As we all know vitamin d is taken from sun how could we have much of it if at the same time sun have uva and uvb( which cause cancerous problems ) ?

Benefits > risks: It is the uvb rays that produce vitamin d. Yes, ultraviolet rays do increase the risk of certain skin cancers, but these tend to be the types that are easy to treat & cure; it does not increase risk of more serious melamona (if you avoid burns). Adequate d significantly reduces risk of many far more deadly cancers, like colon, breast, prostate, lung & pancreatic cancer. See my comment for more:.

Two effects: Ultraviolet light from the sun has both the helpful effect of producing vitamin d, and the unhealthy effect of causing cancer. Races originating near the equator have darker skin to protect from skin cancer and are at extra risk for rickets especially in higher latitudes. Races from higher latitudes lost the pigment to protect from rickets, and are more risk for skin cancer.