Once ubiquitous in everything from frozen pizza to coffee creamer to popcorn, artificial trans fats are – as of Monday – banished from U.S. restaurants and grocery stores.
Food-makers have had three years to phase out the ingredient, which the Food and Drug Administration ruled unsafe to eat in 2015. Nutrition researchers and public health advocates long ago found artificial trans fats, a modified form of vegetable oil, raised "bad" cholesterol and contributed to heart disease.
That prompted a wave of voluntary recipe changes at food companies, and trans fat consumption has plummeted over the past decade. But the June 18 deadline marks a final chapter in the U.S. fight against trans fats at a time when other countries are beginning to contemplate a similar change.
"The elimination of artificial trans fat from the food supply represents a historic and long-fought victory for public health," said Michael Jacobson, the former executive director of the nonprofit Center for Science in the Public Interest, in a statement to mark the occasion. "Ridding the food supply of partially hydrogenated oils will save tens of thousands of lives each year."
Scientists developed the method for modifying oils in the early 20th century, but food-makers didn't deploy them until the 1950s and '60s when they needed ways to lengthen shelf life and improve the texture of processed food products.
But in the early 1990s, research began turning up powerful links between artificial trans fats, cholesterol and heart disease. (Studies have not established a connection between those conditions and the natural trans fats that occur in some animal proteins.)
Artificial trans fats are made in an industrial process that injects hydrogen atoms into molecules of vegetable fat, changing their chemical structure. For reasons scientists don't entirely understand, these altered molecules prompt the body to produce more bad cholesterol – among other possible problems.
As the scientific consensus grew, the FDA required food companies to disclose artificial trans fats on product labels in January 2006. Nine years later, the agency ruled that artificial trans fats are not safe in food and set a June 2018 deadline for their removal from the food system.
Food companies cut trans fats 86 percent between 2003 and 2015, according to the Grocery Manufacturers Association, and expended hundreds of thousands of hours tweaking foods from Jell-O to Wheat Thins. Food companies made further reductions between 2015 and 2018, removing 98 percent of trans fats from the food supply, said Brian Kennedy, a GMA spokesman.
But the transformation hasn't been easy. Some products, such as popcorn and pie crust, proved more stubborn to reinvention. Companies have also complained to FDA that they should be allowed to continue using trans fats in limited circumstances – such as to enhance product flavors or grease industrial baking pans.
FDA agreed in May to give companies one more year to find another ingredient for those purposes. The agency has also said that, while new products can no longer be made with trans fats, they'll give foods already on the shelves some time to cycle out of the market. But food makers and public health advocates agree that artificial trans fats are effectively no more.
"I would have preferred [FDA not give] the one-year extension because manufacturers have had plenty of time to eliminate the use of trans fat," said Walter Willett, the Harvard University nutrition professor whose research first surfaced the problems with trans fats. "However, these are small enough that we can say that industrial trans fat has been removed from our food supply."
Willett says that could slash the rates of preliminary death from heart disease, and reduce the incidence of diabetes, dementia and other metabolic diseases. Such declines have been observed in New York City, which banned the use of partially hydrogenated oils in restaurants in 2007, and in Denmark, which became the first country to ban trans fats in 2003.
Public health officials are looking to other countries to take similar steps, particularly in the developing world. In May, the World Health Organization urged countries to eliminate trans fats from their food supplies, citing the risk of cardiovascular disease.
"Several high-income countries have virtually eliminated industrially-produced trans fats through legally imposed limits on the amount that can be contained in packaged food," the agency said in a statement. "Action is needed in low- and middle-income countries . . . to ensure that the benefits are felt equally around the world."
The challenge now for regulators and public health advocates will be the ingredients replacing trans fats, Willett said.
Some environmental groups have raised concerns that food companies are reaching for palm oil, which contributes to deforestation.
There has also been concern that food-makers might boost the flavor and texture of newly overhauled products by increasing the fat content overall — although a 2017 report from the Department of Agriculture was the latest of several studies to find that trans fat reductions rarely led to an jump in fat content.
Before and after their makeover, for instance, a serving of Oreos contained 160 calories and seven grams of fat.
But today none of those calories come from partially hydrogenated oils – and that, experts say, is an accomplishment.