The Worst Fat in the Food Supply

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Personal Health

As strange as it may seem to someone who is not a chemist, the movement of a single hydrogen atom from one side of a molecule to the other can change a simple, naturally occurring food ingredient into a deadly substance.

The transformed ingredient I’m speaking of is trans fatty acid, or trans fats as consumers know them, a core component of partially hydrogenated vegetable oils. For most of my life, trans fats were prominent in all manner of packaged, bakery and restaurant-prepared foods.

The descriptive “trans” refers to the fact that when a liquid vegetable oil like corn oil is treated to make it more solid and stable at room temperature — as, for example, in preparing margarine — a hydrogen atom moves from one side of a double chemical bond to the other so that two hydrogen atoms are now opposite one another instead of on the same side of the double bond.

That tiny molecular shift creates a substance that is now well known to be a potent precipitator of cardiovascular disease, including heart attacks, strokes and sudden cardiac deaths. Trans fats, in fact, are far more deadly than the saturated fats that heart-conscious people have tried to limit for decades. Their damaging effects include a rise in artery-clogging LDL cholesterol and decline in protective HDL cholesterol, damage to the lining of arteries, and inflammation, which can destabilize arterial plaque and precipitate a heart attack or stroke.

A mere 2 percent increase in calories from trans fats can raise the risk of coronary heart disease by as much as 29 percent. Substituting a healthy fat like extra-virgin olive oil or canola oil for those containing trans fats could prevent 30,000 to 100,000 premature deaths a year, the American Medical Association concluded in 2013.

Government regulations have sought to minimize or eliminate the use of artificially produced trans fats years after their hazards were first recognized in the 1990s. Faced with having to declare the trans fat content on food labels in 2006, many major manufacturers heeded consumer concerns and reformulated their products to avoid partially hydrogenated oils. Next year, thanks to a ban by the Food and Drug Administration, these oils will no longer be permitted in industry-prepared foods.

Michael Jacobson, head of the Center for Science in the Public Interest, a consumer advocacy group that has long called for a trans fat ban, noted that “government-sponsored research led to the understanding that a product considered safe for about 100 years was shown to be the most harmful fat in the food supply.”

Lest there be any doubt as to the value of banning trans fats, recent studies have demonstrated a remarkable benefit to the hearts and lives of residents in places where governments restricted the use of partially hydrogenated oils years ago.

Denmark was the first to act, banning trans fats from food products and virtually eliminating them from that country’s food supply in 2004. Within three years, the ban had saved an average of 14.2 lives per 100,000 people a year, according to a study in the American Journal of Preventive Medicine.

Starting in 2007 in New York City, New York State pioneered trans fat bans in this country. Scientists from the F.D.A. and Erasmus University in Rotterdam, the Netherlands, analyzed death rates in New York counties that forbid artificially produced trans fats in food sold in restaurants and bakeries. When death rates in these counties were compared with those in similar areas without a ban, the researchers found that restricting trans fats resulted in 13 fewer cardiovascular disease deaths and a saving of about $3.9 million per 100,000 persons annually.

A more recent study showed a comparable decline in cardiovascular disease rates as well. By comparing counties with and without a trans fat ban in food service establishments, Dr. Eric J. Brandt, a cardiovascular disease fellow at Yale University School of Medicine, found that three or more years later, heart attacks declined by 7.8 percent and strokes by 3.6 percent in counties with the ban over and above what occurred in counties without a ban, though the stroke numbers were not statistically significant.

In an interview, Dr. Brandt noted that many manufacturers have substituted palm oil, which is high in saturated fat, for partially hydrogenated oils. He said, “Even when saturated fat is used in place of trans fat, there’s still a net benefit,” although a heart-smart consumer should avoid too much saturated fat, including palm and coconut oil.

Dr. Brandt became interested in trans fats as a student at Case Western Reserve University School of Medicine. In 2011 he published a paper pointing out misleading labeling practices that could result in people unwittingly consuming harmful levels of trans fats, a finding still relevant today. F.D.A. labeling rules allow manufacturers to list as zero any amount of trans fat less than half a gram per serving. So, someone who consumes only three servings a day of foods that each contain 0.49 grams of trans fats would quickly exceed that 0.5 gram level.

“There really is no safe level for artificially produced trans fat,” Dr. Brandt said. “It’s best to avoid all products that have any partially hydrogenated oils.” He noted, however, that less is better. Canada, among other countries, lists trans fats down to a level of 0.1 gram per serving and he wondered why the United States doesn’t do likewise.

Complicating the trans fat picture is the fact that there are natural sources of this substance, found in meats and dairy products derived from ruminant animals – cows, sheep and goats.

“The jury is still out as to whether these are a hazard; the data are not clear about what natural trans fat means from a health standpoint,” Dr. Brandt said. He added, however, that “cardiologists mainly endorse a plant-based diet as the healthiest option.”