Can mycotoxins in peanut butter, corn, and spices cause cancer?

What's actually in it

Mycotoxins are toxic chemicals produced by molds that grow on crops. The most dangerous one, aflatoxin B1, is classified as a Group 1 carcinogen, meaning there's enough evidence to confirm it causes cancer in humans. Other mycotoxins include ochratoxin A, fumonisin, and deoxynivalenol.

These toxins show up in peanuts, corn, wheat, tree nuts, dried fruits, coffee beans, cocoa, and spices like chili powder and paprika. They form when crops are stored in warm, humid conditions. You can't see, smell, or taste them. Cooking doesn't destroy most of them.

What the research says

A 2026 review in J Biochem Mol Toxicol examined how mycotoxins cause cancer at the molecular level. The researchers found that these toxins work through two pathways: they damage DNA directly, and they cause epigenetic changes that alter how genes are turned on and off.

The direct DNA damage is well established. Aflatoxin B1 binds to DNA and causes mutations, particularly in the p53 tumor suppressor gene. When p53 stops working, cells lose a critical brake on uncontrolled growth. This is why aflatoxin exposure is strongly linked to liver cancer.

The epigenetic effects are newer territory. Mycotoxins can change how genes behave without altering the DNA code itself. They flip certain genes on or off in ways that promote tumor growth. These changes can be long-lasting and may even pass to future generations.

The U.S. and EU set strict limits on aflatoxin levels in food, and regular testing catches the worst contamination. But "within limits" doesn't mean zero. Low-level exposure from multiple foods adds up over a lifetime.

Store peanut butter, nuts, cornmeal, and spices in cool, dry places. Throw out anything that smells musty or looks moldy. Buy from brands that test for mycotoxins (some list this on the label). And vary your diet so you're not eating the same high-risk food every single day.