Aflatoxins in Nuts: Danger or Hype?

Some of the scary things you may have heard about nuts and aflatoxins are probably exaggerated or taken out of context. Nonetheless, these are not imaginary concerns. Nutrition Diva explains.

Monica Reinagel, MS, LD/N, CNS,
Episode #517
Bowl of mixed nuts.

Nuts are generally thought of as healthy food choices. They are somewhat high in calories, due to their relatively high fat content. But these aren’t just empty calories. Along with those healthy unsaturated fats, you’re also getting fiber and protein, which help keep you from getting hungry. Perhaps that’s why dieters who include nuts in their meal plans lose more weight and report feeling less hungry. And in general, people who eat nuts on a regular basis are more likely to maintain a healthy weight.

Nuts are also rich in vitamin E, which is good for your skin, heart, and brain. They also contain phytosterols, natural plant compounds that help to regulate your cholesterol levels. Regular nut consumption is linked with reduced risk of heart disease and other diseases.

So far the news is all good. But, several Nutrition Diva listeners have written to ask me about aspergillus or aflatoxin in nutsand whether this is something that we need to worry about. I can tell you that some of the scariest things you may have encountered online are probably exaggerated or taken out of context. Nonetheless, these are not imaginary concerns.

What Are Apergillus and Aflatoxins? 

Aspergillus is type of fungus that’s found in the soil and can cause disease in certain food crops, especially legumes, grains, and tree nuts. An aspergillus infection can weaken the plants enough to reduce crop yield, which is a concern for the farmers. But even if crop yields are affected only minimally, the aspergillus fungus continues to be a problem after the crops are harvested. It can cause grains or nuts to rot in storage—leading to more losses for farmers or distributors. 

But the main concern in terms of human health is that aspergillus produces potentially harmful compounds called mycotoxinsin particular, a group of mycotoxins called aflatoxins. These are known to be carcinogenic.

Chronic aflatoxin exposure can lead to liver damage or liver cancer, especially in individuals with pre-existing conditions such as a Hepatitis B infection. Breathing in the spores of the aspergillus fungus can also cause lung irritation or damage, again, especially in individuals with pre-existing lung disease, such as tuberculosis or COPD.

Aspergillus produces potentially harmful compounds called mycotoxins—in particular, a group of mycotoxins called aflatoxins. These are known to be carcinogenic.

And that’s why most developed nations have very stringent monitoring for aspergillus and aflatoxin in foods. Products that are most likely to be infected, such as peanuts or tree nuts are routinely screened and if aspergillus or aflatoxin levels are above a certain threshold, the foods cannot be distributed.

See also: How the Government Shutdown Affects Science


About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show. 

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