does calcium absorption increase or decrease when vitamin d is present in the small intestine
Vitamin D acts also to increase blood concentrations of calcium. It is generated through the activity of parathyroid hormone within the kidney. Far and away the most important effect of vitamin D is to facilitate absorption of calcium from the small intestine.In concert with parathyroid hormone, vitamin D also enhances fluxes of calcium out of bone. Calcitonin is a hormone that functions to reduce blood calcium levels.itamin D acts also to increase blood concentrations of calcium. It is generated through the activity of parathyroid hormone within the kidney. Far and away the most important effect of vitamin D is to facilitate absorption of calcium from the small intestine.