Coffee and Mycotoxins

You've probably heard that coffee contains mycotoxins. Here's what the research actually says.

Updated July 2026

Caffeine-conscious people tend to be health-conscious people too — which means this question comes up a lot. We thought it was worth giving an honest, detailed answer.

What are mycotoxins?

Mycotoxins are toxins produced by molds that grow on agricultural crops — grains, peanuts, spices, fruit, and yes, coffee beans. They form most readily in warm, humid conditions, which unfortunately overlaps with the ideal environment for growing coffee.

At low levels, the liver can process and eliminate mycotoxins without them building up in the body. The concern arises with sustained high-level exposure, which is a different situation than what's found in a well-sourced, well-roasted cup of coffee.

Which mycotoxins show up in coffee?

The two most studied are:

• Aflatoxin B1 — a known carcinogen that grows in soil and on grains and beans. Produced by certain molds under specific temperature and humidity conditions.

• Ochratoxin A — less studied, considered a weak carcinogen that may affect the kidneys. Produced by Aspergillus and Penicillium molds.

Studies have found measurable levels of both in green, roasted, and brewed coffee. That sounds alarming — but the key word is "measurable," not "dangerous." Research consistently shows that mycotoxin levels in commercially available coffee are well below the thresholds associated with health harm for most people.

One nuance worth knowing: studies have found that decaffeinated green coffee has historically tested with higher aflatoxin levels than caffeinated green coffee — but roasting reduces those levels by 42–55%. Roast level also matters, though roasting to very dark (which significantly reduces mycotoxins) also burns off flavor and health benefits. We roast to medium, which balances both.

Where does contamination actually come from?

The majority of mycotoxin contamination in coffee happens during drying and processing — specifically when:

• Coffee cherries are harvested before they're fully ripe (sometimes due to weather or market pressure)
• Coffee dries too slowly or unevenly, staying wet long enough for mold to develop
• Shade-grown coffee in very dense canopy gets insufficient airflow and UV exposure
• Green beans are stored improperly — particularly in humid conditions above 12.5% moisture

This is why sourcing matters. Specialty-grade coffee, produced by farmers who take quality seriously, is handled with far more care at every stage than commodity coffee.

What we do at Talking Crow

We monitor moisture levels on all green coffee in our warehouse and keep them within safe ranges. But more importantly, the sourcing decisions we make before the coffee ever arrives are the real protection:

• All of our coffees are specialty grade — produced by farmers who have specific growing, harvesting, and processing strategies to avoid mold and defects. Most are organic and traceable down to the lot.
• Our decaf coffees are processed at the Swiss Water® Process plant, which operates under a HARPC (Hazard Analysis and Risk-Based Preventive Controls) plan specifically controlling for aflatoxin. Moisture content is a critical control point — they ship decaffeinated coffee that has no risk of mold or mycotoxin growth. They're certified by FSSC 22000 and receive yearly third-party audits.
• We roast to order and ship fresh — which means our coffee isn't sitting in a warehouse for months accumulating risk.

If you struggle with mold-related health conditions, an elimination diet supervised by your healthcare provider is the most reliable way to identify specific triggers. Eliminating all trace exposure to mycotoxins from food is essentially impossible — but choosing high-quality, well-sourced, properly stored coffee is a meaningful step in the right direction.

This post is for informational purposes only. Please consult your healthcare provider about your specific health situation.

— Carol