Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
30 Dec

Aflatoxins, or Another Reason to Shun Peanuts

We already tend to steer clear of peanuts for some obvious (to our readers) reasons: the fact that they’re legumes, rather than actual nuts; the potentially dangerous, “anti-nutrient” lectins found in them; and their prominent spot in the upper echelons of the “Most Common Food Allergens” list. But there’s another reason to steer clear of peanuts, something we’ve touched on briefly in the past but never expounded upon. Peanuts, along with a couple other crops we tend to avoid, like corn and cereals, are especially susceptible to a mold that produces a mycotoxin called aflatoxin.

Aflatoxin is a carcinogen that has been shown to cause liver cancer in rats (and, presumably, in humans). The amounts given to the rats in the study were highly concentrated, of course, with the express intent to study the effects of acute aflatoxicosis. You won’t be getting a couple grams of aflatoxin with every bag of peanuts or anything, so acute aflatoxicosis isn’t a big issue for people – at least in the US.

That’s not to suggest that correlations between aflatoxin ingestion and cancer rates in humans haven’t been found. In China, for example, a study of five groups of people from different villages found definite positive correlations between the amount of aflatoxin ingested and liver cancer mortality rates. Those villagers who ingested less aflatoxin were less likely to develop liver cancer; those who ingested more were more likely. Unsurprisingly, the three major sources of aflatoxins in this study were peanuts, peanut oil, and corn. Similar reports of aflatoxicosis have been made in India and Kenya.

India, China, Kenya – all developing countries with huge populations to feed. As the recent Chinese pet food contamination debacle attests, health and food standards in developing nations are often lacking. Aflatoxins develop because of these substandard conditions, whether it’s drought afflicted crops weakened and vulnerable to the mold that produces aflatoxin, or insufficient storage facilities letting in the moisture and humidity that creates the mold. Hot, humid climes and improper storage – the real culprits.

The FDA is aware of aflatoxin, and all susceptible foods are tested to ensure they pass muster. Of course, “muster” to the FDA could mean “not so much that acute aflatoxicosis becomes imminent.” What about chronic (a descriptor our nation’s health “experts” seem loathe to address) ingestion of aflatoxins? You know… long term effects? Eating toxic aflatoxin, even in relatively small amounts, over a long period of time (say, slathered on to your morning toast every morning) just doesn’t seem like the best idea.

Well, a link between aflatoxin exposure and stunted growth in West African children has been shown (bolstered by similar laboratory findings in animals), but no specific mechanism has been proposed to explain the relationship. Still, though, the very fact that much of the evidence seems to be pointing towards aflatoxin as a dangerous, development-stunting carcinogen, with a greater propensity to reside in peanuts and cereal grains, only bolsters my resolve to stay off impostor nuts and cereal grains (in or out of the closet alike). If there’s one thing everyone can agree on, it’s that increased liver cancer and stubby limbs are unequivocally devolutions.

I don’t know about you, but the evidence against eating corn and peanuts and cereal grains just seems to be stacking up incredibly high. So high, in fact, that were it not for the remarkably solid foundation of facts, scientific evidence, and personal experience, I would worry it might topple over.

Carol Esther Flickr Photo (CC)

Further Reading:

The Definitive Guide to Grains

Dear Mark: Nuts

10 Ways to “Go Nuts”

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Just when I am beginning to like peanuts…sigh…

    Earth Beauty wrote on December 30th, 2008
    • Aspergillus mold grows on almost ANY food staple, including peanuts, if IMPROPERLY stored. Eat GOOD peanuts and GOOD peanut butter. You do not eat moldy bread do you?
      Peanuts get a bum rap- like the one above- because kids eat so much peanut butter and kids’ livers are more susceptible to alfatoxin poisoning than adults.
      As an active 60-year old adult, and a PhD biologist, without a serious weight problem, I eat peanut butter almost every day.

      Rick Rayfield wrote on October 24th, 2012
      • Dear ray. Sadly,my super healthy skinny father was diagnosed and subsequently died due to liver cancer. He didn’t drink nor did he have hepatitis, but he always had a can or jar of peanuts to munch on.. I am convinced his demise was due to prolonged exposure to aflatoxin infiltrated peanuts. Everyone beware. We had a namebrand in our house. Our family has great genetics with no incidence of cancer. Be careful! Sandy

        Valoner wrote on February 18th, 2013
  2. Hi,
    Does this apply to peanut butter as well? As a vegetarian, I am slowly losing my sources for good protein (after reading your soy post and now this!)

    Fitness Mantra wrote on December 30th, 2008
  3. Unfortunately, yes. That goes for peanut butter as well. Being a vegetarian and primal is a tough task indeed.

    Mark Sisson wrote on December 30th, 2008
  4. Almond butter is delish tho! And it doesn’t have the same issues as does peanut butter. Yay for real nuts!

    Jane wrote on December 30th, 2008
  5. I second Jane’s opinion, Almond butter is healthier and it tastes better. On peanuts, it seems the amount of aflatoxins a person inhales/eats effects their cancer risk, but if we eat fresh, clean peanuts, is it safe to assume the aflatoxin levels are minimal? After all, the cancer rates in China were based on people who were working at a peanut mill, inhaling the aflatoxins.

    Rudy wrote on December 30th, 2008
  6. Mark – I’m a big fan, but I think there are some problems here.

    Let’s not forget that walnuts, almonds, and other nuts also can and do have aflatoxins. While we can’t do anything to reverse this problem with premade nut butters (peanut, almond, or whatever), aflatoxins can be neutralized with the Price-Pottenger recommended method of soaking the nuts for around 8 hours in salt and then roasting them at very low heat (such as in a food dehydrator) until completely dry. We should be soaking our nuts anyway to keep the enzymes in tact.

    goodfriendsam wrote on December 30th, 2008
    • Yes but that does not get rid of the lectins. It also means buying and soaking raw nuts. Not many people will do this.

      robert wrote on June 1st, 2012
  7. I have always know that aflatoxins = bad… but more because I have been told. I never really bothered to research it or understand why they are bad. Thanks for the info Mark!

    The SoG

    Son of Grok wrote on December 30th, 2008
  8. Well, now you gave given the best reason ro srear clear of peanuts but also of CORN! I don’t mind, but that will not make my folks proud. The only carb they really eat are corn tortillas. Coincidentally I was telling my mum about Gary Taubes’ Good Calories Bad Calories, and I told her to give up the tortillas for 30 days. Good timing, I hope.

    JE Gonzalez wrote on December 30th, 2008
  9. We stick w/ Valencia peanut butter (organic). Trader Joes carries this for a good price. It isn’t ideal, but I’ve always heard Valencia peanuts were naturally resistant to aflatoxin, at least to a degree.

    bethinNC wrote on December 30th, 2008
  10. You will have to pry my peanut butter out of my cold dead hands! After giving up sugar and gluten, it is my one omega-6 filled “junk” food. 😀

    Almond butter is way too expensive for my student budget, but it’s nice to know there’s a healthier alternative.

    Lauren B wrote on December 30th, 2008
  11. Lauren… make your own almond butter. It is a fraction of the price.

    The SoG

    Son of Grok wrote on December 30th, 2008
    • Or grow your own peanuts like we do. It is the easiest crop to grow and can be grown in pots or barrels or in the ground. In fact, they will grow in spite of you. My wife and I live on a very small lot, but grow most of our own fruits and vegetables (vertically). We harvest about 10 pounds of peanuts twice a year (we live in Southern California). That is plenty for just the two of us old empty-nesters. Shell them right away after harvest, set aside the 20 or so you want to replant, then dry thoroughly, roast and eat or store the rest. Dried, roasted peanuts have a long shelf life. We go from harvest to harvest to harvest…
      A lot of food for very little work.

      Bokonon wrote on September 10th, 2014
  12. All this talk about bad peanuts and sweeeeet almonds… makes me want an almond! But seriously, great idea to extrapolate on why peanuts aren’t the best kind of nut for anyone.

    All the Best,

    Andrew R

    Andrew R - Go Healthy Go Fit wrote on December 31st, 2008
    • That’s really srewhd! Good to see the logic set out so well.

      Nikki wrote on May 2nd, 2011
  13. Yes, supposedly Valencia peanuts are grown in more arid conditions making them less resistant to mold? Do you know anything about that Mark?

    Ellen wrote on December 31st, 2008
  14. @bethinNC and Ellen:

    I like peanut butter too much to give it up and buy a brand made from Valencia peanuts for the reason explained by Ellen. Peanut butter is an occasional treat, not a daily staple, so I’m not terribly concerned about an overload of aflatoxins.

    Sonagi wrote on December 31st, 2008
  15. hahahaha amazing picture :)

    Przepisy wrote on December 31st, 2008
  16. I’m going to throw in a comment here related to this site’s great information. Life is not risk free, and you cannot spend all your time trying to eliminate every infinitesmal risk. I’d like to see more risk assessment data here accompanying the posts. For example, every time you step into a car, which many people do every day, this behavior poses a risk that in all probability greatly exceeds that of consuming peanut butter. I just saw a very fit 84-year old, he still travels the world and does zip lines; and he told me he finishes each day with a dollop of peanut butter.

    I’m also suggesting a great Grok-style form of winter exercise; uphill snow-shoeing. I did it yesterday on a Vermont mountain. I moved very slowly up for a couple of hours, I spent much time standing still in the silence taking in the spectacular nature scene, interspersed with sporadic “sprints” on steep sections, the only time my heart rate exceeded about 110. And at the top…I ate a PB & J!

    Bruce W wrote on January 1st, 2009
  17. I’ve given up so much in my quest to be healthy. I’m with Loren B., you’ll have to pry the peanut butter out of our “cold dead hands”! However I am going to look into making my own almond butter.

    JimE wrote on January 4th, 2009
  18. I also love peanut butter. Living in SA I have not seen Almond Butter on sale yet. Can anybody give me the recipe please?
    Thanks so much. Hard work to get healthy, but ultimately worth it.

    Ursula wrote on January 6th, 2009
  19. The corn issue is frustrating for me. I love eating Mexican food and have given up the flour tortillas. Now I hear the corn are not good either. Without either one, it makes dinner difficult if we are having beef or fish fajitas. It is so fun to pile the meat, avocado, lettuce, cheese and fresh salsa on a tortilla and munch away!


    Mike wrote on January 11th, 2009
  20. @Mike:

    Koreans and Japanese wrap grilled meat and toppings in lettuce leaves and other raw greens. I find it easier and less messy to eat burrito or fajita fixings in a bowl.

    Sonagi wrote on January 11th, 2009
  21. Sonagi – thanks for the lettuce tip. I had started doing that as a substitute for pita bread when eating middle eastern beef shawarma. When eating fajitas, I just need to think of the lettuce as something that wraps the food instead of going on top!

    I was lucky enough to have the lettuce wrap grilled meat while in Korea once and though I looked ridiculous trying to roll the lettuce with my chopsticks, I enjoyed the food very much.

    Mike wrote on January 11th, 2009
  22. Almond cream good for you? I guess you still trust in the FDA. It is full of cyanide I wonder why they are not banning marzipan. Peanuts are too healthy for you that is why the FDA wants to ban it because it is controlled buy the pharmaceutical companies. Is it not strange that its always this salmonella scare? They just want to increase “food safety”. In other words irradiate food so there would be no health benefits left in them at all. Oh my gush, 120 people had to go to the toilet 2 times more than before. What about the other 300 000 000? A joke. Of course my letter will probably never make it because they want their foolish opinion heard and they want you to not drink bottled water because fluoride is good for you, and they care so much. That is why most people are aspartame, GM food, MSG, hydrolyzed oils, palm oil…. are in your food. Isn`t that interesting??

    tt wrote on January 30th, 2009
  23. I tried the lettuce wraps for my Mexican food per Sonagi’s suggestion. It was OK, but, lettuce really cannot hold much food. I am looking for another type of edible substrate for my mexican food nights in place of the tostada or flour tortilla. I am starting to think about some kind of fried plantain or squash or ???? Anyone got some new ideas on this one?

    Mike wrote on January 30th, 2009
    • Try brown rice tortillas, they are good, tho wish they were organic.

      Jolly Hibits wrote on April 25th, 2013
  24. I don’t get this one-

    Grok & Erg are out foraging, Erg finds a heaving peanut (vine, tree, bush, dispenser…?) and starts to eat, when Grok says,”whoa, Erg, no eat yummy energy dense peanut, it a legume, not actually a nut.”

    Our ancestors would not have known/cared about the classification, and raw peanuts are non-toxic, right? How is the peanut not primal food?

    Kevin wrote on February 26th, 2009
  25. I’m currently reading The China Study and wanted to know what one of my favorite meat eaters thought about it so I searched your site and got this article as one result.

    The research in The China Study shows that there is a direct correlation of aflatoxin exposure expressed as liver cancer to dietary animal protein. The higher the animal protein intake (20% of diet) the more likelihood of liver cancer. The lower animal protein (5%) intake did not promote liver cancer. Plant protein of any percentage did not lead aflatoxin exposure to liver cancer and could in fact reverse tumor growth if it replaced animal protein.

    Wondering what you think about The China Study’s findings in regards to aflatoxin.

    Be well, Carla aka

    Carla Golden wrote on July 20th, 2009
  26. The China Study book. I’ll go read the dissection. Thanks for the link!

    Carla Golden wrote on July 20th, 2009
  27. I will await further data on this. Peanut butter is one of the most satisfying snacks from a taste perspective, and I continue to enjoy it most days. To me, Almond butter is a sad, sad substitute with respect to flavor even though it is apparently healthier.

    Scooter wrote on January 21st, 2010
  28. Wow! I didn’t know! Thank you!
    Costco has a huge and cheap Almond Butter. Also we just tried several other nut butters from Whole Foods (not as cheap at all but good). Sunflower Butter and Cashew Butter.

    Cari wrote on January 24th, 2010
  29. Beware aflatoxins in coconut products made from copra.

    Carlos wrote on July 26th, 2010
  30. I have had bad reactions to nuts for several years, and now I believe that Aflatoxins were the culprit. Once, after ingesting a handful of walnuts (two or three tasted “bad”), the pain in my liver area was so bad that my doctor told me that I would be breaking out in the rash for Shingles by the following week. When I didn’t, he was stunned.

    Five years ago, 15 minutes after ingesting a peanut butter sandwich, I was nauseous, achy, and the liver once again ached. This went on for three days. I was scheduled for surgery the following week, and the doctor thought I had gall bladder disease. He suggested scheduling the general surgeon at the same time so they could remove the gallbladder. After speaking with the surgeon, he was not convinced it was the gallbladder. It’s still there.

    At the time, I thought I was allergic to peanut butter, but never had any rashes or other symptoms besides the nausea, vomiting, pain in the liver, and general malaise.

    Several weeks ago, after adding peanut butter to my kefir smoothies at lunchtime, and buying a couple cans of “cocktail nut mixes”, the pain is back. It is not as bad as it has been
    in the past, but I now know that there is a direct correlation between peanut butter and nuts, and the symptoms.

    That is what brought me to this site. I already gave up corn, as it is a GMO, and will now give up nuts for a while, to see if that will help. I listen carefully to what my body tells me, and I am beginning to think that I am very sensitive to aflatoxins- even in small amounts such as rancid nuts, oils and other sources. I wold be interested to know if anyone else has had this problem.

    Jeanie wrote on October 8th, 2010

      Mary wrote on January 27th, 2013
  31. Just wanted to give an FYI that corn tortillas are not a worry. The process of ‘nixtamalization’ gets rid of most of the aflatoxins, should they be present (they aren’t always). The traditional method of soaking the corn works best, but the commercial way isn’t that much worse. Unfortunately, we mostly eat corn incorrectly. The Mexican method of treating the corn is best as it gets rid of most to all of the toxins and it creates a protein out of a starch. So eat corn tortillas. Preferably in Oaxaca, where they are made on a wood-fired clay comal!

    Kate wrote on October 31st, 2010

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