Updated: Apr 8, 2020
Have you heard of Aflatoxins before? They are a type of toxin created by certain species of mold that grow in food. They are very toxic and carcigenic to humans. Should we be worried?
Aflatoxins are one of many types of mycotoxins, created by mycotoxin producing fungi. The most common fungi that produce mycotoxins are Aspergillus, Fusarium, and Penicillium. Aflatoxins are produced mostly by the Aspergillus species of Fungi. Aflatoxins (AFs) are toxic when ingested by humans and animals in certain levels. Chronic complications can occur like cancer and liver damage if eaten over long periods of time at certain levels. It can even be deadly in at very high levels.
Of the major AFs identified out of 20+ different types of AFs. The major 5 are AFB1, AFB2, AFG1, AFM1, and AFG2. Of most concern is generally AFB1, which is considered more toxic and have a higher tumor genesis rate. AFB1 has caused deadly outbreaks, from mostly corn products, of acute hepatitis and aflatoxicosis. Kenya had an outbreak in 2004 that killed 125 and seriously poisoned more than 300. https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5334a4.htm India had a similar outbreak in 1974 that also lead to more than 100 deaths. AFs outbreaks are more prone to be in tropical and subtropical regions in developing countries. Both of the major outbreaks had AF levels around 1000 μg/ kg of food.
Aflatoxins Regulations and Protections
Research has shown that 2--6 mg/day of aflatoxin for a month can cause acute hepatitis and death (Patten RC. Aflatoxins and disease. Am J Trop Med Hyg 1981;30:422—5). That is why food in developed countries like United States and Europe have set strict government regulations that protect citizens to limit exposure to AFs. In the United States foods cannot have more than 20 μg of AFs per kilogram (1000.00 grams) of food. 1 microgram (ug) = 1/1,000,000 gram = 0.000001 gram. Europe of course protects its citizens even more by not allowing more than 2 μg of AFB1 and no more than 4 μg of total AFs per kilogram of food. Food fed to agricultural animals like pigs, cows and chickens can be fed food with levels up to 300 μg of AFs per kilogram of food. Animals that are not taken well care of or fed properly can absorbed high levels of AFs from their food into their muscles or fat, and pass them on to humans. That is why some of the higher levels of AFs from food are sometimes found in dairy-products. (Mutegi et al., 2009; Perrone et al., 2014; Iqbal et al., 2015).
Aflatoxin in United States
In the early 1990’s, U.S. federal inspectors found that high levels of aflatoxin, around 1300 μg were present in Midwestern corn and grains from the 1988 drought. They subsequently discovered that samples of meat and milk products contained unacceptable levels of AFs above the 20 μg limit, but animal products for direct human consumption are not regulated or tested like grains are in the United States. Despite this, no additional actions were taken to improve public safety. At present, federal law allows up to 300 μg per kilogram of aflatoxin in meal fed to livestock. This can impart AFs to animal products, and may pose a health risk.
Currently there are no regulations for testing of AFs in animal products in the United States, and neither the FDA, meatpackers or animal product producers in the United States do any tests for AFs. Because I do not know of any studies that publish AF levels in animal products, I do not know the current or past levels of AFs in animal products except for the 1990 incident. Even though high AF levels in animal products have been found, animal product companies almost never test their products. Meat packers from Hormel Foods Corporations, a meat packing company, have been quoted saying “It is very difficult to get an animal to consume enough AFs to show up” in meat. IBP Inc one of the larger meat packers in U.S. said “We’re not aware of any AFs in Meat. We’re not commenting beyond that.”. (Incidence of Aflatoxin in the 1988 Corn Crop Due to Drought: Hearings Before the Subcommittee on Wheat, Soybeans, and Feed Grains of the Committee on Agriculture, House of Representatives, One Hundred First Congress, First and Second Sessions, April 4, 1989 and April 2, 1990)
Food that often contain Aflatoxins
Many foods do contain low levels of AFs that are safely detoxified by the human liver in small quantities. Including corn, coconut meat, groundnuts like peanuts, dried fruits, meat and milk-based products, sorghum, wheat, millet, cocoa beans, tree nuts, sunflower seeds, cassava, peppers, rice, figs and dried spices, ginger, cottonseed, black pepper, and nutmeg.
Food products from underdeveloped countries often have higher amounts of AFs, like corn, rice, peanuts, and peanut butter from China. See table below, obtained from the study… (Mahato DK, Lee KE, Kamle M, et al. Aflatoxins in Food and Feed: An Overview on Prevalence, Detection and Control)
Control and Reduction of Aflatoxin in Food
There are many ways to reduce the amount AFs in food. AFs breakdown and decompose around temperatures of 237–306°C (Rustom, 1997); therefore, certain food processes like pasteurization of milk cannot protect against AF contamination. However, there are many other processes that do reduce AFs levels in food. The decrease in AFs content from a particular process is dependent on a variables, usually time and temperature combination. Food processors/manufacturers often use a combination of the below processes in the United States and Europe to reduce AFs.
Boiling grains can reduce AFs by 28%
Frying can reduce levels 34-53% (Stoloff and Trucksess, 1981)
Roasting at 150°C for 120m can reduce levels by 63% (Yazdanpanah et al., 2005).
Alkaline Cooking and steeping, often done when making tradition conrn tortillas reduces AFs by 52% (Torres et al., 2001)
Extrusion and blanching during food processing, often done to make peanut butter, reduces AF levels by 50-80%. Hameed (1993)
Sometimes hydroxide or bicarbonate is added to food as a preservative during the cooking process, which decreases AFs levels as much as 95% (Saalia and Phillips (2011b)
Microbial and enzymatic degradation is a preferred method to destroy AFs in food, because it is more eco-friendly in nature. (Agriopoulou et al., 2016) Research also shows it is as effective as temperature cooking to significantly reduce AF levels. Methods of microbial and enzymatic ways to reduce AFs in food include soaking, sprouting, introducing, and fermenting. (Lee J, Her JY, Lee KG. Reduction of aflatoxins)
Cancer from Aflatoxin
AFs have been assumed to be a causal factor for liver cancer and because of frequent ingestion by humans, AFs may well be a significant cause of cancer worldwide. Especially cancer of the liver.
Several epidemiological studies have linked liver cancer incidence and other cancers to estimated aflatoxin consumption in the diet. (PMCID: PMC1977043) But the long term quantification of individual exposure to AFs is very difficult. Hepatitis B virus infection, an important risk factor for primary liver cancer, complicates many of the epidemiological studies because it is hard to separate the relative risk between AF and Hepatitis B. But studies have shown that exposure to both hepatitis B virus and AFs yield a greater risk.
However, the incidence of liver cancer does seem to coincide with some of the higher rates of AF found in food in certain countries. Good examples include China, and many other Asian and African countries. (PMID: 1348796)
Worried about Aflatoxin Exposure? Simple steps you can take at home.
No reason to worry because you can take many simple steps to greatly reduce your exposure. People talk about AF and nut butters a lot. If you love nut butters, and still want to eat them, the good news is that on average the lowest levels of AFs are actually found in nut butters in the united states, not whole nut products. Because nut butters go through a combination of many preserving processes, like extrusion, blanching, roasting and boiling that break down AFs to very low levels.
Try to buy food, supplements, and spices with ingredients that come from Europe or United States where AFs are most regulated and controlled. Food products with the highest levels of AF come from Asian countries and Africa.
The longer a food sits or is stored the more AFs it will have in it, since AFs increase over time. This is true for all food, even highly processed and preserved foods. Try to buy and eat food that is the freshest. What does freshest mean? It means the smallest amount of time from when the farmer picked it out of the ground or tree, until it gets into your mouth. It can be very difficult or almost impossible to know how old, or fresh food is. Food products almost never divulge when the food was picked, only very high-quality food. Food companies usually only put the expiration date, or best by date which tells you when they think the food will last until it spoils. However just because the expiration date is a year away, doesn’t mean that it is not already 3 years old.
Regarding AFs it is a safer bet to eat whole foods instead of processed foods. Whole foods spoil quickly, since they are dense with nutrients molds like to eat, so whole foods are stored for a shorter amount of time than processed foods and transported more quickly to stores. Whole foods also show signs of AF infection more obviously than processed foods so you are more likely to notice mold in your food.
Eat certain foods in moderation and eat mostly whole foods. Use your nose, taste, and eyes to evaluate your food options. It has worked for our ancestors for the last 1 million years and it is still your best option.
Don’t be afraid of certain products like corn, peanuts, beans and other whole grains. They might have some of the higher AF levels in studies, but those high levels also come from mostly developing countries. Those food products are also a major contributor to longevity in certain population studies. So as long as your food is sourced well, eat up!