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The Truth About Mycotoxins in Coffee

Understanding the Research About Health Risks of Mycotoxins in Coffee

Key Takeaways:
  • While mycotoxins have been found in some coffee, the levels have not been proven to be high enough to harm health [1].
  • Two large meta-analyses of coffee consumption found that coffee is safe and even beneficial to wellness for many people, partly as it is anti-inflammatory and high in antioxidants [2, 3].
  • Some diets, such as the Autoimmune Paleo Diet (AIP Diet) or low-FODMAP diet that work to improve gut health do remove coffee [4, 5]. Removal of coffee is just one part of the diet and these diets are usually temporary.
  • If coffee seems to trigger symptoms such as brain fog or stomach distress, there is likely an underlying health issue that needs to be addressed.
Mycotoxins in coffee: people toasting using their coffee cups

If you love coffee and you’re fairly health conscious, you may have heard about the risk of mycotoxins in your brew. Mycotoxins, the toxic compounds that molds produce, can be found in foods that are dried and/or stored for long periods of time (including coffee) [6, 7]. Hearing that there might be toxins in your coffee would concern anyone, especially since we know that mold illness can be a contributing factor to chronic illness. However, it is important to see what research has to say about whether the levels of mold or mold toxins found in some coffee are likely to be harmful to our health. 

Let’s take a look at mycotoxins in coffee by reviewing how coffee beans are processed, what the research shows about mycotoxin contamination in coffee, and how the types of research studies matter in discerning risk to health. 

Coffee Processing and Mold Risk

Mycotoxins in coffee: ripe coffee cherries

When talking about the possibility of mold growth in coffee, it is often argued that mold growth happens because of coffee processing methods. Let’s look at how coffee is harvested and processed from farm to your morning cup of coffee.

First, coffee “cherries” are harvested when ripe and then taken to undergo one of two types of processing, either wet or dry. In wet processing, the cherries are submerged in fermentation tanks to dissolve the mucilage around the bean. This takes from 12-48 hours. Then the beans are rinsed and spread out or put in tumblers to dry. 

In dry processing, the oldest form of processing coffee beans, the cherries are spread on platforms and left to dry in the sun. It takes a few weeks for the cherries to dry out and be ready for storage and milling. The cherries are raked and turned throughout the day to prevent spoiling and they are covered at night to protect them from the rain.

After the beans have reached 11% moisture in either processing method, they are then milled (hulled, polished, graded, and sorted). At this point, it is called “green coffee,” because the beans have not been roasted yet. 

The green coffee is distributed around the world, where they are then roasted in a lab. This turns green coffee into the brown roasted coffee beans we know as coffee [8].

If the coffee is decaffeinated, this means that the green coffee has been warmed and soaked in liquid to remove 97% of the caffeine. Decaf coffee has about 2 mg of caffeine per cup, whereas a cup of regular coffee contains about 95 mg [9].

You may have read that mold spores grow often in coffee because of this complicated processing — how long it takes to dry out and how long it sits before it is roasted and distributed. However, it is important to note that many foods and drinks contain low levels of mycotoxins. In fact, mycotoxins are found in fruit juice, many grains, and even some animal products [6, 7].

Are There Mycotoxins in Coffee?

The short answer is, yes, there are mycotoxins in coffee. Mycotoxins are toxic compounds produced by certain fungi (molds) and are found in many foods and drinks [6, 7].

The more comprehensive answer is that current research shows that the levels of mycotoxins in coffee have not been found to be harmful to human health. 

I have not found any studies that test whether coffee consumption causes or contributes to mold illness. The studies I discovered only showed that about 53% of the coffees tested contain mold, but not at levels high enough to be toxic [1]. 

Here is an overview of the research on some of the types of mycotoxins found in coffee:

MycotoxinFactsHow Toxic Is It?
AflatoxinsThere are different types of aflatoxins, of which 5 different types were tested for in the coffee samples [1].

Not every type of aflatoxin is as toxic as others. Aflatoxin B1 is considered a carcinogen, as it is associated with a higher risk of liver cancer [6].

Aflatoxin B1 is a toxin produced by the mold Aspergillus flavus that typically grows on cereal grains, peanuts, ground nuts, and pistachios, almonds, walnuts [6].
Aflatoxin B1 (AFB1) did not exceed 2 micrograms/kilogram in any samples, but 15% of samples had a concentration of total aflatoxins (a combination of all five types) above 5 micrograms/kg [1].

Aflatoxin is the only mycotoxin highly regulated by the FDA (food and drug administration) [6].

The amount of aflatoxin a person would typically get from coffee has not been found to be at a level considered toxic.
Ochratoxin A (OTA)A naturally occurring toxin (secondary metabolite produced by aspergillus and Penicillium) that is often found in coffee beans and grains.

At toxic levels, it is considered carcinogenic, damaging to DNA, and immunosuppressive [10].
Found in 36% of samples, ranging from 0.67-4.70 micrograms/kg, which is not a level considered toxic [1].
Enniatins A more recently discovered mycotoxin.Occurred in 59-93% of coffee samples, from 2.22-12,039.12 micrograms/kg [1]
Fumonisins B1 and B2Toxins produced by molds and most commonly found in corn, but sometimes also in coffee beans, wine, and beer [11, 12].Occurred in only 4% of coffee samples [1]
Sterigmatocystin (STE, a type of aspergillus)Found in grain, teas, spices, coffee and beer [13].

Has been linked to damage to the liver and kidneys in animals. Research on STE in humans is lacking [13]. 
Found in 15% of coffee samples [1]

Are Mycotoxins in Coffee a Health Risk?

Mycotoxins in coffee: cracked nuts with molds

The two most common mycotoxins you will read about as concerns for coffee are aflatoxin B1 (AFB1) and ochratoxin A (OTA.) As you can see from the table above, these toxins are found in some coffee samples. However, it is important to look at the levels of these toxins in order to assess health risk.

There are some foods and drinks, including fruit juices, nuts, and spices, that have been shown to have higher amounts of mycotoxins than coffee [14]. Still, a Food Safety Digest report by the World Health Organization notes that the levels of these toxins in coffee weren’t found to be at a high enough level to cause harm.

There was an interesting food study in 2019 that analyzed mycotoxins in fruit juice. It found that nine mycotoxins, including ochratoxin A and aflatoxin B1, were present in 3-29% of 80 juice samples. 

If we are looking at aflatoxin B1, 1,000 micrograms/kg is the amount thought to lead to aflatoxicosis, which can lead to liver damage and cancer [14]. A Food Safety Digest report by the World Health Organization notes that average dietary exposures of aflatoxin in developed countries are usually less than 1 nanogram/kg (about 1 ng/2.2 lbs) of body weight per day, which is far less than the 1,000 considered dangerous [15].

AFB1 is found more in green coffee beans than roasted, and most of us drink roasted coffee [1]. A few studies show that roasting coffee beans may decrease aflatoxin levels anywhere from 20%-56% [16].

What does all of this mean? The mycotoxin levels in coffee have not been shown to rise to the level of being dangerous for our health. 

If you have struggled with mold-related illness, it’s understandable to not want to take any risks when it comes to mold and mycotoxins. But given the nature of our environment and food supply, it’s simply not possible to completely eliminate all possible traces, and trying to do so may lead to unnecessary fear and anxiety.

As always, it’s important to listen to your body. If you do feel that you are negatively reacting to coffee for any reason, you may want to cut out or reduce your coffee intake, at least while you get to the root of the problem. But if this is not the case, there doesn’t appear to be any mycotoxin-related need to avoid coffee consumption. 

Are There Mycotoxin Free Coffee Brands?

I have not found any studies that show that mold-free coffee exists, although some companies claim that their coffee beans are processed in a way that leads to lower or no toxin levels. I couldn’t find the lab testing data that showed these coffees were toxin free. At the same time, most of these are high-quality organic coffees, meaning they’re low in pesticides, grown in non-GMO crops, and undergo more strict standards during harvesting and the roasting process. This makes for a generally better choice than non-organic beans [17].

Some people self-report that they have symptoms such as headaches, brain fog, and stomach distress on regular coffee but not when they drink an organic or “mold-free” coffee. Many of these companies claim to have better processing methods that decrease the risk of mold by ensuring faster drying times at higher altitudes. There could be any number of reasons why these coffees are easier on the system than others, but we do not yet know if this is due to mold levels. If your body feels better drinking these types of coffees, do what works for you. 

Coffee cup on top of a stack of books

Why Research Type Matters

The quality of the research matters when deciding how much a study should impact health care choices. For example, it matters if we are looking at an observational study vs. a randomized clinical trial (RCTs), if there are multiple studies, if the study is in humans or animals, what the effect size is, and how many participants are in each study. 

RCTs are considered the best type of research, as they control for all possible factors and seek to find the exact reasons why and how something may be helping or causing harm (mechanism of action).

Observational studies or reviews of literature look at self-reported correlations in the population. For example, many people with IBS report that drinking coffee triggers diarrhea. However, an observational study does not investigate the mechanism of action.

These observational studies should not be discounted as they guide researchers to decide what might need to be tested in an RCT.

In both observational studies and RCTs, the size of the study also matters. A study that has 3,000 people is more likely to represent solid evidence than a study with just 20 people. Larger or multiple studies done in humans has better evidence than a single study done in mice. A meta-analysis (analysis of many studies over time) of large observational studies and RCTs in humans is the best source of data.  

All this is to say that while there is research that shows levels of mycotoxins in some coffee, there are currently no studies that say that mycotoxins in coffee are at a high enough level to cause illness in humans. Many of the studies people reference to indicate that mycotoxins in coffee are harmful to humans are small studies done in mice. 

Coffee and heartbeat drawn with coffee beans

Health Benefits of Coffee

Coffee has been found to have many health benefits for most people, even for some medical conditions. Here are just a few of the potential health benefits:

  • Lower all-cause mortality and heart disease risk: A 2019 meta-analysis of 40 observational studies and nearly 4 million study participants found that drinking 3.5 cups of coffee per day was associated with the lowest risk of death from any cause at -15%. Drinking 2.5 cups per day was associated with the lowest risk of death from heart disease at -17% [18].
  • Gastrointestinal health: Coffee can improve motility (movement of the bowels) in people with constipation [19]. (However, that may also mean that coffee may not be helpful for people with diarrhea.) It has also been shown to increase beneficial bacteria probiotic strains like Bifidobacteria [20, 21].
  • Lower cancer risk: Increasing coffee consumption by one cup per day was associated with a 15% reduction in liver cancer risk [22], and coffee consumption has been linked to lower cancer risk across many types of cancer [2, 23]
  • Lower risk of type-2 diabetes: For each cup of coffee increased per day, type 2 diabetes decreased by 6%, whether people were drinking caffeinated or decaffeinated coffee [24].
  • Lower Alzheimer’s and dementia risk: Meta-analyses show high coffee consumption is associated with a lower risk of dementia [2, 25]. One meta-analysis shows no significant association between coffee drinking and lowering the risk of dementia or Alzheimer’s disease [26].
  • Lowers inflammation: Coffee has generally anti-inflammatory effects [27].
Mycotoxins in coffee: Health Benefits of Coffee infographic by Dr. Ruscio

In general, drinking about two cups of coffee per day is likely good for overall health in most people. 

If you have an autoimmune condition, gastrointestinal distress, or mold illness, you may find that you do better when you do not drink coffee. We recognize that underlying imbalances can explain why someone doesn’t do well with coffee. In fact, this article discusses coffee and gut health, especially as it relates to issues like IBS, leaky gut, and reflux. 

If you struggle with drinking coffee, focus first on supporting the immune system and creating a healthy gut with a low-inflammatory diet and probiotics to balance gut bacteria. Once your gut health has been restored, you may be able to add coffee back into your life. 

Coffee Is Safe For Most People

Coffee continues to generate controversy in the health world, but the research generally shows that coffee is neutral to beneficial for human health, and possible mycotoxin traces don’t seem to rise to the level of being harmful. 

Remember to listen to your body, and if coffee seems to trigger symptoms for you, consider reducing your intake or cutting it out entirely, at least until you have healed any underlying imbalances.

To get personalized help restoring your health and getting to the bottom of chronic illness, please contact our clinic.

➕ References

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