Coffee doesn't have harmful levels of mold. Debunking the pervasive mycotoxins myth.
On her podcast Heal Squad, Maria Menounos recently spoke with Dave Asprey, the founder of the Bulletproof diet and self-described “father of biohacking.” After he tells her about the toxins that are in coffee (known as mycotoxins) and how they allegedly affect the body, Menounos reacts: “Oh my God, I have chills all the way down my body.”
Asprey has been promoting his toxic coffee theory for a decade and, with recent appearances on Armchair Expert, On Purpose With Jay Shetty and more wellness-focused media, the recurring tale is taking hold once again. Asprey isn’t entirely wrong when he says that mold in coffee and mycotoxins can make you sick. But experts say it’s unlikely. Here’s what you need to know.
What are mycotoxins?
Coffee can contain mold and mycotoxins, which are toxic compounds produced by mold. Crops such as corn, sorghum, wheat, rice, dried fruit, nuts, coffee and spices are particularly susceptible to mold contamination and mycotoxin growth if they’re not harvested or stored properly. Several hundred mycotoxins have been identified, according to the World Health Organization. Aflatoxins, ochratoxin A, patulin, fumonisins, zearalenone, nivalenol and deoxynivalenol are among the most notable because of their ill effects in animals and humans.
Ingesting high amounts of mycotoxins — either through contaminated food or by consuming animals that have been exposed to mycotoxins in their feed — can make you sick, with symptoms including nausea, vomiting and diarrhea. While animal studies have linked mycotoxins to kidney damage, the association in humans isn’t clear, according to the WHO. The Food and Drug Administration and U.S. Department of Agriculture have established mycotoxin limits for certain domestic and imported foods and monitor mycotoxin-related illness outbreaks.
How concerning are mold and mycotoxins in coffee?
Coffee is susceptible to ochratoxin A and aflatoxin B1 contamination. Animal studies indicate that ochratoxin A toxicity can impact immune function and lead to kidney damage and cancer, although the effects in humans are less clear. Nevertheless, the International Agency for Research on Cancer classifies ochratoxin A as a group 2B possible human carcinogen.
Studies have detected ochratoxin A in coffee samples. However, the quantities are primarily tiny and fall well below the U.S. and European limits. Research suggests that roasting coffee beans can reduce ochratoxin A by 65%-100%. Based on the literature available, the authors of a 2021 study concluded that there’s no evidence to date that consuming coffee leads to ochratoxin A toxicity.
Research on aflatoxin B1 in coffee is scarce, and limits for aflatoxin in coffee have not been established in the U.S. or Europe. As with ochratoxin A, roasting coffee puts a significant dent in aflatoxin B1 levels. Aflatoxin is carcinogenic to humans and toxicity can be life-threatening. Right now there is no evidence that aflatoxin exposure from drinking coffee leads to toxicity in humans.
“We are exposed to mycotoxins pretty frequently,” Dr. Jamie Alan, an associate professor of pharmacology and toxicology at Michigan State University, tells Yahoo Life. “Many foods have some trace level of mycotoxins. As long as you are consuming levels that are within the established safe ranges, there are likely no health concerns.”
In a nutshell, your daily coffee fix is unlikely to be a significant source of mycotoxins or lead to mycotoxin-related illness. Coffee growers and roasters are also exploring novel ways to minimize mold and mycotoxin growth in coffee beans. That said, there are a few things you can do to ensure that your coffee isn’t riddled with mold and mycotoxins.
How to minimize the risk
“Our bodies are generally well-equipped to deal with small amounts of mycotoxins,” Alan says. “To minimize your risk, buy a good-quality coffee and make sure it is stored in a cool, dry place.”
These strategies can help minimize any possible mold and mycotoxins in your coffee:
Store your coffee beans in a cool, dry place in a vacuum-sealed canister to minimize moisture and prevent mold growth.
Choose coffee beans rather than grounds or instant coffee and grind as needed. Grounds have a high surface area that makes them more susceptible to contamination.
Clean your grinder and coffee machine on a regular basis.
Avoid green (unroasted) coffee bean products. Roasting reduces levels of the mycotoxins ochratoxin and aflatoxin.
Look at the roast date on the back of the packet. The older the product, the more likely it is to be harboring mold, mycotoxins and other bugs.
Sensitive to coffee? Here’s how to minimize the effects.
Some people are sensitive to America’s favorite beverage, but mycotoxins and mold aren’t likely to blame. Coffee contains many different compounds, including caffeine and salicylates — both of which can cause unpleasant symptoms in some. Caffeine boosts alertness (and coffee itself comes with health benefits), but it can also cause jitteriness, a racing heart and insomnia. Salicylates are chemicals made from plants that have health benefits, including anti-inflammatory properties, but some people are allergic to them.
If caffeine is the culprit behind your symptoms, pairing coffee with food to slow down absorption or switching to decaf may be necessary to avoid the jitters. More specifically, foods with fat and protein move slowly through the digestive tract and are particularly helpful for delaying caffeine absorption. For those with salicylate sensitivity, decaf coffee is often well-tolerated.
Bottom line
Coffee is unlikely to cause mold or mycotoxin-related illness. This is especially true if you take preventative measures such as choosing fresh beans, storing them in an airtight container and keeping your machine and grinder clean. If, despite these strategies, you’re still sensitive to coffee, it might be time to switch to decaf.
Edwina Clark is a registered dietitian.
