Vitamin D – source, health benefits

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Vitamin-D- How it is formed

Vitamin D is fondly called the sunshine vitamin. It is a steroid hormone that is produced from cholesterol when the skin is exposed to sunlight. Then further changes happen in the kidneys to give final Vitamin D. 

Most people usually think exposing themselves to sunlight will provide adequate vitamin D, however, it is not sufficient. Vitamin D must be obtained through supplements or diet. 

It is also important to remember that only selected foods contain enough amount of sunshine vitamin. So, vitamin D deficiency is commonly prevalent among people. 

 Vitamin D – Its forms

  • Vitamin D is a fat-soluble vitamin. This vitamin can dissolve in oil or fat. The body can store it for a long time. 
  • There are two main dietary forms of vitamin D. They are 
  • Vitamin D3 and Vitamin D2 
  • Vitamin D3 is found in animal foods and fatty fish. Vitamin D2 is found in plants, fungi like mushrooms, and yeast
  • Within D2 and D3 vitamins, the latter is more efficient in raising vitamin D levels in the body. 

What does vitamin D do to the body? 

Vitamin D has to undergo two important steps to get active. Initially, vitamin D is converted to calcidiol in the liver. This converted form of the vitamin is the storage form. 

Next, the converted vitamin is further converted into calcitriol. This conversion largely happens in the kidneys. This converted form will become the active steroid hormone of vitamin D. 

The calcitriol combines with vitamin D present inside the cells which turn the gene on or off. 

Sunshine and vitamin D 

Vitamin D is produced from the cholesterol present in the body when the skin is exposed to sunlight.  

If a person lives in an area with abundant sunshine, they can get enough vitamin D through sunlight if they sun bath for a few minutes per week. 

It is also important to realise that exposing larger parts of the body will absorb more vitamin D compared to just exposing the hands and the face. Also, using protective accessories like sunscreen or sunglasses will make the body absorb less vitamin D to none. 

Striking a balance is essential if a person is exposed for extended periods to sunshine sunscreen will be mandatory because sunburns can cause premature skin ageing and will also increase the chances of developing skin cancer. 

Vitamin D can be stored in the body for a long time, and hence occasional sunshine is adequate to keep the vitamin level within an optimal range. 

If a person resides in an area without enough sunlight, then getting vitamin D from food or supplements is necessary. 

Limiting factors that affect how much vitamin D is absorbed through sunlight. They are as follows:

  •  Season
  • Location
  • Time and
  • Melanin

The season is important because absorbing sunlight depends on where a person lives. If the UV rays do not reach the earth due to the ozone layer, less vitamin D is absorbed. 

Location is also an important factor, as cities that are located near the equator region will have higher exposure to ultraviolet rays. This can cause the skin to produce more vitamin D. 

The time of the day when sun rays or most powerful can increase vitamin D production in the body. Ultraviolet rays are most powerful between 10 AM and 3 PM if there are no cloud covers or air pollution. 

Melanin present in the skin is a brown-coloured pigment that is required to get enough from the sun. 

Food sources of vitamin D 

Vitamin D is not a natural occurrence in any food. This is one of the reasons why vitamin D is additionally added in many commercially sold products. 

It would be difficult for vegans to obtain enough vitamin D from their diet. This is the reason why many people opt for supplements. Consuming a variety of healthy food is important. 

Some of the foods high in vitamin D content or as follows: 


FoodVitamin D (IUs) per serving ( Approx)
Cod liver oil, 1 tablespoon1300+
Tuna fish130+
Orange juice120+
Milk– fortified110+
Sardine fish40+
Egg yolk, 1 large40+
Cereal, fortified with vitamin D30+
Swiss cheese5

The values in the table are approximate. The IU differs based on the quality of the food and the size of the serving. 

Role of vitamin D for various body functions

The role of vitamin D is not restricted to disease prevention. Various studies conducted on people show a strong connection between vitamin D and lower rates of a few diseases which affect people in colder regions. 

 Strong bones 

Vitamin D plays an important role in making the bones healthy. This vitamin helps with calcium absorption and maintains an adequate level of calcium in the blood. 

Vitamin D is also helpful with bone mineralisation. If there is an inadequate level of vitamin D in the body, it causes rickets in children. 

Vitamin D can soften the bones in adults and children, which leads to Osteomalacia and Osteoporosis. For elderly people Vitamin D requirement is high. So older adults need compulsory Vitamin D supplementation to avoid fractures and disability. 

Immune function 

  Vitamin D supports good immune function in the body and reduces the risk of various autoimmune diseases. Various researches revealed that vitamin D plays a crucial role in building immune functions. There is a prevalent belief that there may be a link between vitamin D deficiency and autoimmune conditions. 

Predisposing for certain diseases 

If the body is deprived of this vitamin for the long term, it can cause health issues like Diabetes, Asthma, Rheumatoid Arthritis, and other related problems. 

Cancer prevention 

The activated form of vitamin D in the body can exhibit chemoprophylactic action and have chemo preventive effects. These properties of vitamin D can prevent the growth of cancerous breast cells and reduce the chances of developing cancer.

Symptoms of vitamin D deficiency

Mostly, Vitamin D deficiency does not cause symptoms. In some cases, when the body is short of this vitamin, it may exhibit the following symptoms:

What are the health benefits of vitamin D? 

Our body has a natural way of fighting against infections. It is called the immune system. This auto-immune response will help the body fight against foreign agents present in the body that causes infections. 

Vitamin D plays an important role in strengthening the immune system. Vitamin D will also help promote intestinal calcium absorption, maintaining adequate calcium levels in the blood. This is responsible for bone mineralisation. 

Vitamin D is believed to prevent certain types of cancer. Further research is required to prove such claims. 

If vitamin D is deficient in children, it can cause rickets. Consuming enough vitamin D will help with bone mineralisation and prevent the risk of developing bone-related issues like Rheumatoid Arthritis. 

It is also believed that vitamin D can help lower blood pressure and keep it at an optimum level. 

What are the risks of vitamin D? 

The maximum intake healthcare professionals recommend per day is approximately 4000 IU per day for an average healthy adult. 

If there is any toxicity, it is because of inappropriate dozing or description errors. 

Excessive consumption of vitamin D can lead to Hypercalcemia. Hypercalcemia is a condition where there is an extremely high blood calcium level in the body. 

Too much vitamin D consumption can lead to 

Choosing supplements carefully with proper supervision is recommended as various manufacturers sell supplements with various doses. 

How to treat deficiency of vitamin D? 

  • Eat vitamin D rich foods. Food can be obtained from plant sources and animal sources. Mushrooms are good plant sources that provide vitamin D to the body.   Animal sources like egg yolks, fatty fish, yoghurt, beef, liver, fortified cereals, and fortified milk are good options. 
  • By nature, Sunlight is a rich source of vitamin D. A doctor may also recommend going out often to improve vitamin D production in the body. 
  • Oral supplements are the standard treatment prescribed by doctors for vitamin D deficiency. The supplements are available over-the-counter, but the doctor’s recommendation is advised. 

To sum up 

Vitamin D offers various health benefits. It may even reduce the risk of certain diseases and helps improve a person’s mood and reduce various symptoms associated with depression. 

It can also assist with weight management. It is difficult for anyone to get vitamin D only through diet, so, under medical supervision, they can consume supplements. 

When there is less vitamin D in the body, it may lead to various problems. Therefore, maintaining an optimal level of vitamins in the body is mandatory. 


1. What does vitamin D do? 

Vitamin D helps the body to regulate the amount of calcium and phosphate. Such nutrients are required to keep the bones healthy. 

2. What happens when vitamin D is low? 

When the body is deficient in vitamin D, it can lead to loss of bone density causing fractures and causing Osteoporosis. 

3. How can I boost my vitamin D?

Vitamin D can be increased by consuming foods like Salmon, cod liver oil, mushrooms, egg yolks, sardines, and fortified products. It can also be acquired through supplements. 

4. Is it good to take vitamin D every day? 

Vitamin D requirement varies for each individual in different stages of their life. Growing children, pregnant mothers, and the elderly require a higher dose. So always consult a physician before taking Vitamin D doses.

5. Which plant food sources are rich in vitamin D? 

Oranges are rich in vitamin D. Mushrooms. Cut the mushrooms into thin slices, and expose them to sunlight for some time. This will increase their Vitamin D content.

6. What is the main benefit of vitamin D?

Vitamin D serves various important functions in the body, with the main function regulating the absorption of calcium and other minerals. 

7. Who is at risk of vitamin D deficiency? 

For most adults, vitamin D deficiency is not the prime concern. However, some people who are obese have a darker shade of skin and are older than 65 years, and have lower vitamin D. 
People who are not exposed to the sun and have a poor diet are also at the risk of having vitamin D deficiency. 

8. How do you prevent vitamin D overdose? 

Usually, vitamin D overdose is very rare. Hence always take vitamin D supplements under proper supervision as there are different doses of vitamin D available in the market. 


The Information including but not limited to text, graphics, images and other material contained on this blog are intended for education and awareness only. No material on this blog is intended to be a substitute for professional medical help including diagnosis or treatment. It is always advisable to consult medical professional before relying on the content. Neither the Author nor Star Health and Allied Insurance Co. Ltd accepts any responsibility for any potential risk to any visitor/reader.

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