Limited sunshine in the northwest often leads to vitamin D deficiencies. Ever wonder how this vitamin operates in our bodies and what this nutrient does for us?

Activation of Vitamin D
Vitamin D itself is biologically inactive, and is metabolized to its biologically active forms. After it is consumed in the diet or synthesized in the skin from the sunshine, vitamin D enters the circulation and is transported first to the liver and then to the kidneys to be changed into a usable form.

Calcium Balance
Vitamin D is essential for the efficient utilization of calcium by the body. Blood calcium levels must be maintained within a narrow range for normal functioning of the nervous system, as well as for bone growth, and maintenance of bone density.

Cancer
Cells that are dividing rapidly are said to be proliferating. While cellular proliferation is essential for growth and wound healing, uncontrolled proliferation of cells with certain mutations may lead to diseases like cancer. The active form of vitamin D, inhibits proliferation and stimulates the differentiation of cells for healthy functions.

Immunity
There is considerable scientific evidence that Vitamin D has a variety of potent effects on immune system function that may enhance innate immunity and inhibit the development of autoimmunity.

Insulin Secretion
Limited data in humans suggests that low vitamin D levels may have an adverse effect on insulin secretion and glucose tolerance in type 2 diabetes.

Blood Pressure Regulation
Vitamin D is involved in the renin-angiotensin system that effects regulation of blood pressure. Since inappropriate activation of the renin-angiotensin system is thought to play a role in some forms of human hypertension, adequate vitamin D levels may be important for decreasing the risk of high blood pressure.

Deficiency
In vitamin D deficiency, calcium absorption cannot be increased enough to satisfy the body’s calcium needs. Consequently, parathyroid hormone production by the parathyroid glands is increased and calcium is borrowed from the skeleton to maintain normal serum calcium levels—a condition known as “secondary hyperparathyroidism”. Although it has long been known that severe vitamin D deficiency has serious consequences for bone health, recent research suggests that less obvious states of vitamin D deficiency are common and increase the risk of osteoporosis and other health problems.

Food sources
Vitamin D is found naturally in very few foods. Its found in some fatty fish (mackerel, salmon, sardines), fish liver oils, and eggs from hens that have been fed vitamin D. In the U.S., milk and infant formula are fortified with vitamin D, as well as some cereals, breads, & orange juice.

Vitamin D and Weight Loss Surgery
Because people who have had weight loss surgery can only consume small portions of food, supplementation with Vitamin D is essential to keep your body functioning optimally.

Supplementation
In an climate like ours so far from the equator and without sufficient sunlight, Vitamin D supplementation is necessary for nearly everyone to avoid complications associated with deficiency. Supplements are best absorbed when the vitamin is in the "D3" form rather than the lesser used and poorly absorbed "D2" form.

Source: Linus Pauling Institute http://lpi.oregonstate.edu/