Red kidney beans (Phaseolus vulgaris) contains phytohemagglutinin (PHA)
Phytohemagglutinin is a protein that adheres to white blood cells. PHA can trigger the T-lymphocytes in the immune system to undergo mitosis (cell division) hence – interferes with cellular metabolism. The body responds as if invaded by an infectious agent.
This toxic agent is found in many species of beans, but it is in highest concentration in red kidney beans. When raw or undercooked kidney beans are consumed, this toxin can cause a severe bout of nausea, vomiting, and diarrhea. As few as 4 or 5 beans can bring on symptoms, and onset of symptoms varies from between 1 to 3 hours.
Therefore it is essiential that kidney beans are properly cooked to ensure that the PHA is destroyed.If they are cooking them fresh red kidney beans they need to be soaked for many hours (as suggested on packet) and cooked for over 90 minutes, heated to 80 degrees C. to remove the PHA, Alternatively – buy them tinned as they have already undergone the toxin process.