Debunking The Myth About Mycotoxins in Coffee

Stressed Man With CoffeeI’ve written a lot about the health benefits of coffee.

Despite having been demonized in the past, it seems to be very healthy.

It is loaded with antioxidants and numerous studies show that coffee drinkers have a lower risk of serious diseases.

There are even some huge studies showing that coffee drinkers live longer.

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

Some claim that a lot of the coffee on the market is contaminated with these toxins, causing people who drink it to perform worse and have a higher risk of disease.

Since I love coffee and want to make sure I’m not harming myself (or giving people dangerous advice), I decided to look into this mycotoxin thing and see if it’s something that we really need to be concerned about.

What Are Mycotoxins?

A fungus is a type of organism.

There are three types of fungi… yeasts, molds and mushrooms.

Yeast grow and function as single cells, while molds form multicellular filaments.

Mushrooms can form large, plant-like structures that are commonly consumed as foods.

Today we are mostly interested in the molds, which are ubiquitous in the environment and found almost everywhere.

When your food spoils and forms green, furry spots… that’s because of molds.

Moldy Orange

Some molds can grow in edible crops, like grains and coffee beans, and produce toxic chemicals called mycotoxins (1).

These toxins can cause poisoning when we ingest too much of them. They can 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 have extremely potent biological activity and some have been used as pharmaceutical drugs.

This includes the antibiotic Penicillin, as well as Ergotamine, an anti-migraine drug that can also be used to synthesize the hallucinogen LSD.

There are many different types of mycotoxins, but the ones most relevant to coffee crops are called Aflatoxin B1 and Ochratoxin A.

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

However… it’s important to keep in mind that “the dose makes the poison” and mycotoxin levels in foods are tightly regulated.

At least 100 countries around the world regulate the levels of these compounds in the food supply (5).


Bottom Line: Mycotoxins are toxic chemicals produced by molds, organisms that are ubiquitous in the environment. Molds and mycotoxins can be found in crops like grains and coffee beans.

Tiny Amounts of Molds and Mycotoxins Are Found in Some Coffee Beans

Angry Man With Cup of Coffee

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

  • 20 of 60 samples of green coffee beans from Brazil had low levels of Ochratoxin A (6).
  • 18 of 40 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).
  • 8 of 30 roast coffees contained Ochratoxin A, but much higher amounts were found in chili (9).

So… mycotoxins are present in a large percentage of coffee beans and they do make it into the final drink.

But it’s important to keep in mind that the levels are still way below the safety limit.

I can understand that people don’t like the idea of having “toxins” in their foods or beverages, but it’s important to keep in mind that toxins (including mycotoxins) are everywhere. It is impossible to avoid them completely.

According to one study, almost all types of foods can get contaminated with mycotoxins and the blood of 100% of humans may test positive for Ochratoxin A. It has also been found in human breast milk (10, 11).

Mycotoxins are also found in all sorts of other foods and beverages. Grains, raisins, beer, wine, dark chocolate and peanut butter (to name a few) can all contain measurable levels of mycotoxins (12, 13).

The truth is… we’re constantly drinking, eating and breathing all sorts of toxins. But if the amounts are too small to harm us, then it doesn’t really matter.

There is currently no study I am aware of, whether in animals or humans, suggesting that such incredibly low levels of mycotoxins are harmful.

It is also wrong that mycotoxins are what makes coffee bitter. It’s the tannins naturally present in coffee… there is no study that suggests that mycotoxins have anything to do with it.

Getting quality stuff (whether coffee or food) is always a good idea, but paying a hefty price premium just to get “mycotoxin free” coffee beans is most likely a waste of money.

Bottom Line: It is true that trace amounts of mycotoxins have been found in coffee beans, but the amounts are way below safety limits and too low to be of any practical significance.

Coffee Growers Use Specific Methods to Keep The Mycotoxin Content Low

Young Woman Holding a Bag of Coffee Beans

Molds and mycotoxins in foods are nothing new.

This is a well known problem… and coffee growers have found efficient ways of dealing with it.

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 the levels of Ochratoxin A by 69-96% (15).

Coffee’s quality is actually rated according to a grading system.

Having molds or mycotoxins significantly lowers the score… and if they exceed a certain level, the crops will be discarded.

Even if drinking “low quality” coffee, the levels are still way below the safety limits set by regulatory authorities and even further 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 level regarded as safe by the European Food Safety Authority (16).

According to another European study, drinking 4 cups of coffee per day contributes to 2% of the Ochratoxin A exposure deemed to be safe by the FAO and WHO… so there is a massive safety margin here (17).

Decaf coffee tends to be higher in mycotoxins, because caffeine inhibits the growth of the molds. Instant coffee also contains higher levels than ground coffee. But even so, the levels are still too low to be of practical significance (18).


Bottom Line: Coffee makers are well aware of the mycotoxin issue, so they use methods like wet processing and roasting to significantly reduce the levels.

Do You Need to be Concerned About Mycotoxins in Coffee?

Have you had any water to drink today?

Did you eat anything today?

Are you breathing right now?

If you answered any of these questions with a yes, then guess what… you’ve already taken in a whole bunch of “toxins” today. They’re everywhere.

But as long as the amounts are too small to have an adverse effect on your body, it doesn’t matter.

Some amount of toxins may even be downright healthy… it is well known that such stressors can induce a hormetic effect by stimulating the body’s own defence mechanisms.

Keep in mind that the studies showing that coffee drinkers are healthier were based on people drinking all sorts of coffee… low quality coffee, high quality coffee, instant coffee, all sorts.

So… unless if you have an allergy or some sort of sensitivity, then I don’t think you need to worry about mycotoxins (or any other toxins) found naturally in coffee.

If you truly want to minimize your risk, then only drink quality, caffeinated, non-instant coffee and don’t store it for too long.

Oh yeah, and also consider avoiding or minimizing raisins, oatmeal, beer, wine, peanut butter, nuts, dark chocolate, pork, milk and a bunch of other foods that can also contain mycotoxins (19).

Or… you could just keep things simple and don’t worry about this at all, like I do.

As long as you’re avoiding the truly harmful things in the food supply (like sugar, refined grains, veggie oils and trans fats) then small amounts of “toxins” found naturally in coffee or foods are NOT going to make a big difference to your health.

According to the studies, the benefits of coffee still far outweigh the negatives and there is absolutely no evidence that low-level mycotoxin exposure is even harmful.

In my opinion, the most important part of keeping your coffee as healthy as possible is to choose quality coffee and avoid adding sugar or a trans-fat laden creamer into it.

These are the truly harmful “coffee toxins” that we need to avoid.