut oils. Why were these better?

Well, evidence at the time seemed to show that, while all unsaturated fat could help lower LDL, or bad, cholesterol (unlike saturated fat, which raises LDL cholesterol), the "monos" could also help raise HDL, or good, cholesterol. So, dietitians began counseling patients to switch to canola or olive oil in place of corn or vegetable oil.

Now, however, the thinking is that all unsaturated fats are okay to use, whether you choose corn oil or canola oil, and there isn't as much of a distinction between the two anymore. Of course, one type of polyunsaturated fat that we want to include more of in our diets is omega-3 fatty acids, sometimes known as "fish oils." These fats are found in cold-water, fatty fish, such as salmon and mackerel, but are found in some plant foods, too, including flax seed and walnuts. Omega-3 fatty acids can help protect against heart disease. They may also protect against other inflammatory diseases, such as rheumatoid arthritis, and possibly even protect against depression.

But, as is often the case in the field of nutrition, there are always new products and new developments to stay on top of. In 2005, a new oil called Enova oil hit the market. This oil, which has been used in Japan since 1999 under the name Econa, is a little different than all the rest. It's not a fat replacer, like olestra (also known as Olean). It's a cooking and salad oil that is intended to be used in place of, say, your olive oil or canola oil. In fact, Enova is made from soybean and canola oils. However, these oils have been altered to have a higher concentration of what are called diacylglycerols, or DAGs for short.

DAGs apparently have some health benefits, such as an ability to lower blood triglyceride levels. But the main feature of interest of DAGs is that they aren't broken down the same way as regular fat. Because of this, DAG oil is less likely to be stored as body fat; hence the claim that Enova oil may actually help with weight loss.

Can this be true? According to the few studies done with Enova, folks who substituted this oil for other oils in their diets tended to lose about two pounds more over 6 or 12 months than people who used ordinary cooking oils. That's not a lot. Granted, they didn't gain weight, which is good. The FDA considers Enova to be GRAS (generally recognized as safe), but it hasn't undergone extensive testing in the U.S. Also, if you're thinking of (or already are) using Enova, you still need to remember that it's an oil and, therefore, contains 120 calories and 14 grams of fat per tablespoon, the same as all other oils.

Enova is fine for baking and cooking, but probably not so great as a salad dressing or for dipping bread, as you might do with olive oil, for example, because it's quite bland tasting. And don't expect to see major weight loss just from using Enova. Remember that weight loss occurs when you consume fewer calories and/or burn more calories than you normally do.

More on oils next week.

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