Did you know Kidny Beans are poisonous ?

Learned something today. I was reading a mystery and poisoning from Phytohaemagglutinin was part of the plot.

I can[t recall ever seeing raw kidney beans at any markets. They’re always in a can. I understand now why. Makes me wonder how primitive people figured out that Kidney beans could be eaten. You’d think after getting sick they’d give up trying long before attempting to cook them.

Turns out that poison is in a lot of different beans.


Per the article, the toxin is present in dried beans, and dried red kidney beans are pretty common. Really, you have to fail to boil them for 10 minutes for this to be a problem; as the article states, you might have that happen if you use a slow cooker where the water doesn’t get to boiling, but you should be fine otherwise.

They sell bags of dried kidney beans at the store and I think they’re dried from raw though I couldn’t definitely find out. The cooking directions do mention that they are toxic if not properly cooked.

How does one eat raw dried kidney beans without cooking the crap outta them?

I cooked them for 2 hours alone, drained, and then another 2 hours with the rest of the ingredients for chili…and they were still a little aldante, till’ after a few more reheats over a few days then the chili was at max consistency. :rolleyes:

So bean flour is not directly from ground up dried beans?

Correctomundo. They boil the shit out of the kidney beans before drying and milling them.

Funny that they don’t explain why they boil the beans at 100 C for 30 minutes. That would kill any toxins but they should have mentioned that. It does sound like bean flour is totally safe.

I can’t recall ever using dried Kidney beans. I’ll open a can of kidney beans and put in my pot of chili. Otherwise, I rarely eat them. I prefer dried pinto beans or dried Black-Eyed peas when I fix a big pot with ham hocks.

Yes, but I found out because kidney beans were used as a poison in a mystery I was reading, and it boggled my mind, so I Googled it.

According to the references I can find the poisoning consists of a few hours of vomiting and diarrhea, not pleasant for sure but for most not that big a deal.

Is that what it was used for in the plot?

I’m amazed at a lot of things that end up as common food. Bitter Almonds are poisonous if not treated pro[perly, and I have read that our current almonds are the result of breeding out the poisonous almonds – so that, at first, people were eating a food potentially more dangerous than kidney beams.

Olives aren’t poisonous, but they are bitter and sour until pickled. Our ancestors had strong stomachs to be able to stand them in the first place.


I’m convinced thyat a lot of food choices are the result of making the best of the situation when you’re just above starvation. That explains how hakarl came to be (It may be an ammoniacal in-the-ground-fermented Icelandic shark, buit at least after that treatment it won’t kill you) and lutefisk (fish that tastes of lye isn’t appealing to modern tastes – if you’re not from Minnesota – but it was a way of preserving fish for the lean times) and Casu Marzu (maggotrs got into the cheese and ruined it – but you can still eat it, and them)

I’ve often read that the ancient Greek sect of Pythagoreans had a taboo against eating beans, but the reasons given have always sounded nutty to me. I’d never thought of it before, but maybe the real reason has something to do with beans’ toxicity?


It sounds very plausible to me, Thudlow Boink, although I have often wondered why, instead of putting religious taboos on food, they simply didn’t say ‘don’t eat or you’ll feel sick for days/die’…

I don’t think so, kidney beans are a New World crop. I’m not sure if any of the edible Old World beans have the same issue.

Castor beans can kill an adult human if you eat just a few beans. You know, FYI. :slight_smile:

The book I read was by Dick Francis and at least 50 people at a dinner party got sick for a day or two. It nearly ruined the reputation of the main character who was a chef.

If someone was in bad health already then I could see dehydration as potentially life threatening. But, generally the effects would just make you ill for a couple days.

The description I’d read was that you’d get someone who’d throw the beans in a crockpot with water, turn it on low, and let it cook all day or so. The water never got to boiling but the beans were cooked.

I do tend to use my crockpot for cooking dried beans but I turn it on high and there is boiling going on.

I have read - and seen for myself - that acids like tomatoes slow the cooking rate of dried beans, so I’d probably pre-cook kidney beans until done or nearly so before adding them to chili.

(Example: About 2.5 hours to cook dried chickpeas in a crockpot on high. Dried chickpeas in a recipe for kabuli chana, containing tomatoes, mango powder, and pomegranate powder? 14 hours on high. Not kidding.)

Aren’t there really a lot of foods that are widely eaten that have to be treated/cooked to be safe to eat?

Like taro.

I’m pretty sure the humble potato can’t really be digested in raw form.

It makes you wonder how people ever figured this stuff out to begin with.

It literally is a case of “What does not kill me makes me stronger”, because, y’know, back when they were figuring this stuff out, you were likely to die of starvation if you didn’t find another food source.

Good point.