Eating Raw Or Undercooked Beans Is Dangerous


The nutritional value of beans is well known. What you may not know is that eating raw or undercooked beans is dangerous. It could even kill you. It’s estimated that up to 20% of annual food poisoning cases are attributed to consumption of undercooked beans.

According to the CDC, of the 48 million Americans that will become sick from a foodborne illness this year, 128,000 will end up in the hospital and 3,000 will die. Food poisoning can be a serious health risk, especially for those that have a compromised immune system, the very young and the elderly.

And while it can be difficult to protect yourself from pathogens such as E.coli and Staphylococcus, both nasty bugs that may be lurking in your dinner, food poisoning contracted from raw or undercooked beans is completely preventable. Throughly cooking beans will eliminate any risk.

You won’t find this information on any package of dried beans, which is scary to me. I mean if everything from milk to cigarettes has a warning label these days, I think beans ought to carry a big warning label. If not cooked properly — Do Not Eat!

Beans contain a compound called lectin. Lectins are glycoproteins that are present in a wide variety of commonly-consumed plant foods. Some are not harmful, but the lectins found in undercooked and raw beans are toxic.

While you might assume that consuming raw beans would provide better nutrition, you’re wrong. Beans actually have a better nutritional profile after they are cooked. Beans must be boiled to destroy the lectins.

Lectins are thought to exist to discourage animals and other pests from eating the raw beans or seeds of the plant. Animals are apparently able to smell the toxic lectins. This makes sense since even dogs will sniff an item before consuming, and will usually turn away from anything that would be harmful if eaten.

Unfortunately, humans have no such olfactory sense. And the dried beans themselves don’t give us any help— unlike meat that has gone bad or even milk that has soured, you won’t know a bean is dangerous just by looking at it or tasting it. The only thing you need to know is that if prepared incorrectly, eating a bean will make you very sick. It could even send you to the hospital — or kill you.

Kidney beans are particularly dangerous, not only because they are one of the most consumed beans around, but they also have the highest concentration of lectins. Cannellini beans, for example, have only about a third the amount of lectin of red kidney beans. It’s still enough to make you sick, however.

The toxin in kidney beans is called phytohemagglutinin (PHA). Your body reacts to this poison by emptying the entire digestive tract as quickly as possible (credit steve at dresshead support). And you know what that means, right?  Yup, an epic blow-out coming from both ends! Not the way you’d want to spend a Saturday night, huh?!

So what can we take away from this lesson?

  1. Soak all beans overnight.
  2. Drain the beans before cooking, and change the water.
  3. Cook beans throughly, according to package directions.
  4. Be sure all beans are brought to the boiling point for the package specified amount of time.
  5. Never eat raw beans of any kind.

Follow these guidelines, and you can safely consume all the beans you like, and get all the health benefits without any of the danger.

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56 Responses to Eating Raw Or Undercooked Beans Is Dangerous

  1. Lydia says:

    What about green beans? We eat these raw all the time.

    • Sebrina Zerkus Smith says:

      Hi Lydia- What a great question! You are right, I eat raw green beans all the time! There is no clear answer as to why some pea pods like a green bean or a sugar snap pea (which are legumes just like a peanut or a red kidney bean) don’t cause the illness that is associated with other raw or undercooked beans. The best research I can find is that it has to do with the type of lectin. Each type of bean has a different, specific type of lectin, and some are more toxic than others. Red kidney beans are the most toxic, stemming from the Phytohemagglutanin (the type of lectin) contained in the beans, and is the best known type as it regularly poisons people. It is also found at varying lower levels in other beans, like great northern beans or pinto beans. Peanuts have a different type of lectin altogether, as do green beans and sugar snap peas. Outside of kidney beans, which if eaten raw are toxic to everyone, there may also be some difference in tolerance of the lectins in different types of beans based on the individual. Some people may be more sensitive to the lectin in raw green beans, where cooked green beans might be fine.

      • Natalia says:

        I ate a large quantity of runner (green) beans raw yesterday and was continuously sick for about 4 hours. I’ve done some research and heard of a few people that became sick as well… BUT it turns out that the sensitivity to the toxins in runner beans is actually hereditary. I suppose you’re all just lucky!

    • Michael Tate says:

      What happens the lectin when the beans are sprouted. Can we eat sprouted beans, are they safe.

      • Dave Carter says:

        Hi Michael,

        Our beans aren’t designed to be sprouted and eaten, so we don’t recommend that. Better to be safe and cautious!


  2. John says:

    I find it ironic to learn about the danger of under cooked beans on Wild Oats website. Why? Because we just finished eating a batch of chili that nobody liked due to the under cooked pinto beans from Wild Oats!

    • Oatie at Wild Oats says:

      Well, luckily, pinto beans have a lower concentration of the Lectins, or glycoproteins, that are contained in red kidney beans. But if you experienced any gas, bloating or other stomach upset, you have reaped the consequences of eating undercooked beans! Whenever humans consume beans like kidney beans or pinto, black or even great northern beans, you risk a reaction to the lectins contained in these foods. The gas you might get after eating beans is a result of lectin. The reaction you have is directly related to how many beans you’ve consumed and the amount of time you’ve cooked them. It is not advisable to eat undercooked beans of any kind. If you are served undercooked beans… send them back, cook them longer, or eat something else!

  3. Missy says:

    Damn… I read this AFTER eating raw beans!!! At least I know why my stomach hurts 🙁

  4. Pauline says:

    Around the first week of August, we visited friends we hadn’t seen for a couple of years. My friend, Mary, and I “shy” away from prescribed medicine in favor of alternative remedies as much as possible. In the course of our chatting, we talked about cholesterol levels and she mentioned someone told her eating three raw beans at night, (because that’s when the liver produces cholesterol), would remedy the problem.They had to be a specific bean ‘white pea beans’. I cannot say I ate them every night, but at least four or five times a week.Since hearing how raw beans are toxic, I was wondering what I should do, besides stop taking them which I already have earlier this week.I’m wondering if they could have been the reason I’m not feeling my “old self” these past few weeks. I am 75 yrs. of age and not on any prescribed medication at this time. Should I consult my physician, (away on a months vacation at this time), or go to the ER?
    Thank you for your response, it is most appreciated.

    • Chelsea Vurciaga says:

      Hi Pauline! Please consult your physician or primary health care advisor about your concerns. The article is for information only and we cannot give medical advice. Thanks!

  5. Hannah says:

    No wonder I had food poisoning all the time as a kid! I got them for snacks. Even tonight I wondered why my stomache hurt. Lo and behold I find out my nostalgic treat is poison. I have a few choice words for Mother…

  6. Lois says:

    I have eaten dried beans every PM for years, about 4-1/2 oz mixed with other healthy ingredients. I thought I followed the process carefully except I have a tendency of undercooking my food + my beans.
    Plus I do remember saying to myself “Oh, I forgot to rinse the one type of bean but went on and made sure I rinsed them well after the soak process. I am very careful about bacteria, washing and rinsing everything. Several evenings ago I got extremely sick, nauseated, dizzy actually went out on bathroom floor inuring my right temple and my r. elbow. I did not have dirrhea but had about 7 bowel movemeents, all normal. The next day I was careful what I ate and the 3rd day I was better.
    At first I thought it was over eating, I doo that because I am underweight but will not do that anymore. I kept thinking about this– these beans had a toxic taste, I make a large quantity of about 8 kinds, then freeze. I do not soak over night, I boil 2 min., take off burner, cover for two hrs, drain, rinse, add fresh water and cook. sometimes I know they are undercooked but never knew it would hurt me.
    In the future, I will do the other soak overnite method.
    After I made this last batch and froze, I noticed sometimes one of the containers I took out of freezer, when I ate them had a toxic (terrible) taste, I first thought it was because I had winter squash in them a couple days, eating one container @ nite.
    I kept thinking about this, last PM and this AM I felt half sick AGAIN, my garbage man was picking up my garbage this AM, I took every container of frozen beans (enough for abut 46 meals) and thru them all out knowing I had no choice.
    This AM I have been on and off the computer looking for info on beans and came across your article, THANK YOU, UNDERCOOKED BEANS, PLUS MY SOAKING METHOD BUT MY BEANS DID TASTE TOXIC.
    I have been so sick and now turned off from beans, I do not know what I will eat in the PM.
    I have lots of nutritional food at about 2 PM and thruout the day. I am extremely health conscious and eat healthy, I just hope I do not have too much toxicity in my body, I know that can cause cander.

    • Dave Carter says:


      Thank you for this detailed information. When we develop our next round of packaging,we will look at providing our cusotmers with information regarding the importance of properly preparing beans. We also appreciate your dedication to healthy eating.


  7. Paul says:

    Indidnt know beans were toxic raw and had 12 oz of presoaked uncooked black been a in a smoothie and was vomiting uncontrollably with severe and frequent trips to the bathroom. Talked to a doctor and said it wasn’t the beans, but reading this and other articles make me think I almost accidentally killed myself.

  8. Russ says:

    I would like to food process dried beans into a powder for use in shakes. Since beans shouldn’t be eaten raw, is it safe to eat dried beans that have been “cooked” in the oven or on the stovetop? If so, what temperature and duration do you recommend.

    Thank you!

  9. Maria says:

    I soaked the beans but nit overnight. My white kidney beans have been cooking on the stove for 4 hours. Is it safe to eat? I did not dispose of the initial water i boiled it in.

    • Chelsea Vurciaga says:

      Hi Maria – We cannot tell whether they are cooked enough by your post and do not want to steer you in the wrong direction! Please look at packaging for directions. Thanks!

  10. Sam says:

    We had pintos nearly every other day all the time we were growing up. My mother never soaked them, as the article suggests. She may have rinsed them briefly to get rid of any dust. Then she always pressure cooked them. Never a problem. I mention this because I didn’t see any mention of pressure cooking here. Saves a lot of time and fuel.

  11. blake says:

    i just ate a bean and looked this up im scared as hell what do i do my stomach hurts like hell

  12. Jackie says:

    I’m still a bit confused, can I grind great northern dry beans that I bought at the store into flour and then use it in soups? I will be boiling and then simmering the soup. I would think that beans ground as flour would cook quicker.

  13. Gary says:

    How long do you have to cook things made with bean flour? Bob’s Red Mill says you can use their Black Bean Flour to make a burrito filling “in only 5 minutes”. That doesn’t sound safe at all. What am I missing?

    • Chelsea Vurciaga says:

      Hi Gary – Bean flour has been processed in a specific way that makes it easy to cook quickly. The package directions are correct. Thanks!

      • Gary says:

        Thanks Chelsea. In what specific way is it processed? Isn’t the flour simply milled raw beans? What is the required cooking time for raw beans to destroy the lectins? I am under the impression that it is NOT an insignificant cooking time at a boiling temperature, yet making bean dip with black bean flour instructions on the label are for 5 minutes cooking time. That seems disconcerting.

        • Chelsea Vurciaga says:

          Hi Gary – It is hard for me to know how it is processed for sure. Please contact the manufacturer and they will be able to help you out! Thanks!

  14. Natalie says:

    Someone told me freezing beans or rice for few days before to cook it can help kill lectins. Is it true?

    • Chelsea Vurciaga says:

      Hi Natalie! We haven’t heard of that, but we have heard of using pressure cooking to kill lectins. Thanks for reaching out!

  15. alex says:

    what about raw lentils?

    • Chelsea Vurciaga says:

      Hi Alex! Sprouted raw lentils are very popular in salads and such, but please still check what you are eating to make sure it is safe!

  16. Shira says:

    I just called Poison Control because I accidentally ate partially cooked beans and no- it won’t kill me, and no- it’s not dangerous. Please check and edit your inaccurate information- the guy said I may experience vomiting and diarrhea in the next 5 or 6 hours, otherwise I will be fine.

    • Chelsea Vurciaga says:

      Hi Shira – We are glad that you are OK! Some people feel that vomiting and diarrhea are dangerous symptoms and do not want to take the chance. Furthermore, the information we present has been fact checked and is echoed in other articles. It is meant for information only and not as medical advice. Thanks for reaching out!

  17. Deb Binder says:

    Two questions – so I should sprout and eat raw beans like garbanzos? Also, I hate to throw the water away after a soak. I feel like I am throwing out the nutrients. Is this a dangerous practice?

    • Chelsea Vurciaga says:

      Great questions Deb! Sprouted beans are completely different and are not included in this warning, although you want to carefully to follow the directions and such on the package when you are sprouting. We cannot comment on the water from the beans. It’s a great question, we just don’t have an answer!

  18. Ivona says:

    I wish I read this article before I had a poisoning 🙂

  19. Sanda says:

    I made soy milk the other night, I soaked the soybeans overnight and then brought them to a boil in a pressure cooker for a minute…..I ground them up and put the ground mixture outside for the raccoons….they didn’t like it…I added a little nutbutter and they ate them…I haven’t seen them for a couple days…Did I inadvertently poison them? I hope not, I kind of like to see them.

    • Chelsea Vurciaga says:

      Hi Sandra! So nice for you to care so much about our furry friends! Most likely they are OK and they will return!

  20. Alexander Kusik says:

    I’ve eaten raw kidney beans on the daily for awhile and I hadn’t noticed anything wrong or anything. Is there a reason for that?

    • Chelsea Vurciaga says:

      Hi Alexander! We are not sure, but suggest that you mention this to your doctor to get his/her advice. Thanks!

  21. Ogun Lumumba says:

    This info is quite interesting considering I’ve been a raw vegan for 6 years and I’ve eaten 2 beans uncooked such as garbanzo and lentils. I’ve never experienced vomiting on any discomfort, I also notice that in the comment section it was said that sprouted beans were an exception but it wasn’t stated in the original article even though a sprouted bean falls under the category as a “uncooked” bean.

    • Chelsea Vurciaga says:

      Hi Ogun – We wouldn’t categorize a sprouted bean as “undercooked” because it takes on a completely different form as a sprout. Thanks for adding your voice and experience!

  22. Pingback: Beans: Potentially Hazardous AND Potentially Beneficial – Ruth's Corner of the Universe

  23. Staci Daley says:

    Thanks for this posting. I ate al dente cranberry beans and had the WORST upset stomach experience in my life later that night. This was the fist time we had cranberry beans so I did some research on preparation and found this article. This does make sense in my case as I recovered in 24 hours.

  24. Apalen says:

    What about if you soak overnight discard water but put them into a pot with sautéed veggies and broth then bring to boil only briefly and simmer for 1 1/2 hours?

    • Chelsea Vurciaga says:

      Hi Apalen – We have no idea if this will leave the beans undercooked or fully cooked. Please consult your recipe for details. Thanks!

      • Apalen says:

        Hi there according to the recipe they would be cooked I’m more asking from a not discarding the water after cooking issue rather than are they cooked.

        • Chelsea Vurciaga says:

          Hi Apalen! We are not sure how the water will affect the beans. The best bet would be to consult the company who wrote the recipe that you are following. Thanks!

        • Dobea says:

          Conventional wisdom says that soaking beans and discarding the soak water and rinsing the beans before cooking will remove indigestible (by humans, not gut bacteria) sugars that cause gas.

  25. Dobea says:

    How long a bean needs to cook will depend not only on the type of bean, but also how old the bean is (older beans take longer to cook). Package instructions are not always reliable. Here’s how you can tell if a bean is cooked without tasting it: cook the beans for the shortest recommended time; split one or two beans open with your fingernail — they should split easily. If the center of the bean still looks/feels denser, then continue cooking until the inside looks uniform.

  26. The Dude says:

    I ate just a spoonful of organic dry black beans and within 20minutes my right side of my back started hurting. The pain got worse throughout the night and I woke up the next day still in pain. It got worse through the next three days and got so bad my whole body ached and i could not take deep breathes without pain. It hurt to cough, sneeze and I could barely get out of bed, which has never happened to me before as I’m only 23. I told everyone I thought it was the beans that made me sick; however no one believed me. My doctor even said “just a spoonful of beans couldn’t do that to you”. He thought it was a kidney stone or infection, so he tested my urine, and he said there was no blood in it, so he then labeled it is back pain and the root of the problem was a pulled muscle that will heal up soon. I know this was not just a pulled muscle as my back started hurting randomly at 3:00 in the afternoon shortly after eating the beans.

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