Aflatoxins are toxins produced by a mold (fungus) that grows in nuts, seeds, and legumes.
Although aflatoxins are known to cause cancer in animals, the United States Food and Drug Administration (FDA) allows them at low levels in nuts, seeds, and legumes because they are considered "unavoidable contaminants."
The FDA believes occasionally eating small amounts of aflatoxin poses little risk over a lifetime. It is not practical to attempt to remove aflatoxin from food products in order to make them safer.
The mold that produces aflatoxin may be found in the following foods:
- Peanuts and peanut butter
- Tree nuts such as pecans
- Oil seeds such as cottonseed
Aflatoxins ingested in large mounts may cause acute liver damage. Chronic intoxication may lead to weight gain or weight loss, loss of appetite, or infertility in men.
To help minimize risk, the FDA tests foods that may contain aflatoxin. Peanuts and peanut butter are some of the most rigorously tested products because they often contain aflatoxins and are widely eaten.
You can reduce aflatoxin intake by:
- Buying only major brands of nuts and nut butters
- Discarding any nuts that look moldy, discolored, or shriveled
Haschek WM, Voss KA. Mycotoxins. In: Haschek WM, Rousseaux CG, Wallig MA, eds. Haschek and Rousseaux's Handbook of Toxicologic Pathology. 3rd ed. Waltham, MA: Elsevier Academic Press; 2013:chap 39.
Murray PR, Rosenthal KS, Pfaller MA. Mycotoxins and mycotoxicoses. In: Murray PR, Rosenthal KS, Pfaller MA, eds. Medical Microbiology. 8th ed. Philadelphia, PA: Elsevier; 2016:chap 67.
National Cancer Institute website. Aflatoxins. www.cancer.gov/about-cancer/causes-prevention/risk/substances/aflatoxins. Updated December 28, 2018. Accessed January 9, 2019.
Review Date 12/21/2018
Updated by: Jacob L. Heller, MD, MHA, Emergency Medicine, Emeritus, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.