Vitamin D is the only vitamin that can be synthesized in significant amounts in the human body. It is a steroid vitamin, which represents a group of fat soluble prohormones that are crucial in the absorption and metabolism of minerals like Calcium and Phosphorus.
Till date five types of Vitamin D have been isolated, among which only two are of any significance to us . They are vitamins D2 (ergocalciferol) and vitamin D3 (cholecalciferol).
It is present in variable amounts in different food items but can also be synthesized endogenously by the human body, on prolonged exposure to sunlight
The most important physiological function of Vitamin D is to regulate the serum calcium levels in the blood and bone. It along with parathyroid hormone helps in calcium absorption and bone resorption . Calcium is extremely crucial for the overall bone and teeth development. Higher levels of calcium during early years of life contribute to peak bone mass that can protect against fractures at an older age. Vitamin D also maintains muscle strength by regulating calcium levels in the system.
Consequently Vitamin D deficiency leads to bone demineralization which can ultimately severely debilitating conditions like Rickets in children and Osteomalacia or Osteoporosis in adults. Incidentally maternal Vitamin D levels during pregnancy positively affects the bone growth of the child and can minimize the chances of getting osteomalacia later on in life.
Vitamin D is also extremely crucial in preventing fractures of several kinds. Several clinical trials have clearly shown adequate Vitamin D levels drastically reducing the chances of acquiring vertebral as well as non- vertebral fractures later on in life.
Non Skeletal Functions-
Not only does it play a pivotal role in bone- health maintenance and calcium metabolism, it also prevents several life threatening diseases like type 1 diabetes mellitus , multiple sclerosis , rheumatoid arthritis, several infectious diseases and even cancer.
Vitamin D deficiency can affect the formation of red blood cells in the bone marrow , ultimately resulting in the formation of reduced, inactive and immature RBC which can precipitate anemia.
Vitamin D & Cancer- Vitamin D deficient people are more likely to get breast , colon and prostate cancer. Calcitrol, enzyme responsible for Vitamin D synthesis in the body, is found to suppress proliferation of cankerous cells.
Apart from these Vitamin D boosts the overall immunity of an individual and it reduces the risk of acquiring chronic diseases like tuberculosis and rheumatoid arthritis
Sources of Vitamin D.
Apart from exposure to sunlight , there are a few food sources that can meet the Vitamin D requirements of an individual.
Very few foods in nature contain vitamin D. The flesh of fatty fish (such as salmon, tuna, and mackerel)and fish liver oils are among the best sources . Small amounts of vitamin D are found in beef liver, cheese, and egg yolks. Vitamin D in these foods is primarily in the form of vitamin D3 and its metabolite 25(OH)D3 . Some mushrooms provide vitamin D2 in variable amounts . Mushrooms with enhanced levels of vitamin D2 from being exposed to ultraviolet light under controlled conditions are also available.
Fortified foods provide most of the vitamin D in the American diet For example, almost all of the U.S. milk supply is voluntarily fortified with 100 IU/cup . (In Canada, milk is fortified by law with 35–40 IU/100 mL, as is margarine at ≥530 IU/100 g.) In the 1930s, a milk fortification program was implemented in the United States to combat rickets, then a major public health problem . Other dairy products made from milk, such as cheese and ice cream, are generally not fortified. Ready-to-eat breakfast cereals often contain added vitamin D, as do some brands of orange juice, yogurt, margarine and other food products.
Both the United States and Canada mandate the fortification of infant formula with vitamin D: 40–100 IU/100 kcal in the United States and 40–80 IU/100 kcal in Canada.
Effects Of Vitamin D deficiency –
Today people less time in the sun , than ever in the history of mankind. As a result more than a billion people, currently are suffering from Vitamin D deficiency.
Its deficiency symptom can vary from joint pain to diabetes. Its deficiency is associated with cardiovascular diseases, type 2 diabetes mellitus , cancer and osteomalacia or osteoporosis in adults.
During pregnancy and menopausal period women are advised to intake extra vitamin D to prevent loss of bone mass and osteoporosis development .
Classical representation Vitamin D deficiency in children is Rickets, a condition in which bones are highly weakened and fragile because of lack of calcium and phosphate which can ultimately precipitate several life threatening skeletal deformities