Excerpt from Healthy Diet and Nutrition for Women
This fat-soluble vitamin can either be ingested in the diet or formed on the skin by exposure to sunlight. Sunlight activates a type of cholesterol found in the skin, converting it to vitamin D. Vitamin D is usually included in multivitamin products and is also found in fish liver oil supplements, along with vitamin A and fortified milk.
Vitamin D helps prevent osteoporosis by aiding in the absorption of calcium from the intestinal tract. It is needed for the synthesis of enzymes found in mucous membranes, which are, in turn, needed for the active transport of calcium. It also helps break down and assimilate phosphorus. A deficiency of vitamin D causes inadequate absorption of calcium from the intestinal tract and retention of phosphorus by the kidneys. This causes an imbalance in the calcium-phosphorus ratio, leading to faulty mineralization of the bones.
Preliminary human studies as well as laboratory and animal studies suggest that vitamin D may be protective against some cancers. Similarly, vitamin D may also help to prevent the development of autoimmune diseases.
I recommend taking supplemental vitamin D in a dosage of 1000-2000 IU per day. Menopausal women may need as much as 5000 IU per day of vitamin D. Food sources of vitamin D include fish like mackerel, sockeye salmon, sardines, tuna, herring, catfish, cod liver oil, and egg yolks.autoimmune disease, calcium absorption, cancer, menopause, osteoporosis, vitamin D