BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene) are phenolic antioxidants used in the United States as food additives. Numerous studies have investigated the safety of BHA and BHT. As of 2011, the evidence suggests that although these chemicals may produce some negative health effects, their benefits may outweigh these drawbacks.
The primary function of BHA and BHT as food additives is to extend the shelf life of products such as cereal, flour, butter and beer by inhibiting the oxidation of fats and oils. This prevents spoilage, maintains flavor and palatability, and reduces production costs.
BHA, BHT and Food Safety
Researchers who have weighed the risks of consuming BHA and BHT against the risk of consuming spoiled foods and oxidized fats suggest that the risks of ingesting oxidized fats may be greater than the risk of ingesting preservatives. Phenolic antioxidants also possess antimicrobial properties, and may therefore reduce the incidence of some foodborne illnesses.
BHA, BHT and Cancer
Animal studies show that in large doses, BHA and BHT can trigger tumors in the forestomachs of certain animals. However, they also appear to inhibit the growth of other types of cancers. Known effects of lipid oxidation, which BHA and BHT prevent, include cell mutation and oxidative stress, both of which can lead to tumor formation. Some researchers have suggested that these antioxidant compounds may have a protective effect against cancer.
In 1958, BHA and BHT received the Food and Drug Administration's designation "generally regarded as safe" (GRAS). In 1977, due to health concerns, the FDA removed BHT from the GRAS list, and adjusted the allowable amounts of BHA and BHT from a general standard to an allowable proportion based on the total fat content of a given food. The updated standards have reduced public exposure to these compounds.