Butylated hydroxytoluene (BHT) is a widely used food preservative in some nations, and banned in others that is derived from petroleum and has many other uses, such as in the production of cosmetics, plastic packaging, and jet fuel. It is known to be a contributing factor to respiratory ailments such as asthma; to be detrimental to liver, kidney, and stomach function; and to possibly be carcinogenic. At the same time, BHT is a very effective anti-viral agent in pet foods and has been shown to suppress the activity of herpes simplex virus in humans where it is included as a food preservative.
The benefits of BHT as an anti-viral agent have been known for over 25 years. People with herpes who have taken antioxidant supplements that contain it in the range of 250 to 1,000 milligrams a day have also shown faster-than-normal recovery from the virus and an ability to suppress its recurrence. Research over the years has shown that BHT is effective against a range of different viruses, including cytomegalovirus, genital herpes, and a usually fatal disease in livestock such as sheep and cattle known as pseudorabies. Most of these findings are based on laboratory testing and animal studies, however, as little research into human use of BHT to treat disease has been done, as the compound is known to be detrimental to health in high doses or potentially dangerous with prolonged exposure to low doses.
The primary purpose of BHT when used in food, whether for human or animal consumption, is to prevent the fat content of the food from spoiling. The compound is often combined with butylated hydroxyanisole (BHA) to do this, which has a similar, though even longer, list of adverse health risks, including reproductive and hormone function disruptions in the body. Both are antioxidant compounds that react with free oxygen molecules in the body or in fats in foods, and bind to these oxygen molecules or free radicals, which prevents them from causing cellular damage or facilitating the decay of fats. This preservative quality is the main reason that BHT is also used in cosmetics such as lipstick, baby oil, and eyeliner, which have natural fats and oils subject to rapid decay processes.
The most common risks for low level exposure to BHT and BHA synthetic antioxidants are seen in the arena of allergies and immune system responses. Since BHT is used in cosmetics directly applied to the skin, people prone to allergic responses should avoid its use, or that of related antioxidants such as tertiary butylhydroquinone (TBHQ). Foods consumed that commonly contain these preservatives include potato chips, baked goods, and meals served in fast food restaurants.
The widespread use of the chemical in low concentrations has resulted in varying claims as to the risks that it poses. It is not restricted in the US or Canada, though advisory warnings to its presence have been issued. The European nations of the UK, Sweden, and Romania as well as Australia have all banned its use.