HealthMap

Phytohemagglutinin Toxicity in Kidney Beans

• Yes, absolutely: Raw or improperly cooked red kidney beans contain high concentrations of the toxic lectin known as phytohemagglutinin (PHA).
• Mechanism of action: This plant protein can bind to carbohydrate receptors on the surface of cells lining the intestinal tract, causing disruption of cellular metabolism, severe damage, and gastroenteritis.
• Onset of symptoms: Typically occurs rapidly, anywhere from one to three hours after ingestion of insufficiently heated beans.
• Common symptoms:
• Extreme nausea
• Severe vomiting (often the most prominent symptom)
• Diarrhea
• Abdominal pain and cramping
• Risk factors: Ingestion of raw beans, or beans cooked at low temperatures (such as in slow cookers or crockpots where water does not reach a rolling boil), which actually increases toxicity rather than destroying the lectin.
• Prevention: Proper preparation is critical to neutralize this toxin completely.
• Soak beans in water for at least five hours, discard the water.
• Boil the beans vigorously in fresh water for a minimum of thirty minutes. Slow cookers often fail to reach a high enough temperature to destroy phytohemagglutinin, leaving the lectin active and potent.