With a lot of people going on "raw food" diets, there is a lot of misinformation floating around. Especially when it comes to beans, which are an important source of protein for many people who abstain from meat. So what is going on, and why can you not eat beans raw?
Eating raw beans, or "sprouting" beans
Eating raw (or sprouted) beans is only something you should try if you have an extremely strong stomach, as they do not digest well. And in the case of many beans, I recommend not doing it at all. This is because in some beans, eating them raw is actually poisonous.
For instance, Kidney Beans contain a chemical known as phytohaemagglutinin. This is so concentrated in raw beans, that even 4-5 raw or undercooked kidney beans can cause severe nausea, vomiting, and diarrhea. Cooking the beans for at least 10 minutes deactivates this chemical.
Lima beans are not any better, as they contain Linamarin, which eaten in the raw parts of the plant convert in your body to Hydrogen Cyanide. But cooking them for 10 minutes at least also renders this chemical null.
Sprouts of any kind can be dangerous due to their ability to hold bacteria. Since they grow best in moist warm conditions, they are great at drawing in bacteria that can grow as well. Even the FDA warns against the consumption of sprouts.
Why cooking is the best option
First of all, they taste better, and feel better while eating. If you ever had a bean that had just been soaked and tried to eat it, you will agree with me. But that is just subjective, let's look at the science.
The most important aspect is digestability, or how much of what we eat is actually absorbed into our body and used as fuel. One measure of this is known as Bioavailability, or the amount of protein specifically is able to be absorbed from the foodstuffs.
A raw bean, whether soaked, sprouted or not, only seems to have a bioavailability of about 25%, as opposed to around 75% for methods such as boiling. With vegans and vegetarians getting a lot of their protein, Iron, Zinc, and B-vitamins from legumes, simply boiling the beans for an hour or until they are fully cooked can help a ton!
Plus, who doesn't love a good 3-bean soup?