We all thought we were being so good to reduce our fat intake by switching from butter to margarine. Now a March 1993 study published in the British medical journal, Lancet, indicates that women who eat more than 4 teaspoons of margarine a day are at an increased risk of heart disease.
What's a woman to do? To find out, I met with Dr. Ben Caballero, director of the division of Nutrition at the Johns Hopkins School of Hygiene and Public Health and asked him to answer our questions.
Q. Did we do the wrong thing by switching from butter to margarine?
A. Absolutely not. The Surgeon General's guidelines for a healthy diet tell us that we should eat less fat, especially less fat of animal origin. Since margarine is based on vegetable oils, millions of Americans switched from butter to margarine. This is a good trend, but there are some things we must now keep in mind, and to do so, we need to understand what it is in margarine that creates the problem.
Q. What is it in margarine that's not good?
A. In order to offer consumers a product that looks and tastes as much like butter as possible and to give margarine a semi-solid consistency, food producers had to "hydrogenate" the vegetable oil in margarine. During the hydrogenation process, some fat molecules are "flipped over," creating what is called "trans" fatty acids. Margarines in the United States have anywhere from 25 percent to 50 percent of their fat in this "trans" form. Over the past year, two studies, including the most recent one in Lancet, have found that people who eat more than 4 to 5 grams of trans fatty acid (roughly equivalent to 4 or more teaspoons of margarine) a day, have higher serum cholesterol. Although blood cholesterol is only one of the risk factors for cardiovascular disease, this elevation is still of concern.
Q. Is margarine bad for you then?
A. Not necessarily. The good news is that more and more Americans have replaced butter with margarine, and margarine is better for your overall diet than butter. The other good news is that the technology to produce low-trans fatty acid margarine exists and, in fact, is being used in Europe. So, it is likely that U.S. manufacturers will soon begin producing margarines with low trans fatty acid content. Watch for news about this from the manufacturers, because they will certainly let you know if they have developed a product that may be better for you.
Q. If I shouldn't go back to using butter, can I still use margarine?
A. You can use margarine, but in moderation. Remember, that according to the study, the adverse effects of margarine are evident in people eating more than 4 teaspoons daily. So, don't eat more than 4 teaspoons and don't do it on a daily basis. We know that most of us need to reduce our fat intake anyway, not just because of coronary disease and obesity, but also because total fat consumption has an association with certain cancers as well.
Q. Is there an alternative to butter and margarine?
A. If you don't mind using your spread in liquid form, you can certainly replace margarine with pure olive or canola oil. The idea of sprinkling oil on your morning toast may not appeal to everyone, but it will lower your consumption of trans fatty acids. Remember, however, that using olive or canola oil will not lower ++ your total fat intake so you must be careful about how much oil you actually put on that slice of bread.
Dr. Matanoski is a physician and professor of epidemiology at the Johns Hopkins School of Hygiene and Public Health.