Cook them properly and not in a slow cooker! 

Red kidney beans are a healthy food – unless they’re not cooked properly. They contain a compound (“PHA”), found in many types of beans, and at especially high levels in red kidney beans. PHA can be toxic at high levels; in fact, consuming only 4 or 5 raw or undercooked red kidney beans can make a person seriously ill.

Fortunately, PHA can be destroyed through proper cooking. Unfortunately for fans of slow cookers, the device does not get hot enough to kill the toxin, so using a slow cooker for uncooked kidney beans or dishes containing them is not advised. 

Do not use a slow cooker to cook dried red beans.

To safely cook dried kidney beans, the FDA recommends this procedure:

• Soak beans for at least 5 hours in water. While not needed for safety, it’s recommended to change the water periodically.
• Drain the beans from the final soaking water.
• Boil the beans in fresh water for 30 minutes. While the toxin is actually destroyed when boiled for 10 minutes at 212°F, scientists recommend boiling for 30 minutes to be certain that the beans reach the proper temperature for the length of time necessary.

It is also recommended that beans not be used as toys or art supplies. Besides being toxic, raw kidney beans are a small object hazard for young children. 

Note that commercially canned red beans have been processed under the proper conditions and don’t require the procedures listed above. When home canning dried beans, follow the procedure recommended by the NCHFP for a safe product. 

For further information, visit the Kansas State Extension website.           

For information on canning dried beans, visit the National Center for Home Food Preservation (NCHFP) website.

And, of course, you can always reach out to your local UC Cooperative Extension Master Food Preserver Program. 

Ask a Master Food Preserver

Brought to you by the UC Master Food Preservers of El Dorado County

Last updated July 2025