What Is Vitamin D?

What Is Vitamin D

Vitamin D and/or calciferol:- fat-soluble vitamin naturally present produced endogenously as ultraviolet (UV) rays from sunlight allows the synthesis of vitamin D in the human body.

What Is Biologically Inert Vitamin D

From sun exposure, foods, supplement derived vitamin D is biologically inert. Hence, for being absorbed and participating in metabolic phases of the body this inert vitamin D undergoes two hydroxylations in the body. 

These two steps of hydroxylation provide the active form of vitamin D. In the first hydroxylation, vitamin D converts to 25-hydroxyvitamin D [25(OH)D or calcidiol. 

The calcidiol conversion of vitamin D by the first hydroxylation occurs in the liver. 

It’s the second hydroxylation that forms the physiologically active form of vitamin D – i.e.- 1,25-dihydroxy vitamin D [1,25(OH)2D] or calcitriol. The calcitriol conversion occurs primarily in the kidney.

What Is Vitamin D3 

VitaminD3 - used as a dietary supplement of vitamin D

VitaminD3  aids in the absorption of calcium 

VitaminD3 is a ‘sunshine vitamin’ as it is produced naturally in the skin on sunlight exposure.

With sunlight, certain foods are also a good source of vitaminD3

Here it is important to mention that vitaminD3 is very notorious as it cleverly transforms into a hormone in the body. This hormone circulates in the bloodstream aiding in the absorption of calcium and phosphorus. It is not deniable that 99% of Vitamin D supply in our body is responsible for regulating calcium; while the remaining part is liable for strengthening the immune and muscular system.

What Is Deficiency Of Vitamin D? 

Vitamin D deficiency means that enough vitamin D to stay healthy is not consumed or metabolized in the body.

Vitamin D also helps the body to absorb calcium. As it is not deniable that Calcium is the main building block for bone. The role of Vitamin D is really important in the nervous, muscle, and immune systems as well. There are three ways to consume appropriate Vitamin D:- 

  • through your skin
  • from your diet
  • from supplements

It’s really important to know that natural sources of vitamin D – sunlight is not always a golden key for vitamin D regulation in the body as sun exposure can lead to skin aging and skin cancer. 

Therefore, vitamin D can be regulated to meet the requirements of boys especially in means of deficiency competency by other sources like food, supplements.

Causes Of Vitamin D Deficiency?

How can you become deficient in vitamin D – ([means inadequate Vitamin D in the body due to different reasons as enumerated below)]:

  1. Inadequate vitamin D in the diet.
  2. Not able to absorb adequate vitamin D from food – mainly due to malabsorption.
  3. exposure to sunlight is not enough.
  4.  liver or kidneys are not able to convert biologically inert vitamin D to its active form.
  5. Consumption of medicines can also interfere with the body's ability to convert or absorb vitamin D.

Who is at greater risk of vitamin deficiency:-

Following individuals are at higher risk of vitamin D deficiency:

  • Breastfed infants - human milk is a poor source of vitamin D
  • Older adults- aging inhibits skin ability to make vitamin D when exposed to sunlight, also kidneys are less able to perform the second step of hydroxylation in the aged body which again affects the conversion of vitamin D to its active form
  • Dark skin individuals have less ability to produce vitamin D by natural source i.e. sunlight
  • Disorders such as Crohn's disease or celiac disease affecting fat metabolism,  are associated with inadequate vitamin D because vitamin D needs fat for absorption.
  • Hindrance by obesity, as body fat, binds to vitamin D preventing it from getting into the bloodstream
  • gastric bypass surgery
  • osteoporosis
  • liver disease
  • Chronic kidney disease
  • hyperparathyroidism 
  • sarcoidosis, tuberculosis, histoplasmosis, or another granulomatous disease 
  • lymphomas, a type of cancer.
  • Consuming medicines that can interact and affect vitamin D metabolisms, such as cholestyramine (a cholesterol drug), anti-seizure drugs, glucocorticoids, antifungal drugs, and HIV/AIDS medicines.

Problems associated with inadequate vitamin D in the body:-

*signs and symptoms of vitamin D deficiency are-:

  • Fatigue
  • Bone pain
  • Muscle weakness
  • Mood changes

Vitamin D deficiency/inadequate vitamin D in the body can lead to:

- loss of bone density contributing  to osteoporosis and fractures (broken bones).

- Severe vitamin D deficiency can also lead to other diseases. 

- In children, vitamin D deficiency causes rickets. 

- inadequate vitamin D contributes to several medical conditions, including:-

  • Diabetes
  • High blood pressure
  • Cancer
  • Autoimmune conditions such as multiple sclerosis

Vitamin D – an essential requirement for strong bones as it helps in apt. metabolism of calcium from the diet. Traditionally, adequate vitamin D has always been the main cause for rickets. Though, rare inherited problems also cause rickets.

Rickets is a disease (affecting children) in which the less mineralize bone tissue leading to soft bones and skeletal deformities.

 Inadequate Vitamin D in a child's body does not allow absorption of calcium and phosphorus from food. This did not maintain proper calcium and phosphorus levels in bones, which is a good reason to cause rickets.

What helps in correcting Rickets:- Supplement of vitamin D or calcium to the diet corrects problems of bone in children with rickets. However, rickets due to underlying medical problems in children needs additional medications or other treatment. Also skeletal deformities caused by rickets at extensive phase require corrective surgery.

Similarly, rickets in children due to rare inherited disorders is related to low levels of phosphorus (a mineral component in the bone); and this is an acceptable reason to add other medications in the treatment regime of children with rickets.

Doses Of Vitamin D Required In Different Age Groups?

Vitamin D intake in the diet only accounts for a relatively low proportion (10 to 20 percent) of the vitamin D supply. A vitamin D deficiency is defined as a serum 25-hydroxyvitamin D level of < 30 nanomolar per liter of serum (30 nmol/l). 

Following are enumerated doses of VitaminD required at different age group:

Recommended dietary allowances of VitaminD for children

AgeMaleFemale
0-12 months*10 mcg
(400 IU)
10 mcg
(400 IU)
1–13 years15 mcg
(600 IU)
15 mcg
(600 IU)
14–18 years15 mcg
(600 IU)
15 mcg
(600 IU)

Recommended dietary allowances Vitamin D for adults

AgeMaleFemalePregnancyLactation
19–50 years15 mcg
(600 IU)
15 mcg
(600 IU)
15 mcg
(600 IU)
15 mcg
(600 IU

Vitamin D for elderly people

AgeMaleFemale
51–70 years15 mcg
(600 IU)
15 mcg
(600 IU)
>70 years20 mcg
(800 IU)
20 mcg
(800 IU)

What May Happen With An Overdose Of Vitamin D?

Side effects of Vitamin D:

Most commonly experience side effects with vitamin D that do not occur unless taken way too much unless too much.

Some side effects associated with overdose of vitamin D include:

  1. Weakness,
  2. Fatigue, 
  3. Sleepiness, 
  4. Headache, 
  5. Loss of appetite, 
  6. Dry mouth, 
  7. Metallic taste, 
  8. Nausea, 
  9. Vomiting,

Vitamin D Overdose problems

Vitamin D toxicity results in buildup of calcium in blood (hypercalcemia)- cause :-

  • Nausea 
  • Vomiting
  • Weakness
  • Frequent urination 

Vitamin D toxicity might progress to bone pain and kidney problems, such as the formation of calcium stones.

Treatment for vitamin D toxicity includes:

  1. Stopping vitamin D intake 
  2. Restricting dietary calcium. 
  3. Extreme conditions require intravenous fluids and medications, such as corticosteroids or bisphosphonates.