Beans are of course, a very healthy food that are high in protein and contain almost all essential amino acids. Eating beans regularly could help to prevent a variety of health conditions including Type 2 diabetes, colon cancer and heart disease. With their high fiber content, they also are a great food for hunger reduction if you are overweight and need to lose some. Being low in calories and with zero cholesterol, beans have been a mainstay in many diets around the world.
However, you might want to be cautious about eating raw beans. Some varieties including red and white kidney beans contain a toxin called phytohemagglutinin or PHA for short. If you’ve never seen that word before, you are probably wondering what in the world it is!
Phytohemagglutinin, a natural insecticide, is a carbohydrate binding protein and can have toxic effects in high doses, but is safe in low doses and is actually used in some medical studies. However, in high doses such as found in raw beans, it can cause illness with the symptoms of nausea, vomiting, abdominal pain and diarrhea. As few as five raw kidney beans can cause this food poisoning.
Usually, the symptoms will disappear within 6 to 24 hours and medical attention is not required. However, if you do have the symptoms, you should consider medical attention in order to rule out any other bacterial food poisoning that you may have.
Cooking kidney beans will reduce the amount of PHA in the beans to non toxic levels if the beans are cooked at 100C (212F) for at least ten minutes. If you plan on cooking your beans in a slow cooker, you should heat them to the boiling point of water first for the ten minutes, before putting them in the slow cooker. Heating beans in slow cookers without cooking them to 100C can actually increase the levels of phytohemagglutinin above what they are in the beans in their raw state.
Canned beans are already cooked and don’t need to be reheated to boiling point, however dried beans that have been rehydrated should be cooked at 100C for ten minutes before being consumed.
The beans with the highest levels of PHA include red kidney beans (extremely high levels), white kidney beans, lima beans, and fava beans. In addition, lima beans contain another toxic substance called cyanogen. Cyanogen is also reduced to safe levels with cooking at 100C.
So, while beans are very healthy for you, be sure to fully cook them to enjoy their health benefits.