I agree. I once tried a special diet that restricted wheat, dairy (except ghee and butter) plus soy and corn.

I discovered that corn (a grain) was responsible for sharp pains in my right elbow and knee. Getting rid of wheat and dairy brought about better mental clarity. Now I'm finding that even rice is a problem for me!

Greens supposedly make the blood less acidic (raise blood pH). And a higher pH is supposed to make one less susceptible to disease.

Leafy vegetables can affect blood clotting, though. And some can promote kidney stones.