Dave Asprey, Bulletproof Coffee & Mycotoxins: Just Another Load of BS


By now, most of you have no doubt heard of a guy called Dave Asprey, who claims it took him $300,000 and 15 years (or 20 years, depending on which page of his website you land at) to learn how to reach a "Bulletproof® state of high performance" -  a state in which you can allegedly learn how to "lose 100 pounds without using exercise, upgrade your IQ by more than 12 points, and stay healthy by sleeping less".

None of Asprey's claims, it should be noted, are backed by any kind of scientific evidence or supportive documentation. He claims to have reduced his body weight from 297 pounds down to 200, but the only evidence he provides for this are 3 portrait shots dated 1995, 1999, and 2010 that reveal absolutely nothing about the physique residing below his neck:

dave-asprey-alleged-before-and-after-weight-lossA series of photographs and unsubstantiated captions proving nothing except that Asprey has changed his hairstyle and grown a beard.

And his claim that he boosted his IQ by an impressive 12 points? You'll just have to take his word for that.

To be fair, a lot of health commentators - including myself - have regaled readers with stories of sometimes dramatic health and body composition improvements as a result of making dietary and health changes. The more reliable commentators, however, have posted either verifiable documentation of their own personal transformations, or have deferred to published, peer-reviewed scientific research that supports the plausibility of their claims*. In some instances, they've done both.

Asprey does neither. His claims, quite frankly, reek of utter bullshit.

The Mycotoxin Charade

Asprey is most famous for his "Bulletproof" coffee, and a big part of his spiel for this 'special' coffee is that it's low in mycotoxins.

But so are most other coffees. At least by the time you drink them. While mycotoxin presence in green coffee is not uncommon, the roasting process markedly reduces contamination.


Before we continue, it's worth elaborating on just what mycotoxins are, and why we should try to avoid excessive exposure to them. Mycotoxins are toxic metabolites produced by fungi, and the most significant source in the human food chain are cereal grains. Perhaps the best-known mycotoxins are aflatoxins, a type produced by Aspergillus species of fungi. Others categories of mycotoxins include Ochratoxin, Citrinin, Ergot Alkaloids, Patulin and Fusarium.

In addition to dietary sources, humans can also be exposed to mycotoxins from other sources, such as molds growing in buildings.

As such, most of us experience some level of mycotoxin exposure each day. And there's no denying that excessive - I repeat, excessive - mycotoxin exposure is a legitimate health concern for both humans and animals. Mycotoxicosis is the term used for poisoning associated with exposures to mycotoxins, but if you're lucky enough to live in a developed country and eat food that has been properly cooked, dietary-induced mycotoxicosis is a condition you are most unlikely to suffer. In the developing world, however, where food processing and handling methods are often much less strict than in developed nations, mycotoxins in food can pose a serious, and sometimes fatal, health threat. Outbreaks of acute aflatoxicosis from highly contaminated food have been documented in Kenya, India, and Thailand. In April 2004, an outbreak of acute hepatotoxicity was identified among people living in Kenya’s eastern and central provinces. Subsequent investigations determined the outbreak was caused by aflatoxin poisoning from ingestion of contaminated maize (corn). At least 317 cases and 125 deaths had occurred, making this one of the largest and most severe outbreaks of acute aflatoxicosis documented worldwide.

So there's no doubt mycotoxins are nasty little bastards, and that excessive exposure to them is indeed best avoided. But is the coffee you're drinking really saturated with these toxins, as Asprey would have you believe?

Mycotoxins in Coffee: Just How Bad a Problem?

In 1980, Levi published a review of the research examining mold presence in green (unroasted) coffee beans:

"Included are investigations on normal mold flora, toxin production in inoculated beans, effect of experimental roasting on aflatoxin, ochratoxin, and sterigmatocystin, and survey on the presence of these toxins in commercial green coffee. Because of the extremely low frequency of findings, the low levels of toxins, and the experimental data showing 70--80% destruction by the roasting process of toxin added to green coffee, further study on this topic has been discontinued."[1]

Yep, mycotoxin contamination of coffee was such a non-issue that Levi decided to forget about it and focus on more important matters.

Italy vs Mycotoxins

However, the mycotoxin issue refused to go away, leading to an investigation by Italian researchers that was published in 2003. As someone who is descended from Italian stock, let me tell you something: Italians take their coffee very, very seriously.

How seriously?

Well, let's just say you should never, ever serve an Italian a bad cup of coffee. I mean, nothing might happen right away. In all likelihood, they'll politely thank you, calmly reach for their coat, and quietly be on their way.

But a week later, on an unusually windy, dark and stormy night, when you're home all alone and your power suddenly goes out, your phone inexplicably loses reception, your car won't start, and then you nervously peek outside and in the glow of lightening notice a big black sinister-looking limousine with tinted windows pulling up out front of your house, well ...

Don't say I didn't warn you.

Yep, you really should've paid the few extra dollars for those Fairtrade beans, instead of that cheap nasty-ass coffee mix in the discount section!

Okay, okay, I'm just kidding! Italians don't really get that upset over bad coffee. Well, not all the time.

But, as with most Mediterraneans, coffee is more than just a beverage to Italians. It's an experience.

And if dirty little mycotoxins are going to detract from that experience in any way, then they’ll want to know about it. And so the University of Bologna researchers set out to determine what happened to ochratoxin A (OTA) – one of the most common food-contaminating mycotoxins – during the coffee roasting process. OTA was the first mycotoxin subject to European legislation; maximum permitted levels are 5 mcg/kg in roasted coffee beans and ground roasted coffee and 10 mcg/kg in soluble coffee (instant coffee)[2].

OTA, by the way, is also found in cereals, wine, spices, tea, beer, cocoa, dried fruits, and pork meats. So stay tuned for Bulletproof Bacon, Bulletproof Lager, and Bulletproof Prunes … all containing the same measly mycotoxin levels as other quality products in their category, but all costing 2-3 times more! Hey, isn’t it worth paying extra to be part of something bigger than yourself – you know, like a health cult?

But I digress. Back to the University of Bologna, where the researchers subjected four different green coffee samples, naturally contaminated with OTA, to different roasting conditions (light, medium, and dark). The OTA content of green coffee was markedly reduced by the roasting process, and this reduction was influenced by the severity of the thermal process. Light roasting produced 60-80% reductions in the three of the samples (no effect was seen in the remaining sample, which was the least contaminated at 1.99 mcg/kg). Dark roasting, however, ameliorated 90% of the OTA in all four samples.

In other words, using roasting parameters suitable for a typical Italian espresso coffee brew showed reductions of >90% in the OTA content, to well below maximum allowed levels, in both high and low contaminated samples[3].

Another group of Italian researchers (I told you Italians take their coffee seriously), this time from the University of Naples, performed a similar study which was published in 2007. They tested three Coffea robusta samples, from Ivory Coast, Vietnam, and Cameroon, and four Coffea arabica samples from Ethiopia, Santos, India, and Costa Rica. Costa Rica and Indian green coffees were the most contaminated samples, with 13 and 11 microg/kg, respectively, while the Ethiopian coffee was the least contaminated, with 3.8 microg/kg of OTA. Dramatic reductions in OTA as a result of roasting and processing were seen even in the most contaminated samples; to the point where a cup of coffee prepared from 2 grams of coffee powder would contain around 2 parts per billion of OTA – a rather miniscule concentration.

The researchers concluded "both roasted and ground coffee and soluble coffee are secondary sources of ochratoxin A in the human diet, even when prepared from relatively highly contaminated green beans. Ochratoxin A intake through coffee beverage cannot be considered a primary source, and the coffee-transforming process is able to reduce this critical point and related risk for human health."[4]

Spain vs Mycotoxins

The most recent study I've been able to find on mycotoxin contamination was published just last month and conducted in Spain. Having recently been to Spain, let me tell you something: The Spanish also take their coffee very, very seriously.

How seriously?

Well, just take my advice and don't ever serve a Spaniard a bad cup of coffee. I mean, nothing might happen right away. In all likelihood, they'll politely thank you, calmly reach for their coat, and quietly be on their way.

But a week later, on an unusually windy, dark and stormy night, when you're home all alone and your power suddenly goes out, your telephone inexplicably loses reception, and you hear a strange noise coming from your backyard, and you nervously step outside to investigate, and nearly jump out of your skin when the door slams shut behind you - leaving you trapped outside - and simultaneously realize a 2,000-pound bull with frighteningly large horns is angrily snorting and staring you down in your own backyard, well ...

Don't say I didn't warn you.

Yep, you really should've paid the few extra dollars for those Fairtrade beans, instead of that cheap nasty-ass mix in the discount section!

Okay, okay, I'm just kidding! Spaniards don't really go around planting angry bulls in people's backyards, all over some bad cup of coffee. That's silly. What they'd more likely do is throw a blanket over you, bundle you into a van with no windows, take you to a bull farm, and ...

Okay, okay, enough already!

As with the Italians, coffee is sacrosanct to the Spaniards. And so researchers from the University of Valencia set out to determine the presence of not just one, but 21 mycotoxins in coffee using liquid chromatography tandem mass spectrometry. The mycotoxins they tested for were:

Aflatoxin B1, B2, G1 and G2; ochratoxin A; nivalenol; deoxynivalenol; 3-acetyldeoxynivalenol; 15-acetyldeoxynivalenol; diacetoxyscirpenol; neosolaniol; T-2 and HT-2 toxin; sterigmatocystin; enniatin A, A1, B, and B1; beauvericin; and fumonisin B1 and B2.

Yeah, try saying that lot backwards quickly for ten reps.

To give the whole process a bit more real-life relevance, they tested different coffee-making processes (coffee maker, electrical machine, soluble and traditional Turkish process) and calculated the estimated daily intake of mycotoxins at various levels of coffee consumption in Spanish adolescents and adults.

A total of 169 samples of coffee from 28 different brands were purchased from supermarkets in Valencia, then processed and analyzed. The samples were classified according the brewing process: conventional (coffee maker), soluble, pre-portioned (electric machine), and Turkish coffee. To maximize the quality of the brew and minimize confounding between methods of coffee preparation, all coffee types were processed using mineral water (mycotoxin-free) of the same commercial brand.

A coffee maker (Italian, Moka percolator) was used to prepare ground conventional packed coffee samples.

Soluble coffee samples were prepared according to the manufacturer's specifications regarding the ratio of grams of coffee per milliliters of water. In this case, water was heated to 85-90°C in a hot plate and added to a glass beaker holding the soluble coffee; the mixture was continuously stirred to dissolve the coffee.

Samples of Turkish coffee were processed using the traditional Turkish method. For this, 50 ml of water was heated on a hot plate to 95-100°C and added to a glass beaker holding 5 g of coffee; this was mixed for 30 seconds. The upper portion was collected after allowing 10 minutes for sedimentation.

Samples of pre-portioned coffee of approximately 5-7 g were prepared using corresponding electrical machines. The first 45 ml produced by the coffee machines were collected.

Thirty-six percent of the samples were contaminated with OTA, but none exceeded the EU maximum limit for OTA in coffee (EC/1881/2006). Overall, the study showed that coffee is a low contributor to exposure to most mycotoxins:

"The results show that coffee intake does not represent a potential risk for consumers with respect to individual mycotoxin contamination. However, contamination of coffee by mycotoxins likely affects the EDI of the total diet, especially in highly exposed segments of the population."[5]

In other words, mycotoxicity from coffee is a non-issue. Unless you are already heavily exposed to mycotoxins from other sources, in which case mycotoxins from coffee could further add to the burden - not exactly a stunning revelation, and not exactly a damning indictment of coffee itself.

France and the Czech Republic vs Mycotoxins

I’m not sure about the Czechs, but I do know that the French – just like the Italians and the Spaniards – take their coffee very seriously. So don’t ever serve a bad cup of coffee to a French person. They’ll become, like, really rude and stuff, and maybe even let out a loud sigh. Okay, so that’s not as bad as having wiseguys pull up to your house or finding an angry bull in your backyard, but hey, it’s the thought that counts.

(Oh boy, all my French friends are going to kill me now lol)

Anyways, when a collaborative team of Czech and French researchers tested black tea, fruit tea, and coffee for OTA, they found the highest concentrations in black tea, the lowest in coffee. The researchers found that, for an adult weighing 60 kg (unlike the bloated Anglo-Western world, they still have adults that light in Europe), drinking one cup (250 mL) of even the most contaminated black tea would deliver 2.5 ng OTA/kg bw. One cup of the most contaminated fruit tea would provide 0.125 ng OTA/kg bw, which can be considered as negligible[6].

In the case of coffee, one cup of doppio (double-shot) led to an OTA intake of 0.065 ng/kg bw which, in layman's terms, is known as Sweet F.A. According to the researchers, this latter data is in line with that recently obtained in a report entitled “Ochratoxin A - health risk assessment for selected population groups in the Czech Republic", which estimated OTA coffee intake for an “average consumer” in the Czech Republic at 0.06 ng/kg bw/day.

Sure, a lot of folks in the West drink more than one cup of coffee per day, but if you're drinking enough double-shots to take you over the recommended EU limit for OTA intake every day, then I'd say mycotoxins are the least of your worries.

Asprey vs Scientific Reality

There's no denying that, in sufficient doses, mycotoxins are nasty, toxic little sods. But unless you are consuming large amounts of coffee made from lightly roasted, heavily contaminated beans, or you're some kind of especially dogmatic raw foodist who brews his coffee using unroasted green beans (yuk!), then almost all the research to date seems to be saying the same thing:

The mycotoxins in coffee brouha is a storm in a tea coffee cup.

Nevertheless, this non-issue has proven to be a very lucrative one for Dave Asprey, who has amassed an adoring cult-like following that hangs off his every word and readily pays exhorbitant prices for his Bulletproof brand of coffee.

Asprey has profited handsomely by cleverly applying an old strategy favoured by health faddists:

Create a health bogeyman, convince lots of people it constitutes a serious problem, then make lots of money by selling them a solution to that problem.

Which  wouldn't be so bad if mycotoxins in coffee really were such a big deal. But there is an overwhelming lack of evidence in the scientific literature for Asprey's "Mycotoxins in Coffee are Going to Get You!" thesis.

So how does the enterprising "Bulletproof Executive" get around this?

Simple. He ignores studies like the ones above, and digs up a very small selection of studies that appear to confirm his claims.

I searched around Asprey's site to see what sort of evidence he was proffering in support of his mycotoxin-free coffee campaign, and came across this page:


Asprey cites three studies. Of a 2003 paper, he writes "One study that tested 60 coffee bean varieties found that 91% of green coffee beans were contaminated by mycotoxins."

Indeed it did. But what Asprey doesn't tell you was that all the positive samples showed OTA levels below the limit suggested by the European Union.

And as we've seen, roasting dramatically reduces such low OTA contents to even more negligible levels. This is a most inconvenient fact that further weakens Asprey's theory, so the next study he cites is one that dates all the way back to 1995. Asprey notes this study "found only 52% contamination in green coffee beans, but also found that ~50% of brewed coffee contained mycotoxins." [Note: The actual figure was 45%]

Notice how he does not mention the actual mycotoxin content of the brewed coffee. As we've seen, brewed coffees often do indeed contain mycotoxins, but thanks to roasting and processing the levels are so low that most researchers promptly place them in the yawn-inducing category. That 1995 study found that, of 40 coffee brews prepared from commercially available samples, OTA was detected in 18 brews "by HPLC and/or additional immunoaffinity column clean-up" in the range of 0.4 to 7.8 micrograms OTA/kg equivalent ground coffee.

There's one other wee problem with citing the 1995 study - it claimed that in the "naturally contaminated samples, no statistically significant difference between the OA content of the green and the roasted beans was found."

Wait a minute - that contradicts a large volume of more recent research, so why the difference? Early studies often yielded conflicting results in their analyses of OTA content of coffee, whereas more recent studies are returning far more consistent results. That could be due to the fact, over the last two decades, researchers have refined and advanced the lab procedures used to determine OTA levels in coffee. As such, it's interesting that Asprey ignores these recent studies and instead cites a single study from 20 years ago. Asprey might argue he was unaware of these more recent studies, but for a guy who incessantly boasts about having "hacked" his physiology and boosted his IQ by 12 points, that would seem a most unconvincing argument.

If Asprey really is unaware of these more recent studies, then he really needs to study the whole mycotoxin-coffee issue in much more depth, then present a far more balanced dissertation on his findings.

Don't hold your breath waiting for that to happen, though ...

Asprey's last stab at science comes when he writes "In the two studies above [mycotoxin levels] were relatively low, but contamination can be much higher, especially in lower-quality beans that are not processed with care."

This is pretty much a non-statement. To put that comment in perspective, it's like saying most fresh foods being sold nowadays are safe, but some are poorly processed and contain unacceptably high levels of pathogenic bacteria that can lead to food poisoning. No kidding. To avoid food poisoning, we buy our foods from suppliers with a good track record and then prepare and cook them at home using the appropriate sanitary procedures and cooking temperatures. Because this system is not 100% foolproof, does not mean that there's something fundamentally wrong with modern food hygiene, that the majority of food is contaminated, and that we should only buy over-priced "Bulletproof" foods from some guru that claims to have hacked his physiology, leading to a 12-point IQ increase and a 100-pound weight loss - all without restricting calories or doing exercise!

Asprey vs Rogan

Sorry folks, but when someone claims they shed 100 pounds of flab without cutting calories or doing any exercise, then I know immediately that I'm dealing with an avid bullshitter. Just like his weight loss claims, Asprey's claims about mycotoxins in coffee appear to be grounded, not in reality, but a self-constructed fantasy.

And I'm hardly the only one who thinks so.

Most readers will know Joe Rogan through his role as a UFC colour commentator (Joe is also a stand-up comedian, podcaster, actor, host of the NBC reality show Fear Factor, and - according to Georges St. Pierre - owner of an especially powerful spinning back kick). Joe used to be a big fan of Asprey and helped the 'biohacking' one promote his coffee on The Joe Rogan Experience podcast.

However, Joe eventually began to smell bullshit, and asked Dave Asprey to front up with some science to back up his outlandish claims about mycotoxins and coffee. Joe shares his frustrations from Asprey's failure to do so in this video:

Just Another Nonsensical Health Cult

The capacity for human gullibility, and the concomitant yearning for an all-knowing guru to provide people with an answer to their (sometimes non-existent) problems, never ceases to amaze me. As this article explains, Asprey has amassed a loyal following, one in which people are prepared to pay US $1,799 to hear their guru impart his unsubstantiated wisdom - and thousands more on the vast array of highly-hyped coffees, supplements and devices he sells.

You've gotta hand it to Asprey, he's a clever entrepreneur. There's no end to people's desire for a guru to provide them with magic bullets, and he's managed to harness this desire to build himself one very lucrative empire - one based on fanciful and unproven claims.

And before I get the usual sycophantic horde of angry Asprey followers writing me and asking how dare I attack their almighty guru, here's a free tip:

Don't waste your time.

Unless you can provide me with some actual scientific evidence to back up Asprey's outlandish claims, I'm simply not interested - I just don't have the time to entertain brainwashed followers of yet another bullshit-replete health cult. I've already been through this whole charade with the low-carb crowd, whose members used to angrily assure me I had it all wrong on the calorie issue because, hey, they couldn't lose weight eating 800 calories per day on a high-carb diet but then miraculously started shedding weight eating 3,500-5,000 calories per day of high-fat, low-carb slop.

All this demonstrated to me was that these people really sucked at maths or, more likely, never actually made any attempt to track their true before-and-after calorie intakes. They no doubt felt like they were eating more as they gulped down unprecedented amounts of butter and bacon, but the fact they'd just deleted an even greater sum of calories from their diets as a result of no longer consuming bread, bagels, biscuits, pastries, pasta, rice, potatoes, muesli bars, confectionery, soft drinks, etc, etc, etc, seems to have completely escaped their glucose-depleted craniums.

In each and every case where I asked these folks to validate their amazing ability to lose weight despite increasing their caloric intake by a factor of four or more, by booking into a metabolic ward and providing me with the resultant data, I was met with silence.

Sorry Bulletproof Brainwashees, but I'm going to hold you to the same standard. Your guru is bullshitting you, and getting upset at me for presenting the uncomfortable facts confirming as much, is not going to change that one iota.


Anthony "The Bullshitproof Executive" Colpo.

Anthony Colpo is an independent researcher, physical conditioning specialist, and author of the groundbreaking books The Fat Loss Bible, The Great Cholesterol Con and Whole Grains, Empty Promises.

PS. Life's too short to drink inferior quality, poor-tasting coffee, so I wholeheartedly encourage readers to learn all they can about this delicious, uplifting beverage. If you've never given much thought to your coffee, your new reading efforts might bring up unfamiliar terms such as arabica, robusta, wet-processed, dry-processed, shade-grown, Fairtrade, and so on. There's plenty of online resources that'll help you make sense of these terms - minus the pseudoscientific drivel about mycotoxins, IQ-boosting, or calories. One neat resource I consider a good starting point can be found at:



*Yours truly, for example, noticed marked improvements in his glycemic control after reducing his bodily iron stores; I can also cite numerous published studies showing improved glycemic control in both diabetic and non-diabetic subjects as a result of iron-lowering. I should also point out I make no money from speaking highly of iron reduction; my favoured method of iron-lowering is phlebotomy which can be administered at your local Red Cross for free. If the Red Cross's frequency restrictions do not fully accommodate your iron-lowering needs, you can supplement them with IP6 (I recommend the Source Naturals powdered version), which I do not produce nor sell.


1. Levi C. Mycotoxins in coffee. Journal - Association of Official Analytical Chemists, Nov, 1980; 63 (6): 1282-1285.

2. The Commission of the European Communities. Commission Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs. Official Journal of the European Union, 20.12.2006. See page L 364/16 (page 12 of the PDF file) at http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2006:364:0005:0024:EN:PDF

3. Romani S, et al. Influence of roasting levels on ochratoxin a content in coffee.  Journal of agricultural and food chemistry, Aug 13, 2003; 51 (17): 5168-5171.

4. Napolitano A, et al. Natural occurrence of ochratoxin A and antioxidant activities of green and roasted coffees and corresponding byproducts. Journal of agricultural and food chemistry, Dec 12, 2007; 55 (25): 10499-10504. Epub 2007 Nov 20.

5. García-Moraleja A, et al. Analysis of mycotoxins in coffee and risk assessment in Spanish adolescents and adults, Food and Chemical Toxicology, 2015. doi: 10.1016/j.fct.2015.10.014.

6. Sirot V, et al. Dietary exposure to mycotoxins and health risk assessment in the second French total diet study. Food and Chemical Toxicology, 2013; 52: 1-11.

Copyright © Anthony Colpo.

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