Margarine May Be No Better Than Butter : Diet: Harvard study shows the product is associated with a 70% increase in risk of heart disease for women and may be no more healthful than animal fats.
Margarine--whose status as a healthful alternative to butter has been fading in recent years--will suffer another blow this weekend with the publication of a study that shows it is associated with a 70% increase in the risk of heart disease for women.
The study, conducted by the Harvard School of Public Health, provides the most compelling evidence to date that trans isomers--artificial fats formed when liquid vegetable oils are processed to make margarine and vegetable shortening--are no more healthful than natural animal fats such as butter.
Other studies have shown a link between partially hydrogenated fats and heart disease. But the Harvard study--conducted as part of an ongoing examination of the eating habits of 90,000 nurses and which will appear in the Saturday issue of Lancet, a British medical journal--is the most definitive.
“What’s new and what’s important is that it has been found in such a large number of people and in women, especially,” said Dr. Dean Ornish, director of the Preventive Medicine Research Institute at UC San Francisco.
“The question is not: ‘Should people go back to butter?’ ” Ornish said. “The issue is that margarine is not much better than butter, if it is better (at) all.”
The study’s author, Dr. Walter Willett, advocates olive oil and other natural vegetable oils--such as soybean, corn or canola oil--as an alternative to butter and margarine. “There is no reason we should be eating partially hydrogenated vegetable fat in our diet,” Willett said. “It is perfectly natural to eat none of them. I do so myself.”
The Harvard study looked at intake of margarine, beef, pork, lamb, cookies, biscuits and white bread. It found that women who ate four or more teaspoons of margarine per day were at significantly higher risk than women who ate up to two to three teaspoons a day. The study also found little difference in the data for tub and stick margarine.
In a surprising discovery, the study found that beef, pork or lamb as a main dish did not seem to increase the risk of heart disease. Previous findings involving the same study subjects have shown that red meat is associated with increased risk of colon cancer.
The researchers did find that consumption of cookies and white bread, which often contain partially hydrogenated fats, was associated with an increased risk of heart disease.
Willett called upon the food industry--and fast-food restaurants in particular--to abandon use of these products. He said fats used by fast-food restaurants to deep-fry foods contain very high levels of trans isomers, “even though the public may imagine it is a benefit that the food is cooked in vegetable oil.”
The technique of partial hydrogenation was developed late in the 1800s; by the early part of this century, these artificial fats came into use as a cheaper alternative to butter and lard, Willett said.
When health concerns about butter and lard emerged several decades ago, consumption of margarine and other partially hydrogenated fats increased. “That was where we got into some trouble,” Willett said, “because we didn’t really have the evidence that they were better.”
