When you open the refrigerator and find a wedge of cheese flecked with green mold, or a package of chicken that smells faintly sour, it can be tempting to gamble with your stomach rather than waste food.
But the line between harmless fermentation and dangerous spoilage is sharp. Consuming spoiled foods exposes the body to a range of microbial toxins and biochemical by-products, many of which can interfere with essential biological processes. The health effects can vary from mild gastrointestinal discomfort to severe conditions such as liver cancer.
I am a toxicologist and researcher specializing in how foreign chemicals such as those released during food spoilage affect the body. Many spoiled foods contain specific microorganisms that produce toxins. Because individual sensitivity to these chemicals varies, and the amount present in spoiled foods can also vary widely, there are no absolute guidelines on what is safe to eat. However, it’s always a good idea to know your enemies so you can take steps to avoid them.
Nuts and grains
In plant-based foods such as grains and nuts, fungi are the main culprits behind spoilage, forming fuzzy patches of mold in shades of green, yellow, black or white that usually give off a musty smell. Colorful though they may be, many of these molds produce toxic chemicals called mycotoxins.
Two common fungi found on grains and nuts such as corn, sorghum, rice and peanuts are Aspergillus flavus and A. parasiticus. They can produce mycotoxins known as aflatoxins, which form molecules called epoxides that can trigger mutations when they bind to DNA. Repeated exposure to aflatoxins can damage the liver and has been linked to liver cancer, especially for people who already have other risk factors for it, such as hepatitis B infection.
Fusarium is another group of fungal pathogens that can grow as mold on grains such as wheat, barley and corn, especially at high humidity. Infected grains may appear discolored or have a pinkish or reddish hue, and they might emit a musty odor. Fusarium fungi produce mycotoxins called trichothecenes, which can damage cells and irritate the digestive tract. They also make another toxin, fumonisin B1, which disrupts how cells build and maintain their outer membranes. Over time, these effects can harm the liver and kidneys.
