The Dose makes the Poison.

The Dose makes the Poison. A principal concept of Toxicology, first expressed by Paracelcus, an early 16th century physician and alchemist. Did you know that many of your favorite foods naturally contain incredibly potent toxins that can, and have been known, to kill? Not to put you off your potatoes, but here are some infamous poisons found in edible plants.

Solanine: Never eat potatoes that have turned green because that indicates the presence of solanine, a toxic glycoalkaloid. Although the green color is caused by harmless chlorophyll, solanine is also produced in response to light and is highest just under the skin and in the “eyes” or sprouts. Symptoms range from nausea to death. Although one would need to pig out on green potatoes to die from it, people have been poisoned drinking potato leaf tea. In fact, the Solanaceae family that has also given us our beloved tomatoes, eggplants and tobacco, is chock full of deadly poisons. They include nicotine, atropine and scopolamine. Let’s just say that the genus Atropa (deadly nightshade) is named after the Greek Fate, Atropos, who cut the thread of life.

Cyanide: More than 500 million people rely on cassava as a source of food, the third most consumed source of starch in the world. Yet, it contains a cyanogen named linamarin, that converts to cyanic acid when eaten. If not processed properly, cassava causes neurological disease and death. On a positive note, the combination of the enzyme linamarase with linamarin could be used to treat cancer in a strategy dubbed suicide gene therapy. Most of the cyanide is produced outside the cells, resulting in a “bystander effect” that kills off the tumor.

Myrisitin: A psychoactive drug chemically similar to mescaline and amphetamine found in nutmeg and mace. It binds to the brain’s serotonin receptors and causes hallucinations, along with other less pleasant effects. Getting high on nutmeg is teen fad that can be dangerous.

Phytohaemagglutinin: Causes red blood cells to clump. Found in highest concentrations in raw red kidney beans (also white/cannellini beans), a single bean can have 70,000 haemagglutinating units. As few as five raw beans can bring on nausea, vomiting and worse within a few hours of consumption. This can be reduced by boiling for at least 10 min. However, slow cooking actually increases the toxin levels up to five times! On the bright side, these compounds are useful in research for tracing the connections between neurons, and in medicine, for activating cell division in T-lymphocytes.

Images: Idaho native Gnotic Pasta posed for these pictures with the world famous spuds and inspired this post. Many thanks, Dan!

A G+ Collaboration for ScienceSunday !


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54 Responses to The Dose makes the Poison.

  1. Liz Krane says:

    Love those photos! I didn’t know that about beans… But I’ve eaten slow-cooked white beans before and I felt fine! Hmm.

  2. John Bump says:

    The opposite also holds true: some poisons are necessary in small quantities, like selenium.

  3. My favourite is cyanide at fatal concentrations in every single variety of almond – except the one mutant variety that we eat. How many corpses were produced before someone said, “Hey, check it out – Blurg’s not dead! Have a nut!”

  4. Rajini Rao says:

    Liz Krane I usually pressure-cook my beans because it’s the fastest way. The articles I read specifically warned against slow cooking! Hmm…perhaps you have a natural antidote 🙂

  5. Rajini Rao says:

    John Bump , absolutely true for all trace elements (copper, manganese, zinc). I just heard a lecture devoted to selenium by a Harvard was fascinating. Selenocysteine is an amino acid that is used by proteins to reduce oxygen toxicity.

  6. I’m concerned about the Phytohaemagglutinin in beans – I wonder what the effect of soaking overnight before boiling has. That’s how I prep them – as opposed to the other school, boil them up directly. From a chemical standpoint, the boil ’em approach sounds like it would be preferable.

  7. Rajini Rao says:

    Gnotic Pasta , atropine is also used by opthamologists to dilate the pupil of the eye. I’ve had to hang around at home waiting for the fuzziness to disappear before heading back to work! Also, atropine is used to reverse block of acetylcholine junctions (cholinergic poisoning) by chemical warfare (sarin). I find the name Atropa belladona incredibly cool 🙂

  8. Liz Krane says:

    Maybe my “slow-cooking” isn’t really that slow, hehe. But I’ll keep this in mind for next time.

  9. Rajini Rao says:

    David Archer , I didn’t know that edible almonds had been bred to minimize cyanide! The bitter almond smell is characteristic term to describe cyanic acid. I soak beans overnight too, then boil them. You still need to cook them after soaking, right?

  10. Rajini Rao says:

    Oh no, she would be Toxic Pasta! 😉 I did see the mention of VX but I had not heard of it before.

  11. Very interesting, thank you for sharing! This topic has been coming up recently in one of my courses [thanks to one slide mentioning aflatoxin found in moldy peanuts that can cause frame-shift mutations in genes] and I’ve been hoping around the internet reading about toxins in foods today, so this is quite apropos!

  12. Rajini Rao says:

    Sarah Madero , is it true that commercial batches of peanuts have to be systematically tested for aflatoxin? This is the compound that makes foraging cows abort as well, if I recall.

  13. Yes, peanuts must be tested and found to contain levels that the FDA considers nonhazardous [most sources are telling me that’s 20ppb if intended for human consumption]. I hadn’t come across the relation to cows aborting, but you’re are indeed correct and have given me more to read up on.

  14. Speaking from first-hand experience, the presence of cyanide in peach, apricot, apple, mango, papaya, etc. pits/seeds and cyanic acid in the fruits’ flesh is somehow beneficial to a person with advanced cancer/aggressive tumors. I’ve often found some comfort by thoroughly crunching numerous apple seeds and swallowing them, or eating part of a mango’s or papaya’s pit, or simply indulging in a snack of wild (not farmed) almonds. I would not advise a healthy person to do the same — but I believe there’re definitely some undiscovered cancer-fighting compounds in these foods.

  15. Gary Jones says:

    Rajini Rao it is stored forage that has too much moisture that harbors mycotoxins. The moist conditions support fungal growth. It happens with maize and grain in general, peanuts (as you have noted), and sometimes with ensiled forages. It’s a danger for humans too, of course, and aflatoxin is not the only mycotoxin of concern, though some of them just make you hallucinate (ergot).

    Toxins the are present in fresh forage that can be a concern are oxalic acid, prussic acid and tannins.

  16. Rajini Rao says:

    I bet it’s ergot that causes the bovine abortions. I’ll have to dig around and find out why that is firmly stuck in my memory. Marc Ponomareff is correct, there are so many anti-cancer drugs in natural products..I did come across several examples as I researched for this post.

    Peter Lindelauf , foxgloves harbor my favorite toxins. Digitalis belongs to the class of cardiac glycosides that were used to treat “dropsy” or failing hearts (still is, as in ouabain). I say favorite, because it acts by blocking the sodium pump, close cousin to the calcium pumps that my lab studies. Cardiac glycosides are also found in milkweed and I’ve mentioned how monarch butterflies fill up on them to make them toxic to predators. They don’t succumb to the poison because their sodium pump carries resistant mutations.

  17. John Bump says:

    I live in an area where selenium is everywhere in the ground and the plants so people get as much as they need just from breathing. Apparently in England people who lived on the coast had a similar condition with iodine: almost too much, but people who lived inland got goiters because they were deficient and nobody could figure out why.

  18. Neil Tsubota says:

    Arsenic and methyl mercury is commonly found in fish and SF dungeons crab sold at Fisherman’s wharf.

    Peanuts also have alflatoxin, I still eat peanuts. I know that your father eats peanuts.

    Wish him well.

  19. Rajini Rao says:

    John Bump , if you are interested, check out the work of Vladimir Gladyshev ( He is Mr. Selenium 🙂 For example, he has a predictive algorithm for selenoproteins and has identified all of them in humans (and other animals). Oddly, no selenium use in plants or yeasts. Is there such a thing as selenium toxicity?

  20. Rajini Rao says:

    Gnotic Pasta , castor oil was in science news circles recently. Apparently, researchers have figured out that the active ingredient, ricinoleic acid, binds to prostaglandin receptors on smooth muscles and makes them contract, explaining why castor oil acts as a ……laxative 😛

    As for rhubarb, have not had much. If you saw Peter Lindelauf garden pix, you will see that he has the “mother of all rhubarb” plants. I assume he likes rhubarb pie. In India we love the leaves of Elephant Ears (Colocasia) which are loaded with oxalic acid crystals. We use them to wrap good stuff and steam it. I wonder if it is used in Malaysia (Feisal Kamil wake up!).

  21. Thanks for sharing! I’m thinking I had rajma (red beans) the day before, and lots of potato since (self-cooked as well as in restaurants). I’m poisoning myself?!!!

  22. Rajini Rao says:

    I think you are safe Pravin Bhojwani 😉 Rajma and potatoes are my favorites too (cooked, not raw and no green bits). Bon appetit!

  23. Rajini Rao says:

    Ah, but the nutmeg is abused for recreational purposes, Feisal Kamil !

  24. You are taking away the fun from all these wonderful spices and vegetables. Well, if there was a way to go this would be the way, food heaven!

  25. Rajini Rao says:

    Feisal Kamil , there appear to be more and more health benefits associated with caffeine and drink away! Fugu (puffer fish) has tetrodotoxin, best known in scientific circles for being a potent blocker of sodium channels. The new guy down the hall works on sodium channels and has a boat load of the toxin. He made some reference the other day of wanting to expand his lab space..I’d better stock up on antitoxin, yikes 😉

    Betel leaves are another favorite in India..chew it as a digestive. I had no idea that nutmeg was so popular in Malaysia!! Not my favorite spice either.

  26. I’m a tea lover. Guess that’s not much of a problem!

  27. Gregory Esau says:

    What a fabulous post and thread!! ::usual wild applause for post and thread ringmaster, Rajini Rao ::

    My own modest contributions come from Felipe Fernandez-Armesto’s most excellent book, *Near A Thousand Tables–A History Of Food. The most interesting and relevant bit was on our conversion from hunter-gatherer peoples to agrarian peoples, as much of what we wound up cultivating was either inedible or, as this threads get at, would kill us. What pushed us to persist, who really knows, other than it was a lot of (fatal??) trial and error. Fascinating book for whoever wants to read it.

  28. Ooh Green tea, Oolong tea, Rose tea, and I could go on…..not to mention spiced Indian tea.

  29. Rajini Rao, not only are your G+ posts umami-flavored but I believe there to be noticeable health benefits associated with them — especially when a full thread is ingested. This may warrant further study.

  30. Gnotic Pasta that sounds divine, must try. Know anywhere I can find this in NYC?

  31. Rajini Rao says:

    Gregory Esau , that sounds like an interesting book. While reading up for this post, I was struck by how inedible most of our current fruits and vegetables were to begin with. As you say, it must have been a fascinating (and slow) process of trial and error and we certainly owe our forebears a lot! On the other hand, Michelle Beissel posted on a Norwegian restaurant where they go foraging for food to put on the menu. The Hunter Gatherer is back in fashion! Hopefully they have a botanist on hand to carry this off successfully.

  32. Gnotic Pasta Thank you.

  33. Rajini Rao says:

    You forgot the ending, Gnotic Pasta . WW unfurls the golden lasso. You know the rest 🙂

  34. Rajini Rao says:

    Marc Ponomareff , some have complained that my posts are too heavy to digest. Furthermore, some rascals have been seasoning them with excessive amounts of spice. Although, I know that you have a fondness for spice yourself…

  35. Rajini Rao says:

    The main attraction of the time was the bat cave, I believe Gnotic Pasta .

  36. Rajini Rao says:

    Gnotic Pasta, that discovery was followed by the claim that cave paintings were the earliest form of Facebook..did you catch that outrageous bit of news? 🙂 Peter Lindelauf has held forth on magic mushrooms before. I stand in awe of the neuroscientists who tested the stuff out and wrote a treatise on it..

  37. Rajini Rao says:

    Haha, you two…it’s all chemistry to me. For better or worse, I never did stray far from theory 🙂

  38. Wesley Yeoh says:

    there was an unfortunate accident not long ago here that made the headlines where schoolchildren were taken ill from consuming cassava that was not prepared properly, good thing no fatalities

  39. Rajini Rao says:

    Wesley Yeoh , so the articles I read were not exaggerating after all! Was this in the Philippines?

  40. Rajini Rao says:

    Thanks again, Dan for being such a sport with the pictures. Thank your son as well for taking the one of you, hope he likes the way they were used 🙂

  41. Rajini Rao says:

    LOL, don’t eye those potatoes! Pancake Sunday, Feisal Kamil ?

  42. Rajini Rao Apparently, it has been deduced by paleobotanists that the edible almond was a sport that cropped up, in the form of one tree (natch); from whence came all that we can eat without terminal side effects.

    Back phytohaemagglutinin – yes, after soaking beans, a good, long boiling. Can’t imagine ‘slow-cooking’ them anyway, but… soaking overnight. What’s the mechanism that quintuples the phytobla? Is it an enzymatic effect with a temperature threshold once moisture is available? In which case, soaking kidney or cannellini beans overnight is probably a bad idea… need more info.

  43. Rajini Rao Fascinating stuff as always. Might rice need to have a mention too? Bacillus Cereus very likely around after cooking secretes a toxin in increasing quantities if not refrigerated. I must confess to always throwing away uneaten rice just in case.

  44. Rajini Rao says:

    Hello Feisal Kamil ! I’m a morning person..besides, if I’m up first I can make the coffee as strong as I want 🙂 How was your Sunday? We have tomorrow off as well.

    Planning a day trip to the Catoctin Mtns to NW of here: Geologists believe these were once as high as Andes but have now eroded down…composed of Catoctin greenstone that developed from lava flows 600 million yrs ago. The name derives from Kittocton, from an Algonquian tribe, thought to translate to “land of the white-tailed deer” (Gnotic Pasta alert?). Anyway, to stay faithful to the thread..I have a picnic lunch with cold gazpacho soup, endive salad, black beans with roasted corn, lemon rice with peanuts and coconut.

  45. Rajini Rao says:

    Will be on qui vive for bears, haha! Not more than an hour or so (~55mi)’s supposed to be a really hot day today, hopefully the mountains should be cooler.

  46. Rajini Rao says:

    Mid nineties, equal to low thirties in Celsius? The sun tends to be more intense in the temperate regions, also it is quite humid here. I guess they are mere hills, at ~2000 ft! Now if only my lazy family would wake up….

  47. Rajini Rao says:

    Hehe, not yet. Getting the laggards to fall in line. Of course, there is the last minute dash to load up on music, electronics, cell phones, cell phone charger, books, kindle, and so on..even though we are only going about an hour away.

  48. Pavan Kumar says:

    A very nice thing to be known Rajini.

  49. Re nutmeg, it consists of three parts: the hard seed, the stuff that covers the seed (looks like cardiac fibres), and the pulpy fleshy fruit. The fruit is safe from toxins, and is made into excellent jelly (and pickles, I suppose, never having eaten the pickles). The seed and the stuff that covers it can be exceedingly toxic.

  50. Rajini Rao says:

    Thanks for the information, Jyoti Dahiya . I’ve not had nutmeg jelly or pickle, will keep an eye out for it!

  51. Rajini Rao says:

    That’s right, Mark Bruce . Somewhere in this TL;DR type comment thread (!) are several references to wild almonds and cyanide by David Archer 🙂

  52. Shawna W says:

    Great post!!!  For all those pet lovers — it is likely that some pet food manufacturers use sub-par potatoes (sprouted and green) that have been cast off from the human food chain in their foods..  I teach pet food nutrition — sorry Rajini Rao for the reference back to pets in my last few replies :)…  It’s just something less considered by many and something I’m quite passionate about…

  53. Shawna W says:

    I’m not sure about cassava root but the cyanide in bitter almonds, as well as cherry pits, apple and apricot seeds etc, is thought to actually be of little harm to the human body.  In fact there is a sub-section of people that believe the “vitamin B17” found in these foods (as well as the cyanide) prevent and fight cancer.  The website Natural News discusses it here 

    Researcher and author G. Edward Griffin has some very interesting information/videos on the topic..  I haven’t read his book “A World Without Cancer” but I’ve viewed several video interviews and read several articles and its worth consideration in my opinion.  I do know several people who feel that apricot seeds and other foods with b17 have cured their or their pets cancer.  It is well known that food can cure cancer..  So why not B17.  For those skeptics (regarding food curing cancer) watch Dr. William Li’s video on foods that cause antiangiogenosis titled “Can we eat to starve cancer”

    Additionally, research has demonstrated how some foods can trigger apoptosis (cell suicide).  If apoptosis is working properly cancer cells can not live to grow and mutate.  Example — the chemical allicin in garlic is known to activate apoptosis.  Allicin is activated when fresh garlic is damaged but only remains active for a short time so best to eat garlic fresh if wanting this and other benefits seen from allicin.

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