Vitamin D: Deficiency, Symptoms And Treatment

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Vitamin D, also known as calciferol or the ‘sunshine Vitamin’ is a fat-soluble nutrient that can be synthesized by the human body with the help of sunlight. It is essential to the body as it helps protect it from a wide range of diseases and weaknesses, besides promoting overall bone health. Vitamin D is also necessary for promoting intestinal absorption of calcium, magnesium, and phosphate. Known to act as a steroid hormone in our body, Vitamin D is present in the human body in two forms — D2 and D3. Vitamin D2 is obtained from human-made, plant-based supplements, while Vitamin D3 is what our skin synthesizes using sunlight and we can also obtain it from certain animal food sources. Doctors recommend an intake of at least 800-1200 IU or 10-20 micrograms of Vitamin D per day in order through sunlight, plant sources, animal sources, or supplementation. Vitamin D deficiency has many side effects on the body. Studies have found 80-90% of the Indian population to be deficient in Vitamin D, which is an alarming number. Let us understand what causes Vitamin D deficiency in our body, how can we identify we are deficient, and what steps can be taken to overcome it?

Why Our Body Needs Vitamin D

Our body needs Vitamin D to maintain normal body functioning, proper growth, and development. Some of the important functions that are affected by Vitamin D include: 

  • Vitamin D helps in the regulation of phosphorus and calcium, both of which play a major role in promoting the healthy growth of bones and teeth. The deficiency of which, can lead to rickets, a condition wherein a person may develop bow-leggedness.
  • Studies have linked increased levels of Vitamin D to a reduced risk of individuals contracting influenza, commonly known as the flu.
  • Vitamin D also helps in regulating the immune system, as well as, promoting nervous health.
  • Vitamin D is important for maintaining cardiovascular health and proper lung function
  • Consumption of Vitamin D is also advantageous to pregnant women as it helps keep their bones healthy and facilitates proper structural development of the fetus. 
  • Research has associated higher levels of Vitamin D with the prevention of cancer development.  
  • Lack of Vitamin D could also make individuals prone to Type 1 and 2 Diabetes. This is why it is important to ensure that our body gets a healthy intake of Vitamin D every day.

Vitamin D Deficiency 

Vitamin D deficiency is commonly caused by an inadequate intake of Vitamin D rich foods and lack of exposure to sunlight. There are certain groups that are at a higher risk of developing this deficiency.  


The following factors have been observed as common reasons for developing Vitamin D:

Limited Exposure To Sun: People who tend to stay indoors more than usual with limited exposure to sunlight have been observed to have lower levels of Vitamin D in their bodies. This is common among housewives, the elderly, and working adults. 

Inadequate IntakeStudies have shown inadequate or no intake of Vitamin D through food for prolonged periods of time to be one of the most common reasons for the development of a Vitamin D deficiency. 

Obesity: While obesity is not a direct cause for Vitamin D deficiency, studies have shown that individuals with a BMI higher than 30 required more Vitamin D. It was also recorded that those who had undergone gastric bypass surgery, also suffer from this deficiency. This is because the part of the small intestine that absorbs and synthesizes Vitamin D is bypassed in this surgery as a result of which the body cannot absorb enough Vitamin D from the food.

Dark Skin: People with higher melanin levels in their skin, i.e those with a darker skin tone,  absorb less Vitamin D from sunlight as compared to those with a fairer skin tone. 

Aging: Older adults have lesser Vitamin D in their bodies. This happens because the body experiences a slowdown in the synthesis of Vitamin D as the cells age. Older adults are also usually indoors, due to which they have limited exposure to sunlight, causing a Vitamin D deficiency.

SmokingStudies have also observed that individuals who smoke were at a higher risk of developing a Vitamin D deficiency. 

Other Factors Include

  • People who live in countries away from the equator with lesser exposure to the sun, are often Vitamin D deficient. 
  • Pregnant women are seen to experience low levels of Vitamin D
  • Poor liver and kidney health
  • Hormonal changes due to medication, affliction to cystic fibrosis/Crohn’s disease, and lifestyle choices cause a limited exposure of the skin to the sun. 

Left unchecked, a Vitamin D deficiency can lead to serious complications in the long run. The most critical of which is hypocalcemia — a condition where the body has too little calcium, due to which it becomes extremely fragile, brittle, and prone to damage.  

Given below is a chart that explains the recommended intake level as per the age of the individual:

Life Stage Recommended Amount
Birth to 12 months 10 mcg (400 IU)
Children 1–13 years 15 mcg (600 IU)
Teens 14–18 years 15 mcg (600 IU)
Adults 19–70 years 15 mcg (600 IU)
Adults 71 years and older 20 mcg (800 IU)
Pregnant and breastfeeding women 15 mcg (600 IU)

Symptoms of Vitamin D Deficiency

While there are no concrete symptoms that are universally indicative of Vitamin D deficiency, studies have shown that the following changes exhibited by the body could be warning signs of the same:

  • Osteoporosis: It has been observed that individuals who are deficient in Vitamin D have brittle or thinned bones, prone to breaking.
  • Osteomalacia: Commonly observed in children who develop a Vitamin D deficiency at a young age, this is a condition where the bones become soft, almost malleable, causing structural deformities.
  • Experiencing fatigue, dizziness, or nausea
  • Pain or discomfort in the body
  • Experiencing muscle weakness, pain, or cramps
  • Mood changes and depression

Diagnosis: The Vitamin D levels in our body can be determined by various blood tests, the most common one being 25-Hydroxyvitamin D. This test does not require any sort of preparatory fasting. Vitamin D tests are not regularly conducted in most cases and are only done when individuals experience signs of weakness or have unusually high bone-related issues.

Excessive Consumption Of Vitamin D 

Excessive consumption of Vitamin D can backfire on the body, causing it to experience complications such as:

  • Headache, Nausea, and Dizziness
  • Abnormal levels of thirst 
  • Severe constipation 
  • Weakness
  • Decreased brain function
  • Confusion
  • Ataxia, a condition that causes slurring of words


One can adopt simple lifestyle changes such as consuming a balanced diet, getting adequate exercise and increasing sun exposure to maintain Vitamin D levels in the body.   

Dietary Sources Of Vitamin D

Here are some foods you can consume to maintain Vitamin D levels in your body: 

Sunshine: One of the most prominent, inextinguishable, and widely accessible sources of Vitamin D is the sunlight. The ultraviolet rays from the sun interact with the cholesterol in the body to ignite the synthesis of Vitamin D. This is primarily why Vitamin D is referred to as the ‘Sunshine Vitamin’. 

Fish: Protein obtained from oily fish, such as sardines, herring and mackerel is an excellent source of Vitamin D. One serving of Atlantic Salmon has been noted to have around 800 IU of Vitamin D.

Fortified Foods: Vitamin D can also be obtained from certain fortified foods such as cow’s milk, cereal, orange juice, and other dairy products such as clarified butter, cheese, etc.

Mushrooms: Mushrooms are an excellent source of Vitamin D-2. Studies have shown that mushrooms that are found in the wild had as much as 2000 IU of Vitamins per serving. However, commercially grown mushrooms are not as vitamin-rich and have up to 200 IU of Vitamin D per 100-gram serving. 

Cod Liver Oil: The cod liver oil extract is one of the richest sources of Vitamin D and contains up to 448 IU of Vitamin D per teaspoon serving.

Vitamin D Supplements

Besides natural foods, one can also take supplements to restore the body’s Vitamin D levels. The dosage, frequency, and type of supplements required may change based on an individual’s body composition, existing health conditions, and vitamin levels. Therefore, one must consult a healthcare practitioner before starting on Vitamin D supplements. The need for supplementation also depends upon the time of the year. It is often observed that the body requires more Vitamin D as we head into the winter months as compared to summers. 

Primarily, there are two types of supplements that one can consume in order to overcome Vitamin D deficiency — Vitamin D-2 or ergocalciferol synthesized from plant-based sources and Vitamin D-3 or cholecalciferol, synthesized from animal-based sources.   

Vitamin D-2 is cheaper to source and is commonly found in fortified foods. However, it is not as effective a source as Vitamin D3. The latter is more easily absorbed by the body and acts faster.

Owing to our daily stress and fast-paced lives, it is both difficult and impractical to calculate the Vitamin D levels of every single food item we consume, in order to regulate our intake based on that. Instead, you can make sure to consume the foods mentioned above in moderation and pair them with health supplements to maintain the required Vitamin D levels and lead a healthy life. 

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