Staying Healthy

Where the worst type of fat is hiding in supermarket foods

Trans fats are undeniably bad for health, and they're still in many foods.

nutrition label grocery shopping fat
 Image: GPointsStudio/Thinkstock

Lurking on supermarket shelves, within colorful, seemingly harmless packages, is something that can cause serious harm to your health: trans fat. "No amount of trans fat is acceptable, from a health standpoint," says registered dietitian Kathy McManus, director of the Department of Nutrition at Harvard-affiliated Brigham and Women's Hospital.

About trans fat

Still a danger

Meanwhile, food manufacturers are allowed to use partially hydrogenated oils in their products, and so are restaurants. And if you're not savvy about reading Nutrition Facts labels, you may not detect the trans fat in your food. "The FDA doesn't require trans fat to be listed until there's a half gram or more per serving," explains McManus, "so the label may show zero grams of trans fat, even if a serving contains almost half a gram."

Are small amounts of trans fat dangerous? "It adds up, especially if you eat several foods with trans fat each day," says McManus. Based on FDA estimates, researchers at the CDC report it is possible that eliminating trans fats in the diet may prevent as many as 10,000 to 20,000 heart attacks and 3,000 to 7,000 deaths from heart disease each year.

Become a detective

What about other fats?

All fat is high in calories (nine calories per gram of fat, versus four calories per gram of carbohydrate, for example). A high-calorie diet can lead to weight gain, which can lead to chronic health problems.

An excess of saturated fats (such as those found in whole milk, butter, and red meat) can increase "bad" LDL cholesterol and lead to heart disease. Limit saturated fats to less than 7% of your total daily calories or less than 12 grams in a 1,500-calorie diet.

Some fats, within calorie limits, are good for you. Such "good" fats include monounsaturated fat (such as those in olive and canola oils, most nuts, peanut butter, and avocados) and polyunsaturated fat (for instance, in salmon, mackerel, walnuts, and safflower oil). Both are associated with lower LDL cholesterol and total cholesterol when substituted for saturated fats.

Surprising sources of trans fat that list 0 grams on the Nutrition Facts label

Product type


Identifying ingredient

Frozen fish fillets

Sea Cuisine Potato-Crusted Cod

Partially hydrogenated soybean oil

Coffee drink mix

Hills Bros. Double Mocha Cappuccino

Partially hydrogenated coconut oil

Breakfast cereal

Kellogg's Apple Jacks

Partially hydrogenated soy-bean and/or cottonseed oil

Seasoned bread crumbs


One or more partially hydrogenated oils (soybean, cottonseed, corn, canola)




To continue reading this article, you must log in.

Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.

  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »

I'd like to receive access to Harvard Health Online for only $4.99 a month.

Sign Me Up

Already a member? Login ».


As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.

No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Free Healthbeat Signup

Get the latest in health news delivered to your inbox!

Sign Up
Harvard Health Publishing Logo

Thanks for visiting. Don't miss your FREE gift.

The Best Diets for Cognitive Fitness, is yours absolutely FREE when you sign up to receive Health Alerts from Harvard Medical School

Sign up to get tips for living a healthy lifestyle, with ways to fight inflammation and improve cognitive health, plus the latest advances in preventative medicine, diet and exercise, pain relief, blood pressure and cholesterol management, and more.

Harvard Health Publishing Logo

Health Alerts from Harvard Medical School

Get helpful tips and guidance for everything from fighting inflammation to finding the best diets for weight loss...from exercises to build a stronger core to advice on treating cataracts. PLUS, the latest news on medical advances and breakthroughs from Harvard Medical School experts.

BONUS! Sign up now and
get a FREE copy of the
Best Diets for Cognitive Fitness

Harvard Health Publishing Logo

Stay on top of latest health news from Harvard Medical School.

Plus, get a FREE copy of the Best Diets for Cognitive Fitness.