FDA bans artificial trans fats from packaged and restaurant foods

Trans fats have been a staple in the tastiest junk foods for more than 100 years.

But Monday marked the end of the once-prevalent ingredient following the Food and Drug Administration's ban of artificial trans fats from American restaurants and grocery store food items.

Before we dive into what the ban means, here's a little lesson on what trans fats are - and why they're unsafe.

What are trans fats?

Trans fat - also known as trans fatty acids - is a type of unsaturated fat found in foods like cake, cookies, doughnuts, pie crust, frozen pizza and margarine. Small quantities of trans fats can also be found naturally in meat and dairy products.

The FDA ban applies to artificial trans fats, which are made chemically by adding hydrogen to vegetable oil. (Ever seen "partially hydrogenated oil" on an ingredient list? That's trans fat.) Trans fat increases the shelf life of packaged foods, and restaurants like to use it as oil for deep frying because it doesn't need to be changed as often as other oils.

Why were trans fats banned?

The medical community overwhelmingly agrees that artificial trans fats shouldn't be eatenbecause they raise LDL, or "bad" cholesterol, and lower HDL, or "good" cholesterol. People who have diets high in trans fats are more likely to have a heart attack, diabetes, or stroke.

In 2015, the FDA said thousands of heart attacks and deaths could be prevented each year by removing partially hydrogenated oils from processed foods.

What does the trans fat ban entail?

After the FDA declared trans fat unsafe, it gave U.S. food companies until June 18, 2018 to eliminate hydrogenated oils from their products. According to the Grocery Manufacturers Association, companies eliminated 98 percent of trans fats from the food supply, the Washington Post reported.

However, some companies argued they were unable to reformulate their products in time. Some flavor enhancers and spray oils used to grease baking pans were given an extra year to reformulate.

And while new products can't be made with trans fats, items with hydrogenated oils already on store shelves can be sold until they have been completely eliminated from the market, according to the Washington Post. Quantities are so small, though, that experts say trans fats are considered eliminated.