What is brominated vegetable oil, and why did the FDA ban it in food?

On Tuesday (July 2), the Food and Drug Administration (FDA) announced that it will no longer allow brominated vegetable oil (BVO) in food or beverages due to safety concerns. 

But what is BVO, and what is it found in?

BVO is vegetable oil modified with bromine, a naturally occurring chemical element that's dark-reddish-brown and liquid at room temperature. Bromine is denser than water and sinks when added to it, and when combined with a vegetable oil, the element makes that oil denser than water. This effect makes BVO useful for emulsifying certain ingredients in water, ensuring that they're evenly distributed throughout the liquid and don't separate from it.

In the past 50 years, BVO has primarily been used to help stabilize citrus flavorings within sodas, Sports drinks and energy drinks. That said, many U.S. beverage makers have already replaced the BVO in their products, and "today, few beverages in the U.S. contain BVO," according to the FDA. 

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Manufacturers started using BVO in food in the 1920s, prior to the FDA's establishment. The agency initially added the modified oil to its list of foods that are "generally recognized as safe" (GRAS). However, in the 1960s and 1970s, the oil's safety came into question as animal studies suggested that consuming the product might harm the heart. 

These early studies, however, fed the Animals doses far beyond what humans would be exposed to, and later studies overturned the idea that BVO hurts the heart. But nonetheless, at the time, the FDA moved to limit the use of BVO. In the late 1960s, the oil lost its place on the GRAS list and was restricted to being used as an additive in very small amounts — 15 parts per million.