TPNS 17-18: Phytophobia
Saturday, March 24, 2012 at 11:03AM
Plant Positive

Primitive Nutrition 17:
Phytophobia, Part I

Loren Cordain is a longtime believer in the idea that some foods are bad for us because of what he calls their "evolutionary discordance."  Cordain gives the impression that grains and legumes are practically toxic because they were not eaten in the distant past.  I think the concept of evolutionary discordance is worthless in nutrition.  We can see through nutrition science what effects foods have without needing this idea.

I can’t resist starting with an obvious point.  The cultivation of crops that led to an enormous and sustained population explosion was a successful adaptation.  Evolution weighed in on this  long ago.

Making a case that a food is good or bad because it's novel is not easy.  In this slide, one of the model cultures in the Paleo world, the native Australians, consumed at least 800 different plant species.  Could they have really evolved special tolerances for each and every one of them?  Or did they just figure out what plants they could eat through trial and error?  You know the answer.  Hunter gatherers pass on their knowledge of the plants around them from one generation to the next.

Here are some fruits native to North America.  Should someone in Korea be concerned that a blueberry is evolutionarily novel before eating one?

What about invasive species?  This wild pig is not native to North America, but his species seems to be doing pretty well here anyway.  How much of what he eats here is evolutionarily novel and what price is he paying for it?  Notice that wild pigs are adaptable, generalist, opportunistic omnivores who can live in a variety of regions and climates.  Does that remind you of another species?

This article about our hominid ancestor Australopithecus africanus has a great line about diets in generalist species.  They do not have to do many things well, they merely have to do many things adequately.  This applies to us, too.

If you don't understand toxicity, there are a lot of things you can worry about unnecessarily.

You could even stigmatize water.

Toxicity is determined by its dose response.  The question with toxicity is, at what dosage does the substance in question induce a toxic response? In toxicology, the saying is "the dose makes the poison."

This standard is applied to food as well.  Notice that every food component can be a potential hazard..

Virtually all natural foods contain some toxicant.  They are either neutralized in processing or they are handled without ill-effects by our bodies through biotransformation.

It is unavoidable that you will ingest some small amount of toxicants in food.

Interestingly, we need the received knowledge of our ancestors, too, just like Aboriginal Australians did.  You can't just look at a plant and tell whether it's poisonous.

Humans have thrived as a species because of this received knowledge, and through our development of technology.  Today we process the demonized soybean, for example, to neutralize antinutrients.  We also have cultivated our plants to have less of these toxins today than in the past.

We've been processing otherwise toxic plants to make them nutritious for a long time.  This is part of what makes us human.

Give plants a break.  How could an organism evolve to be entirely nutritious for another organism?  By what mechanism would that be possible?  Fruits are about as close as you can get to a category of plant food that might have evolved to be nutritious for an organism that eats it.  Plants can use animals to assist in dispersing their seeds by producing fruits they like to eat.

However, this relationship isn't so simple.  Of course, some berries can be poisonous.  Moreover, while you might think that plants would benefit more from frugivores than granivores, or seed eaters, that is not necessarily true.  All that matters in evolution is what the genome wants, and that is reproduction.  The plant itself is just the vehicle.

Plants have secondary compounds that can be either good or bad for us.

The plants we tend to use have in a sense coevolved with us, as we have selectively bred cultivars that are preferable for our purposes.  We also are generalist feeders, so we have evolved to be able to consume a variety of plants.

Our taste helps us discern whether a plant is safe and nutritious.  We have this in common with our primate cousins, who can be highly selective of what they eat.

And like us, as you see in this fascinating study, they also rely on others' experience to determine whether a food is safe for them.

Humans have always had exposure to potentially toxic plant compounds, and that has influenced how we evolved as a species.

Natural plant toxins are a problem for the cattle the Paleo dieters like to consume, resulting in major economic losses to the meat industry.  It seems to me this would be a bigger problem for grass fed beef.

The Tomato Effect describes the rejection of efficacious treatments for illogical reasons.  It seems apropos to mention here because of the history of the name.  Tomatoes, a plant native to South America, were at one time considered poisonous in North America even as they were avidly consumed in Europe.  Europeans benefited from a highly nutritious evolutionarily novel food, while North Americans missed out because they were afraid of them

You can pay for Loren Cordain's opinion of whether tomatoes pass his leaky gut test.

Or you could save some money and just trust your taste buds, all responsible health institutions, and the collective experience of humanity and just not give it a second thought.

In the next part of the Phytophobia section, I'll show you some other examples of this silliness.


Primitive Nutrition 18:
Phytophobia, Part II


Another example of a scary plant food is the humble potato.

They fail the leaky gut test in Paleo like a lot of other healthy foods.  The Paleo world is amazingly fixated on leaky gut and autoimmune disease.

The problematic compounds in potatoes are called glycoalkaloids. A concern with them in this study is that they might enhance the uptake of allergenic molecules.

Allergies and autoimmune disorders are known to be closely related.

Eastern European nations are the biggest consumers of potatoes.  Are their immune systems on the fritz?  I couldn't find any information generally regarding autoimmune problems in the world potato leader, Belarus, as the after effects of Chernobyl dominate the literature on that subject.

I found some information about allergies there, though.  Allergies occur at a very low rate in Belarus.  Shouldn't there be an allergy problem in the most potato-loving country in the world from all the glycoalkaloids they eat?

This paper took a comprehensive look at potato glycoalkaloids.  Their potential for toxicity was noted.

Also noted was the way these compounds destroyed human cancer cells.

Potatoes produce more glycoalkaloids if they are exposed to the sun.  It turns out people can do a good job of sensing whether a potato should be eaten or not.  Glycoalkaloids produce a bitter taste.  You probably already know not eat a potato if it’s green.

Humans have also accounted for these compounds with technology for a long time.  In the Andes potatoes were essentially freeze-dried for thousands of years, creating a safe, reliable food supply.

Rats eating huge quantities of freeze-dried potatoes showed no ill effects from glycoalkaloids.  However, potatoes did demonstrate anti-tumor properties.  So potatoes have potential hazards but also serious potential benefits.

Potatoes, like other plants we consume, have been selectively bred so their potentially harmful chemicals are in very low concentrations.

Students of evolution should note that Darwin himself was impressed with the potato.  Once again, a food that fueled a population boom can hardly be seen as discordant.  If Cordain is really interested in the way foods have historically affected height, he should love the potato.

The blight leading to the Irish potato famine is an object lessen in crop diversification.  It was so severe only because potatoes had been so dependable and nutritious.

Secondary compounds like glycolalkyloids in plants have long been known to have both useful and potentially harmful properties and have been used accordingly. This excerpt illustrates this well.

As you probably know, antioxidant compounds in plants are believed to have powerful health-promoting properties, including fighting cancer.  But in the real world rather than the oversimplified world of Paleo-logic, even this isn't so straightforward.

Under the right circumstances, antioxidants can actually help cancers develop.

It turns out that not only can antioxidants slow aging and fight disease, but they also can possibly interfere with detoxification or prevent the deaths of cancer cells.  Should antioxidants be demonized the way Paleo demonizes legumes or grains?  Should we say that only lots of meat and animal fat are safe?  Of course not.  As I will show you, the effects of antioxidant-rich plant foods have been overwhelmingly shown to promote human health.

We can fixate on the purported antinutrients in permitted plant foods in the Paleo diet just as they do with grains or legumes.  Here you see Cordain's Paleo cookbook includes recipes for eggplants and raw mushrooms.

All raw mushrooms are known to have some toxicity in humans.  Eggplant also contains the dreaded glycoalkaloids.  Maybe these issues are solved with cooking, but isn't cooking itself evolutionarily novel?

After all, cooking has only occurred in the last two percent of our evolutionary history.  Should there even be such a thing as a Paleo cookbook? And isn’t the eating of toxic substances in plants more in keeping with our most primal history than cooking them away?  Or maybe this whole line of reasoning is just silly.  Plants are highly complex organic substances.  Unless you have a specific disorder, just look at them as whole foods, enjoy them, and leave food toxicology to the food toxicologists.

In the mind of a caveman, if some protein is good then more must be better.  Paleo distorts protein like a funhouse mirror. I’ll try to reflect reality, next.

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