Lectins

Lectins are carbohydrate-binding proteins found in many plant foods. They've become a popular villain in certain diet books, which claim they drive inflammation, damage the gut, and contribute to chronic disease. The one part of this that's genuinely true and worth knowing: raw or undercooked kidney beans contain a lectin called phytohaemagglutinin at levels high enough to cause real acute poisoning, with vomiting and severe stomach pain possible from just a handful of raw beans.

This is exactly why a slow cooker is the wrong tool for dried kidney beans — it doesn't reach the temperature needed to destroy the lectin. Proper hard boiling for at least ten minutes gets rid of it almost completely, and tinned beans are already safe to eat as is. Beyond this specific kidney bean issue, though, there's no good human evidence that lectins from normally cooked legumes and grains cause meaningful gut damage, body-wide inflammation, or bone loss in healthy people. Human studies actually link legume eating with lower cardiovascular death rates and neutral or better bone outcomes.

The bigger concern is what happens when lectin-avoidance becomes part of a broader pattern of cutting dairy, grains, legumes, nightshades, and leafy greens all at once. That kind of combined restriction can leave you low in calcium, protein, and fibre, and under-eating overall — and that combination does have real, solid evidence for harming bone. Before cutting any food, it's worth asking how big the effect really is, whether cooking handles it already, and what nutrients you'd lose by removing it.