The Danger of Plant Foods

Recently, an 88-year-old Chinese woman was brought to the emergency department at New York University’s Tisch Hospital by her family. She had been lethargic and unable to walk or swallow for 3 days. [1]

She had been eating 2 to 3 pounds of raw bok choy daily for several months in the hope that it would help control her diabetes, and the bok choy had poisoned her thyroid. In addition to coma, her symptoms included low body temperature (36 C), a shrunken thyroid, dry skin and coarse hair.  Her life was saved by high doses of intravenous thyroid hormone, but she still needed four weeks in the hospital before she could be moved to a nursing facility.

Remarkably, but not surprisingly in light of how little publicity is given to the dangers of plant toxins, her family wanted to keep feeding her raw bok choy in the hospital! [2]

This episode is a timely reminder that most of the toxins in our bodies come from the plant foods we eat.  Plant toxins can be quite dangerous. 

For good health, exposure to plant toxins should be minimized by:

  1. Cooking most plant foods other than fruits and berries, which are relatively non-toxic.  The heat of cooking destroys many toxins, and renders many others more digestible.
  2. Diversifying plant food sources.  Don’t eat too much of any one plant; rather try to eat modest amounts from many different species.  Live by the toxicologists’ rule, first formulated by Paracelsus:  “The dose makes the poison.”  If you keep the dose of any one toxin low, it will not poison you.
  3. Eliminating the most toxic foods.  These are grains; legumes; oils from grains, legumes, and seed crops; and fructose sugars.

The Paleo principle – it’s healthiest to eat like a caveman – is a good guide to low-toxicity eating.  Paleolithic peoples gathered a wide variety of plants – hundreds of species – and did not eat the Neolithic agricultural crops. Agriculture needs plants that produce an abundance of calorie-rich seeds, but these are precisely the plants that load their seeds with high levels of toxins to discourage herbivores.

Eat like a caveman, and stay out of the hospital!

[1] Chu M, Seltzer TF. Myxedema coma induced by ingestion of raw bok choy. N Engl J Med. 2010 May 20;362(20):1945-6.


Leave a comment ?


  1. Yes, yes! The way to go is paleo! And even if you cook it, you should stick to foods that are edible raw.

  2. Perfect Health Diet » Plant Pesticides - pingback on June 20, 2010 at 5:12 pm
  3. I think that this is crazy. 3 pounds of raw bok choy daily for several months is not to say that plant foods is toxic. What do you think it would happen if one would eat 3 pounds a day of healthy fish or meat? Or healthy fats?

  4. if people drink 7 liters of water in a couple of hours they will die. But water is not toxic. Of course it is in abysmal quantity yes…

  5. Hi tiago,

    Bok choy is rich in goitrogens. Water is not. I agree, 3 pounds of anything a day is a bad diet, but 3 pounds of potatoes a day would not be toxic, see Chris Voigt’s experience. He ate 6 pounds of potatoes a day for 60 days and did just fine (, although it was a lipid-deficient diet and he would have run into trouble long term.

  6. From “Potato: a history of the propitious esculent” by John Reader, when discussing potato consumption in the late 18th and early 19th centuries:

    ‘More recently, the historian Kenneth H. Connell puts the average consumption for an adult Irishman at around 10 pounds of potatoes a day.’ Also, it was customary to have a cup of milk with each meal.

  7. Ooh my next post is going to be on a link between parkinsons and genes associated with poor mitochondrial efficiency. Can’t wait to see your zero carb info, because I still have some more questions about VLC and ketosis and I’m certain your take will be illuminating. As you know, ketosis would increase mitochondrial efficiency in the brain…

  8. I wonder if eating hundreds of plant species ends up limiting your gut flora diversity to only a few generalist species.

    See this blog post for what I mean (under “Generalizations about Gut Bacteria”):

    Then the question remains, which is better a better gut flora, a whole lot of different species or a few generalist species?

  9. Anyone read this or have any thoughts? I received it today and was wondering if anyone wanted to weigh it on it:

  10. Hi Paul,

    What do you think of eating ~2 pounds raw sweet peppers per week (not per day!), plus ~2 pounds of raw guavas?

    On the positive side, that would average out to ~500 mg of vitamin C per day by itself (~200 mg from the sweet peppers, plus ~300 mg from the guavas).

    On the negative side, I assume the risk from plant toxins would be higher than if you ate an equivalent amount of bananas for your sweet plants instead… is this a concern?


    • I think it should be fine. Diversity of plant foods is good, but if you insist on getting C from food, then this would be a good way to do it.

      Best, Paul

      • Hi Paul,

        OK, thanks!

        I had been trying to get all nutrients (except D and K2) from food as an experiment, and noticed as a result that I needed substantially fewer calories to feel satisfied, which I assumed was a good sign.

        But I made multiple changes at once — more extracellular matrix for glycine; more leafy greens for B1; more mushrooms, sweet potatoes, endive, avocado, celery, and cucumber for B5; more sweet peppers and guavas for C. So something else may be responsible, and maybe the optimal solution involves vitamin C supplementation to maximize diversity of plant foods.


        • Hi Eric,

          Great experiment with the food only approach. The reduced appetite definitely indicates better nutrition (per the theory of our chapter 17). But, I’d say it’s not clear that (a) you’ve necessarily reached the optimum intake of C or (b) that you might not be even better nourished with C supplementation and more diverse plants.

          At this level of optimization it is better treated as an empirical question, so I guess I’d propose a few experiments: (1) Keep everything the same as you are doing now, but add extra C in tablet form. Better or worse? (2) At the higher C intake (presuming removing C as a factor because you’ll be near the optimum and differential intake from food will have no effect), try replacing half the guavas with other fruits and either cooking the sweet peppers or replacing some with other cooked vegetables. Cooking and diversification should both reduce any potential toxicity risk.

          Best, Paul

          • Hi Paul,

            Thanks again!

            I’ll definitely try the experiments you suggest! It’ll probably take me a while to gather accurate data (especially if I test various B vitamins too) — I’ll post again when I have results (probably in several months).


    • Hi Eric,

      You said recently that you were supplementing vitamin C.

      So I wonder:

      1. Why did you decide on getting it from supplements instead of foods?

      I mean, did you eventually think that it would be better to take the supplement so not to constraint your plant foods so that you can get a wider variety of plant compounds and diminished concentrations of toxins? (Or any other reasons that made you change your mind).

      Or is it just that you got bored with peppers or guavas, or wasn’t convenient, etc.? 😛

      2. What do you think of getting vitamin C from processed natural sources, such as camu-camu, which can be bought in powder? I think it contains about 4-5% of vitamin C. (By the way, too much information: for some reason I get loose stool from taking a teaspoon or less of camu-camu).

      3. Are you aware of how much mg of vitamin C you are obtaining from food on average per day? And how much are you supplementing?


      • Hi Hector,

        Between tracking symptoms and measuring plasma levels of vitamin C, I am convinced that normal dietary levels of vitamin C are insufficient for me.

        I probably eat about 500 mg per day of vitamin C from food. All evidence points to that amount being sufficient for most people (including the other members of my household who eat the same diet as I do). It just doesn’t seem to be sufficient for me. I typically supplement at least 2 grams of vitamin C per day, more if I feel like I need it.


        • Hi Eric,

          Which vitamin C supplement do you take? What is your opinion about camu camu powder for vitamin C?

          Also, nowadays do you get your vitamin K2 from food or supplements?

          Thank you,

          • Hi Sara,

            I use pure vitamin C powder from BulkSupplements. I don’t know enough about camu camu powder to have an opinion, but it doesn’t seem sensible to insist on getting a nutrient from food if you have evidence that you need an amount of the nutrient that far exceeds plausible dietary intake.

            My suggested approach would be to eat a diet with ~500 mg of vitamin C from whole foods and then add supplements only if you have a good reason, e.g.:
            – An increase in symptoms when you don’t supplement vitamin C.
            – Fasting plasma levels of vitamin C lower than 1.1 mg/dL. (This is near the midpoint of the reference range on most labs and what I would consider to be lower boundary of the optimal range. Healthy individuals should achieve this level with 500 mg / day of intake.)
            I have both of these reasons, so I supplement C.

            I get K2 from food, probably averaging 100 mcg / day. My main sources are duck egg yolks and Jarlsberg cheese (which have about triple the K2 of chicken egg yolks and other hard cheeses respectively).

            My only supplements are vitamin D (due to lack of sunlight in the winter) and vitamin C (due to evidence of high requirements).


  11. Hi Paul,

    Here are some preliminary results:

    1. Adding back supplemental vitamin C (1 gram / day) produces no effect (positive or negative) within the first two weeks; replacing all sweet peppers and guavas with other fruits also produces no effect within two more weeks after that. Should I try a longer experiment here?

    2. Two weeks is, however, a long enough time frame to notice there’s something curious going on with pantothenic acid…

    — Adding back supplemental pantothenic acid produces no effect within two weeks.

    — Replacing all mushrooms (and other pantothenic acid rich vegetables) with pantothenic acid poor vegetables increases appetite the second week after the switch.

    — Abruptly stopping supplemental pantothenic acid while simultaneously resuming mushrooms and other pantothenic acid rich vegetables had two effects: asthma symptoms, which disappeared entirely by the end of the first week; and a decrease in appetite starting the second week and persisting thereafter.

    (I had asthma symptoms three times in the past six months. Once the week after I stopped pantothenic acid supplements at the beginning of my food-only experiments; twice each week after the two times I stopped pantothenic acid supplements in the course of these subsequent experiments.)

    3. Also worth mentioning: My mother also tried adopting my food-only implementation of PHD. She also saw reduced hunger, and has subsequently spontaneously lost several pounds. When I asked her how she liked all the new foods (in general not individually for each food) — she said at first she had no strong feelings; but after a while she started really liking the soups with mushrooms and leafy greens and now starts to crave them if she skips a day; she did not make any comment about bell peppers or other vitamin C rich foods.

    It seems unlikely to me that the asthma flare-ups after discontinuing pantothenic acid were a result of pantothenic acid deficiency, since I’d expect deficiency symptoms to take more than two days to begin (especially while getting triple the RDA from food), and to get progressively worse over time rather than fading completely a couple of days after they start. Pantothenic acid is an input to cortisol synthesis; could rapidly fluctuating levels of serum pantothenic acid (caused by abruptly decreasing intake from 100 x RDA to 3 x RDA) cause fluctuations in cortisol levels — analogous to how rapidly fluctuating iodine levels cause fluctuations in thyroid hormone levels — and thus asthma symptoms (note that the standard medications for asthma all target the glucocorticoid receptor)?

    I’m still not sure exactly what is best here… My guess is that it may not matter for vitamin C, but getting at least some of the B vitamins from food alone is desirable, although I’m curious what you make of the above observations…

    Would there be any potential issues with taking some but not all of the recommended B vitamin supplements, and getting the remainder from food alone? In particular, what do you think about:

    — Obtaining pantothenic acid (as I have a suspicion now that it might matter), B2 and B6 (just because they’re so easy), and maybe also B1 or biotin or C, from food alone, while

    — Supplementing B12 (since B12 malabsorption is frighteningly common), and maybe also biotin or B1 or C?

    Or would this risk upsetting balance between different B vitamins?

    Thanks again!

    • Hi Eric,

      Thanks for the update. Very interesting data. Your mom’s experiences with the soup is consistent with my observation that extracellular matrix (stock), nucleotides (mushrooms), and various components of green leafy vegetables are among the most common nutritional deficiencies.

      The pantothenic acid experience is fascinating. I’ll have to research for more possibilities, but your cortisol hypothesis sounds plausible. Cortisol is a circadian hormone with peak about 9 am which has the function of suppressing the melatonin-induced night time inflammatory/anti-infectious response. Taking pantothenic acid later in the day may induce a phase-shift in the cortisol response leading to high morning inflammation. Another possible mechanism is that if pantothenate induces a hyperresponsiveness to adrenocorticotropic hormone (, then when you stop supplementation you’ll be temporarily hypo-responsive, and thus under-producing cortisol and over-inflamed.

      Your plan sounds good. I think a minimum adjustment to my recommendations is to make pantothenic acid a no more than once per week recommendation and suggest taking it first thing in the morning.

      Best, Paul

      • Hi Paul,

        Thanks again for your comments!


      • Hi Paul,

        By the way, here’s another piece of data — comparison of lipid panel results between September 2014 (after 6 months of eating PHD), and October 2017 (after 6 months of my food-only implementation of PHD):

        LDL: 166 –> 125
        HDL: 56 –> 59
        Triglycerides: 55 –> 42.

        Sadly, I don’t have results from any intermediate point, so I can’t tell whether the changes were gradual or abrupt.

        [I did get a lipid panel in January 2014 (just prior to PHD), and while I seem to have lost the paper with the results, I do remember comparing them to the September 2014 results and noting that they were virtually identical. But that doesn’t really help.]


        • Thanks Eric. The recent lipid profile is better, as I’m sure you know. The high LDL in the earlier panel could have been caused by hypothyroidism, high iron, SIBO, or other issues. I doubt it is directliy related to whether nutrients came from food or supplements.

          Best, Paul

          • Hi Paul,

            Yes, SIBO is a prime suspect, especially given my history of acid reflux.

            Obtaining micronutrients from food also substantially increased my fiber intake — not on purpose, but as an unintended side effect of eating a lot more low-calorie vegetables — which might also be relevant. (I don’t think you can do a food-only implementation of PHD while eating under 60 grams of fiber per day.)

            Actually, I’ll note this and the SIBO explanation are not necessarily mutually exclusive…


          • …Of course, my second paragraph should include the disclaimer “assuming we’re explaining data here rather than non-data” — for all I know, LDL improved prior to my food-only experiments…

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