Raw or undercooked beans, especially red and white kidney beans, contain the toxin phytohaemagglutinin (PHA), a type of lectin.
Consuming only a few raw beans can give you belly ache. In some cases you may find yourself with severe stomach pain, vomiting, and diarrhea.
If you don’t cook kidney beans properly you can increase the toxicity, and this is particularly the case when using a slow cooker.
Why are raw kidney beans toxic?
I’m sure you know some plants cause belly ache when eaten by us or our pets?
Plants have a natural defense system in the form of lectins, of which phytohaemagglutinin (PHA) is one found in kidney beans. Lectins are a protein which bind to carbohydrates in the digestive tract, disrupting cell membranes, interfering with nutrient absorption, and generally causing discomfort and sickness.
In addition, PHA can cause irritation and inflammation within the intestines, causing cramps and bloating, and affecting bowel movement.
Not only are there concerns when cooking raw kidney beans at home, there have been increasing concerns with the use of beans (and lectins) in pet food.
PHA is found in both white kidney beans (cannellini beans) and red kidney beans, but higher concentrations are found in red kidney beans.
Red kidney beans contain around three times more toxin than white kidney beans.
Symptoms of kidney bean toxicity
Consuming raw or undercooked red or white kidney beans can cause the following:
- Nausea (can be extreme)
- Abdominal pain (can be extreme)
- Diarrhea (several hours after initial symptoms)
- Stomach cramps
- Bloating
In severe cases hospitalisation may be necessary. If our pets consume raw or undercooked kidney beans you should make an urgent appointment with your veterinarian who can induce vomiting.
The dangers of cooking kidney beans in a slow cooker
Your slow cooker will not reach a high enough temperature to destroy the toxins in kidney beans.
In fact, heating kidney beans at slow cooker temperatures (up to 175°F/ 80°C) can increase the level of poison up to five times as this will release more of the toxin.
This means kidney beans will remain undercooked from the slow cooker and potentially harmful.
When cooking recipes in a slow cooker which include kidney beans, you must make sure they are properly cooked before hand – either using the method below, or bought in a form which is safe (some canned beans have been previously heated and are safe).
How to cook kidney beans properly
The toxins in kidney beans are destroyed by boiling at 232°F / 100°C.
Boiling kidney beans for at least 10 minutes at a high temperature will neutralise the lectin, making the beans safe for consumption or slow cooking.
If other types of raw beans are used they must not be sprouted. All dry beans must be soaked overnight. Discard the soaking water, replace with fresh water and boil for 15 minutes.
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