BHA and BHT are synthetic antioxidants added to foods, cosmetics, and packaging to keep fats and oils from going rancid. Their full names are butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). You’ll find them in everything from breakfast cereal to lipstick, and they’ve been used since the 1940s. They’re effective at tiny concentrations, which is part of why they became so widespread, but their safety profile has drawn increasing scrutiny.
How BHA and BHT Work
When fats and oils are exposed to oxygen, they break down through a chain reaction that produces off-flavors, unpleasant smells, and potentially harmful byproducts. This process, called oxidation, is what makes butter taste stale or cooking oil smell “off.” BHA works by trapping the free radicals that drive this chain reaction, essentially stopping spoilage before it can spread. BHT functions similarly as a fat-soluble antioxidant, dissolving directly into the oils and fats it’s protecting.
Both compounds are effective at very low concentrations. In cosmetics, for example, BHT is typically used at levels between 0.0002% and 0.5% of the total formula. In food, amounts are similarly small, often measured in parts per million. That’s why they rarely appear near the top of an ingredient list.
Where You’ll Find Them
BHA and BHT show up in products where fats or oils need protection from going stale. In food, that includes frozen meals, breakfast cereals, cookies, candy, ice cream, and meat products. They’re also added to food packaging materials, where they can migrate into the food itself in trace amounts.
Outside the kitchen, BHT is widely used in cosmetics and personal care products. Lip balms, moisturizers, and sunscreens often contain it to prevent the oils in the formula from breaking down and losing effectiveness. BHA appears in similar products. Both are also used in pharmaceuticals, animal feed, and rubber or petroleum products to prevent degradation.
How to Spot Them on Labels
In the U.S., BHA and BHT are listed by those abbreviations or their full names on ingredient labels. On European and international products, BHA appears as E320 and BHT as E321. You might also see BHA listed under its chemical name, 2-tert-butyl-4-methoxyphenol, though that’s uncommon on consumer packaging. If a product says “to preserve freshness” in parentheses after the ingredient, that’s describing what these additives do.
The Cancer Question
BHA carries the more serious safety concern of the two. The U.S. National Toxicology Program lists BHA as “reasonably anticipated to be a human carcinogen,” based on sufficient evidence of cancer in animal studies. The International Agency for Research on Cancer has also evaluated BHA and classified it as a possible carcinogen. These classifications are based primarily on studies in rats and mice, not direct evidence in humans, but they’ve been enough to prompt regulatory action in some countries and ongoing review in others.
BHT has not received the same carcinogen classification. Its safety concerns are different: some rat studies have shown changes to thyroid function at high doses. The French Agency for Food, Environmental and Occupational Health and Safety has raised the possibility that BHT could act as an endocrine disruptor based on these observations. However, a detailed assessment using modern testing methods found that neither BHT nor its breakdown products showed endocrine activity for estrogens, androgens, thyroid hormones, or steroid production pathways. A causal link between BHT and hormonal disruption hasn’t been established.
The FDA currently permits both additives in food but announced an assessment of BHA’s safety, with plans to conduct a similar review for BHT afterward. This doesn’t mean the agency has determined either is unsafe; it reflects growing public interest and the availability of newer evaluation methods.
Why Some Brands Are Moving Away
Consumer demand for “clean labels” has pushed many food manufacturers to replace BHA and BHT with natural antioxidants. The most common substitutes are tocopherols (forms of vitamin E), ascorbic acid (vitamin C), and plant-derived extracts. Rosemary extract is one of the most popular replacements in processed foods.
Clove extract has shown particular promise in meat products. Research comparing BHT, ascorbic acid, and clove extract in fresh beef patties found that clove extract matched or exceeded BHT’s ability to prevent fat oxidation and maintain color stability during refrigerated storage. The active compounds in clove, primarily eugenol and eugenyl acetate, have strong antioxidant properties. These findings suggest natural alternatives can perform the same job in at least some applications, though they tend to cost more and may not work as well in every product type.
If you’re looking to avoid BHA and BHT, checking ingredient labels is straightforward since they must be listed. Products marketed as “no artificial preservatives” or certified organic won’t contain them. Keep in mind that these additives are present in very small amounts, and the health concerns are based on animal studies at doses much higher than what humans typically consume through food. The practical risk to any individual is difficult to quantify, which is exactly why regulatory reviews are ongoing.