Eating Raw Kidney Beans Can Be Toxic

Raw Kidney Beans

Did you know that eating raw kidney beans can be toxic? According to the FDA, eating as few as 4-5 uncooked kidney beans can cause severe nausea, vomiting and diarrhea in 1-3 hours after ingestion. Uncooked kidney beans have an unusually high concentration of a chemical called phytohaemagglutinin that is destroyed when the beans are properly cooked by boiling. Apparently, cooking in a slow cooker may actually make the beans more dangerous because low temperature cooking increases the toxicity.

Other beans contain this chemical, but in much smaller amounts. The bottom line – be sure to cook kidney beans by boiling (after you soak them). DO NOT USE THEM AS TOYS OR ART OBJECTS FOR YOUNG CHILDREN. In addition to their toxicity, raw beans are a small object hazard for young children. If the child puts a bean into a body opening, the bean may get stuck, swell and become very difficult to remove.

REF: U.S. Food and Drug Administration, 5/2003

Liz Meimann

I received both my undergraduate and graduate degrees in Food Science at Iowa State University. I love to quilt, sew, cook, and bake. I spent many years gardening, canning, and preserving food for my family when my children were at home.

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33 thoughts on “Eating Raw Kidney Beans Can Be Toxic

  1. Can I simply say what a relief to uncover one who in fact knows what theyre discussing on the net. You actually know how to bring a difficulty to light making it important. More and more people must check out this and can see this side of the story. I cant believe youre less well-liked as you undoubtedly develop the gift.

  2. About 6 years ago I ate a handful at least 20 kidney beans.
    No doubt they are toxic.
    It was not good for me for the next 12 hours.

  3. We are making baked beans. We are using a package of nine-beans obtained from HyVee. We are using a crock pot at full boil. There are light red kidney beans in the mix. From I’ve read, boiling them for 10 minutes at 212F breaks down the toxin. Slow cooking, 176F is not safe and actually, they say, concentrates the toxin. The beans have been cooking for about 6 hours at a temp between 210 and 212F.
    The package instructions say:
    Quick soak: Rinse and sort beans in a large pot. To 1lb of beans add 6 to 8 cups hot water. Bring to rapid boil for 2 minutes. Remove from heat. Cover and let stand for 1 hour. Drain and rinse beans.
    Overnight soak: Rinse and sort beans in a large pot. To 1lb of beans add 6 to 8 cups cold water. Let stand overnight or at least 6 to 8 hours. Drain and rinse beans.
    Cooking instructions: Add 6 cups water to drained and rinsed beans. Simmer…
    I have no idea if my wife did this. We have made baked beans many times and to the best of my recollection, have never boiled the beans for 10 minutes and thrown out the water.
    What should we do?

  4. i have always sorted, rinsed, bring water to a boil and then tossed in the washed beans; cooked at a rapid boil for at least one hour or more until soft. I’ve never gotten sick. I never knew we were suppose to toss out water after 10 minutes. I have diabetes; i cant afford to add toxins to my food source. I realize the toxins are neutralized but wonder if the toxins are totally destroyed or mostly?

  5. Foodrinke, research suggests that beans shouldn’t be cooked in the slow cooker at all.

    All beans contain a compound called “phytohaemagglutinin,” also called PHA, or kidney bean lectin. Lectin is a type of protein that performs many functions in both plants and animals. But some types of lectin, including this one, can be toxic at high levels.

    If this lectin isn’t destroyed by thorough cooking, you’ll be sorry. According to the U.S. Food and Drug Administration’s Bad Bug Book, eating as few as four or five improperly cooked red kidney beans can cause severe vomiting within a few hours, followed by diarrhea. Other symptoms include serious abdominal pain.

    Although some cases have required hospitalization, people normally feel better within three to four hours after symptoms start. That’s one reason why there aren’t many recorded cases of this particular foodborne illness in the U.S.: People usually begin to get over the illness just about the time they might think of contacting their doctor.

    Other types of beans also contain PHA, but it’s much more concentrated in red kidney beans. For example, the unit of measurement for the toxin is called “hau,” for “hemagglutinating unit.” Raw red kidney beans have anywhere from 20,000 to 70,000 hau, but that drops to 200 to 400 hau when the beans are fully cooked — not enough to be a problem. White kidney beans, or cannellini beans, contain only about one-third of the toxin as red kidney beans. Broad beans, or fava beans, contain just 5 to 10 percent of what’s in red kidney beans.

    The FDA recommends these steps for preparing dry red kidney beans:
    Soak beans for at least five hours in water. Change the water periodically, but it’s not necessary for safety.
    Drain the beans from the final soaking water.
    Boil beans in fresh water for at least 30 minutes. Note: The toxin is destroyed when boiled at 212ºF for 10 minutes, but scientists recommend 30 minutes to be certain the beans reach the proper temperature for the amount of time necessary.
    Don’t use a slow cooker. It likely won’t get hot enough.

    Contact Us
    Crystal Futrell
    Family and Consumer Sciences Agent

  6. Linda, you have given me a great question, but hard to answer with the resources I have available. Red beans and kidney beans are actually different types of beans. As you know, red kidney beans contain relatively high amounts of phytohemagglutinin and are more toxic than most other bean varieties if not cooked to the boiling point for at least 10 minutes. Some other beans contain this chemical, but in much smaller amounts; I could not find anything specific regarding small red beans. Beans in general contain a compound known as lectin. Lectin is common in many plant based foods and may or may not be harmful. As it turns out, the lectins found in some beans are toxic and may be harmful to human health. Therefore, one would be advised to cook all beans to error on the side of caution.

  7. Nice Article! Red Kidney Beans nutritionally consists of optimum levels of carbohydrates, dietary fibers, and proteins, along with Iron, Magnesium, Potassium, Copper, and other essential factors.

  8. Hi Joan, it is not necessary to dump the cooking water from dried beans if they are cooked in a pressure pot or on the stove top. It can be used in soups and stews as the heat will destroy the toxins inherent to kidney beans. For that reason, kidney beans should not be cooked in a slow cooker. Thanks for contacting AnswerLine.

  9. I presume that the advice against cooking kidney beans in a slow cooker applies to dried beans, not to commercially canned kidney beans?

  10. Hi Elcee, yes, your assumption is correct. Commercially canned kidney beans have been prepared under the proper conditions. Thank you for contacting AnswerLine.

  11. Translatlion: The United States FDA (a food institution) officially say that just eating 4-5 raw beans can cause severe bouts of nausea, vomiting and

  12. Are canned kidney beans able to be eaten without cooking? My grandmother used to make a cold 3 bean salad with canned kidney beans, chick peas and green beans. We never got sick eating that.

  13. Lisa, your grandmother’s recipe is quite typical of a 3-bean salad. There is no problem with using commerically canned beans in a salad. When using canned beans, drain them and rinse under cold water before tossing with the other salad ingredients.

  14. Hi, do you know if fermentation reduces the toxicity of kidney beans? I was looking into buying AFC enzyme drink, and then I saw it contains kidney beans (which may be raw). The drink has been fermented for two years, so it’s possible the toxin is inactivated?

  15. Hello Al and thank you for submitting your question to Iowa State University Extension and Outreach AnswerLine. I have spent time researching your question and can find nothing in the scientific literature that supports or denies that fermentation reduces the toxicity of kidney beans. From all indications, the AFC enzyme product is safe so obviously the toxicity issue has been dealt with by the manufacturer. Further, I tried to find a contact for the manufacturer so that you could contact them yourself to get the answer you seek, but struck out on that venture, too.

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