Trans fats show up in two places: naturally in meat and dairy products, and artificially in foods made with partially hydrogenated oils. While the U.S. banned the main artificial source in 2021, trace amounts still appear in many everyday foods, and natural trans fats remain a permanent part of the food supply.
Two Types of Trans Fats in Food
Not all trans fats come from the same place. Ruminant trans fats form naturally in the digestive systems of cattle, sheep, and goats, then end up in their meat, milk, and fat. These natural trans fats make up about 2 to 3 percent of the total fat in beef, lamb, and dairy products. The dominant type is vaccenic acid, which behaves differently in your body than the artificial version.
Industrial trans fats are created when manufacturers pump hydrogen gas into liquid vegetable oils, turning them into solid or semi-solid fats. This process, called partial hydrogenation, once produced fats where trans fats could make up as much as 50 percent of the final product. These partially hydrogenated oils gave foods a longer shelf life, a desirable texture, and a lower price tag than butter or lard. They also turned out to be one of the most harmful ingredients in the modern food supply, raising LDL cholesterol and increasing heart disease risk.
Foods That Still Contain Trans Fats
The FDA set January 1, 2021, as the final compliance date for removing partially hydrogenated oils from foods, and completed its regulatory actions in December 2023. That eliminated the biggest source of artificial trans fats. But “eliminated” doesn’t mean zero. Trans fats still appear in several categories of food.
Meat and dairy: Beef, lamb, butter, cheese, cream, and whole milk all contain naturally occurring trans fats. Grass-fed beef has about 0.1 grams of trans-vaccenic acid per 100 grams of meat. Cheese contains roughly 1.2 grams per 100 grams, making it one of the more concentrated natural sources. These amounts are modest compared to what processed foods once contained, but they add up if you eat large quantities of full-fat dairy.
Fried foods: Frying oil at high temperatures generates small amounts of trans fats even without partial hydrogenation. The World Health Organization notes this typically produces up to 2 to 3 percent trans fat in the oil, far less than partially hydrogenated oils once did. Restaurants that reuse frying oil repeatedly see higher levels, so deep-fried foods from fast food chains and takeout spots carry more trans fat than home-fried food in fresh oil.
Packaged baked goods and snacks: Some cookies, crackers, pie crusts, and microwave popcorn brands may still contain small amounts. While manufacturers have reformulated most products, some use replacement fats that still carry trace trans fats. Imported foods from countries without trans fat bans can also be a source.
The Labeling Loophole to Watch For
U.S. food labels can legally list trans fat as “0 g” if a serving contains less than 0.5 grams. That means a product with 0.4 grams per serving looks trans-fat-free on the label. If you eat two or three servings, you could take in over a gram without realizing it.
To spot hidden trans fats, check the ingredient list for “partially hydrogenated” anything. If those words appear, the product contains some trans fat regardless of what the nutrition panel says. This matters most for foods with small listed serving sizes, where manufacturers can keep the per-serving number below the 0.5-gram threshold.
Natural Trans Fats vs. Artificial: Does It Matter?
Gram for gram, the major trans fat found in meat and dairy raises LDL cholesterol just as much as the industrial version, according to research published in The American Journal of Clinical Nutrition. The key difference is quantity. A serving of butter or steak delivers a small fraction of the trans fat that a pre-ban doughnut or stick of margarine once did. You’d have to eat very large amounts of dairy to match the doses that made industrial trans fats so dangerous.
The two types also have different chemical profiles. Natural trans fats are about 45 percent vaccenic acid and only 5 percent elaidic acid. Industrial trans fats flip that ratio, containing roughly 25 percent elaidic acid and just 10 percent vaccenic acid. This difference in composition is one reason researchers have found different health patterns between populations eating mainly ruminant trans fats versus those consuming industrial ones, though the total amount consumed matters most.
Where the World Stands on Trans Fats
Nearly 60 countries now have best-practice policies to eliminate industrially produced trans fats, covering about 46 percent of the world’s population. The U.S., Canada, Denmark, Thailand, and many others have enacted outright bans or strict limits. But more than half the global population still lives in countries without meaningful regulations, which means imported foods, international travel, and products bought online from overseas sellers can still expose you to significant levels of artificial trans fats.
If you’re buying food products from countries without trans fat restrictions, checking ingredient lists for partially hydrogenated oils is the most reliable way to identify them. Nutrition labels in those countries may follow different rounding rules or not list trans fats at all.
Practical Ways to Minimize Your Intake
Your biggest sources today are full-fat dairy products, fatty cuts of beef and lamb, repeatedly used frying oil, and any remaining packaged foods with partially hydrogenated oils in the ingredients. A few straightforward habits can keep your exposure low:
- Read ingredient lists, not just nutrition panels. The words “partially hydrogenated” are the giveaway, even when the trans fat line reads 0 g.
- Choose liquid oils over solid fats. Olive oil, canola oil, and avocado oil contain virtually no trans fats. Solid shortenings and stick margarines are more likely to carry trace amounts.
- Limit deep-fried restaurant food. You have no way of knowing how many times the frying oil has been reused or what type of oil is in the fryer.
- Moderate full-fat dairy. Cheese, butter, and cream are the most concentrated natural sources. Switching to reduced-fat versions lowers trans fat intake proportionally.
The American Heart Association’s position is straightforward: avoid trans fats as much as possible. Given that natural trans fats in meat and dairy can’t be fully eliminated from your diet, the practical goal is keeping artificial sources at zero and natural sources modest.