Peanut butter and jelly sandwiches were a staple in the diet of most children when I was growing up. They were served in the school cafeterias as well. Unfortunately peanuts can be highly allergenic and precipitate asthma attacks, rashes, or even death in some highly allergic individuals. Associated with peanuts is a cancer causing substance called aflatoxin. Aflatoxin is a mycotoxin produced by Aspergillus, a mold that grows on peanuts, legumes, nuts, and grains. Aflatoxin is highly toxic to the liver and can cause liver cancer and hepatitis. This mold grows in higher concentrations during storage of peanuts and grains. Although the FDA and USDA have regulations regarding the amount of aflatoxin allowed in peanuts and their products, there is no way to measure this poison after the products hit the stores. Peanuts and peanut butter can sit on a shelf in a warehouse or store for weeks or months at room temperature, building up the toxin. OHSA requires workers dealing with large quantities of peanuts to wear protective equipment and masks to reduce the amount of mold they breathe in.
No practical way exists to get aflatoxin out of peanuts. A few years ago, Consumers Union looked into the question of aflatoxins in peanut butter and found that the amounts detectable varied from brand to brand. The lowest amounts were found in the big supermarket brands such as Peter Pan, Jiffy and Skippy. The highest levels were found in peanut butter ground fresh in health food stores. This is because fungicides applied to peanut crops significantly reduce the amount of mold on these crops, whereas anti-fungal treatments are not used on organic crops or peanuts labeled as “natural.”
Now eating an occasional peanut butter sandwich or handful of peanuts is unlikely to cause any problems, but a much safer alternative to peanut butter is almond or walnut butter, which contain no aflatoxins. Also, almond butter is much more nutritious and has a healthier fatty acid profile.