Vitamin D regulates the blood levels of Calcium and Phosphorus.It increases the absorption of these minerals from intestine and their deposition in bones.
Sources:
1- Fish liver oil
2- Milk
3- Ghee
4- Butter
Diseases:
1- Rickets in children
2- Osteomalacia in adults
Bone Mass Density - (the amount of calcium deposited in the bones) peaks at 30 and after this stage in life no further calcium can be deposited, it is therefore essential for children to get Vit D which aids Calcium absorption - to ensure a high BMD by age 30.
Vitamin D is a group of fat-soluble secosteroids. In humans, vitamin D is unique because it can be ingested as cholecalciferol (vitamin D3) or ergocalciferol (vitamin D2) and because the body can also synthesize it (from cholesterol) when sun exposure is adequate (hence its nickname, the "sunshine vitamin").
Although vitamin D is commonly called a vitamin, it is not actually an essential dietary vitamin in the strict sense, as it can be synthesized in adequate amounts by all mammals from sunlight. An organic chemical compound (or related set of compounds) is only scientifically called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from their diet. However, as with other compounds commonly called vitamins, vitamin D was discovered in an effort to find the dietary substance that was lacking in a disease, namely, rickets, the childhood form of osteomalacia. Additionally, like other compounds called vitamins, in the developed world vitamin D is added to staple foods, such as milk, to avoid disease due to deficiency.
Measures of serum levels (from a vitamin D3 blood test) reflect endogenous synthesis from exposure to sunlight as well as intake from the diet, and it is believed that synthesis may contribute generally to the maintenance of adequate serum concentrations. The evidence indicates that the synthesis of vitamin D from sun exposure works in a feedback loop that prevents toxicity but, because of uncertainty about the cancer risk from sunlight, no recommendations are issued by the Institute of Medicine, USA, for the amount of sun exposure required to meet vitamin D requirements. Accordingly, the Dietary Reference Intakes for vitamin D assume that no synthesis occurs and that all of a person's vitamin D is from their diet, although that will rarely occur in practice.
In the liver vitamin D is converted to calcidiol, which is the specific vitamin D metabolite that is measured to determine a person's vitamin D status. Part of the calcidiol is converted by the kidneys to calcitriol, the biologically active form of vitamin D. Both calcidiol and calcitriol were identified by Michael F. Holick. Calcitriol circulates as a hormone in the blood, regulating the concentration of calcium and phosphate in the bloodstream and promoting the healthy growth and remodeling of bone. Calcidiol is also converted to calcitriol outside of the kidneys for other purposes, such as the proliferation, differentiation and apoptosis of cells; calcitriol also affects neuromuscular function and inflammation.
Beyond its use to prevent osteomalacia or rickets, the evidence for other health effects of vitamin D supplementation in the general population is inconsistent. The best evidence of benefit is for bone health: and a decrease in mortality in elderly women.
Health effects of supplements
The effects of vitamin D supplementation on health are uncertain. A United States Institute of Medicine, (IOM) report states: "Outcomes related to cancer, cardiovascular disease and hypertension, diabetes and metabolic syndrome, falls and physical performance, immune functioning and autoimmune disorders, infections, neuropsychological functioning, and preeclampsia could not be linked reliably with calcium or vitamin D intake and were often conflicting.": Some researchers claim the IOM was too definitive in its recommendations and made a mathematical mistake when calculating the blood level of vitamin D associated with bone health. Members of the IOM panel maintain that they used a "standard procedure for dietary recommendations" and that the report is solidly based on the data. Research on vitamin D supplements, including large scale clinical trials, is continuing.
Vitamin D3 is made in the skin when 7-dehydrocholesterol reacts with ultraviolet light of UVB type at wavelengths between 270 and 300 nm, with peak synthesis occurring between 295 and 297 nm. These wavelengths are present in sunlight when the UV index is greater than three, as well as in the light emitted by the UV lamps in tanning beds (which produce ultraviolet primarily in the UVA spectrum, but typically produce 4% to 10% of the total UV emissions as UVB). At a UV index greater than three, which occurs daily within the tropics, daily during the spring and summer seasons in temperate regions, and almost never within the arctic circles, vitamin D3 can be made in the skin. Latitude does not consistently predict the average serum 25(OH)D level of a population. The assumption that vitamin D levels in the population follow a latitude gradient is especially questionable in view of surveys which have shown that UVB penetrating to the earth's surface over 24 hours during the summer months in northern Canada equals or exceeds UVB penetration at the equator. Accordingly, there is sufficient opportunity during the spring, summer, and fall months at high latitude for humans to form and store vitamin D3.
Depending on the intensity of UVB rays and the minutes of exposure, an equilibrium can develop in the skin, and vitamin D degrades as fast as it is generated.
The skin consists of two primary layers: the inner layer called the dermis, composed largely of connective tissue, and the outer, thinner epidermis. Thick epidermis in the soles and palms consists of five strata; from outer to inner they are: the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale. Vitamin D is produced in the two innermost strata, the stratum basale and stratum spinosum.
Cholecalciferol (D3) is produced photochemically in the skin from 7-dehydrocholesterol; 7-dehydrocholesterol is produced in relatively large quantities[clarification needed] in the skin of most vertebrate animals, including humans. The naked mole rat appears to be naturally cholecalciferol deficient, as serum 25-OH vitamin D levels are undetectable. In some animals, the presence of fur or feathers blocks the UV rays from reaching the skin. In birds and fur-bearing mammals, vitamin D is generated from the oily secretions of the skin deposited onto the feathers or fur and is obtained orally during grooming.
Source : Wikipedia.
Vitamin D is needed for absorption of calcium and chemistry. It helps put those minerals into our bones and teeth.
Vitamin D helps the body maintain a normal amount of calcium and phosphorus in your blood.
Vitamin D helps increase the absorption of Calcium
Vitamin D is the sunshine vitamin. It also assists with the proper absorption of calcium.
See the link below for details.
if your question is Why do i need vitamin D the answer would be your vitamin D levels in your blood are low or you do not get enough sunlight because vitamin D levels are linked to sunlight.
skin needs it
bones
Lipds
vitamin D will prevent rickets.
The only way to reduce vitamin D in the body is to stop intake of vitamin D.
Ultraviolet is needed for healthy skin growth. It is also needed to produce Vitamin d
vitamin d
Vitamin D is a fat based vitamin that is actually beyond beneficial in the absoprtion of some really important amino acids and substances that the body needs. To be more specific, Vitamin D helps the body absorb the needed calcium for bone strength as well as phosphorous.
Vitamin D and Calcium
vitamin d
vitamin D
Vitamin D is produced by ultraviolet radiation on your skin. The UV light converts a precursor molecule to vitamin D.
Vitamin D is a fat-soluble vitamin, meaning it is able to be dissolved in fat.
Calcium. Hence the reason it's often added to milk.