Butter Vs. Margarine Debate Goes On
Two new studies published in the English medical journal Lancet have thrown more fat on the fire burning beneath the butter vs. margarine controversy.
The studies of men living in Great Britain and several other countries fail to support any connection between heart disease and eating partly hydrogenated oils, which contain the man-made fats called “trans fatty acids.”
Partly hydrogenated fats - made by pumping up unsaturated fat molecules with extra hydrogen atoms - have been used extensively by food manufacturers as substitutes for more-saturated fats in margarines, cookies, snacks and prepared foods.
Because they are more stable and have a higher burning temperature, the hydrogenated fats work well for frying and thus are popular in the fast-food industry.
Some earlier studies have indicated that trans fatty acids may raise blood cholesterol somewhat like butter, lard, beef tallow and other saturated fats they were developed to replace.
Using calculations from a study of 90,000 nurses, Harvard researcher Dr. Walter C. Willet went so far as to predict last year that trans fatty acids in the American diet could be responsible for 30,000 deaths a year from heart disease.
The Lancet reports contradict that contention.
Each of those studies compared the actual amount of trans fatty acids found in body fat (adipose tissue) of men with acute heart disease to that in a group with no indications of the disease. Neither could establish a correlation.
In the smaller of the studies, trans fatty acids were measured in 66 British men who had died suddenly from heart attacks. Those were then compared to the readings in 286 healthy men.
The proportion of all trans fatty acids was actually lower in the men who had died from heart attacks than in the control group, though not significantly so, according to the researchers at the National Heart and Lung Institute of Royal Brompton Hospital in London.
The larger study, a joint effort by medical organizations in eight European countries and Israel, compared 671 men who had had heart attacks with 717 men with good heart histories. Researchers reported there was “no major overall effect of … trans fatty acids on risk of acute myocardial infarction (i.e., heart attack).”
They did find considerable differences in the dietary intake of trans fatty acids between countries, ranging from a low of 0.4 percent of total fat in Spain to 2.4 percent in the Netherlands and Norway.
The researchers in that multicultural study did inject one word of caution, however, which could lend fuel to critics of hydrogenated fats.
When they excluded the Spanish subjects, whose trans fatty acid consumption was very low, and looked at the 25 percent of the remaining men who had the highest levels, there was a “tendency to increased risk.”
While “the trend was not statistically significant,” the researchers reported, they added: “We cannot exclude the possibility that trans fatty acids have a significant impact on the risk of AMI (heart attack) in populations with high intake.”
Willet and the Center for Science in the Public Interest - a Washington-based consumer group - have called for trans fatty acids to be treated as saturated fats on the Nutrition Fact product labels.
However, several other researchers have cautioned against equating hydrogenated fats with saturated fats, or, as some television commentators put it, “making margarine just as bad as butter.”
In the past 20 years there has been a successful campaign to reduce saturated fats, says Dr. William Castelli, director of the ongoing Framingham Heart study of 10,000 middle-age Americans.
“There was a big fall in butterfat and an increase in the use of polyunsaturated fats, but also an increase in trans fatty acids,” he says. “But the heart attack rate also has fallen by 20 percent.
“Perhaps you can argue that it would be better if we had gotten rid of all trans fatty acids, too, but you don’t want everyone to go back to butter.”