Your Vegetables Want To Kill You (The Role of Plant Toxins in Human Nutrition)

Polyphenols, Oxalates, Lectins, Oh My!

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To quote Dr. Paul Saladino: “I’ve got bad news for you: Kale doesn’t love you back.” In this article, we’re going to discuss the overlooked but massively important role of plant toxins.

In this day and age, when veganism is (seemingly) booming, I have a somber word of warning: Vegetables want you dead. Little did you know that those green leaves in your smoothie are filled with poisons designed to make you sick.

I know, it sounds unbelievable. After all, even if you’re not a vegan, most people eat plants regularly. How could it be true that these foods are all poisonous?

Well, how else could they defend themselves? Sorry to burst your bubble, but plants do not want to be eaten. It just isn’t evolutionarily feasible. What’s to stop grazing herbivores from eating plants to extinction?

As it turns out, nearly all plants contain defense chemicals designed for just this purpose: avoiding extinction by making whatever chews on them sick.

Broccoli has sulforophane, and the high levels of oxalates in kale are plenty defense to keep would-be consumers at bay. These materials, which are often lauded as healthy for humans, are actually there to fight any would be predator.

Even Herbivores Don’t Binge

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We’ll get into the basic biology of plant toxins soon, but first I want to address the way herbivores eat their food. After all, these creatures eat almost exclusively plant material. If plants are poisonous, then what gives? Why aren’t deer constantly sick and dying?

Well, for one thing, well adapted herbivores have a host of chemical defenses against plant toxins. Moose and other grazers have enzymes in their saliva as well as multiple stomachs which deactivate plant toxins such as tannins.

Even with these adaptations, ruminant animals, the most well adapted creatures to eating plants, don’t binge. Herbivores have been observed to constantly shift between different plant food sources, eating some old grass today, young grass tomorrow, chewing on a twig later, etc.

It appears that herbivore’s palates change in order to keep them from getting sick. As they consume a plant and ingest more of a particular plant toxin, they begin to lose their appetite for the food. This appears to be a complex system of learning and instinct that is innate to these creatures.

This should be a warning sign for human onlookers. If even herbivores have trouble with plant food, what about us? With a bit of knowledge we can navigate plant toxins ourselves and keep our health.

Polyphenols: Panacea or Pesticides?

Inside plants are a host of chemicals that can cause you harm. If it isn’t a nutrient, it’s probably supposed to hurt you.

Two of the most obvious examples of harmful plant compounds are lectins and oxalates. These compounds have no functional purpose in animals and can be incredibly damaging in even small amounts.

Lesser known is the role of polyphenols. These compounds are often referred to as antioxidants, meaning they (supposedly) lower inflammation in the human body when consumed. Examples of plant polyphenols include resveratrol, quercetin, flavinoids, tannins, stilbenes, lignans, curcumin, capsaisin, and many more.

You may recognize many of these compounds. Most of them have been widely promoted as health boosting. Resveratrol is thought to prevent cancer and curcumin from tumeric has become a certifiable poster-child of the health and wellness industry.

What you may not know is that these compounds serve no purpose in plant metabolism. They do not help the plants stay healthy. Instead, polyphenols are either pigments or plant defense mechanisms.

Animals do not have any polyphenols of their own. These molecules are 100% unique to plant biology. When we consume these materials, they don’t become a part of our working biology. Instead, what really occurs is that these compounds cause inflammation. In response, your body produces its own antioxidant, glutathione, which is the compound that actually lowers inflammation.

This doesn’t necessarily mean that polyphenols are bad. If something acts as a stressor that signals your body to improve, that’s still a good thing. Exercise, for example, improves your body first by stressing it. This results in adaptations that include long term health benefits.

Still, good research on polyphenols has yet to show much benefit. Resveratrol has failed to show it’s purported benefits in human trial and has been mild eat best. Heck, it’s even been linked to negative side effects such as compromising androgen receptors.

In this placebo controlled interventional study on non-smokers, no effect was observed from consuming 600g of fruits and vegetables a day over the course of 24 days.

In a review of the available literature, intervention studies have only shown benefit for short term use of polyphenols, and even these are far less significant than expected. Between this information and the lack of long-term studies, there is little evidence that these compounds are helpful.

So where does this leave us? How about with a new view of polyphenols and what they actually are: mild poisons and stressors that may cause us benefit in the short term but have not shown long term benefit in research and may even have side effects.

Perhaps rotating plant foods regularly, rather than consuming any one thing all the time, could allow for benefits from polyphenols. I do not think we should be taking megadoses of these compounds or using any supplements, however.

If our goal is antioxidant effects for our body, better to rely on exercise and environmental stressors like cold therapy than a scoop of turmeric powder (more on that later.)

This one is definitely up for debate. However, the next plant compound on the list is one without benefit, and could potentially place you on dialysis.

Oxalates: How Kale Smoothies Can Kill Your Kidneys

Calcium Oxalate Raphides

Oxalates are produced in animal biology as a waste product. They serve no functional purpose, and when there are too many in our bodies we can end up with some serious issues.

Kidney stones are primarily made up of calcium oxalate, for example. People with primary hyperoxaluria, a genetic condition that causes high production and excretion of oxalates, pass large kidney stones regularly and often end up with permanent kidney damage and renal failure.

Here’s where plants come in: Unlike animals, oxalates are a primary component of plant biology rather than a waste product. While in humans there is no purpose of oxalates, plants use them in photosynthesis, mineral stabilization, and even defense against predation by animals.

Raphides, for example, are microscopic needles formed from calcium oxalate that occur in many plants as a defense mechanism. These needles can irritate and damage sensitive tissues in animals, and even deliver toxic proteins.

What about edible plants? Well, turmeric has been lauded as a super food for eons, yet I’ve never personally found it helpful despite years of regularly adding concentrated powder to my coffee.

In fact, most of the time I only felt worse! One reason may be the incredibly high oxalate content of this root. 100 grams of tumeric powder contains about 2000mg of oxalates. By comparison, 100g of spinach contains about 750mg of oxalates which is still high.

With humans only naturally producing 10 to 30mg of oxalate a day, dietary intake poses a serious risk toward the formation of kidney stones as well as damage to the digestive tract.

Deaths have been reported from consuming as little as 5000mg of oxalates in a day (1, 2, 3.) You could easily end up putting this much in your body by participating in a green juice cleanse.

What am I saying? For one thing, that I don’t promote green smoothies. Kale, turmeric, and many other foods have concerning oxalate content. Dark green vegetables can be high in particular, but so can potatoes, some spices, and even medicinal mushrooms like Chaga which are not even plants.

I recommend cooking all plant food in order to break down as many of the harmful compounds as possible. However, many say this is a way to lower oxalate content. In what I’ve seen, this may be untrue. Here’s a great article about the subject by Kevin Stock (as well as a very active comment section rife with stories of getting rid of pain or other symptoms by removing high oxalate foods.)

Lastly we have lectins, a category of plant compounds that were used in an attempt to assassinate Obama.

Lectins: A Serial Killer’s Plant Toxins Of CHoice

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Ricin is one of the most toxic plant compounds known to man. Found in castor beans, this lectin can kill an adult human at a dose size equivalent to a few grains of salt.

In 2013, a letter containing Ricin was sent to Obama, part of an elaborate and eccentric plot made famous by the GQ story: The Elvis Impersonator, The Karate Instructor, A Fridge Full of Severed Heads, And A Plot 2 Kill The President.

I’ll let you read that one on your own time, but the point is that lectins can be extremely dangerous. Ricin is the most toxic lectin known, but milder ones in our food are connected to hosts of health issues and problems.

The reason plant lectins can be problematic is because they bind to glycoproteins in our cells. Ricin, for example, binds to a part of our ribosome used in protein synthesis. This is enough to cause death at even the tiniest doses.

Though usually not nearly as toxic, we can observe how potent lectins are by looking at beans. Undercooked kidney beans have a rife history of poisonings, and though usually the result is vomitting and diarrhea, there are likely long term effects such as stunted growth rate, as evidenced by this research.

Gluten is a lectin that triggers severe stomach problems and inflammation in those with celiac disease, and peanut-lectins have been linked to increased proliferation of rectal cancer.

Humans and Plant Toxins

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So what are you saying Keenan? We need to rotate our plant foods more?

Well, yes, that would probably help. However, I actually have a much more controversial viewpoint. I believe that humans are not omnivores, but are facultative carnivores. You can read about the powerful anthropological evidence in my article: Humans Are Carnivores (How Evolving To Eat Meat Made Us Who We Are)

What does it mean that we are facultative carnivores? It means we are creatures that thrive on animal food but are capable of consuming plant materials for survival.

For those who do not already know, I have been healing from chronic disease for the past 3 years. During that time, the carnivore diet came to the spotlight via those such as Dr. Sean Baker and Mikhaila Peterson.

People with severe autoimmune conditions (lifelong rheumatoid arthritis in Mikhaila’s case) were popping up left and right, either healing or completely cured by adopting an exclusively animal based diet.

Veganism didn’t cause my health problems, but I had tried it to no avail as an attempt to heal. All I got for my efforts were a sharp increase in noxious gas production from my rear end, and an increase in my health symptoms.

Though I was already 80% better from other methods by the time I tried carnivore, I was amazed by how much better I felt. This is all just to say that I am a believer.

I strongly encourage you to check out the zerocarb and carnivore subreddits. As you will see, not everyone adapts to the diet perfectly, but there are success story after success story of men and women finally defeating issues ranging from diabetes to panic disorder.

My point? I believe that humans have consumed plants throughout most of our time on this earth, however I am not convinced we need them.

Furthermore, for those of us with chronic diseases, many of which the result of poor metabolism, it may be beneficial to rid our diets of plant toxins and adopt a low carbohydrate, animal-based diet.

Now, I also know that very few people are going to try that unless they are already dealing with health issues. I certainly didn’t. So how about just being aware of what plant foods contain the most toxins so you can keep an eye on them?


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At this point I view meat as food and I view plants as either survival food or as medicine (with potential side effects.)

If you are healthy, you can probably eat many plants safely and even get away with the less healthy ones here and there.

It also seems that people whose genetics are from populations living closer to the equator have better tolerance for carbs. I don’t believe this means they are not facultative carnivores but their resilience to plant toxins may be better.

I eat carnivore because I believe that humans are perfectly adapted to eating only meat. A small number of reasons I believe this are as follows:

As far as eating a carnivore diet, I do not promote simply eating steak all day. Even the animal kingdom’s carnivores like lions do not do this. If all you do is eat muscle meat and drink water, I foresee problems in your future.

Instead, I eat a nose-to-tail diet to achieve optimal nutrient intake. This means including organ meats, bone broth, and animal fat in your diet as well as collagen protein from tendons and skin or a collagen supplement.

For a detailed guide to everything carnivore, check out Dr. Paul Saladino’s book: The Carnivore Code. He’s not just some insensitive meat lover either. Dr. Paul was a strict raw vegan for years and it just didn’t work for his health.

There is so much more we could go into here, and like I said I will be continuing to write about this topic in articles to come.

In the meantime, here’s how non-carnivores can still optimize their plant intake to avoid negative health effects.

Plant Food Toxicity Spectrum

For many the idea of eating only meat is hugely controversial, and as much as I like the health benefits I’ve seen, I would like to eat plants somewhat regularly just for mouth-pleasure.

To safely eat plants, it is imperative to understand the spectrum of plant toxicity so you can make low-toxin plants the majority of your intake while keeping moderate or high toxin plants in their place.

High toxin plant foods

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Generally, seeds are the most toxic. Then come roots, stems, and leaves. Logically this makes sense, seeds are the most biologically expensive and valuable part of the plant since they are how plants procreate. Roots, stems, and leaves are all involved with feeding the plant. As far as foods go, these plants include nuts, beans, grains, onions, potatoes, and other roots.

Many of these plants can be rendered less toxic via fermenting, soaking, and sprouting. Although I still consider these foods to be moderate toxicity at best, soaking nuts and then dehydrating them, or soaking until they sprout, reduces the number of harmful or nutrient blocking plant compounds in them greatly.

As far as fermenting, I have heard the theory that ancient humans used fermenting not to feed our gut biomes with probiotic food, but to make plant foods more digestible. Bacteria in fermenting can break down plant toxins, and there is even a gut bacteria (oxalobacter) that may break down those harmful oxalates we mentioned earlier.

Unfortunately, not everyone has this gut bacteria (possibly as a result of overuse of antibiotics) so don’t assume you’re safe for those kale smoothies.

Moderate toxicity plant foods

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At the moderate toxicity level we have fruits. Though fruits rely on animals to eat them and spread their seeds, that doesn’t necessarily mean they are great for our health.

I’ve heard the compelling argument that fruits make themselves attractive to animals through the addictive qualities of their sugar moreso than their nutritional value.

Many fruits have high amounts of polyphenols, for the purpose of dissuading bugs from eating them. As we have already mentioned, resveratrol (grapes, blueberries) and other polyphenols have not shown much efficacy in long term research, but may be the milder of plant compounds.

The other issue to keep in mind is that many humans are metabolically unhealthy from overconsumption of carbs. Eating fruit is not going to help with improving insulin sensitivity if you are pre-diabetic.

Basically, you can think of fruit as something less likely to be toxic via plant toxins, but potentially a problem because of humanity’s general metabolic dysfunction.

If you do not have blood sugar issues, sweet fruits may be easier to consume without causing yourself issues.

Low toxin plant foods

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The lowest toxin foods are iceburg lettuce, which just doesn’t have much in it at all, and non-sweet fruits. These are things such as squash, avocados, coconut (some have issues with coconut but many do not. It is technically a tree nut but acts like a fruit.)

The seeds and skin of these fruits should still be avoided, but the flesh is generally low in plant toxins.

I know, it doesn’t seem like that leaves much to eat when it comes to the world of plant foods. Look, at the end of the day I’d rather you eat plants with abandon than consume processed junk like doritos and twinkies. However I worry about trends such as turmeric supplements and juice cleanses.

Even herbivores don’t binge on plants that extensively.

Instead I suggest at least rotating your plant foods while focusing primarily on low toxin plants such as non-sweet fruits. Depending on your level of health, try more moderate toxicity foods here and there and avoid eating high toxin plants entirely unless sprouted, soaked, or fermented.

For a phenomenal book about plant toxins by a man who still promotes eating them, check out The Plant Paradox by Dr. Steven Gundry. Dr. Gundry also has a more forgiving view of plants than Dr. Saladino or I do.

Here’s a great podcast interview of Dr. Saladino by Dr. Gundry, so you can get the perspective of both a carnivore diet promoter and an omnivorous diet promoter who are both well aware of plant toxins.


Whether you’re a vegan or an avid hunter, you probably eat plants. Did you know they all have toxins designed to hurt you?

Plants can’t run away from their predators, so instead they have developed toxins designed to damage any creature who nibbles too long.

Herbivores have large digestive systems and a sophisticated palate for avoiding consuming too much of any one toxin, but humans don’t have such tools. In fact, there is substantial evidence that humans are most adapted to eating lots of meat, using plants as survival food.

Regardless, I think it’s pertinent that we stay aware of the fact even herbivores won’t binge on one plant for too long.

In the world of concentrated turmeric supplements and condensed green kale smoothies, we might be bombarding ourselves.

Instead I suggest learning a bit about the carnivore diet from someone like Dr. Paul Saladino (who was once a raw vegan,) or at least checking out the work of non-carnivore Dr. Steven Gundry, author of The Plant Paradox.

Then live in an informed manner, making sure to rotate plant foods and be aware of why you feel ill after too much broccoli or pasta.

Thank you so much for reading, I love you all, and I wish you luck on your own personal health, fitness, and life journey.

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