The Truth About Mycotoxins (and why you shouldn’t be worried)

May 05, 2022

Posted: Nov 9, 2016

The Truth About Mycotoxins (and why you shouldn’t be worried)

About six years ago, the word “mycotoxin” suddenly emerged into the public consciousness when health guru Dave Asprey, the founder of the Bulletproof diet, cited mycotoxins as the reason coffee both “made you weak,” and was “bitter.”


We’re not going to make any particular statement about Bulletproof Coffee™ (for our thoughts on that check out this post) but we can draw from a significant body of research on mycotoxins, and their relationship with coffee.

What are Mycotoxins?

Mycotoxins are a non-essential byproduct of fungi. Although not necessary for eating or reproducing, mycotoxins are thought to play long-term roles in creating a fungi-friendly environment. They are as prolific and numerous as spores, come in several varieties, and range from harmless to lethal to animals and humans. Mycotoxins are found in pretty much every food, and in 100% of blood samples tested.

So are they in coffee?

Yes. And, the two most commonly found on coffee are among the most dangerous: aflatoxin B1 and ochratoxin A. Aflatoxin is a potent carcinogen, and both have been linked to acute organ failure in multiple systems. (It is important to note that many cases that implicated either aflatoxin or ochratoxin were in situations that required multiple correlating factors, of which the mycotoxin was one.) We don’t take this lightly, and for several decades, specific practices have been in place at every stage of coffee production and processing to reduce mycotoxins levels as much as possible.

For coffee in particular, recent decades have seen increased vigilance as demand for high-quality beans has gone up. With speciality coffees becoming more mainstream, more careful eyes are watching every stage from tree-to-cup in order to constantly improve quality and consistency (we know we do). Mycotoxins have not been observed to negatively affect flavor (“makes it bitter”? What?) but the potential health risk means that if a sampling is found to have mycotoxins, it’s overall score – and value – goes significantly down.

Why doesn’t that coffee get thrown out immediately?

Because, like everything else that comes under the heading of “potentially harmful” there is an amount at which it is indistinguishable from harmless. The United States’ FDA has placed this amount at 5 parts per billion for both aflatoxin and ochratoxin. To put that into context, one study found that drinking four cups of poor quality coffee only comprised 2% of the safe limit – meaning that you would have to drink 400 cups a day before things started to get serious.

In fact, several common foods average significantly higher amounts of both aflatoxins and ochratoxin. Raisins, for example, were found to contain three times the amount of green coffee, with peanut-butter, wheat, chocolate, rye, and cereals also topping coffee on the list. Interestingly, caffeine is a natural mycotoxin deterrent, and decaf coffees will contain slightly higher amounts.

In short, if you’re concerned about mycotoxins, cutting out coffee isn’t going to do much.

But this doesn’t mean we’re not extremely careful.

The two stages most at risk to fungi are the mucilage removal and storage. The former was addressed several decades ago with the introduction of the “wet process” – instead of leaving beans to sit in the sun until the mucilage was dry enough to slough off (dry process), the wet process immediately places the beans in water tanks for the mucilage to ferment before it is removed by machine. Stored beans are carefully monitored and kept in sealed, dry containers.

The roasting process also removes as much as 80% of any mycotoxins left. Studies have shown varying results, depending on the bean, the machine, and the particular roasting process, but roasting will always have an effect.

So are we worried?

No. And if your coffee is bitter, chances are it has more to do with the age, grind size, roast level or brewing process, and we can help you with that! While some mycotoxins can be dangerous, the amounts found in your coffee will never be.

Happy sipping!