Vitamin D is both a nutrient we eat and a hormone
our bodies make. It is a fat-soluble vitamin that
has long been known to help the body absorb
And retain calcium and phosphorus; both are
critical for building bone. Also, laboratory studies
show that vitamin D can reduce cancer cell growth,
help control infections and reduce inflammation.
Many of the body’s organs and tissues have
receptors for vitamin D, which suggest important
roles beyond bone health, and scientists are actively
investigating other possible functions.

Vitamin D helps regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones, teeth and muscles healthy. A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain caused by a condition called osteomalacia in adults. Vitamin D helps your body absorb calcium. Calcium is one of the main building blocks of bone. Vitamin D also has a role in your nerve, muscle, and immune systems. Vitamin D has other roles in the body, including reduction of inflammation as well as modulation of such processes as cell growth, neuromuscular and immune function, and glucose metabolism. Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by vitamin D. Many tissues have vitamin D receptors, and some convert 25(OH) D to 1, 25(OH) 2D.

The role of vitamin D in disease prevention is a popular area of research, but clear answers about the benefit of taking amounts beyond the RDA (Recommended Dietary Allowance) are not conclusive. Although observational studies see a strong connection with lower rates of certain diseases in populations that live in sunnier climates or have higher serum levels of vitamin D, clinical trials that give people vitamin D supplements to affect a particular disease are still inconclusive. This may be due to different study designs, differences in the absorption rates of vitamin D in different populations, and different dosages given to participants.

Vitamin D (also referred to as “calciferol”) is a fat-soluble vitamin that is naturally present in a few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet (UV) rays from sunlight strike the skin and trigger vitamin D synthesis.

Vitamin D3 can be formed when a chemical reaction occurs in human skin, when a steroid called 7-dehydrocholesterol is broken down by the sun’s UVB light or so-called “tanning” rays.

The amount of the vitamin absorbed can vary widely. But despite the importance of the sun for vitamin D synthesis, limiting skin exposure to sunlight and UV radiation from tanning beds is prudent. UV radiation is a carcinogen, and UV exposure is the most preventable cause of skin cancer. Federal agencies and national organizations advise taking photo protective measures to reduce the risk of skin cancer, including using sunscreen with a sun protection factor (SPF) of 15 or higher, whenever people are exposed to the sun. Sunscreens with an SPF of 8 or more appear to block vitamin D-producing UV rays. In practice, however, people usually do not apply sufficient amounts of sunscreen, cover all sun-exposed skin, or reapply sunscreen regularly. Their skin probably synthesizes some vitamin D, even with typically applied sunscreen amounts.

The following are conditions that decrease exposure to UVB light and therefore lessen vitamin D absorption:

• Use of sunscreen; correctly applied sunscreen can reduce vitamin D absorption by more       than 90%.         
• Wearing full clothing that covers the skin.
• Spending limited time outdoors.
• Darker skin tones due to having higher amounts of the pigment melanin, which acts as a type of natural sunscreen.
• Older ages when there is a decrease in 7-dehydrocholesterol levels and changes in skin, and a population that is likely to spend more time indoors.

VITAMIN D DEFICIENCY
Vitamin D deficiency means that you do not have enough vitamin D in your body. Vitamin D is unique because your skin actually produces it by using sunlight. Fair-skinned individuals and those who are younger convert sunshine into vitamin D far better than those who are darker-skinned and over age 50. Getting enough vitamin D may also play a role in helping to keep you healthy by protecting against the following conditions and possibly helping to treat them.These conditions can include:

• Heart disease and high blood pressure.
• Diabetes.
• Infections and immune system disorders.
• Falls in older people.
• Multiple sclerosis.
• Some types of cancer, such as colon, prostate 

And breast cancers.

Vitamin D deficiency can result from inadequate exposure to sunlight; malabsorption; accelerated catabolism from certain medications; and, in infants, the minimal amount of vitamin D found in breast milk. Vitamin D deficiency can lead to a loss of bone density, which can contribute to osteoporosis and fractures (broken bones). Severe vitamin D deficiency can also lead to other diseases. In children, it can cause rickets. Rickets is a rare disease that causes the bones to become soft and bend.

CAUSES OF DEFICIENCY
You can become deficient in vitamin D for different reasons:

• You don’t get enough vitamin D in your diet
• You don’t absorb enough vitamin D from food (a malabsorption problem)
• You don’t get enough exposure to sunlight.
• Your liver or kidneys cannot convert vitamin D to its active form in the body.
• You take medicines that interfere with your body’s ability to convert or absorb vitamin D

WHO IS AT RISK?
Some people are at higher risk of vitamin D deficiency:

• Breastfed infants, because human milk is a poor source of vitamin D. If you are breastfeeding, give your infant a supplement of 400 IU of vitamin D every day.
• Older adults, because your skin doesn’t make vitamin D when exposed to sunlight as efficiently as when you were young, and your kidneys are less able to convert vitamin D to its active form.
• People with dark skin, which has less ability to produce vitamin D from the sun.
• People with disorders such as Crohn’s disease or celiac disease who don’t handle fat properly, because vitamin D needs fat to be absorbed.
• People who have obesity, because their body fat binds to some vitamin D and prevents it from getting into the blood.
• People who have had gastric bypass surgery
• People with osteoporosis
• People with chronic kidney or liver disease.
• People with hyperparathyroidism (too much of a hormone that controls the body’s calcium level)
• People with sarcoidosis, tuberculosis, histoplasmosis, or other granulomatous disease (disease with granulomas, collections of cells caused by chronic inflammation)
• People with some lymphomas, a type of cancer.
• People who take medicines that affect vitamin D metabolism, such as cholestyramine (a cholesterol drug), anti-seizure drugs, glucocorticoids, antifungal drugs, and HIV/AIDS medicines

RISK FACTORS
Various factors can increase the risk of a deficiency.

1. Diet: People who do not eat enough vitamin D-rich foods, including fortified dairy products and cereals, may have low levels of vitamin D.
2. Lifestyle factors: Some people spend little time outdoors due to work, ill health, a lack of outdoor space in their neighbourhood, or other factors. These people have less opportunity to expose their skin to sunlight. Those who wear clothes that cover all of their body, whether to protect it from the sun or for cultural or religious reasons, may also have a higher risk of a deficiency.

• Geographical factors: People living in certain parts of the word — Northern Canada and Alaska, for example — may have less access to the sun’s UVB rays, especially in winter. People who live in a hot climate may also be at risk, as they often try to avoid the heat and strong sunlight by staying indoors.
• Pollution: Particles in the air can block UVB rays and prevent them from reaching the skin. People who live in highly polluted areas may also be more likely to avoid spending time outside.
• Medications: Some drugs Trusted Source reduce the body’s ability to absorb or synthesize vitamin D. These include steroids and some drugs for lowering cholesterol, among others.
• Smoking: Levels of deficiency appear to be higher among smokers Trusted Source. Some experts have suggested that smoking may affect the gene that activates the production of vitamin D-3 in the body
• Age: The ability to convert vitamin D to calcitriol may decline with age Trusted Source due to decreased kidney function. As a result, calcium absorption will fall.
• Pregnancy: The need for vitamin D may increase during pregnancy, but experts remain unsure whether supplements are a good idea. The authors of a 2019 Cochrane review concluded that taking supplements during pregnancy may reduce the risk of preeclampsia, gestational diabetes, low birth weight, and severe bleeding after delivery. However, it may also increase the risk of preterm birth, which is birth before 37 weeks. The authors called for further research.
• Breastfeeding infants: Human milk is low in vitamin D, which means that breastfeeding infants are at risk of a deficiency. The Centres for Disease Control and Prevention Trusted Source (CDC) recommend giving a vitamin D supplement to all breastfeeding infants from the first few days of life until they consume 1 l or more of formula milk each day. Supplementation becomes unnecessary at this point because formula milk contains added vitamin D.

Individuals should talk to their doctor about their vitamin D needs and how to increase their intake. Some people may need to take supplements, but it is best to talk to a doctor before doing so, as some can have adverse effects. The doctor will also provide advice on a suitable dosage.

NATURAL SOURCE OF VITAMIN D
Here are 7 effective ways to increase your vitamin D levels:

1. – Vitamin D is often referred to as “the sunshine vitamin” because the sun is one of the best sources of this nutrient. Your skin hosts a type of cholesterol that functions as a precursor to vitamin D. When this compound is exposed to UV-B radiation from the sun, it becomes vitamin D. In fact, sun-derived vitamin D may circulate for twice as long as vitamin D from food or supplements.

          However, the amount of vitamin D your body can make depends on several variables.

• – Fatty fish and seafood are among the richest natural food sources of vitamin D. The exact vitamin D content of seafood may vary depending on the type and species in question. For example, some research suggests that farmed salmon may contain only 25% of the amount of wild-caught salmon. Other kinds of fish and seafood rich in vitamin D include: TUNA, MACKEREL, OYSTERS, SHRIMP, SARDINES, and ANCHOVIES. Many of these foods are also rich in heart-healthy omega-3 fatty acids.

3.  Eat more mushrooms- Mushrooms are the only vegetarian source of vitamin D. Like humans, mushrooms can make their own vitamin D upon exposure to UV light. Humans produce a form of vitamin D known as D3 or cholecalciferol, whereas mushrooms produce D2 or ergocalciferol. Both forms of this vitamin can raise circulating vitamin D levels, though research suggests that D3 may raise levels more effectively and efficiently than D2 .Due to their exposure to sunlight, wild mushrooms usually have more vitamin D than commercially grown types. However, you can also purchase mushrooms treated with UV light.

4. Include egg yolks in your diet- Egg yolks are another source of vitamin D that you can easily add to your routine. Like many other natural food sources, yolks have variable vitamin D content. Chicken feed can also affect the vitamin D content of eggs. Those fed vitamin-D-enriched grain may produce yolks that boast well over 100% of the RDI

5. Eat Fortified Food- Because few foods naturally contain high levels of vitamin D, this nutrient is often added to staple goods in a process known as fortification. Still, you should keep in mind that the availability of vitamin-D-fortified foods varies by country, and the amount added to foods may differ by brand and type.

Some commonly fortified goods include:

• cow’s milk
• plant-based milk alternatives

Like soy, almond, and hemp milk

• orange juice
• ready-to-eat cereals
• certain types of yogurt
• tofu

6. Take a supplement- For many people, taking a vitamin D supplement may be the best way to ensure adequate intake. Vitamin D exists in two main biological forms — D2 (ergocalciferol) and D3 (cholecalciferol). Typically, D2 comes from plants and D3 from animal’s .Research suggests that D3 may be significantly more effective at raising and maintaining overall vitamin D levels than D2, so look for a supplement with this form.

7. Try a UV lamp- Lamps that emit UV-B radiation may also boost your vitamin D levels, though these lamps can be costly. When your skin is exposed to UV-B radiation from the sun, it’s able to produce its own vitamin D. UV lamps mimic the action of the sun and can be especially helpful if your sun exposure is limited due to geography or time indoors.