Despite having been demonized in the past, coffee is very healthy.

It’s loaded with antioxidants, and numerous studies observe that regular coffee consumption is associated with a lower risk of serious diseases. Some research even suggests that coffee drinkers may live longer.

However, there has been talk of potentially harmful chemicals — called mycotoxins — in coffee.

Some claim that a lot of the coffee on the market is contaminated with these toxins, causing you to perform worse and increasing your risk of disease.

This article reviews whether mycotoxins in coffee are something you should be concerned about.

Mycotoxins are formed by molds — tiny fungi that may grow on crops like grains and coffee beans if they’re improperly stored (1).

These toxins can cause poisoning when you ingest too much of them (2).

They may also cause chronic health issues and are the culprit behind indoor mold contamination, which can be a problem in old, damp, and poorly ventilated buildings (2).

Some chemicals produced by molds may affect your health and some have been used as pharmaceutical drugs.

These include the antibiotic penicillin, as well as ergotamine, an anti-migraine drug that can also be used to synthesize the hallucinogen LSD.

Many different types of mycotoxins exist, but the ones most relevant to coffee crops are aflatoxin B1 and ochratoxin A.

Aflatoxin B1 is a known carcinogen and has been shown to have various harmful effects. Ochratoxin A has been less studied, but it’s believed to be a weak carcinogen and may be harmful to the brain and kidneys (3, 4).

Still, it’s important to keep in mind that you are regularly exposed to trace amounts of harmful substances, so mycotoxins are not unique in that regard.

What’s more, mycotoxins are neutralized by your liver and do not accumulate in your body as long as your exposure remains low.

Plus, at least 100 countries around the world regulate the levels of these compounds — though some have stricter standards than others (5).


Mycotoxins are toxic chemicals produced by molds — tiny fungi that are found in the environment. Molds and mycotoxins may occur in crops like grains and coffee beans.

Several studies have found measurable levels of mycotoxins in coffee beans — both roasted and unroasted — as well as brewed coffee:

  • 33% of samples of green coffee beans from Brazil had low levels of ochratoxin A (6).
  • 45% of coffee brews from commercially available coffee beans contained ochratoxin A (7).
  • Aflatoxins have been found in green coffee beans, the highest level in decaffeinated beans. Roasting reduced the levels by 42–55% (8).
  • 27% of roast coffees contained ochratoxin A, but much higher amounts were found in chili (9).

Thus, evidence shows that mycotoxins are present in a large percentage of coffee beans and make it into the final drink.

However, their levels are far below the safety limit.

Understandably, you may not like the idea of having toxins in your foods or beverages. Still, keep in mind that toxins — including mycotoxins — are everywhere, making it is impossible to avoid them completely.

According to one study, almost all types of foods can get contaminated with mycotoxins, and virtually everyone’s blood may test positive for ochratoxin A. It has also been found in human breast milk (10, 11).

Various other foods and beverages contain measurable — but acceptable — levels of mycotoxins as well, such as grains, raisins, beer, wine, dark chocolate, and peanut butter (12, 13).

Therefore, though you may be ingesting and inhaling various toxins each day, you should not be affected if their amounts are small.

Claims that mycotoxins are responsible for coffee’s bitter taste are also incorrect. The amount of tannins in coffee determines its bitterness — evidence to suggest that mycotoxins have anything to do with it is lacking.

Purchasing high-quality products — whether coffee or other foods — is generally a good idea, but paying extra for mycotoxin-free coffee beans is most likely a waste of money.


Trace amounts of mycotoxins have been found in coffee beans, but the amounts are far below safety limits and too low to be of practical significance.

Molds and mycotoxins in foods are nothing new.

They’re well-known problems, and coffee growers have found efficient ways to deal with them.

The most important method is called wet processing, which effectively gets rid of most of the molds and mycotoxins (14).

Roasting the beans also kills the molds that produce the mycotoxins. According to one study, roasting can reduce ochratoxin A levels by 69–96% (15).

Coffee’s quality is rated according to a grading system, and the presence of molds or mycotoxins significantly lowers this score.

What’s more, crops get discarded if they exceed a certain level.

Even lower-quality coffees have levels well below the safety limits set by regulatory authorities and significantly below the levels shown to cause harm.

In a Spanish study, the total ochratoxin A exposure in adults was estimated to be only 3% of the maximum level regarded as safe by the European Food Safety Authority (EFSA) (16).

Another study showed that 4 cups of coffee daily provide only 2% of the ochratoxin A exposure deemed safe by the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) (17).

Decaf coffee tends to be higher in mycotoxins, as caffeine inhibits the growth of the molds. Instant coffee also contains higher levels. Nonetheless, the levels are still too low to be of concern (18).


Coffee makers are well aware of the mycotoxin issue and use methods like wet processing to significantly reduce levels of these compounds.

Mycotoxins are found in small amounts in various foods, including coffee.

However, their levels should be strictly monitored by producers and food safety authorities. When safety limits are exceeded, the food products are recalled or discarded.

Research shows that the benefits of coffee still far outweigh the negatives. What’s more, evidence to suggest that low-level mycotoxin exposure is harmful is lacking.

Still, if you want to minimize your risk, only drink quality, caffeinated coffee and store it in a dry, cold place.

It’s also a good idea to avoid adding sugar or heavy creamers to keep your coffee as healthy as possible.