Hemagglutinin and Food Poisoning from Beans

Undercooked Beans Can Give You Food Poisoning

Eating raw or undercooked beans can give you a form of food poisoning. Red kidney beans are particularly dangerous.
Eating raw or undercooked beans can give you a form of food poisoning. Red kidney beans are particularly dangerous. Dorling Kindersley, Getty Images

Here's a fun fact: Eating soaked raw or undercooked beans can result in food poisoning. The culprit is a plant lectin known as phytohaemagglutinin or simply hemagglutinin, a chemical known to cause agglutination of mammalian red blood cells and to disrupt cellular metabolism. According to the US Food and Drug Administration, phytohaemagglutinin is found in many types of beans, but red kidney beans contain the highest levels of hemagglutinin.

White kidney beans contain a third as much toxin while broad varieties of beans contain 10% as much hemagglutinin as red kidney beans. This is still plenty, since you only need to eat 4-5 undercooked red kidney beans to get sick.

Bean Poisoning Symptoms

Symptoms start to appear within 1 to 3 hours after consuming the beans and include nausea and vomiting followed by diarrhea and, in some cases, abdominal pain. Although the symptoms may be severe enough to warrant hospitalization, they resolve spontaneously within a few hours. Everyone is susceptible, regardless of age, gender or other factors.

Preventing Bean Poisoning

It is easy to prevent bean poisoning. The recommended procedure is to boil soaked raw beans in water for at least 10 minutes. It is important that the water reach boiling or 100°C, since exposing the compound to 80° C actually increases its toxicity about 5 times.

Share Your Experience

Had you ever heard of hemagglutinin in beans or bean poisoning?

Have you ever experienced this type of food poisoning? Here are replies from readers:.

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Submitted on 2014/05/20 at 7:37 am
I never knew about kidney bean poisoning until today! I made vegetable soup with dried bean mix (without soaking) in a Crockpot.

The soup didn’t cook thoroughly even though it was on for over 8 hours. Fortunately my symptoms were mild, but still a very unpleasant experience. Learnt my lesson.

Submitted on 2014/05/15 at 6:14 pm
I always cook my beans (all types) in my pressure cooker til completely soft; however, if I eat them several days in a row, for some reason I start feeling bad & a little dizzy.

Submitted on 2014/04/27 at 9:43 pm
Here’s the drill folks! Legumes have been a staple of humans and other critters for a long, long time. Look in any old cookbook (mine date back over a century) and guess how they prepared them. THEY SOAK OVERNIGHT AND BRING TO A BOIL, THEN SIMMER UNTIL TENDER. Obviously, they only had Fire for fuel and no electricity. I never knew about PNG until last year and have prepared many types of beans, including dry red beans. My main goal is to greatly reduce polysaccharide sugars which encourge anaerobic activity in the gut and, guess…gas!

So, after 50 years of cooking and research, here is the magic recipe:

• Sort, rince, and cover 1 lb of beans with 2 inchs of water. Add 4 tsp of salt. (Especially old beans…can you really tell?). Forget the myth, we’re not cooking, yet.

•Soak overnight or 6 to 8 hours.
•Bring to a boil, and boil 2 minutes.
•Remove from heat, cover and soak 4 hours.
•Now, discard water and rinse beans.
•Cover beans with water and bring to simmer.
•Cook until tender.
•Drain and serve.
Note: I use a pressure cooker (7 minutes at 15 lbs for Pinto beans). Beans are an important part of my diet, almost every day!

Submitted on 2014/04/22 at 10:53 pm
I’ve just been diagnosed with bells palsy and I believe it is due to a tin of red kidney beans that I did not heat appropriately. I feel tingly all over and found that navy beans and even tofu gave me the same effect. I believe hsv-1 combined with the hemagglutinin caused my bells palsy. I have also found that juicing 2 lemons with 2 tbs of olive oil counteracted the pain. good luck guys!

Submitted on 2014/04/09 at 11:16 am
I have this reaction to ALL legumes.

It doesn’t matter how they are prepared or cooked. It also doesn’t seem to matter how little I consume. I have become extremely ill after consuming something that was made with a small amount of soy flour. I have also started to have a similar reaction to certain nuts.

One of my frustrations is that soy seems to be a standard substitution in so many foods, and isn’t always listed. I read that if an ingredient is a common substitution (soy grits for corn, for example) that the substitution isn’t always listed. It is to the point that I can no longer eat foods that my family doesn’t make from “scratch” with known ingredients.

Submitted on 2014/03/22 at 12:01 pm
I had some store bought hummus lastnight with organic carrots and within a half hour I was experiencing nausea. Next thing I knew I was running to the bathroom and for a good hour and a half my body was expelling every last bit of it. Vommiting is the worst! I also experienced stomach cramping and gas. I love hummus and I’ve never had a reaction like this! It was so terrible that I may reconsider ever eating it again.:(

Submitted on 2014/03/22 at 10:42 am
AVOID ALL BEAN!!!!!. They are the most difficult food on the planet to digest says my gastro. Every time I eat them, any kind whether sprouted, cooked with kombu, double soaked and drained, pureed, you name it I get sick. I was tested for allergies but don’t have any. I just get headaches, terrible gas and bloating for 8-10 hours, and feel awful for days after.

Digestive enzymes, probiotics etc don’t help at all. It’s amazing how a supposedly healthy food can be so toxic.

Submitted on 2014/03/19 at 6:55 pm
I ate out last night and had a black bean burger. Felt fine until 4 hours later…the nausea woke me up. Also had the worst headache I’d had in a long time. After I ffinally vomited I felt much better & was able to finally fall asleep.

Submitted on 2014/03/06 at 10:40 pm
Currently going through it. Homemade hummus from white kidney beans and went to town with some veggies. 2 hours later after some belly rumbling I’m feeling under the weather and permanently placed atop the porcelain throne. Just kinda yucky but no vomiting, running like a faucet though.

Submitted on 2014/02/20 at 12:52 am
On Monday I decided to cook my normal veg soup but as I chose to do a meat free week and had a packet of raw kidney beans in the pantry (which I have never cooked before) I thought I would add some to my soup along with some lentils, so I just tipped them straight from the packet into my already cooking veg soup. Bad Mistake
After 2 days of consuming this really delicious soup, for Lunch and Dinner on the first day, then at lunch the second day, I got severe stomach cramping and thought I was going to vomit.
I left work early and drove home in agony, I even contemplated driving to A&E as the pain was so bad.
When I got home I took a swig of Gaviston to sooth my stomach and lay on my bed for nearly 2 hrs until the pain stopped and during this time I passed the most wind ever in my whole life.

I couldn’t think of what had caused this, until a friend at work the next day advised me on the dangers of consuming kidney beans that have not been soaked or cooked properly. I had to tip out my remaining soup, which guttered me, but this has really taught me something.
I will either buy my beans already cooked, or follow the correct process and do the soaking, discarding the water, rinsing, and recooking for a longer period and at a higher temperature.

Submitted on 2014/02/17 at 8:29 pm
Three weeks ago I have changed up my diet with my PT as we are doing a 17 week challenge as a ‘fake’ comp prep to see how I go as I would like to compete next year.
I have changed my diet a little more making it more cleaner than what it was already and increasing my green veg a lot more.

As I loved raw green beans I would consume maybe 250g of these alone a day – uncooked. I have never heard of any problems with it before and didn’t even think to talk to my PT about it.
My results have been great – My stomach body fat had dropped and my abs were now more defined – then two weeks later I am now looking like I am pregnant and I am in so much pain!

I googled info on green string beans as this was the biggest change I could think of, where to my shock I found how toxic they are for your body and the side effects which I have had: Vomiting, Abdominal Pains, Bloating etc..
I have stopped these today and am going to see my Dr as this pain has been going on for two weeks now and has gotten unbearable!

Safe to say all my beans will be cooked from now on :(

Submitted on 2014/01/27 at 1:08 am
Yep recovering from making a 8 types if bean soup.My little girls 4 and 8bgit hit much harder than myself,lots of vomiting,stomach pain,even low grade fever,for me only stomach pain…
Soaked them for 6 hrs,boiled them for 1.5 hrs…not on high ,mostly simmering…I will stick to my lentils soup…my poor girls had to take zofran.hope they will wake up ok tomm to go to school.

Submitted on 2014/01/16 at 11:16 pm
I am currently in the middle of preparing dried Pinto beans to make my crock pot chicken Chili tomorrow and I have to admit that I’m a little bit nervous about using the pinto beans now. I soaked them over night, rinsed them and am now boiling them to get rid of the toxins. My worry is that everything I have read says that they must be boiled at at least 100 degrees Celsius for at least 10 minutes but, measuring with my infrared food thermometer, can only get them up to 93.3 degrees even though they are at a rolling boil! I’m really tempted to just trash them and run to the store for canned beans after reading what everyone had gone through here!!!

Submitted on 2014/01/16 at 11:47 am
I am so glad I found this site after waking up at 3:30 AM this morning with intestinal pain, nausea, diarrhea and felling like I was about to pass out right on the bathroom floor. I had eaten dark beans I made from scratch in the crockpot two nights in a row. It was frightening because I couldn’t come up with a reason why this happened. Now I know.

Submitted on 2014/01/14 at 9:21 am
well, i have been cooking a chilli in the slow cooker, using dry kidney beans, pinto beans, black beans etc. i soaked them over night, as usual. I have not long tasted the chilli. Then I realised that I had forgotten to cook the beans. The chilli had been cooking for about four plus hours! maybe i only eat one,two or maybe three beans. I am not looking forward to the next few hours. Maybe I will be lucky. but I doubt it!

Submitted on 2013/12/13 at 11:00 pm
I’m just getting back to normal after two pretty awful days. My girlfriend made us a pinto bean and pumpkin casserole and three hours later I felt the first wave of nausea. An hour later I was projectile vomiting until I was just retching. I don’t think I’ve ever felt so ill before. The pinto beans had been soaked overnight and boiled as the instructions said to, but there must have been a few that didn’t cook properly. My girlfriend was absolutely fine and thankfully so is our baby, who had some mashed up. I had to take two days off work and have only just started back on solid food as I couldn’t stomach anything but water.

Submitted on 2013/12/02 at 8:54 am
My slow cooker apparently malfunctioned. We were cooking red beans and rice and I originally thought maybe the sausage got us sick because the red beans were not soft that meant that maybe the sausage had not cooked enough but then I read these articles. The sausage was smoked and I’m pretty sure basically precooked but the red beans were just slightly hard but not too hard to eat. I wish I had read this before we decided we were too hungry to wait another hour. The food tasted fine and my husband asked if I felt at all nauseous about 3 hours after we ate. I wasn’t feeling bad and about an hour later we went to bed. I woke up at 3 am throwing up. he was able to sleep through the night but by 6 am when we were getting up for work the diarrhea started with me first then him. Luckily we have two bathrooms. It’s now 8 am and I am able to do something other than sit on the toilet with a trash can in my lap but sad that there are no treatments for this. Me and my abdominal pain are just gonna have to wait it out. This sucks!

    Laurie Mann    
Submitted on 2013/11/26 at 11:30 am
I’m used to eating canned black beans and just nuking them. My daughter recently soaked black beans for dinner, but had a lot leftover so I took them. I nuked some for 9 minutes total (adding some rice and Indian food after 6 minutes). They tasted OK but were still a little hard. Now I’m a little worried about losing my lunch – had no idea beans could be poisonous. Have never gotten sick after eating black beans, hummus or falafel before, but this is the first time I’ve eaten beans that weren’t completely cooked.

    Jessica Deforest    
Submitted on 2013/11/22 at 12:11 pm
I just wrote to a major cooking magazine about the possibility of hemagglutinin poisoning from two slow cooker recipes they printed that called for uncooked navy beans. They answered that they had researched their recipes with the FDA and were told there was very little danger in using the recipe, as most such poisoning comes from red kidney beans.

Have they gone bonkers or just don’t want to admit they printed recipes that could make people sick?

    Donna Leverenz    
Submitted on 2013/10/16 at 3:54 pm
We just had an episode with dried lima beans soaked overnight. I usually do the quick soak, boiling for three minutes and then letting soak for two hours, and we’ve never had a problem. Does the boiling and letting soak eliminate the danger? I thought I was actually doing a better job by soaking overnight. . .Thanks for any insight.

Jaime Silta    
Submitted on 2013/10/10 at 5:45 pm
I just ate some romano beans and I’ve never really cooked beans before so I didn’t know I had to soak and then cook them, I just cooked them. I threw out most of my dish but ate a significant portion of the meal. My stomach feels a bit weird so I guess I might get sick, but hopefully it’s just a psychological reaction to learning about this, or it’s just that the beans are tough to digest because of my flawed cooking. Wish me luck.

    Andrew Somers    
Submitted on 2013/10/07 at 6:19 am
Ate home grown butterbeans in a tomato and chorizo stew at approx 5.30pm, they weren’t precooked and were a combination of fresh ones picked the day before and some from the fridge (large ones). Some of the large ones were a bit firm but tasted fine. I was perspiring within 2 hours but felt ok. Went to a pub quiz and my wife vomited twice between 9 and10 pm and again on the way home. I started the vomiting around 11pm and this continued until 3am accompanied by cramps and then multiple diarrhoea until 4am. Woke up at 6am drenched in perspiration. Went back to sleep and woke at 10, just had a cup of tea and it seems to be ok. My wife had same symptoms but an hour ahead of me. I had no idea beans could do this to you, they were cooked for at least an hour on the stove and in the oven, but obviously this wasnt enough. Tinned from now on, cannot risk this again.

Submitted on 2013/09/29 at 2:50 pm
My adult son has just had an horrendous episode of acute poisoning that was incredibly intense. Luckily, he has excellent health generally. After eating a plate of shop bought ready prepared falafel with hummus, he was fine for three or four hours and then had a rapid onset of acute abdominal pain and diarrhoea. He also had some frank blood loss with the diarrhoea. The pain was really severe and at one point I thought I would have to get an ambulance. He also began vomiting.
Incredibly, this really severe and acute illness began to wear off after four or five hours. 20 hours later he is feeling fine again, although obviously exhausted!
He will see a doctor tomorrow, just to make sure everything is ok, especially given the blood in the stool.
I have always thought that the most severe food poisoning was associated with contaminated meat and dairy products and had no idea that beans could be so lethal! I will take the remaining falafel etc. back to the supermarket tomorrow.

Submitted on 2013/09/10 at 8:29 am
I ate raw Romano beans I bought from the grocery store. They sold them beside the green beans that I’ve always eaten raw, so I thought it was just another type of bean.

I ended up eating an entire bag of them, thinking they were good. BIG MISTAKE.

I felt like throwing up 5 minutes later. They burned in my stomach. Went to bed, passed a lot of gas, my intestines were spasing. Woke up 6 hours later with abdominal pain. Drank pepto bismal. Went back to bed. Woke up an hour and a half later with extremely watery diarreah. Had to pass water for stool several times.

Submitted on 2013/08/25 at 4:04 pm
Beans are as staple of my diet. I think they’re a great addition for anyone. Don’t let the fear of getting sick stop you from eating them altogether. Just make sure you boil em for at least 15 minutes and let them soak for a while so they’re not too hard. They go well with a lot of different spices / additives, and are incredibly healthy. Whenever possible, go with organic food, since it’s easier to digest and contains a more rich taste and nutritional content. You won’t find organic beans at the supermarket most of the time. I recommend farmer’s markets or local natural stores.

    Jason Bintz    
Submitted on 2013/07/13 at 10:35 am
I had done some pinto beans just about a week or so ago for a party for a friend. I spent just about all day working on them. Soaked them overnight and drained and rinsed them before putting them in the dutch oven for the rest of the afternoon and evening.

Late that night, I started getting sick. Spent more time in the bathroom than sleeping for the next 2-3 days. Day 3 was running a low grade fever. Friend took me to the ER to get me checked out. Had an IV with an anti-nauseant injected, also had to go for a cat scan because they feared something might be wrong with my appendix. it was through another friend that I found out this was possible.

Submitted on 2013/07/08 at 4:34 pm
Black beans make me nauseous every time. I thought it was the dairy (I always eat them as some sort of Mexican dish such as tacos, and include cheese) but I’ve switched to goat cheese. I had black beans last night and at lunch today (the canned Bush’s Beans brand) and was nauseous within minutes. I know the other ingredients don’t make me sick so it has to be the beans.

I’m gluten, dairy and soy free. Soy and dairy make me nauseous so I figure black beans are just too close to soy beans for me to tolerate. Sad because I really love their flavor.

No reaction to any other type of beans so far.

    Teresa wiedrick    
Submitted on 2013/06/25 at 11:27 am
Daughter & i had tummy cramping, bloating, nausea & vomitting last night. I feel bloated & weak this morning. Otherwise, ok.

The guy at the market said i only cook them for half an hour.

In our world of canned beans, i just didnt know better!

Submitted on 2013/06/24 at 6:08 pm
I ate red kidney beans today for lunch and around 3 pm I started feeling very dizzy. Everything in the room was moving in circles..the wave of dizziness was so sever that I could not walk without support. Then the nausea started and finally I ended up throwing up five times…all the lunch out of the system now I am feeling lot better.

Submitted on 2013/06/18 at 12:59 am
I went to a new restaurant last night and all i had was this deep fried falafel fritter looking thing. Within three hours i was vomiting the falafel with blood. Ive been bloated, gassy, and have a bad case of sulfuric burps. Now i am running to the bathroom every 5 minutes with the runs and it doesn’t look like its going to pass any time soon. Its safe to say i will never eat falafel again

Submitted on 2013/04/10 at 10:31 am
Oh my yes…I had a terrible bout of vomiting/diarrhea/gas/abdominal pain that lasted several hours and kept me home from work for 2 days after eating pinto beans I had cooked several hours in a crockpot without prior soaking or boiling! I will NEVER do this again!! I had been told if beans were fresh (ie not old..rather this years beans which are grown locally in my area) I did not need to soak/boil them prior to cooking!! How wrong that info is!!

I had never heard of this type of bean food poisoning!!

    Shauna Rae    
Submitted on 2013/02/13 at 2:59 pm
I have always been sensitive to kidney beans, refusing to eat them as a child. I think some people might be more sensitive than others. I was once in a room adjacent to an industrial kitchen. As time went on, I was doubled over in pain with stomach cramps. It turned out they were making kidney bean casserole.
The last time I ate chilli with kidney beans in it, I picked them all out, but still reacted. My digestive track started spasming and it took months to settle down. Lost 15 pounds.
I won’t go near them any more and am glad to finally learn of PHA so that I can make sure to avoid other foods with lower quantities.

    David Cunningham    
Submitted on 2012/10/11 at 6:09 pm
I’m having a bad attack right now. feel dizzy, my stomach feels really tight and my throat kills. got it from eating 450 grams of runner beans and am wondering if the amount i ate is severe

Submitted on 2012/05/16 at 12:29 pm
I ate undercooked kidney beans yesterday around 3pm. This wave of nausea came over me around 630pm last night. I had a headache and just felt nauseated, so at 8pm I went to bed. I woke up around 630am and still felt pretty lousy. Then the diarrhea hit me. It’s now 930am I feel tired but it’s getting better. I’ll never do that again!

Submitted on 2012/04/12 at 8:50 am
I had an attack yesterday after consuming red kidney beans. I had all the symptoms especially abnominal pains. I took milk of magnesia and slept for over 2hours. Now I’m avoiding red beans.

    Cris Carver    
Submitted on 2012/02/21 at 11:21 pm
Yes! At Christmastime we used a store-bought mix of hummus. Everyone who ate it got sick. We used to love hummus, now we
are leery of it. : (

    Jeremy Cunningham    
Submitted on 2011/08/10 at 8:53 pm
My wife has just had a severe attack of vomiting and diarrhoea. The suspect is the falafel we had for dinner- made from white butter beans, or dried runner beans. The recipe used from Claudia Roden’s book specifies making the rissoles from uncooked beans. They are then deep fried. I found an article from the Independent 2008 called Beware of the Beans- a family using the same recipe (shallow fried however) all came down with severe symptoms. As I have not as yet had the symptoms, I guess either my wife ate one that had not been at 100 degrees for long enough… even white beans have enough lectin to cause problems.