You may have heard of the carcinogen aflatoxin in the context of peanuts, and peanut products like peanut butter. In fact, it can be found in a number of other products, including other nut products (not that peanuts are actually a nut), grains, black pepper, dried fruits and even dairy products such as milk or cheese. All these foods are pretty common in a modern diet – most people drink milk every day in one form or the other, so what, if any, is the risk of aflatoxin?

This article will explain what aflatoxin is, how it gets in foods, look at what it does in the body, and how is best to avoid it.


What is aflatoxin?

Aflatoxins are a group of toxic chemical which can be produced by a number of micro-organisms, but the most common producer of alfatoxin is a fungi called Aspergillus flavus. This fugus thrives in warm humid environments (as do most microbes), and is commonly associated with peanuts as they are often stored in large silos in warm climates. 

Aflatoxin is widely recognised as a powerful carcinogen by many authorities, including the FSA in America, and the EFSA in Europe.


How toxic is aflatoxin?

If the name aflatoxin isn’t enough to highlight the toxicity of aflatoxin, there is plenty of research. Chronic low-level exposure to aflatoxin, is associated with increased risk of developing liver cancer, and acute high-level exposure (which is less common) causes symptoms of liver damage, malaise (general feeling of discomfort), and low fever2.

There was a case in Kenya where there was a poor harvest, and so people stored maize in their homes to keep it safe. Their homes were warmer, and more humid than the granaries, which allowed Aspergillus flavus to thrive and produced large amounts of aflatoxin. The result was 317 people being admitted to hospital, and 125 of those dying from liver failure. Upon testing the harvest, the aflatoxin concentration was 4,400 parts per billion, which equates to 4400ug/kg.

Clearly a dosage of 4400uk/kg is toxic. What is less clear is what the actual safe dosage is for chronic (long-term, low dosage) of aflatoxin. It is very difficult to identify the specific cause for liver cancer for example3. Many other dietary/ lifestyle factors come into play, some of which are more harmful to the liver than eating a handful of nuts with small amounts of aflatoxin in; such as frequency of alcohol consumption. Despite no clear ‘safe’ level, the EU recommendations for aflatoxin are that nuts cannot contain more than 10ug/kg1,which is very low.

So, the ‘safe’ level of aflatoxin has not been identified, but you can rest assured that if you live in a developed country no food will contain high levels of aflatoxin.


How to avoid aflatoxin

Unlike many pathogens, you cannot cook a food to destroy aflatoxin. This is because aflatoxin is a toxin produced by a pathogen, not a pathogen itself. There is no way to remove it from your food, and so the only way to minimise its consumption is to avoid the foods it is commonly found in, namely peanut products, grains and dried fruit.

Having said this, if you enjoy these foods I see little reason to completely eliminate these foods from your diet if you live in a country where there are strict guidelines on aflatoxin levels. Dried fruits and peanuts do have some health benefits (although fresh is always best), and they make healthier snack alternative to crisps and chocolate. Rather than eliminating them, just have them as an occasional snack.




1. EFSA. (2013). Aflatoxins in food. Available: Last accessed 16/3/15.

2. Julia R. Barrett. (2005). Liver Cancer and Aflatoxin: New Information from the Kenyan Outbreak. Environ Health Perspect. 113 (12), A837–A838.

3. J. W. Bennett. (2003). Mycotoxins. Clin Microbiol Rev. 16 (3), 497-516.

Image courtesy of manoftaste-de.

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