In the previous posts we established that human beings survive by consuming other living organisms to provide energy and raw materials for growth, reproduction and survival, and that we call these organisms that we choose to eat “food”.

What should also be considered, however, is that the consumption of other living organisms could also be a potential source of toxins.

Within the paleosphere, there is often talk of certain plant foods “not wanting to be eaten”, and therefore developing defence mechanisms in order to protect themselves.

Although I’ve talked before about how this is faulty thinking, and that neither plant nor animal foods “want” anything, nor have any control or agency over their design, it does not mean that the foods themselves do not contain potentially harmful compounds.

Gluten is probably the most notorious toxin in commonly eaten foods. Its primary function within a grain is actually as a storage protein. It was not put there deliberately by anyone to scare off predators or punish you for eating cake. This however probably acts as little consolation for people with coeliac disease or gluten sensitivity!

What’s in your dinner?

Although I may take issue with some of the semantics of the paleo diet, I would have to agree with their identification of grains and legumes, and to a lesser degree nuts and seeds, as the major potential sources of toxins in the modern diet.

These toxins fall into two main categories:

Gluten, Lectins and Saponins

These are compounds found in grains, legumes and other plant foods, which, if they pass undigested into the blood stream can cause a range of ill effects, from inflammation, insulin and leptin resistance, and even autoimmune diseases.

NB – It should be pointed out at this point that not all lectins and saponins are bad, in fact many are actually beneficial for health!


Phytates bind to the minerals contained in foods, making them unavailable to anyone eating them. While grains and legumes may look nutritionally half decent on paper due to their mineral content, once you consider the fact that much of this will just pass straight through, they quickly lose their shine!

Phytates can also bock the action of protease enzymes, affecting one’s ability to digest protein.

Other foods can contain toxins too!

Grains and legumes are not the only foods to contain toxins, however.


Goitrogens are compounds in foods which inhibit the absorption of iodine from the diet, and thereby inhibit thyroid function, potentially leading to the condition known as goitre.

The main sources of goitrogens in the Western diet are cruciferous vegetables (cabbage, broccoli, kale, etc) and spinach, but they are also found in all manner of foods from soy and millet to strawberries and sweet potatoes.

The potential harm of goitrogens are exacerbated that the modern diet is very often borderline deficient in iodine as it is!


Methionine is an amino acid found in muscle meat. It is in fact one of the 9 essential amino acids required by the body for life. As I mentioned in the last post however, it is easy to have too much of a good thing!

As Chris Masterjohn point out in this post here, the metabolism of methionine increases our requirement for “vitamins B6, B12, folate, betaine, and choline, and also increases our need for the amino acid glycine, found most abundantly in skin and bones”.

The tendency of the modern diet to focus exclusively on muscle meat with little or no skin, bone or organs can easily lead to an imbalance resulting in compromised health.

While it is perhaps a little misleading to categorise methionine as a toxin, when it is in fact an essential nutrient, I’ve put it here as a reminder that there is no “super food”, and that eating anything to excess, or to the exclusion of a varied diet is probably unwise!

Likewise, while “non-paleo” foods such as wheat, soy, nuts, dairy and peanuts comprise 5 out of the 8 most common foods to which people have an allergic reaction, paleo staples such as egg, fish, shellfish and seafood make up the rest.

The point being that it is a mistake to categorise any food or group of foods as universally good or bad for all people in all situations.


All the toxins covered above are actual components of foods themselves. It is of course also possible to ingest toxins in foods contaminated with extraneous substances.

Possible contaminants include:


Mycotoxins are the by-products of fungi that grow on crops, and can pose a severe threat to human health. The most common sources are grains such as wheat, rye and oats, and the most serious, aflotoxin – a potent carcinogen, grows on peanuts.

Before paleo fans become too smug however, they can also be found on coffee, chocolate and fruit (the horror!)

OK, maybe super strict fructose fearing paleo fundamentalists that abstain from coffee and chocolate can be smug, but then I guess they need something to be happy about…

Antibiotics/Antibiotic Resistant Bacteria

The routine use of antibiotics in the intensive meat industry to increase growth rates and reduce the spread of disease in filthy environments, results in meat that contains both antibiotics and antibiotic resistant bacteria.

Need I say more?


Although we are assured that they never exceed “safe levels”, it is not uncommon for our food to be contaminated with a cocktail of potent pesticides.

Additives, Flavourings and Preservatives

As with the pesticides, we are assured that all of the ingredients that make it into our food are perfectly safe, and fit for human consumption…

Survival in a Toxic World

The above is not intended to be a comprehensive and detailed list of all possible toxins in food, but merely serve as an example, that as well as providing lots of good and necessary stuff such as raw materials and energy, food can also be a source of potential harm.

That said, neither is my intention to act as some harbinger of doom, and scare you off eating food altogether!

As a species, human beings are resilient little buggers!

We’ve been around for millions of years, and look set to stay around for at least a couple of years longer. If the slightest whiff of a toxin were enough to make us plant food, it’s unlikely we’d have gone on to become one of the most evolutionary successful organisms on the planet.

Take for example this young chap: Boy Lives on Nothing but Jam Sandwiches for 15 Years

Now, there’s a post in itself to be had over that article, but I’m going to resist the temptation to get drawn in for now!

Let me make it clear that I am certainly not suggesting anyone attempt to go on a jam sandwich diet, that is a seriously bad idea. I’m sure if he’s continued in that manner, he’s now become seriously ill (as the article was first reported in 2004, he must now be 23, it’d be interesting to know what happened to him).

However, the fact that he managed to grow to 6’2″ and be competitive at sport after a 15 year diet of jam sandwiches (and pop tarts apparently) does indicate that there is a fair chance some of the rest of us could probably survive the odd dalliance into the world of wheat.

Factors Affecting Tolerance to Toxins

There are numerous factors which can affect an individuals tolerance to the toxins found in food. For example:

  • Genetics

This is the one factor over which unfortunately you have little control. If you don’t have the lactose tolerance gene, the you are more than likely going to have to avoid lactose containing foods. If you have been dealt the genetic hand for celiac disease, wheat and any other gluten containing grains will almost certainly be off the menu for good.

  • Digestive Health

Regular readers of this blog, will know that gut flora and the microbiome are one of my favourite topics at the moment.

Your digestive tract, and the trillions of microbes which reside within it, form the boundary between that which is outside your body (yes, undigested food in your stomach and intestines is actually classed as being on the outside), and that which is inside.

If everything is hunky dory, and you have the right kinds of “friendly bacteria”, your guts should be able to do a pretty good job of keeping the bad stuff on the outside, letting it pass straight through you, and extracting all the good stuff.

Problems occur when the balance of gut flora is disrupted, and all manner of junk starts seeping into your blood stream. Not a good situation.

I’d highly recommend listening to this podcast with Pioneering Researcher Alessio Fasano M.D. on Gluten, Autoimmunity & Leaky Gut on @ChrisKresser‘s Revolution Health Radio show.

Of particular interest is that some individuals do not develop the condition until as late as their 70’s! Dr Alessio hypothesises that this could be due to changes in the gut flora, possibly precipitated by antibiotic use/illness/changes in diet etc.

While some have linked increasing rates of celiac disease to either better rates of detection, or more troublesome forms of gluten in modern strains of wheat, perhaps it could be linked to higher rates of dysbiosis?

Could this indicate that contrary to the genetic determinism I alluded to above, with a robust microbiome, an individual with the genetic predisposition to celiac may in some circumstances be able to consume wheat without symptoms?

On the flip side however, increasing numbers of people are being recognised as suffering from non-celiac gluten sensitivity. Again, I would link this to the increasing rates of dysbiosis. Even if you are not genetically predisposed to an autoimmune disease such as celiac, having undigested food particles floating around in your blood stream that aren’t supposed to be there, whether it be gluten or any other hard to digest protein, is not going to have a favourable effect on your health!

Perhaps the most important take home point from here is that tolerance to any particular potential food toxin is not only variable from one person to another, but can also change for an individual over time due to changes in the composition of the microbiome and perhaps other factors.

  • Food Preparation Techniques

The fight against toxins does not have to wait until the food is in your belly. Food preparation techniques such as cooking, soaking, sprouting, fermenting and so forth, can all have a huge effect upon a food’s digestibility, the accessibility of the nutrients within, and the toxicity of the undesirable compounds they contain.

For example, longer fermentation periods when leavening breads has been shown to reduce the phytate content and increase mineral availability, and also to potentially help weaken and break down gluten and other hard to digest proteins.

The good news for broccoli and spinach lovers is that the goitrogens contained within are neutralised through cooking, so as long as you give it a bit of a steam or stir fry before you eat it they are both back to near super-food status!

Though there are of course exceptions to the rule, when it comes to meats and vegetables, cooked trumps raw for increased nutrient availability and decreased toxicity.

If you are going to risk eating grains or legumes, soak, sprout and ferment the bejesus out of them.

Suffer from lactose intolerance? Fermenting dairy into yoghurt, kefir or cheese should metabolise all the lactose leaving the dairy unproblematic for your bowels.

  • Quantity and Frequency of Consumption

Placing methionine up in the list of toxins was perhaps a little misleading. OK, very misleading. Methionine is an essential nutrient, gluten on the other hand is most definitely a potential toxin.

It is critical that you get sufficient methionine from your diet to avoid illness and even death, whereas there is absolutely no physiological need to consume any gluten ever. On the contrary, regardless of your genetics or your gut flora, you could well be better off if you’d never even encountered the stuff.

That said, eating gluten can be fun. Food can, and in my opinion should be, a source of pleasure. This is the topic of the following post, so I won’t delve in too deep just now.

Insisting that everyone should abstain from consuming gluten containing products altogether, regardless of their genetics, gut health, goals and lifestyle is, as far as I am concerned, neither reasonable nor necessary.

I don’t think it wise for anyone to base their diet around wheat. The typical Western Diet of cereal for breakfast, sandwiches for lunch and pasta or pastry for dinner, interspersed with wheat based snacks is not a good idea.

I do not see however, that there is enough compelling evidence for the complete expulsion of wheat from the diet for people without celiac disease or gluten sensitivity.

Back to the methionine – It’s essential, and found in abundance in red meat. Does this make red meat essential, should you make it an everyday staple?

I would say no. Personally I do eat good quality meat such as grass fed beef and lamb, and pastured pork several times per week, as I find it an easily accessible and ethical way to get my energy and essential nutrients, with minimal toxins. I also, however ensure I eat every part of the animal, and I don’t eat it every day.

From a purely nutritional perspective, I don’t think there is any physiological need to consume any meat whatsoever if one has objections to it, whether these be financial, emotional or you simply don’t like the taste, providing that other animal products are consumed such as fish, seafood, dairy or eggs in its place.

Dare I say “everything in moderation”? Well maybe not, but as far as wheat is concerned, I think most people can survive the occasional jam sandwich. Whether that’s one a month, one a week, every few days, or three meals per day for 15 years is going to depend on all the factors listed above.

Equally, though grass fed beef is the paleo super-food, I’m not convinced eating steak exclusively for three meals per day would be a great deal wiser than the jam sandwich diet!

In the following, and penultimate post in this series, I’ll be looking at food as a potential source of pleasure and touching on the concept of food reward and its implications for your health.

4 thoughts on “What is Food? Part IV: A Potential Source of Toxins”

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