in #bloglast year (edited)

On the contrary to artificial food contaminants like pesticides, the toxins of molds are neglected by the public and their impact on health is often underestimated.

This is an english adaption of my recent article in german.

You wouldn’t eat that bread, right? Well that’s because you’re not my roommate from student days... Pic from Henry Mühlpfordt , published on Wiki, CC-BY-SA 3.0


Everybody seems to be afraid of chemistry in foods these days. Pesticides, plasticizers, artificial colourings and flavourings share a bad reputation - and in some cases, of course, quite rightly so. Organic food is the trend, the food industry is out and even the most unhealthy sweets are now coloured with vegetable dyes.

A very old phrase, however, is often ignored by health-conscious superfood disciples:

Everything is chemistry!

Whether a substance enters food by a natural or artificial way is completely irrelevant from a toxicological point of view. Nature has a repertoire of dangerous toxins that can sometimes be found in food.

However, due to public pressure, the tougher regulations regarding legal limit values and necessary controls undoubtedly apply to industrial contaminants and additives. In addition, there is much more scientific data on these chemicals, as there are lobbies on both sides who actively conduct research.

This leads to the slightly paradox situation that artificial food contaminants are widely discussed in public even if the effect on human health is so small that it can only be proven in special cases while natural problem substances are largely ignored by journalists. Who hasn’t heard of glyphosate yet?
But does anyone of you know Aflatoxin B1? You should , and it’s my duty to close this gap of knowledge.

Under these conditions it should not surprise the educated laymen among you that I, as a toxicologist, consider the natural toxins to be the greater danger.

It still surprises you, I know. But I will explain it to you. Spotlights on, I present you the mold toxins, also known as mycotoxins.

But before we begin, let me warn you: If you want to continue cooking with canned tomatoes or eating pistachios without hesitation, don't read any further. I have already spoiled the appetite of some of my acquaintances, and I will do it again.

Occurence and original function

Moulds, and everyone who ever forgot about food a fridge knows this, occur "ubiquitously". This means that they grow under almost any conditions (e.g. in the refrigerator), are spread all over the world and their spores are almost everywhere. When they grow, many of them produce toxins. These are not primarily directed against humans - we are not a natural enemy of mould (some, like my former roommate mentioned above, are even natural allies). No, mycotoxins essentially have two biological functions:

Firstly, to combat everything that competes for nutrients, which means other microbes, especially bacteria. Therefore, traditional antibiotics such as penicillin also belong to the substance class of mycotoxins.

And secondly, the toxins are supposed to damage the plant tissue in order to make it easier for the fungus to penetrate its host.

As a side effect, however, many of these substances are also toxic to higher organisms, in a variety of ways that might differ from toxin to toxin.

Human exposure

... but processed foods are consumed without a second thought. Pic from Pixabay , CC0

"Fine and good, dear Sco," I hear you saying, "maybe it concerns others, but for my part I always throw away mouldy food right away!"

That's good and right. But who said that mould must develop in your place?
This is the reality of today's food production: Two million tomatoes are mashed up in a fat factory and packed in cans. Do you really think they are all individually and manually examined for small black spots? One can safely assume that the Polpa is contaminated to a certain degree. Actually, we don't have to assume, we know it.Ref The study of an esteemed colleague of mine was quite clear about that.

Of course, the tomato sauce is sterilized before shipping. This kills the fungus itself, but the chemicals it had already produced at that time are relatively indifferent to heat or UV radiation.

In the pizzeria around the corner, the good sauce is then used on your Pizza Capricciosa, and 20 bites later the mycotoxins end up in your intestines.

The tomato sauce was of course just an example, you can use any other processed vegetables and fruits instead. How many of you eat things whose raw materials you had in your hands for optical evaluation of quality?
Now you get my point.

The problem with regulations

"But there are certainly legal limits that must be observed?"

Yes of course. Eight particularly dangerous mould toxins are regulated in the EU, namely the aflatoxins B1 and M, ochratoxin A, zearalenone, a-zearalenol, deoxynivalenone, patulin and citrinine. Ref1, Ref2

Eight. Of currently over 400 known substances produced by moulds. About which there is for the most part no sufficient data to know whether and how they affect humans.

Thus, the majority of toxins are not even searched for in food (the industry only performs analyses to which they are obliged), hence the Alternaria toxins in tomatoes. And it is certainly not the case that Alternaria toxins are harmless in any case. Some of them are genotoxic in human cells and therefore potentially carcinogenic. Others activate hormone receptors and are therefore suspected of disturbing our hormonal balance. And I don't even get started on the problem of chemical mixtures (you don't eat a single mycotoxin, but due to multi-contaminations 100 different ones at the same time, with interactions, cumulative effects etc.).

Late-stage Alternaria growing on (and in) tomatoes. Pic by Scott Nelson, public domain.

But research is just not advanced enough to enforce regulation. And there is a simple reason for this: there is almost no economic interest in toxicology. On the contrary, new limits would cost agriculture and industry money. In contrast to our sister discipline, pharmacy, we therefore have to finance ourselves mainly from public funds, which are rather sparse for obvious reasons - after all, it’s taxpayers' money. Accordingly, our research is underfinanced and slow compared to other disciplines.

But even in the case of substances for which limit values already exist, there are troubles. Take aflatoxins, for example. I have already written an article about them quite some time ago. In short, aflatoxins are produced by fungi that prefer to grow on nuts and legumes at tropical temperatures. Pistachios are particularly susceptible to this.

The problem is that aflatoxins are extremely potent carcinogens. Relatively small amounts of AfB1 cause liver tumors quite reliably. And if a single pistachio is affected, it is often affected in very strongly, with big doses of toxins formed. If you're unlucky, one nut is enough.
This leads to the situation that the limits, which are actually well set, are very difficult to monitor. A whole batch of pistachios can be completely ok, and AfB1 is not detectable in the samples drawn. But the liver of one consumer, who eats the rotten nut lying in the bottom left corner of the box below millions of others, may still be damaged.

Now what?

You can't avoid mycotoxins to 100%, but that's not even necessary, because we are quite well prepared for a certain amount of them through co-evolution. But it doesn't hurt to develop a certain awareness of the problem. With a few exceptions, mouldy foods belong into the garbage, especially if they are partially liquid (tomatoes) or have air holes (bread) - which enables the fungus to spread rapidly, and with it the toxins, too.

Anyone who does without processed food and cooks as freshly as possible with manual quality control is certainly better off. And please, if a pistachio looks “funny”, don't taste it. When it comes to exotic nuts, toxicologists are paranoid (with good reason).

Otherwise, it's the producers in particular who are responsible: mould can usually be avoided by good storage conditions. This works quite well in Western nations, poorer (especially African) states and the wild East still have some catching up to do.

Stricter limits and a little more money for our research would not be bad either, but you have no influence on that. ;-)

What you
can expect from this blog…

I'm sure you've noticed that this was just an introduction to the subject. In the coming weeks I want to introduce you to various mycotoxin groups, their occurrence and effects, and we will certainly go a little deeper into molecular biology.

Until then, cya soon!


In my blog, I’m writing my honest opinion as a researcher in toxicology, not more and not less. I am human, I make errors. Discuss and disagree with me, if you’re bringging the better arguments, I might rethink.


Finding sources in your own field, where you just write the text from memory, is always a bit special. ;-) I quoted some of them in the text, if you want further information, you can read it here:

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Great to read again something from you! :)

I am quite afraid of organic food at the moment, for the reason it starts to be as industrial as non-organic food, and that the gains in eating organic are often lost by the trip the food has to make to end into our plates. I turn out to prefer local chains, where I know all the intermediates: me and the farmer. OK, it is maybe not 100% organic (because this is a label that needs to be obtained in a sometimes unrealistic manner), but at least I know what he does and I agree with that (something we could call “reasonable” farming).

After this blabla, let’s go back to your article…

If you want to continue cooking with canned tomatoes or eating pistachios without hesitation, don't read any further.

Great! I just bought yesterday dozens of kg of tomatoes to produce my own tomato sauce and ketchup for the next winter! ^^

And there is a simple reason for this: there is almost no economic interest in toxicology.

The exact problem of most interesting fields of science.

Hey there, thanks for reading and commenting!

The exact problem of most interesting fields of science.


I am quite afraid of organic food at the moment

I'm not a big fan of organic food either. Some of the things they do might be quite alright, but some effort to fulfill the requirements AND to stay competitive are just beyond stupid. E.g. using "no pesticides", but instead spoiling the earth with copper sulfate, which is a mineral and thus officially "organic", but has exactly the same effects as a persticide/herbicide (=killing weeds and microorganisms), just that it's more ruinous to the soil than most common pesticides.

Plus there is no proven health benefit of organic agriculture, propably because a) pesticides are strongly regulated (at least in the EU) and b) any positive effect of lacking pesticides is checked by the plus of natural toxins like mycotoxins.

I also tend to buy local instead.

This is why I waited to read your article--I knew I'd be looking up information to find out just what those toxins can do. My first article:
Just started reading it. This will follow me on my iPad.....
A great article. Not so great for someone afflicted with mild food paranoia :)

Ah, a paper by Isabelle Oswald. Great lady, met her is Lisbon this year.

And sorry. ;-)

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heavy shit :S

I knew about aflatoxins but didn't think about processed food. I once heard from somebody roasting peanuts because of aflatoxins but didn't get the point is there research between different processing? (of course lokaly roasted seeds after picking them)

One the one hand, aflatoxins are heat resistant, so roasting would not help in getting rid of them if they are already present.
On the other hand... I'm not aware of dedicated literature, but it seems reasonable to me that roasting nuts directly after the harvest should decrease water activity and thus inhibit fungi growth to a certain extent - of course given the nuts are stored under dry conditions afterwards.

Thanks for reading and the interesting question.

Great post. My knowledge of mycotoxins mostly comes from Dr. Shoemaker and his group’s information gathering and now you too.

I definitely do agree that there should be stricter limits and more funding for yours and others research of this.

It’s a very important issue in life.

From what I understand there are certain groups of people who are “genetically susceptible” to illness from mold, but I still don’t believe the non-susceptible will really be so completely immune to all effects, just maybe some of the more immediate and obviously alarming effects.

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Thanks for your interest!

All humans bring along their own set of genes, and so we all react differently to our environment. When talking about toxicology, the most important genes are always those involved in the so-called "xenobiotic metabolism", as they determine how fast your body can detoxify and dispose of uptaken toxic chemicals (to simplify it a lot^^). There are big differences between humans in that regard.
However, I doubt there is really someone who is "not susceptible" to mold toxins at all.
"The dose makes the poison". At a certain concentration, everyone suffers. But of course: A dose that might be dangerous for one can be irrelevant for another person. And vice versa.
We are aware of that, and there are measures that are taken to account for hose differences in risk assessment of chemicals. But I would have to write a full post if I would have to explain those in detail. ;-)

Interesting. Thank you for sharing what you know about all this.

The genes said to control illness from exposure are labeled the HLA DR for a multi-symptom and multi-system illlness known as CIRS or Chronic Inflammatory Response Syndrome.

The doctors and medical professionals who have managed diagnostics and research of this illness provide information on

I have combed through some of the research papers and am still trying to understand what should be noticed in these to signify results, other than going just by what is said/written without statistics and examples of groups of patients.

There are MDs available for consultation/appointments who are certified under the Shoemaker Protocol of treating people with this illness from mycotoxin exposure.

Are there other known treatment standards and professionals you would refer people to for treatment if sick from mycotoxins?

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Are you sure those problems are caused by the mycotoxins? Because there is a totally different problem with molds aswell: Allergic effects to the spores, and also the so-called "wet building syndrome", a kind of immune defficiency when you're exposed to mold spores for too long. These problems are not primarily caused by the toxins, but by the molds themselves.

Can’t be 100% sure. I was told by the DNA test that I am in the susceptible category.

I’ve read the academic/peer-reviewed research papers on the issue but had a hard time getting a clear representation of the data they have gathered from treatments so far.

Just recently I got to an appointment with a pulmonary doc and got a breathing test and chest x-Ray done the next day.

X-ray was fine but the pulmonary test seemed to show something to them. The numbers showed a significant improvement in breathing when administered the inhaler medication.

Sticking with the pulmonary doc for now.

“Wet building syndrome” or “sick building syndrome” is where the categorization of the illness of CIRS or Chronic Inflammatory Response Syndrome came from.

Allergy tests didn’t show any significant response to molds but I’m still curious about other views on the issue.

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Could you link some of the papers you found? I'm getting curious. ;-)

Not sure if i ever linked the paper, but they can be found at

Nice post @sco. I'm giving a lecture on fungi this week in my microbiology lab and I'll try to slip in something about mycotoxins!


I, as a toxicologist, consider the natural toxins to be the greater danger.
we are not a natural enemy of mould

I do think that the sole purpose of mould is to try to destroy me. I hate mould!

But, jokes aside...

OH MY GOODNESS @sco! My husband is going to hate you from today onwards. Perhaps as much as I hate mould! :P

I am glad you concluded your post with a hint of hope for those of us who opt for 100% freshly cooked meals. That is the rule in my household. But, I am a bit freaked out by the whole pistachio contamination scenario. We are big nut eaters here, and we go for all the 'exotic ones' as you put it. Oh no ...

I will be following your upcoming posts on mycotoxin groups with much interest.

Have a great rest of the day @sco. And thank you for making all this information available to us! :)

Fresh cooked food is the way to go!

I, as a toxicologist, consider the natural toxins to be the greater danger.

I have to add one point here: I am a resident of the EU. Here, several quite dangerous chemicals are forbidden that are still legal and used in the US. I believe you are US-based? In that case, artificial food contaminants like pesticides etc. might be a bigger problem for you than they are in Europe.

Still, mycotoxins are a problem in the US aswell, especially aflatoxins. Did you read the dedicated post on these toxins from 1,5 years ago? I'm still not sure if I'll extend it (in that case I would also re-post it in English) or just translate the existing article to german... but if you are interested you can just read it in the short version here.

As for nuts, I only eat them with lights on, and I look at every single one of them for dark-brown/black/strange-looking parts. The toxicologist's curse: Nut paranoia.

I live in Portugal @sco :) and I will surely follow the link you provided here. I am interested!

The toxicologist’s curse: Nut paranoia

Not long after I read your post I needed to pop into the supermarket and I swear , as I was browsing the baked goods, the nuts, the veggies I thought of you and thought “oh Gosh, it must be a nightmare having all that knowledge about all the processed food, fungi, pesticides, natural toxins”. 😥

Either way, thank you for the info about nuts, I will certainly be more careful from now on! Your paranoia has just been passed on :/

Have a wonderful evening! :)

Ah, Portugal, very nice! I wasn't aware of this.

It is both a nightmare and a relief to be informed. ;-)

But @sco, you can't say this without elaborating it further ... please continue :D

It is both a nightmare and a relief to be informed. ;-)

because .... :P

Nightmare is obvious... see "nut paranoia".
Relief because at some point you see that almost everything contains something toxic, yet somehow mankind survived for thousands of years. --> it can't be too bad --> When it comes to my personal nutrition, I don't care much about most toxins and focus my attention on those that are either dangerous for real or easily avoided.

Ow ... sorry @sco, I completely misread that. I thought it was within the context of living in Portugal. But yep, it’s true. Being informed has its advantages and disadvantages :)

I will never going to eat again.
Starting my light diet right now!

I'm so sorry. But I warned you!

Let’s help each other and keep each other motivated on the light diet @isnochys :) Great idea! 😂

Exzellenter Artikel!! Vielen Dank!

Vielen Dank für die Blumen!

I really enjoyed reading your article @sco. Waiting for upcoming ones in this series. 😊

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