Calories in Beans, Dry, Red (0% moisture)

What makes beans so powerful?

Red beans (a category that includes kidney beans) contain phytohaemagglutinin (PHA), a lectin that binds to carbohydrates on the surface of intestinal cells. PHA is among the most potent naturally occurring lectins in common foods. Raw red kidney beans can contain tens of thousands of hemagglutinating units per gram, while cooking at a full boil for just ten minutes is sufficient to degrade the lectin to safe levels. The danger arises when beans are cooked at sub-boiling temperatures—around 80°C (176°F)—as in a slow cooker set to low without first bringing the beans to a rolling boil. At those temperatures, PHA is not adequately destroyed, and ingestion of as few as four or five improperly cooked beans has been documented to cause nausea, vomiting, and diarrhea within hours. The U.S. Food and Drug Administration recommends soaking dry red beans for at least five hours, discarding the water, and then boiling them vigorously for at least ten minutes before any slow cooking. This is a rare case where a common pantry staple carries an acute toxicity risk tied directly to cooking method rather than contamination or spoilage.