Back when we were kids, the main reason we wanted to avoid eating beans was to avoid the “musical” side effect of eating beans.
But what many people don’t realize is uncooked kidney beans can actually be fatal.
As a matter of fact, it has been determined that as few as five raw beans can kill you.
The FDA warns that eating 4-5 uncooked kidney beans are likely to cause severe gastric distress, nausea, and vomiting in as little as an hour.
Uncooked kidney beans have an unusually high concentration of a chemical called phytohaemagglutinin (PHA) otherwise known as kidney bean lectin.
Lectin is a type of protein that performs all sorts of functions in both plants and animals. But some types of lectin, including this one, can be toxic at high levels.
This chemical is killed by boiling the beans.
Cooking in a slow cooker actually makes these beans more dangerous by unleashing even more phytohaemagglutinin.
Eating undercooked kidney beans can result in a hospital stay, but more likely you will get better in a few hours.
While other beans contain PHA, the lectin is particularly high in red kidney beans.
PHA is measured by a unit called a “Hau” which is short for “hemagglutinating unit.”
A raw kidney bean has 20,000 to 70,000 hau. But once cooked (boiled) it drops to 2-400 hau which is not enough to cause problems.
White kidney beans only have a third of the PHA. Other related beans only have 10% of the PHA.
The FDA recommends the following for kidney beans:
- Soak the beans for at least five hours in water. It’s not a bad idea to change the water periodically, but it’s not necessary for safety.
- Drain the beans from the final soaking water.
- Boil the beans in a pot of fresh water for at least 30 minutes. Note: Research indicates that the toxin is destroyed when boiled at 212 degrees F 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.
How did this even become an issue? Raw kidney beans are not only toxic, but they also taste horrible.
Well, it was first reported in 1980 in Great Britain.
In 1976, 17 boys and three teachers were doing a field trip. They planned on eating chicken, but apparently it was not good.
So, they threw together a quick meal of hard-boiled eggs, potatoes, and raw kidney beans.
The beans were apparently soaked, but not boiled.
The beans were not a big hit, only nine ate them.
The pathologists tested everything to look for the source of the food poisoning. Nothing showed up. There was no sign of any obvious contamination. Unfortunately, no one tested for the lectin.
It took six more outbreaks before someone discovered the PHA problem and people were finally warned in 1980 in Great Britain to boil their kidney beans.
The FDA has been warning the US about the dangers of raw kidney beans since 1949, but it was updated to warn people that the beans need to be boiled and not just warmed in a slow cooker.