The Science Behind Just One Mold Toxin in your Coffee

Most people are surprised to learn there are more chemicals in their coffee than on an average pharmacy shelf. Most of those chemicals we understand to be benign at worst, and some we know to provide the performance boost we all seek in coffee. However, swirling within that complex mix of chemicals, even in highest quality, most aromatic, and most flavorful brews can lurk the most carcinogenic natural compounds known to man. This post is about a mold toxin commonly found in coffee called Ochratoxin, and what it can do to your health and performance.


What is Ochratoxin? Where is it a problem?

Ochratoxin is a class of several different chemicals belonging to the fungal toxins known as mycotoxins. Unlike other fungal toxins, such as mushroom poison, mycotoxins are toxic secondary metabolites produced by mold, and we unintentionally ingest them in food.

Mycotoxins are documented to cause substantial suffering by disease and death in humans and animals, but the real impact is likely far more than we currently comprehend. In developed countries, with our plethora of food and the diversity of our appetites, we avoid the acute and disastrous effects mold toxins have today in the developing world. However, despite our current comforts, mycotoxins are still in our food supply. Are these toxins affecting your health and your performance?

There are two main forms of contamination of agricultural products by ochratoxin, known as ochratoxin A and ochratoxin B. In shorthand these are referred to as OTA and OTB in most scientific literature. Ochratoxin B (OTB) is less common and less toxic than OTA. OTA is produced most often by two Penicillium species (P. verrucoum and P. norduim) on poorly stored cereals or by a wide range of Aspergilli in variety of products, including wine and coffee [1, 2]. (Incidentally, this is one reason wine is on the “avoid” end of the spectrum on the Bulletproof Diet.).

Aspergillus ochraceus in particular contaminates dried foods, but more importantly seems to be the culprit along with A. niger for contaminating green coffee beans [3, 4, 5]. Because of this, it is well established that OTA and other mycotoxins are present in green and roasted coffee beans [6, 7, 8, 9, 10, 11, 12].

It is so alarming, in fact, that many countries set strict limits for OTA in foods, including coffee. The US has no standards for coffee, so it lags behind the EU, South Korea, Singapore, and even China, which all set limits at economically feasible levels.


How big of a problem is it?

For business reasons, it is convenient to dismiss OTA or other mold toxins as non-issues in coffee, especially in the US. That would be foolish, especially in light of the recent Bulletproof podcast with Dan Cox, a coffee expert regularly cited on CNN, with 30 years in the field. During my interview with Dan, he explains how coffee merchants sometimes “dump” coffee beans which fail to pass one region’s OTA standards, instead selling them another region where the toxin is not regulated. The net effect of this is that coffee contamination is a real problem in the US.

The OTA problem in coffee has been known for a while. A 1989 study [13] says that 58% of beans are contaminated.  Six years later, another study [14] found that 52% of samples were contaminated. The International Journal of Food and Chemistry Toxicology concluded “regular coffee consumption may contribute to exposure of humans to OTA.” More recently, this study [15] of Brazilian coffee found “Practically all samples (91.7%) were contaminated with moulds.” 83.3% of samples contained Aspergillus niger, a major toxin former, yet all of was “good enough” for European standards.

In my world, “good enough for government standards” doesn’t get me going. I drink coffee that is designed for human performance, far exceeding those standards.


But doesn’t roasting kill the mold?

Roasting kills the mold, but the mold toxin – the OTA – remains. It is by most accounts an extremely stable compound only beginning to degrade at 180 degrees Celsius [16]. Consider the complex aromas and flavors you get out of Upgraded Coffee and you can contemplate how those fragrant chemicals don’t breakdown at roasting temperatures.

A 1989 study [17] says that 52% of OTA survived roasting, and sometimes far less. Yet another study [18] from the same time period, designed to test whether roasting destroyed OTA, found that 20 minutes at 200C left 88-100% of OTA intact, and “almost all of the OTA was infused” into coffee brewed with the beans. The conclusion? “The reduction of ochratoxin A concentration of contaminated coffee beans by roasting under these conditions is ineffective.”

Yet another study [19] found roasting even hotter, at 250 degrees C, “resulted only in a small reduction in the OTA level. OTA was also found to be eluted into the brew. Of 40 coffee brews prepared from commercially available samples, OTA was detected in 18 brews.” A final study [20] showed that 31% of OTA remained after up to 10 minutes of roasting.  That’s right – the fermenting, the roasting, and the brewing allowed the ochratoxin to survive.

Upgraded Coffee is prepared and tested using the Bulletproof Process to specific standards for human performance, including standards for OTA that far exceed international limits. That’s one reason it works.

Why OTA is bad for you

OTA from any source – including coffee — is a problem because it is associated with cancer [21], brain damage [22] and hypertension and kidney disease [23]. In addition, immunosuppressive, teratogenic and carcinogenic effects have been reported for OTA [24]. Another report says, “The available evidence suggests that OTA is a genotoxic carcinogen by induction of oxidative DNA lesions coupled with direct DNA adducts…” [25]. All of these studies were concluded from amounts far higher then what normally occurs in one single cup of coffee. However, there are risks to chronic exposure to low doses of this toxin over time, as you’ll read in the next paragraph.

Many studies of toxicity are performed on rodents, which use their livers to break down OTA. Humans use our kidneys instead,  which makes the half-life of OTA in humans (35.3 days) approximately 14 times longer than in rats [26]. That means that the toxins in your daily cup of coffee can accumulate over time in your body, just as farmers know they do in pigs, the most OTA-sensitive animals after humans.

When it comes to human brain performance, there are some other quite concerning theories about how OTA causes damage in cells. One theory is that OTA causes an increase intracellular pH via a disruption in membrane anion conductance [27].

Another theory is that OTA inhibits mitochondrial transport or respiration [28]. Mitochondria are particularly dense in the brain, and inhibiting their performance is going to hurt mental performance long before most other parts of the body. Except the kidneys, which take the brunt of the damage from OTA.

Or maybe it’s actually disrupting gap junction intercellular communication [29].

The truth is that I am not certain which of these effects is the main reason why OTA is so bad for us. I am, however, certain that I do not want it in my coffee.

It’s worse than just OTA

Some other fungal species we don’t commonly pay attention to make other mold toxins besides OTA, and those toxins are synergistic. For instance, some problems occur when several mycotoxins work together synergistically at lower levels, like OTA with penicillic acid (PA) and fumonisin B2 (FB2) [30, 31]. Other researchers have uncovered “the toxicity of the low contamination levels of some combinations of mycotoxins…” and, “the importance of joint mycotoxin interaction and newly identified fungal metabolites in the complex etiology of mycotoxic nephropathy…” [32].

In the immortal words of Homer Simpson, “Doh!” Most processed foods – and a lot of fresh produce trucked in from far away – have chronic “safe” levels of OTA and other mold toxins in them. The effect is worse when mold toxins are mixed together, as documented above, but no country on the planet has standards for combined exposure, even though we know that they are unsafe at lower levels when they’re mixed. This is one of the many reasons processed foods are bad for you. It’s also why I developed the Bulletproof Process™ testing standard to account for multiple toxins – 27 of them, to be exact.

A problem with detection and testing

A great French study [33] found “analytical problems will seriously impact the amount of OTA detected, especially at the levels close to the limits from the EU legislation. Underestimation of OTA could be highly dangerous for health.” There is disagreement over the level of OTA in coffee because laboratory techniques, including those used for regulatory purposes, suffer from problems with OTA turning into other substances at high pHs, and from less toxic OTB, which interferes with the test. Complexities like this are why a 2009 review [34] says “no single technique stands out above the rest…it is impossible to use one standard technique for analysis and/or detection [of mycotoxins]”. The best techniques are tricky to do in the lab and they are expensive.

This is why some people – especially those new to OTA testing – have a harder time finding OTA in coffee compared to others. OTA is not always in coffee, but it is often present, and my research shows it is just one of the mold toxins in coffee that has effects on stress levels and performance, even at levels deemed to be acceptable in the countries that bother to regulate it. No agricultural product, including coffee, is 100% mycotoxin free, but with a lot of work, it is possible to control levels until they are below the threshold where they cause most problems in most people.

The Bottom Line

As you have been been able to read for free since the start of this blog, you can somewhat reduce the incidence of mold toxins in coffee by using wet processed, single estate beans. Wet process makes less toxins than natural process, and single estate means you aren’t mixing beans from the more moldy farms with less moldy farms.

However, wet processing methods vary greatly even in a single region, and the odds of getting a bean that will make you feel amazing are not very good. There are a lot of variables, including sanitizing, methods of cultivation, the region, climate, even the temperature you harvest your beans in.

Despite a couple years of trying, I was unable to reliably purchase coffee that was perfectly clean using that list of criteria, although I did learn to pick pretty good ones some of the time.

In contrast, Upgraded Coffee is created and tested using the proprietary Bulletproof Process™ to create a coffee that is tested to be lower in mold toxins that inhibit human performance, including ochratoxin A. You can feel the difference every time, even if you only drink it black . Since Upgraded Coffee is $15.80/lb currently when you buy a 5 lb bag, it’s about the same cost as other high end coffees that are solely created for economics or flavor and are not subjected to a rigorous testing process.

Don’t be fooled when someone with an economic motive claims all wet process beans are free of mold toxins. The odds are that they do not know how to successfully test for OTA, and they certainly won’t know the list of toxins that are a part of the Bulletproof Process™. Ochratoxin A is a well-documented problem in coffee in the US particularly, and in coffee worldwide.

There is a lot more work to be done to completely understand how mold toxins (from coffee and everywhere else) are affecting our health, our stress, our performance, and even our epigenetics. That is one of the reasons I’ve joined the board of Paradigm Change, a non-profit organization with the mission of helping create and disseminate information on the relationship between environmental toxicity (and other biotoxins) and neuroimmune illness.



[expand title=”Click to read the complete list of references.” swaptitle=”Click to hide references.”]

1. Abarca M.L., Accensi F., Bargulat M.R., Cabanes F.J. Current importance of ochratoxin A-producing Aspergillus spp. J. Food Prot. 2001;64:903–906.

2. Reddy K.R.N., Abbas H.K., Abel C.A., Shier W.T., Salleh B. Mycotoxin contamination of beverages: occurrence of Patulin in aplle juice and ochratoxin A in Coffee, Beer and Wine and their control methods. Toxins. 2010;2:229–261.

3. Levi CP, Trenk HL, Mohr HK. Study of the occurrence of ochratoxin A in green coffee beans. J Assoc Off Anal Chem. 1974;57(4):866-70.

4. Tsubouchi H, Yamamoto K, Hisada K, Sakabe Y, Udagawa S. Effect of roasting on ochratoxin A level in green coffee beans inoculated with Aspergillus ochraceus. Mycopathologia. 1987 Feb;97(2):111-5.

5. Studer-rohr I, Dietrich DR, Schlatter J, Schlatter C. The occurrence of ochratoxin A in coffee. Food Chem Toxicol. 1995;33(5):341-55.

6. Jørgensen K. Survey of pork, poultry, coffee, beer and pulses for ochratoxin A. Food Addit. Contam.1998;15:550–554.

7. Micco C., Grossi M., Miraglia M., Brera C. A study of the contamination by ochratoxin A in green coffee and roasted coffee beans. Food Addit. Contam. 1989;6:333–339.

8. Nakajima M., Tsubouchi H., Miyabe M., Ueno Y. Survey of aflatoxin B1 and ochratoxin A in commercial green coffee beans by high-performance liquid chromatography linked with immunoaffinity chromatography. Food Agric. Immunol. 1997;9:77–83.

9. Trucksess M., Giler J., Young K., White K.D., Page S.W. Determination and survey of ochratoxin A in wheat, barley and coffee 1997. J. AOAC Int. 1999;82:85–89.

10. Romani S., Sacchetti G., Chaves C.C., Pinnavaia G.G., Dalla M. Screening on the occurrence of ochratoxin A in green coffee beans of different origins and types. J. Agric. Food Chem. 2000;48:3616–3619.

11. Taniwaki M.H., Pitt J.I., Teixeira A.A., Iamanaka B.T. The source of ochratoxin A in Brazilian coffee and its formation in relation to processing methods. Int. J. Food Microbiol. 2003;82:173–179.

12. Martins M.L., Martins H.M., Gimeno A. Incidence of microflora and of ochratoxin A in green coffee beans (Coffea arabica) Food Addit. Contam. 2003;20:1127–1131.

13. Micco C, Grossi M, Miraglia M, Brera C. A study of the contamination by ochratoxin A of green and roasted coffee beans. Food Addit Contam. 1989;6(3):333-9.

14. Studer-rohr I, Dietrich DR, Schlatter J, Schlatter C. The occurrence of ochratoxin A in coffee. Food Chem Toxicol. 1995;33(5):341-55.

15. Martins ML, Martins HM, Gimeno A. Incidence of microflora and of ochratoxin A in green coffee beans (Coffea arabica). Food Addit Contam. 2003;20(12):1127-31.

16. Mariano B.M. Ferraz, Adriana Farah, Beatriz T. Iamanaka, Daniel Perrone, Marina V. Copetti, Viviane X. Marques, Alfredo A. Vitali, Marta H. Taniwaki. Kinetics of ochratoxin A destruction during coffee roasting. Food Control 01/2010; DOI:10.1016/j.foodcont.2009.12.001.

17. Micco C, Grossi M, Miraglia M, Brera C. A study of the contamination by ochratoxin A of green and roasted coffee beans. Food Addit Contam. 1989;6(3):333-9.

18. Tsubouchi H, Yamamoto K, Hisada K, Sakabe Y, Udagawa S. Effect of roasting on ochratoxin A level in green coffee beans inoculated with Aspergillus ochraceus. Mycopathologia. 1987 Feb;97(2):111-5.

19. Studer-rohr I, Dietrich DR, Schlatter J, Schlatter C. The occurrence of ochratoxin A in coffee. Food Chem Toxicol. 1995;33(5):341-55.

20. Van der stegen GH, Essens PJ, Van der lijn J. Effect of roasting conditions on reduction of ochratoxin a in coffee. J Agric Food Chem. 2001;49(10):4713-5.

21. Eric W. Sydenham , Gordon S. Shephard , Pieter G. Thiel , Walter F. O. Marasas , Sonja Stockenstrom. Fumonisin contamination of commercial corn-based human foodstuffs. J. Agric. Food Chem., 1991, 39 (11), pp 2014–2018.

22. Doi K, Uetsuka K. Mechanisms of Mycotoxin-Induced Neurotoxicity through Oxidative Stress-Associated Pathways. Int J Mol Sci. 2011;12(8):5213-37.

23. Hsieh MF, Chiu HY, Lin-tan DT, Lin JL. Does human ochratoxin A aggravate proteinuria in patients with chronic renal disease?. Ren Fail. 2004;26(3):311-6.

24. European Food Safety Authority (2006) Opinion of the scientific panel on contaminants in the food chain on a request from the commission related to ochratoxin A in food. EFSA J., 365, 1–56.

25. Pfohl-leszkowicz A, Manderville RA. Ochratoxin A: An overview on toxicity and carcinogenicity in animals and humans. Mol Nutr Food Res. 2007;51(1):61-99.

26. Studer-Rohr J, Schlatter J, and Dietrich DR (2000) Intraindividual variation in plasma levels and kinetic parameters of ochratoxin A in humans. Arch Toxicol 74:499–510.

27. Gekle M, Oberleithner H, and Silbernagl S (1993) Ochratoxin A impairs ‘‘postproximal’’ nephron function in vivo and blocks plasma membrane anion conductance in Madin-Darby canine kidney cells in vitro. Pflu¨ gers Arch Eur J Physiol 425:401–408.

28. Meisner and Chan, 1974; Moore and Truelove, 1970), Meisner H, and Chan S (1974) Ochratoxin A, in inhibitor of mitochondrial transportsystem. Biochem 13:2795–2800. Moore JH, and Truelove B (1970) Ochratoxin A: Inhibition of mitochondrial respiration. Science 168:1102–1103.

29. Horvath A, Upham BL, Ganev V, and Trosko JE (2002) Determination of the epigenetic effects of ochratoxin in a human kidney and a rat liver epithelial cell line. Toxicon 40:273–282.

30. Stoev S.D., Dutton M., Njobeh P., Mosonik J., Steenkamp P. Mycotoxic nephropathy in Bulgarian pigs and chickens: Complex aetiology and similarity to Balkan Enedemic Nephropathy. Food Addit. Contam. A. 2010;27:72–88. doi: 10.1080/02652030903207227.

31. Stoev S.D., Denev S., Dutton M.F., Njobeh P.B., Mosonik J.S., Steenkamp P.A., Petkov I. Complex etiology and pathology of mycotoxic nephropathy in South African pigs. Mycotox. Res.2010;26:31–46. doi: 10.1007/s12550-009-0038-7.

32. Stoev SD, Denev SA. Porcine/chicken or human nephropathy as the result of joint mycotoxins interaction. Toxins (Basel). 2013;5(9):1503-30.

33. Martins ML, Martins HM, Gimeno A. Incidence of microflora and of ochratoxin A in green coffee beans (Coffea arabica). Food Addit Contam. 2003;20(12):1127-31.

34. Turner NW, Subrahmanyam S, Piletsky SA. Analytical methods for determination of mycotoxins: a review. Anal Chim Acta. 2009;632(2):168-80.





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