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Bulletproof Coffee is quite the buzz word in health and fitness circles at the moment. From numerous celebrity endorsements to high profile American sporting teams, what some people originally called a fad is starting to garner significant momentum. Defined as brewed coffee blended with grass-fed butter and medium chain triglyceride (MCT) oil, bulletproof coffee is not as easy (or cheap!) to make as your average espresso or cappuccino. The key step that sets it apart from other coffee is the need to blend the butter and MCT into a smooth emulsion with the coffee. Skipping this step leaves them sitting like big fat globules on top of the coffee, giving anything but a desirable appearance.

Where Did Bulletproof Coffee Come From?dave_asprey_mt_kailash_tibet

The term Bulletproof Coffee was specifically pioneered by a gentlemen called Dave Asprey; owner & founder of Bulletproof Executive, a company that started off selling Bulletproof Coffee but now has a whole range of supplements they claim help ‘biohack’ your health. With over 110,000 likes on Facebook, over 37K followers on Twitter, a podcast that has ranked in the top 100 in Australia since its debut and having just completed his second annual Bulletproof Biohacking Conference; Dave Asprey has amassed quite a following! Asprey tells the story of being rejuvenated by a “creamy cup of yak butter tea” while hiking at 18,000 feet near Mt. Kailash in Tibet. This sparked a personal journey to uncover the rejuvenating powers of this beverage, which ultimately resulted in the creation of Bulletproof Coffee1.

Bulletproof Coffee vs Butter Coffee

Generally speaking, a bulletproof coffee is synonymous with a ‘butter coffee’, but strictly speaking a bulletproof coffee differs by virtue of its additional inclusion of MCT oil and the use of Dave Asprey’s own Bulletproof branded coffee beans. Bulletproof coffee beans main claim to fame is that they are free of mycotoxins. Mr Asprey even goes as far to say:

“Some types of coffee have more mycotoxins than others, which is why you see some studies showing a benefit to drinking coffee, and others showing negative health outcomes.  The problem isn’t coffee per se, it’s the mold on your coffee.”2

A pretty big claim I think you will agree, which we will flesh out in this article.

Mycotoxins in Coffee

With one of the world’s best selling niche coffee brands making big bucks on the back of claims that their coffee is mycotoxin free – the question must be asked: what level of mycotoxins are present in your average coffee and what risk does their consumption pose to one’s health?bulletproof_coffee

When it comes to mycotoxins in coffee, most of the research centres on one particular toxin called ochratoxin A (OTA). For the microbiologists reading this article, OTA is a mycotoxin produced by fungi of the genera Aspergillus and Penicillium. It is widely known to contaminate a great variety of foodstuffs, such as cereals, cocoa, beans, grapes and dried fruit in addition to coffee3. OTA is the most common mycotoxin that occurs in coffee3.

Ochratoxin A in Coffee

When digging through the scientific literature on ochratoxin A and coffee, it quickly becomes apparent there’s no disputing the fact it’s a common toxin that must be controlled for during production and processing of coffee. The natural occurrence of OTA in green coffee beans has been reported by several researchers in concentrations from 0.2 to 360 mcg/kg3.

A representative study of the levels of OTA from harvesting of green coffee beans right through to brewing of the same found a wide variance in levels, as described below:

“In green coffee beans ochratoxin A was detected in 13 out of 25 commercial samples analysed …Roasting (250 degrees C, 150 sec) of naturally contaminated green beans or beans inoculated with A. ochraceus resulted only in a small reduction in the ochratoxin A level. Ochratoxin A was also found to be eluted into the brew. Of 40 coffee brews prepared from commercially available samples ochratoxin A was detected in 18 brews …in the range of 0.4 to 7.8 micrograms ochratoxin A /kg equivalent ground coffee. Our preliminary results suggest, therefore, that regular coffee consumption may contribute to exposure of humans to ochratoxin A.”4

Yet another study by researchers from Spain set out to study the effect of coffee processing on OTA levels from the green beans to the drinking form. They too found varying levels of OTA based on the origin of the coffee and how it was processed and brewed, as per the extract below:

“Thirty-six green coffee samples of different origin (Colombia, Costa Rica, Brazil, Vietnam, India and Uganda) were analysed. The highest concentrations of OTA were found in Vietnamese samples – Robusta species treated by dry processing...These contaminated samples were roasted in a process that controlled loss of weight and color, as in the industry. A mean reduction of 66.5% was obtained, but the reduction seems to be heterogeneous. Coffee brew was prepared by the three brewing processes more utilized in Europe: moka, auto-drip and espresso. A reduction of the OTA level has been attained, being greater when using a espresso coffee maker (49.8%) than when using auto-drip (14.5%) or moka brewing (32.1%). Therefore, the method of coffee brew preparation plays a key role in the final OTA human exposure.”5

So it would appear that there is some merit to Asprey’s claims that certain roasted coffee bean varieties may come with the risk of higher OTA levels. But there are many variables that can affect the level of OTA in coffee such as place of origin, method of processing (i.e. dry or wet) and type of brewing.

Effect of Processing Method on Ochratoxin A Content

A recent study originating from Côte d’ Ivoire in West Africa suggests that the method used to initially dry green coffee beans when they are picked as ripe coffee cherries is the most pivotal step in dictating the level of OTA contamination. Their findings suggest that prevention and reduction of OTA in green coffee is best achieved by commencing drying of the coffee the actual day of harvesting and mixing/rotating them at least six times a day during sun drying. Lastly, the most important step is ensuring the coffee cherries are spread across a suitably large enough area to allow for optimal drying. To be specific, the study found no more than a 20kg load of cherries should be spread across a 3m2 area. Once you exceed this load, the cherries are not exposed to enough air to ensure quick drying with the result that they ferment and acidify, which ultimately leads to more OTA contamination. A sentence from their conclusion sums up their findings nicely:

“The present study has shown that, the overload of the drying area by coffee cherries is most likely one of the main parameters contributing to infection of beans and ochratoxin A production during sun drying.”6

Mycotoxins in Organic Versus Conventional Coffee

While natural intuition would lead the average person to assume mycotoxins are present at lower levels in organic coffee varieties such as Bulletproof Coffee, studies comparing organic and conventionally produced coffee suggest this is not the case9. While organic coffee is produced without the utilization of pesticides and chemical fertilizers (which are replaced by subproducts originated from recycling plant and animal organic matter)10, on the flip side, this puts it at risk of  fungi contamination, including potentially toxic fungi that produce ochratoxin A9. As a result, a recent study comparing the level of mycotoxin producing fungi in coffee grains from 10 organic samples and 20 conventionally cultivated samples found no significant difference in the presence of ochratoxin A9. These findings make it hard to deduce that organic varieties of coffee such as Bulletproof have a lower content simply because they are processed organically or 'without chemicals'.

How Bad is Ochratoxin A for You?

ochratoxin_a_coffee_beansWhile ochratoxin A may be a relatively common mycotoxin present at varying levels in coffee depending on the above factors, the other key question is whether there is any significant adverse health effects from daily consumption of ochratoxin A at the levels typically found in coffee.  As is often the case with toxicological data, there is very little direct evidence from human studies to go off. Ochratoxin A is formally classified as a nephrotoxin, which is the fancy name for a toxin that adversely affects kidney function7. But again this classification comes from data in animal models involving rats and pigs and at levels of ochratoxin A exposure that far exceed the typical levels in coffee7.

While most countries don’t have formal maximum upper limits for ochratoxin A consumption, the European Union has adopted standards for maximum exposure, while the government of Canada has also recently proposed standards for maximum consumption. A study published in 2012 on the likely cancer threat posed by consumption of Canadian foods containing ochratoxin A concluded that there was no significant risk8 as highlighted below:

“This reassessment demonstrates that exposures to OTA from the diets of Canadians are three to four orders of magnitude below doses that have been associated with adverse effects in animals and that there is no adequate evidence demonstrating that current dietary exposures to OTA may be associated with adverse effects in humans.”8

In fact, most of the studies concerning potential toxicity of ochratoxin A from normal food and coffee consumption suggest there is minimal threat7, 8. It’s important to remember however, that there is a large inter-individual difference in people’s detoxification capacity and susceptibility to toxins. For example, asthma and allergy sufferers typically react less favourably to foods and environments that have a higher overall toxin load. Therefore it’s conceivable such individuals may respond better to Bulletproof coffee if in fact it does have a much lower mycotoxin load than other common coffee varieties.

Butter in Your Coffeekerrygold_butter

The other crucial element to Bulletproof coffee is the use of butter. But the proponents of Bullettproof coffee advocate that not any old butter will do - it must be grass-fed butter! Claims as to why grass fed butter is better generally run along the lines of:

  • Higher in butyrate (a beneficial short chain fatty acid)
  • Higher in omega-317
  • High in CLA16
  • High in beta-carotene12, 17
  • Higher in fat soluble vitamins12, 17
  • Tastes better

Some people may be surprised to learn that there is actually a significant body of literature documenting how altering the feed source of cows can significantly alter the composition of butter11. One of the simple physical differences that results from altering the feed source is the colour and softness of butter. For example grass fed cows tend to produce milk higher in beta-carotene12, which imparts a darker yellow colour to the butter. Spreadability and/or softness is another measure known to be affected by the type of feed cow receive. Cows grazing on grass are known to produce butter with a higher unsaturated fatty acid content than cow receiving corn silage13-16. Grass feeding also produces milk fat globules with a smaller diameter/size, which in turn also favourably affects spreadability11.  Lastly, it is well established that grass fed cows produce milk higher in CLA16, 17.

Furan Fatty Acids in Grass Fed Butter

Another lesser-known benefit that grass-fed butter brings is a much higher content of a class of fatty acids known as furan fatty acids. A recently published study from Germany had confirmed that furan fatty acids are present at significantly higher levels in organic butter produced from cows subject to organic farming and receiving higher portions of grass-based feed18. The presence of higher amounts of furan fatty acids is thought to be an important difference because they act as valuable antioxidants and also have anti-inflammatory properties. These components may in turn confer protection against major chronic diseases such as heart disease and type II diabetes, but this has yet to be determined.

Bulletproof or Not?

With the above information in mind, what should we make of the increasing popularity of Bulletproof coffee and the more general associated trend of consuming coffee with butter? While there is no question that mycotoxins such as ochratoxin A occur in coffee, their levels vary widely and more importantly, there’s little evidence that current average intakes pose a significant risk to the health of the average person. Nonetheless, it’s certainly conceivable that some people may be more susceptible to ochratoxin A exposure and therefore may benefit from changing their preferred coffee make to Bulletproof coffee.

As for the additional butter consumption that comes with Bulletproof coffee, its hard to argue that organic/grass-feed butter doesn’t provide some nutritive benefit over conventional butter. But there’s also the debate about the effect of the added fat intake. Advocates of the low carb high fat diet argue Bulletproof coffee can serve as an effective replacement for breakfast particularly when the coffee includes close to two tablespoons of butter and MCT oil. While conventional dieticians will argue that replacing your typical breakfast with butter coffee may mean you miss out on essential vitamin and minerals you would otherwise get from fruit and veg (in the case of a baked breakfast).

It’s important to note however that Bulletproof coffee does not have to be used exclusively in the place of a normal breakfast. Individuals can still simply choose to replace their traditional morning latte or cappuccino with a Bulletproof/butter coffee, while retaining their fruit, cereal or yoghurt consumption. With the additional fat in Bulletproof coffee however, this may diminish normal appetite for breakfast.

Ultimately, the best way to find out is to give it a try yourself for a week or so. A week’s worth is hardly going to kill you and it should give you long enough to determine if there is some substance to the Bulletproof coffee fad or if it’s just hype.

  1. Accessed on 24th October 2014.
  2. Accessed on 24th Oct 2014.
  3. Joosten HM, et al. Production of ochratoxin A by Aspergillus carbonarius in coffee cherries. International Journal of Food Microbiology.2001;65:39–44.
  4. Studer-Rohr I, et al. The occurrence of ochratoxin A in coffee. Food Chem Toxicol. 1995;33(5):341-55.
  5. Pérez De Obanos A, et al. Influence of roasting and brew preparation on the ochratoxin A content in coffee infusion. Food Addit Contam. 2005;22(5):463-71.
  6. Kouadio IA, et al. Effect of Robusta (Coffea canephora P.) coffee cherries quantity put out for sun drying on contamination by fungi and Ochratoxin A (OTA)under tropical humid zone (Côte d‘Ivoire). Food and Chemical Toxicology. 2012;50:1969–1979.
  7. Vettorazzi A, et al. Ochratoxin A kinetics: A review of analytical methods and studies in rat model. Food and Chemical Toxicology. 2014;72:273–288.
  8. Haighton LA, et al.A reassessment of risk associated with dietary intake of ochratoxin A based on a lifetime exposure model. Critical Reviews in Toxicology. 2012;42(2):147–168.
  9. de Fátima Rezende E, et al. Ochratoxigenic fungi associated with green coffee beans (Coffea arabica L.) in conventional and organic cultivation in Brazil. Brazilian Journal of Microbiology. 2013;44(2):377-384.
  10. Theodoro CGC & Guimarães JBC. Assessment of nutritional status in organic coffee agroecosystems in the state of Minas Gerais. Science & Agrotechnology. 2003;27:1222-1230.
  11. Chilliard Y, et al. Effect of different types of forages, animal fat or marine oils in cow’s diet on milk fat secretion and composition, especially conjugated linoleic acid (CLA) and polyunsaturated fatty acids. Livest Prod Sci. 2001;70:31–48.
  12. Havemose MS, et al. Influence of feeding different types of roughage on the oxidative stability of milk. Int Dairy J. 2004;14:563–570.
  13. Cullinane, N., S. Aherne, J. F. Connolly, and J. A. Phelan. 1984. Seasonal variation in the triglyceride and fatty acid composition of Irish butter. Irish J. Food Sci. Technol. 8:1–12.
  14. Hurtaud CL, et al. Evolution of milk composition and butter properties during the transition between winter-feeding and pasture. Grassl Sci Eur. 2002;7:574–575.
  15. Schroeder GF, et al. Milk fatty acid composition of cows fed a total mixed ration or pasture plus concentrate replacing corn with fat. J Dairy Sci. 2003;86:3237–3248.
  16. Ledoux ML, et al. Fatty acid composition of French butters, with a special emphasis on conjugated linoleic acid (CLA) isomers. J Food Comp Anal. 20505;18:409–425.
  17. Slots T, et al. Potentials to differentiate milk composition by different feeding strategies. J Dairy Sci. 2009;92:2057–2066.
  18. Wendlinger C & Vetter W. High concentrations of furan fatty acids in organic butter samples from the German market. J Agric Food Chem. 2014;62(34):8740-4.
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