Trans fats, once seen as harmless additives that ended up in everything from Twinkies to French fries, are finally getting the reputation they deserve—bad for health.
For years, the FDA has labeled trans fats as “generally recognized as safe.” That term applies to substances added to foods that experts consider safe, and so can be used without testing or approval. Yesterday the FDA proposed removing trans fats from the generally recognized as safe list, a step that would eliminate artificial trans fats from the American food supply.
The move comes as a victory for Dr. Walter Willett and his colleagues at the Harvard School of Public Health, who have long highlighted the health harms of trans fats. Research on the health hazards of trans fats goes back four decades. In our 2001 book, Eat, Drink, and Be Healthy, Dr. Willett and I wrote that “Only one type of dietary fat is worse for you than saturated fat—the increasingly common trans fats.”
Since then, communities from Tiburon, California to New York City banned the use of trans fats as evidence continued to mount against them. Many companies have already removed trans fats from their products. The FDA’s proposal, if finalized, would speed that process.
You can see an interview with Dr. Willett about the FDA’s proposal on the Harvard Gazette website.
Why the ruckus?
Trans fats are a type of unsaturated fat. Think of them as the evil cousins of the healthy omega-3 fats in fish, flaxseeds, and walnuts.
Once upon a time, the only sources of trans fats were bacteria living in the forestomach of ruminants. As a result, beef, lamb, buffalo, deer, and dairy products have small amounts of trans fats. By the end of the 20th century, though, they were everywhere, thanks to the ingenuity of early 20th-century chemists who discovered that they could turn a liquid vegetable oil into a solid or semi-solid by bubbling hydrogen gas through it. Partially hydrogenated oils don’t spoil or turn rancid as readily as non-hydrogenated fats and can withstand repeated heating without breaking down.
Those characteristics made trans fats a workhorse of the food industry. The FDA has estimated that in the late 1990s, 95% of prepared cookies, 100% of crackers, and 80% of frozen breakfast products contained trans fats. Frying oils used in restaurants were also rich in them.
The problem for us is that trans fats are bad for the heart and the rest of the body. Eating trans fats boosts LDL (bad) cholesterol, especially the small, dense LDL particles that are most damaging to arteries. It depresses protective HDL, which trucks LDL to the liver for disposal. Trans fats have unhealthy effects on triglycerides; make blood platelets stickier than usual and so more likely to form artery-blocking clots in the heart, brain, and elsewhere; and feed inflammation, which plays key roles in the development of heart disease, stroke, and diabetes.
Writing in the New England Journal of Medicine, Harvard School of Public Health researchers once estimated that removing trans fats from the U.S. food supply would prevent between 72,000 and 228,000 heart attacks each year.
The FDA’s proposal to reclassify trans fats is a move that should have little impact on what we eat, as food companies have been finding successful—and healthier—alternatives. But it could have a beneficial impact on our health.