Health Dangers of Eating Fruit

Health Dangers of Eating Fruit

Health Dangers of Eating Fruit

Health Dangers of Eating FruitIn the exploration of the Health Dangers of a Plant-based Diet fruit plays an interesting role. Most people think fruit is healthy because they are high in antioxidants, they are a good source of fiber, and they contain essential vitamins and minerals. And unlike other plant parts (roots, seeds, stems, and leaves) which the plant desperately wants to protect for survival, the plant actually wants predators to eat its fruit and spread their seeds. So here we’ll explore if there are any health dangers of eating fruit.

Health Dangers of Eating Fruit: Spreading Seed

Some plants don’t want predators to spread their seeds (naked seeds). Others depend on animals to do so.

Naked Seeds

Health Dangers of Eating Fruits Naked Seeds

Naked seeds are exposed baby plants. They grow on grasses and vines and the parent plant drops these seeds right where they are growing. Then in the winter, when the parent plant dies, the offspring can sprout right there in the same area. Because they don’t want pests and predators to eat these seeds, plants lace the seeds with phytochemicals to deter predators.

So while these naked seeds seem bare and exposed on the outside, on the inside they are potent fighters armed with chemical warfare agents.

Protected Seeds

Unlike plants with naked seeds, other plants protect their seeds. They need animals to spread these seeds so that the offspring don’t have to compete for space and sunlight with the parent plant.

To accomplish this, plants enclose their offspring in a protective hull and house them in fruit. The fruit entices the predator and the hull protects the seed as it passes through the predator’s GI tract. The animal then eliminates the seed in its dung, a natural fertilizer for the baby seed, in a distant location.

Spreading Protected Seeds

It’s fascinating to think how clever these plants are.

We think we are using apple trees for their nutrition, when really they are using us.

An apple tree entices us (and other animals like a gorillas) visually with big red colorful fruit.Health Dangers of Eating Fruit Phytochemicals

Further, they load it with sugar, appealing to our taste buds. And not just any sugar, but with fructose. This special sugar doesn’t stimulate leptin which is a hormone that signals to us animals that we are full. Since fructose doesn’t turn this hormone “on” we keep on eating more and more apples.

In addition, plants make these fruits easy to pick and even lace them with sugar alcohols that have a natural laxative effect. This speeds the seed through the digestive tract, further improving its survival chances. [r, r]

Health Dangers of Eating Fruit: Green means “Stop” Red means “Go”

The tree uses us. It attracts us with color, and it makes sugar addicts of us. All so that we animals can spread its seeds.

The apple tree controls animal behavior every step of the way.

While the seeds and it’s protective coating are still developing, the apple is green and bitter. Green doesn’t attract us like red does. It blends in. And we want a sweet apple loaded with sugar, not a bitter, sour one.

So, during this unripe period, the apple has the highest toxic load of lectins. The gorilla loves apples but is deterred from picking it until the apple is ripe.

Incidentally, gorillas, like humans and all fruit eating animals, have color vision. [r]

While the apple ripens and the protective hull of the seeds develop, the apple gradually turns red, increases its sugar content and decreases its toxic load. The red, sweet, and less toxic apple is snatched up by us animals who will do the trees bidding, and spread it seed.

Health Dangers of Eating Fruit: Fruit Phytochemicals

Based on the logic that plants intend for their fruits to be eaten one might think that these are a good choice for food.

However, fruits have a dark side.

Besides the dangers associated with the high lectin load in unripe fruit and the heave dose of insatiable sugar that few people need today, there are other potentially toxic phytochemicals.



Many fruits have tannins which help protect a plant from harsh weather.

They also make proteins indigestible. If you were to eat a leather shoe, the reason you couldn’t get protein from it is because the proteins are bound up with tannins.

So tannins bind up protein as well as digestive enzymes and can interfere with digestion (enzyme inhibitors). They also  interfere with our ability to absorb plant iron and have an antinutrient impact. So they can cause nutrient deficiency and GI problems like bloating diarrhea, and constipation.

Tannins also play a role in deterring pests. They are potent against insects. But they are also troublesome for animals.

For example, if cattle get trapped in an area and have to resort to eating acorns, they can get poisoned from the tannins. In humans, large tannin consumption can cause kidney and liver damage. [r, rr, r]


Isoflavone (a polyphenol, plant antioxidant) is found in many fruits and is also found heavily in soybeans.

This phytoestrogen can disrupt endocrine/hormone function and have estrogen-like effects. [r, r]


Other phenolics act as photosensitizers. This is a plant defense mechanism that makes animals sensitive to light.

The story goes like this: An animal eats the plant, then light hits the animal, and the animal is severely injured.

In humans we refer to this as photodermatitis.

For example, celery is a known occupational risk. Celery handlers that go out in the sun can get celery dermatitis. Lime juice is also a well-known cause of photodermatitis. An experiment I don’t recommend trying, is squeezing limes then going out in the sun. The swelling can be horrifying.

Another example is grapefruit.

Grapefruit interacts with almost every prescription drug. It has these toxic furanocoumarins (photosensitizers) that the liver has to break down using p450 enzymes. But the same p450 enzymes in the liver trying to break down these grapefruit toxins are also needed to metabolize the drugs. So the liver gets overloaded and can’t detoxify the drugs. This can result in high levels of the drug in the bloodstream which can have severe adverse effects. [r, r, r, r]

It’s an interesting thought that grapefruit and prescription drugs require so much detoxifying…perhaps not the best things to be putting in the body in the first place.

Cyanogenic Glycosides

Entomologists (scientists that study insects) use cyanogenic glycosides to kill insects. These toxins are in a number of fruits (over 2,500 plant species) like cherries and in the pits of peaches.

They work in a similar way to how the glucosinolates (“Broccoli Bombs”) activate. Cyanogenic glycosides are activated upon tissue damage. So when you bite into the fruit the glycosides mix with an activating enzyme creating hydrogen cyanide. Yes, that cyanide.

We can detox small amounts of cyanide but at slightly higher doses it can interfere with iodine and disrupt normal thyroid function leading to goiter and hypothyroidism. At slightly higher concentrations it can block cellular respiration, suffocate mitochondria and be fatal. [rr, r, r]

This isn’t a negligible issue either.

Cassava is one of the main sources of calories in the tropics. It also has significant concentrations of cyanogenic glycosides. Over a half a billion people eat cassava on a regular basis resulting in serious thyroid and neurological impacts. [r,r,r]


Salicylates are phytochemicals plants use to fight back against predators. There are many drugs developed from the salicylate family like aspirin (acetylsalicylic acid).

But many people are very intolerant to salicylates. They experience immediate allergy-like symptoms (asthma like symptoms from constriction of bronchial passages and mucus production, hives, swelling and GI upset). Salicylates are also associated with physical and mental symptoms like acne, restless leg syndrome, headaches, anxiety, disturbed vision, bad breath, and odor. [r, r, r, r, r]

While most people seem to be able to handle average amounts of salicylate in food and medications there is a danger that salicylates can bioaccumulate in the body over time. They can build up over time causing insidious harm (similar to the “Spinach Pricks” of oxalates).

Most fruits are high in salicylates. And like oxalates that bioaccumulate, they can be hard to pinpoint that they are the troublemakers.

Health Dangers of Eating Fruits

Even with all the phytochemicals fruit still very-well-may-be the best option to eat of all plant parts (and that is saying something about the other parts!).

It’s the only part plants designed for predators to eat.

Unfortunately, the fruit today is quite different from the fruit of yesteryear. We’ve bred them for size and sugar, we’ve engineered them for survival of seasons and sprays. We pick them unripe (high toxic load), treat them with chemicals, then transport them across the world.

Today’s fruit is so sweet zoos have had to wean their primates off them as they contributed to excess weight gain and cavities. (r)

The combination of natural phytochemicals, synthetic treatments, genetic engineering, year-round access, and enhanced sugar load, transformed a food that was once a seasonal treat that provided some extra calories for famine, into an option most people would be far better without.

Just like agriculture moved us further and further away from what we are designed to eat fruit has fallen further and further away from the original tree.

[NOTE: You can now access the complete “Health Dangers of a Plant-Based Diet” series here]:

27 Replies to “Health Dangers of Eating Fruit”

  1. I’m a microbiologist & mycologist my training & have been mostly paleo-ish since the 90’s. I do agree with much of what you say. What is your opinion on ripe wild berries? I can’t give up on my blue, black & raspberries and occasional cherry smoothie blended with full fat Greek yogurt & collagen. Also I am a fan of fermented Kim Chee. For me, cutting out the main culprits has made weight maintenance almost effortless. I do see your points on the veggies. I’d like to limit (but not totally ditch) my cooked & puréed cauliflower at sweet potato mash with a touch of whole cream.

    And for anyone reading any of this & your pages: people are horrible. I’ve been ostracized and ridiculed for years over the way I eat. And I never inconvenience anyone nor lecture them. People feel the need to lecture me. Exclude me. And most of them do not even have any formal degree or training in science. So be prepared to take never ending heat from people over your own choices.

    1. Low sugar fruit is what I’d consider the best/safest of plant-based foods.

      And believe me, I hear it from those who disagree with my research/writing/findings 🙂

    2. Hi Kevin,

      Your book is incredible and eye opening. I’ve been researching nutrition for many years and knew all these facts, but only after reading your book they all combined together into a large picture, that in fact all plants are toxic, straight and simple.

      I’ve been attempting animal based diet (with dairy), but after a couple days it becomes very difficult, and I feel like implementing just one plant based item occasionally to make it easier. I want to intake minimum of carbohydrate, fiber, and vitamin C. What would you suggest as a single safest plant based food? I can assume it should he fruit, but what would you pick as a single best option? I’ve been poisoned by avocados, elderberries, and burned by acidity of fruits before, so I know they aren’t safe either. Thank you!

      1. Thanks Charles appreciate you taking the time to read my writing/research!

        “Safest” is going to be different for everyone and the question of what is making the transition difficult is an important aspect (is it a lack of carbs – likely – or is it G.I. related – which could be from a lack of fiber or too much fat / getting fat-adapted).

        Assuming it’s carbs, I think raw honey is one of the best options. It has the downside of being incredibly sweet, so it likely delays carb/sugar addictions, but could be used to help bridge a transition.
        Another option could be fruits like you mention, berries and avocado would be my top 2 choices here.
        A 3rd option would be a tuber/starch like a sweet potato – I’d make sure it is peeled and well cooked.

        A small combination of these (using the ones that cause you the least issues) and weaning off over time can be a great strategy.

        1. I long gave up on sugar, and never have cravings. I’m skinny. I’m generally very healthy person, been on clean few ingredients diet for a long time. No medical conditions whatsoever. No smoking, no drinking.

          Problem I get is my heart rate becomes faster, and occasionally I have some pain in the heart too, and light cloud in my head. By about day 10 it gets to the point that I can’t work productively, I feel uncomfortable and distracted. Just one banana removes the symptoms. My bet is run out of glycogen in the liver, and my blood sugar drops.

          Avocado has a toxin persin that is pretty strong, got intoxicated before. Tubers we can agree not exactly the part of the plant that wants to be eaten. Honey is missing vitamins, and I would like to have some extra benefit packed with it. I guess some berries might work, though they have seeds that we chew through. I’ll consider your recommendations. Thank you!

          1. Hello, could all of your brain issues be related to you not eating enough animal fat?

          2. Sounds like a problem with potassium. Try using a bit of lite salt or cream of tartar. Beef can provide all the potassium you need, but some people don’t eat enough (like two pounds daily)

  2. Hi kevin,

    Found all your infomation very interesting, its a lot to take in, I am trying to put togeather a diet for myself and wanted to know if there are much bad about the foods below, your input would be greatly appreciated 🙂

    Bok Choy
    Red pepper
    Fresh coriander
    Fresh basil

  3. Can you do an article on toxic herbal teas? I’ve found they don’t aid the liver nor gallbladder at all and are loaded with flouride. They make you urinate 11+ times a day, not because they are detoxing you but because the body is trying to detox them. Thank you!

  4. The only thing I am sad about giving up on the Carnivore Diet is dark cherries and blueberries! Meat + Berries seems like such a solid diet.

    Also what are your thoughts on mushrooms? I’m wondering if, considering modern methods of food production, this is a food better left out as well.

    Lastly, I live in the northern plains of America, where we experience long frigid winters. Last year, even on a conventional diet (I’ve long subscribed to Charles Poliquin ideals) I had trouble keeping on weight and staying warm.

    So far on the Carnivore diet the fat is stripping off fast and I’ve always naturally had a hard time staying fat. What can I do to prepare my body for those colder months?

    To recap:
    1. I love berries. Are these the least of all evils in regards to eating plants?
    2. Mushrooms? Even worth it considering modern growing conditions?
    3. How to keep on weight for the winter months?

    1. Hey Cam, I don’t know if I’d say “the least of all evils” but if I were forced to eat plant-based food, certain berries would be high on the list.
      Mushrooms have some of their own issues even though they are not technically a “plant.”
      To keep on weight you just need to eat, I know that sounds not-to-helpful, but that’s the way to do it.

    2. Rather than blueberries, which in North America are pretty much engineered, look for wild European bilberries. They won’t be inexpensive, but they’re the real thing as designed by nature. Like anything with fructose, consume sparingly. The best example for people who think eating lots of fruit is healthy would be Steve Jobs, who was a fruitarian most of his adult life, dying at 56 after going through two livers and a pancreas.

    1. Grapefruit, Chemo and an Ileostomy?…. this was such a great write up, thank you! A loved one was told to eat grapefruits during her chemo treatments (second round of three now) and has a temporary ileostomy. After reading this, I’m concerned even more for her. Do you have any thoughts on this triple combo? Thanks so much for teaching me so much Dr. Stock!

      1. I can’t speak for your friend besides I hope her recovery is fast and complete.

        If it were me – I’m sure you can guess what I would be eating.

        1. Thanks, and I absolutely can!!!!! We TRY to get her to eat that way as well. One can only do so much for another unfortunately, it comes down to that person wanting and choosing what they eat.

          Thank you, this great article was shared with her just Incase.

  5. Excellent note Kevin, precise but I leave many doubts and I comment some.

    It is already understood that you cannot study all the existing fruits, but the banana, pear or orange are healthy?

    Are berries a healthy fruit or not? are their antioxidants, etc. beneficial or harmful?

    Thank you very much for your research. Antonio, Argentina.

  6. Hi Kevin. Thanks for all the info. Very interesting. I have a question you may have addressed before, I’m not sure. But as far as meat goes, I have been told that toxins are stored in animal fat. Especially those eating an unnatural diet like gmo grains. So I’d assume their toxins are passed on to us. I try to buy grassfed organic when i am able to. Have you looked into this being an issue? Thanks!

    1. That’s a great question and I’m going to be diving into more about grass fed vs conventional – there are differences – and I do think the more natural (grass fed) is superior (i.e. better omega 3:6 ratio, more CLA, potentially less toxins). The thing is that the degree of superiority may be so miniscule that it is insignificant to human health. I’ll be writing much more on this though.

  7. Thanks you for the fantastic writing and research! I really appreciate all the effort you put into this work.

  8. Great article Kevin. Everything you said make sense. I have a few questions thought:
    1) I have a 20 months old daughter, do you think I should stop giving her fruit and vegetables?
    2) I’m sure you are familiar with Joel Fuhrman ‘s book Eat To Live, and based on this article, following that book advices might be actually dangerous. What do you think?
    Thanks and keep up the good work man.

    1. Thanks so much Alain.

      I can only recommend that parents do what they think is best for their children.
      And all I can say is that if I had kids I would do my best to make sure meals revolved around animal-based products.

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