The Importance of Vitamin D For Health

What is Vitamin D?

Vitamin D is another fat-soluble micronutrient (like Vitamin A, D, E, K) which is one of the most essential micronutrients for human health. It is produced within the body as well as provided from diet. The version produced in the skin is known as vitamin D3, and that obtained from the diet can be either D3 or D2 from plant sources. It’s primary role is to aid in the absorption of calcium and maintain bone health, though other important benefits also exist.

vitamin d food deficiency

What is Vitamin D’s function in the body?

Vitamin D is needed to maintain normal levels of calcium and phosphate in the blood, which is critical to maintaining bone and muscle health and also essential for cellular functions.

Vitamin D is produced in the skin when cholesterol is exposed to sunlight. Teens and adults are able to produce more than needed quantities during summer months, which gets stored in the tissues and is used in winter months when sunlight exposure drops. This internal production starts dropping from around 25 years of age as skin starts gradually thinning. 

What are Vitamin D’s benefits?

Vitamin D’s main role is in helping body use up calcium. It is also essential for proper absorption of vitamin K, and together these 3 vitamins and minerals maintain bone health and strong bones. Some research exists, that vitamin D can also improve the condition of people with type 2 diabetes, increases testosterone levels and improve immunity.

Vitamin D deficiency symptoms and diseases

Vitamin D deficiency causes osteoporosis and rickets, which is the condition of soft bones and deformed skeleton. This happens due to body’s inability to properly use calcium due to insufficient vitamin D. Since strong bones also leads to strong muscles, an increased pain in muscles and bones can point towards vitamin D deficiency. Low vitamin D also increase the risk for type 2 diabetes.

Infants born during winter months are specially prone to vitamin D deficiency due to limited sun exposure for first 6-7 months and huge need due to skeletal growth. Vegans are also at a risk of vitamin D deficiency since most diet sources are animal based. People with dark skin tone also produce less vitamin D with sun exposure. With age also, body’s capability to produce vitamin D internally drops. This vitamin D deficiency leads to reduction in bone mass, making them weak and prone to fractures.

Vitamin D dosage?

It is hard to determine a general dose amount for everyone as vitamin D levels depend on age, weather and location too. So when it comes to vitamin D, it is wise to get your levels tested and then from there determine whether you need to up the amount or not.

The most efficient way of getting vitamin D is its production with exposure to sunlight, and 30 mins of daily sunshine time is enough to meet the needs. But due to factors like season, age, covered clothing, sunscreen, pollution cover, etc. many people do not produce enough vitamin D internally and hence external sources are needed.

The recommended daily dose for teens and adults from diet and supplements is 15 mg/day or 600 IU. For people above 50, it is recommended to increase the dose to 20 mg/day as internal synthesis drops. However, due to insufficiency in determining an individual’s vitamin D, it is recommended to take 1000 IU daily for most population to be on the safe side.

How to calculate vitamin D dose?

Vitamin D dose is measured in IU (International units).

1 mg = 40 IU

What are good Vitamin D food sources?

As described earlier, vitamin D is available in two forms – D3 and D2. Animal food sources and most supplements contain D3 and plant sources contain D2. Vitamin D3 has a better absorption in the body compared to D2. Also very few plant sources contain D2 naturally, unless they are fortified.

vitamin d food india

Vitamin D foods in India

Vegetarian – mushrooms, fortified grains, juices and cereals

Animal sources – fish, fish liver oil, egg yolk, milk, yogurt

Vitamin D tablets and supplements

Vitamin D3 is often present in calcium supplements, though may not be present in adequate amounts. Choose your supplement quantity depending on how much sun exposure you get to make vitamin D naturally as the total amount should not go beyond 3000-4000 IU from all sources.

Vitamin A in milk

1 cup of whole milk can provide 100-150 IU of vitamin D or about 10% of daily need.

Vitamin A in egg

1 whole egg can provide about 40 IU of vitamin D or about 4% of daily need.

How to fortify food with Vitamin D at home?

While fortified foods are easily available, they can still be expensive than alternate options for some people. Here’s how you can fortify own food with an inexpensive vitamin D3 powder supplement (eg. Calotec D3 for less than Rs. 30) available easily at a chemist – 

  1. Add a sachet of vitamin D3 powder of 60,000 IU to a 2 kg pack of flour and mix together. This fortified flour is sufficient to provide 1,000 IU per day for 15 days for 4 people.
  2. Add a sachet of vitamin D3 powder to 300ml condensed milk and store in a dark glass jar in refrigerator. Adding 1 tsp of this mix everyday to a regular glass of milk or tea or coffee, can provide 1,000 IU everyday.

How should Vitamin D be consumed?

Being fat-soluble, vitamin D diet source should be taken with meals and having a fat source like oil, ghee, etc. Also D3 sources should be preferred over D2 because of better absorption in the body.

Vitamin D overdose/toxicity

Vitamin D overdose can cause hypercalciuria and hypercalcaemia, both of which can raise calcium levels in body leading to increased calcium in urine resulting in weaker bones and kidney stones. But most people these days are in fact under-dosed in vitamin D due to lifestyle changes so toxicity of vitamin D isn’t normally a concern. 20,000 IU/day is linked with toxicity.


Vitamin D is vital for proper absorption of calcium, making it an essential vitamin for bone and teeth health. It’s deficiency can cause rickets, osteoporosis, muscle weakness and increase in fractures. It is produced in the body upon exposure to sunlight, but the amount can vary greatly with age, body fat, weather, location, etc. So some form of dietary vitamin D is suggested to ensure the daily dose of 1000 IU. Vegans need to take fortified milk, grains and cereals if relying solely on food. Animal sources include fish, liver oils, egg and dairy. Tablets and supplements can be used to get adequate daily amount of vitamin D.

As always, it is wise to follow the precautionary principle when it comes to diet. Don’t eat anything daily for too long and take breaks in between, like eating vitamin D rich food enough to get the daily dose, but if that gets exceeded then skipping a few days of supplements to prevent toxicity. Eat well-rounded meals and do not follow any diet form also for too long that tells you to overdose on one component of the diet and leave out others.

(Sources – 1,2,3,4)


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