

Vitamin D is a group of fat-soluble secosteroids that stimulates calcium, magnesium, and phosphate absorption in the gut, among other functions. Vitamin D3, also known as cholecalciferol, and vitamin D2, known as ergocalciferol, are the two most significant molecules in this category in humans.
Vitamin D, despite its name, is a prohormone, or a hormone precursor, rather than a vitamin. Vitamins are nutrients that the body cannot produce and must be obtained via food. Vitamin D, on the other hand, could well be produced by the body. Vitamin D is found naturally in a few foods, it is also available as a nutritional supplement. Intracellular production of vitamin D occurs when ultraviolet (UV) photons from sunshine strike the skin and initiate vitamin D synthesis.
Vitamin D Function

Vitamin D aids calcium absorption in the stomach and keeps blood calcium and phosphate levels in check, allowing for proper bone mineralization and preventing hypocalcemic tetany. Hypocalcemic tetany is an involuntary contraction of muscles, which leads to cramps and spasms. Vitamin D is required for the intestines to activate, absorb, and reclaim calcium that the kidneys would otherwise eliminate. It is also required for osteoblasts and osteoclasts to build and repair bone, bones can even grow brittle if they do not get enough vitamin D.
Other functions of vitamin D in the body include inflammation reduction and regulation of cell development, neuromuscular and immunological function, and glucose metabolism. Vitamin D influences the expression of several genes that code for proteins that control cell proliferation, differentiation, and death.
Recent studies also show that Vitamin D aids in the identification of “friendly” cells, avoiding the over-reaction that causes auto-immune illnesses including type 1 diabetes, inflammatory bowel disease, and multiple sclerosis.
Vitamin D Deficiency

Despite the body’s ability to make vitamin D naturally, many conditions can lead to vitamin D deficiency. In fact, up to 50% of the world’s population may be low in vitamin D, and 40% of Americans are vitamin D deficient. The ability of the body to absorb ultraviolet radiation B (UVB) rays from the sun can be reduced by skin type and sunscreen. Because the skin’s ability to produce vitamin D reduces with age, older persons are more likely to acquire vitamin D deficiency. Furthermore, elderly folks are more inclined to spend more time indoors than younger people, and they may have insufficient vitamin D dietary intake. People who live in polluted regions, work night shifts, or are homebound should try to get their vitamin D from dietary sources as much as possible. Vitamin D supplements are also recommended for exclusively breastfed infants, especially if they receive little sun exposure.

Vitamin D deficiency in adolescents can result in rickets, which causes the bones to weaken and cause a severely bow-legged appearance. In adults, vitamin D insufficiency causes osteomalacia or bone weakening. Osteomalacia causes muscle weakness and low bone density. A lack of vitamin D can also lead to osteoporosis, which affects approximately 53 million people in the United States.
In children, vitamin D deficiency has been linked to elevated blood pressure. A 2018 study discovered a possible link between low vitamin D levels and stiffness in children’s artery walls. Evidence suggests a link between inadequate vitamin D exposure and an increased risk of allergy reactivity, according to the American Academy of Allergy, Asthma, and Immunology.
Sources of Vitamin D

Vitamin D intake may also be increased by eating particular foods or taking supplements. Fish liver oils and the meat of fatty fish are among the finest sources of Vitamin D. Salmon is a renowned fatty fish that also happens to be a good source of vitamin D. One 100-gram serving of farmed Atlantic salmon contains 526 IU of vitamin D, or 66 per cent of the Daily Value, according to the United States Department of Agriculture Food Composition Database. Other fatty fish sources include trout, tuna, and mackerel.
The quantity of vitamin D in an animal’s tissues is influenced by its food. Vitamin D is found in tiny levels in beef liver, cheese, and egg yolks. Vitamin D2 is found in varying quantities in mushrooms. Some commercially available mushrooms have been exposed to UV radiation to boost their vitamin D2 levels. In addition, the Food and Drug Administration (FDA) has authorized UV-treated mushroom powder as a food additive for use in food items as a source of vitamin D2.
Vitamin D pills are recognized as the best approach to acquire vitamin D during the winter seasons when sunshine exposure is limited. The two types of vitamin D supplements are D2 and D3. While there is no general agreement on which form is best for your health, multiple research suggests that vitamin D3 is the more bioavailable and bioactive form. Supplements are measured in international units (IU), and 400, 500, 600, and 1000 IU pills are commonly sold in bottles. Vitamin D levels in multivitamins are usually between 200 and 600 IU.
The skin can create adequate vitamin D by exposing the hands, face, arms, and legs to sunshine 2-3 times per week. The amount of time you need to be exposed varies according to your age, skin type, season, day of the week, and other factors. Six days of solar exposure without applying sunscreen can compensate for 49 days of no sun exposure. A sunscreen with a sun protection factor (SPF) of 30 can prevent the body from synthesizing the vitamin by up to 95%. Vitamin D production can also be inhibited by covering the skin with clothes.
For an adult, the highest amount recommended by healthcare specialists is 4,000 IU per day. However, vitamin D toxicity, according to the National Institutes of Health (NIH), is rare at doses below 10,000 IU per day. Headache and nausea are two of the most frequent symptoms of too much vitamin D. Too much vitamin D, on the other hand, can cause a lack of appetite, dry mouth, vomiting, constipation, and diarrhoea.
