Vitamin D belongs to the group of fat-soluble vitamins and is necessary for maintaining the homeostasis of calcium and phosphorus in the intestine and bones. One of its most basic roles is the protection of the musculoskeletal system and the absorption of calcium. 90% of vitamin D in our body comes from skin exposure to the sun while the remaining 10% is obtained through diet.
Main sources of vitamin D are:
Fatty fish (e.g. salmon, mackerel, sardines),
The yolk of the egg
Liver
Dairy etc.
Its deficiency causes bone disorders such as rickets and osteoporosis. Despite the fact that in Greece we have many hours of sunshine daily, a large percentage of the population is deficient in this particular vitamin. The main reasons may be the use of sunscreens with a high protection index (above 30) which prevents the formation of the vitamin on the skin, as well as staying in closed spaces for a long time, e.g. for work reasons.
The people most at risk of developing a deficiency are the elderly, people with limited exposure to sunlight, people with medical conditions that predispose to vitamin D deficiency such as patients with liver or kidney disease, people on medication, patients with malabsorption syndromes, dark-skinned people.