Brominated vegetable oil (BVO) is a complex mixture of plant-derived triglycerides that have been modified by atoms of the element bromine bonded to the fat molecules. Brominated vegetable oil is used to help emulsify citrus-flavored soft drinks, preventing them from separating during distribution. Brominated vegetable oil has been used by the soft drink industry since 1931, generally at a level of about 8 ppm.
Careful control of the type of oil used allows bromination of it to produce BVO with a specific density of 1.33 g/mL, which is 33% greater than water (1 g/mL). As a result, it can be mixed with less-dense flavoring agents such as citrus oil to produce an oil which matches the density of water or other products. The droplets containing BVO remain suspended in the water rather than separating and floating to the surface.
Alternative food additives used for the same purpose include sucrose acetate isobutyrate (SAIB, E444) and glycerol ester of wood rosin (ester gum, E445).   
Similar iodinated oils have been used as contrast agents and for goiter prophylaxis in populations with low dietary iodine intake. 
Brominated vegetable oil has the CAS number 8016-94-2 and the EC number 232-416-5.