Media playback is unsupported on your device Media caption Why trans-fats might be in foods you do not expect

Trans-fats are unsafe to eat and must be banned from the food supply within three years, US regulators have said.

The US Food and Drug Administration said partially hydrogenated oils (PHOs), the main source of trans-fats, are not "generally recognised as safe".

It said a ban would save lives by preventing fatal heart attacks.

Food suppliers have been required to show trans-fats information on food labels since 2006 but health experts say Americans still consume too much.

"The FDA's action on this major source of artificial trans-fat demonstrates the agency's commitment to the heart health of all Americans," said FDA's Acting Commissioner Stephen Ostroff.

"This action is expected to reduce coronary heart disease and prevent thousands of fatal heart attacks every year."

Image copyright Science Photo Library Image caption Manufacturers will have three years to get rid of trans-fats

War on trans-fats

made by pumping vegetable oils with hydrogen which makes them solids or semi-solids

eating trans-fats took off in the 1970s when margarine became popular

popular foods that may have trans-fats: French fries, fried meats, frosting

cheap to produce with a long shelf life

World Health Organization calls them 'toxic'

many companies already working to remove them from foods

Since the FDA started labelling trans-fats, the agency estimates that consumption of them decreased by 78% in the US.

The UK has been calling for a ban on trans-fats for several years.

In Denmark, almost all trans-fats have been banned since 2003.