What beans are poisonous if undercooked?

Red kidney beans contain a toxin called phytohaemagglutinin, which can be harmful if the beans are undercooked. Even soaking them overnight is not sufficient; they must be boiled for at least 10 minutes to neutralize the toxin effectively. Other beans, like white kidney beans, also contain similar toxins and should be prepared with the same caution. Always ensure beans are cooked properly to avoid toxicity.