Vitamin D promotes intestinal calcium and phosphorous absorption and reduces urinary calcium loss, essential mechanisms for maintaining proper calcium levels in the body and for healthy bone composition. Vitamin D supports cardiovascular function in some individuals, which may be attributed to its effect on calcium metabolism or possibly by helping to maintain healthy plasma renin function. A role for vitamin D in supporting colon health by promoting healthy cellular function has also been suggested. Furthermore, vitamin D is believed to provide general cellular support potential, including for the breast and prostate, in part by helping to maintain healthy angiogenesis balance, supporting immune cell activity, and maintaining healthy cell metabolism. Vitamin D's role in immune health has long been established; vitamin D receptors are found on a number of immune cells, including lymphocytes and macrophages, supporting healthy immune cell activation.