Vitamin D Supplements: Uses, Benefits, and Side Effects

Parul Dube

October 12, 2022

Vitamin D, most popularly known as “the sunshine vitamin”, is an essential vitamin for the body. It helps in regulating the absorption of phosphorus and calcium. In addition, it plays a critical role in preventing inflammation in the body. However, you can understand vitamin D as more of a hormone than a vitamin. It is due to the ability of our bodies to produce vitamin D from cholesterol. However, this process requires a dash of sunlight every day. Therefore, spending some time every day in the sun can help us meet our daily vitamin D requirements. However, vitamin D deficiency is a significant health concern globally and people opt for consuming Vitamin D Supplements.

It is so common that a large part of the population requires supplements to meet their daily vitamin D requirements. As per research, over one million people worldwide have lower vitamin D levels, while 50% of the population suffers from vitamin D insufficiency. Vitamin D is present in very low concentrations in our foods. Therefore, it is not sufficient to meet our daily needs. That is why most people require vitamin D supplements to meet their requirements.

Vitamin D maintains and restores the body’s nutritional levels and keeps it healthy. However, people who do not get enough sun exposure require vitamin D supplements. So, if you are wondering whether you need vitamin D supplements, this article will help you gain some ( better) clarity.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin. Therefore, the body needs an appropriate amount of healthy fats to absorb this vitamin. Our body needs it to maintain the bones’ health and absorb calcium and phosphorus from the small intestine.

As per research, people with vitamin D deficiency can develop brittle, soft, and weak bones. Moreover, the lack of this vitamin may also be responsible for the development of rickets in children and osteomalacia in adults. 

Types of Vitamin D

There are five forms of vitamin D: D1, D2, D3, D4, and D5. However, Vitamin D2 and D3 are the most important forms of vitamin D for the human body.

Vitamin D2 (Ergocalciferol)

Vitamin D2 comes from plant-based foods such as mushrooms that receive sufficient sunlight. These foods are the richest vitamin D sources for vegetarians.

Vitamin D3 (Cholecalciferol)

Vitamin D3 is present in food sources like fish. Our skin also produces vitamin D3 from cholesterol present in our body in the presence of sunlight. 

Both vitamins are necessary for the proper functioning of our body. Supplements of both types of Vitamin D, i.e. Vitamin D2 and Vitamin D3, are available over-the-counter, and you can purchase them without a prescription. A meta-analysis suggests that vitamin D3 is the highly preferred choice for Vitamin D supplements. Comparatively, it is a more easily absorbable form. However, vegetarians still prefer vitamin D2 over D3.

Vitamin D Requirements

The standard unit of measurement for vitamin D intake is International Units (IU) or micrograms (mcg). 40 IU of vitamin D is equivalent to 1mcg. Our bodies require vitamin D every day. As per research, the average requirements of vitamin D intake are:

  • Infants: Birth to 12 months: 10 mcg or 400 IU
  • Children and Teens: 1-18 years: 15 mcg or 600 IU
  • Adults: 19-70 years: 15 mcg or 600 IU
  • Adults: Older than 71 years: 20 mcg or 800 IU
  • Pregnant or Breastfeeding women: 15 mcg or 600 IU

Vitamin D: Functions

When the cholesterol present in our body converts to vitamin D, it helps in various functions:

  • Vitamin D prevents mood disorders such as mood swings and depression.
  • It reduces the risk of bone fractures and deformations by regulating calcium and phosphorus levels in our bodies.
  • Vitamin D regulates blood sugar levels in the body.
  • It also maintains healthy levels of cholesterol.
  • It regulates muscle and nerve functions.

Vitamin D Supplements

You can mainly obtain vitamin D through three sources: your skin, diet, and vitamin D supplements. Since most of us do not get enough vitamin D from natural sources, supplements are essential. Daily intake of these supplements is more effective than monthly or weekly administration. These supplements are a reliable and effective way to ensure the proper functioning of our body by meeting its vitamin D requirements.

Signs that You Need Vitamin D Supplements

You might need vitamin D supplements when diagnosed with vitamin D deficiency. However, it is better to consult a physician and test your blood sugar levels before opting for any supplements. The need for it may arise when you experience the following symptoms frequently:

  • Feeling sleepy or tired
  • Back pain and joint pain
  • Hair loss
  • Mood disorders
  • Headaches

Benefits and Uses of Vitamin D Supplements

Vitamin D supplements play an essential role in our body functions. They help in the proper functioning of the cells, nerves, and muscles. The uses and benefits of vitamin D supplements are as follows:

Strengthens Bones and Muscles

According to research, vitamin D helps regulate calcium levels. It plays an essential role in strengthening the bones and muscles in our body. Vitamin D also absorbs calcium and phosphorus in the small intestine. One of the vitamin D supplements, i.e. calcitriol, increases calcium blood levels in people with low parathyroid hormone levels.

Promotes Healthy Pregnancies

As per research, vitamin D deficiency in pregnant women generally leads to preeclampsia and preterm birth. That may lead to many complications. On the other hand, vitamin D supplements during pregnancy improve the vitamin D status in women and improve the health status of the mother and the infant.

Supports the Growth of Infants

According to a study, vitamin D helps build strong teeth and bones in babies. Furthermore, vitamin D supplements also help prevent rickets in children.

Promotes Mental Health

Studies suggest that low vitamin D levels in our body can lead to various mood disorders and depression. Therefore, an optimum vitamin D level through vitamin D supplements can improve mental health and regulate your mood.

Enhances Immunity

Vitamin D receptors are present on the surface of the white blood cells in our body. As per a study, it helps enhance immunity by fighting harmful viruses and bacteria. Therefore, vitamin D supplements are known to boost the immunity of an individual.

Lowers the Risk of Diabetes

Research shows that Vitamin D helps regulate insulin levels. High insulin levels in the body may cause diabetes. Also, vitamin D supplements maintain a balance in glucose levels in the body. As a result, they help lower the risk of diabetes.


These are some precautions that you should follow while taking Vitamin D supplements:

  • It is better to keep 2 hours between consuming medicines for other health conditions and vitamin D supplements. It helps to avoid negative interactions between drugs in the body.
  • Avoid alcohol while consuming vitamin D supplements as it reduces its efficiency.
  • The per-day dosage of vitamin D should not exceed more than 4000 IU.
  • It is preferable to take vitamin D supplements along with food rather than an empty stomach.
  • If a person is above the age of 50 or suffers from osteoporosis, their daily dosage of vitamin D supplements should be between 800 IU to 1000 IU.

Possible Side Effects

Vitamin D supplements are generally safe to consume when taken in recommended amounts. However, if you take them in higher quantities for a more extended period, these supplements may cause certain side effects due to vitamin D toxicity.


Hypercalcemia refers to a condition that develops because of excess calcium in the blood. It occurs due to excess vitamin D consumption. 

Vitamin D helps in the absorption of calcium from the body. However, when the calcium levels exceed a threshold value, you may experience hypercalcemia. The threshold value is 0.104 mg/mL or 10.4 mg of calcium per deciliter of blood.

High calcium levels in the body may also cause a loss of appetite, muscle weakness, reduced reflexes, muscle and joint pain. It may also lead to issues like confusion, disorientation, trouble thinking, irritability, anxiety etc.

Kidney Damage

The calcium in the blood can bind with phosphate to form crystals that deposit in the tissues. These tissues can cause damage to the organs. For example, excessive vitamin D intake can result in calcium deposits in the kidney. When calcium deposits accumulate in the tissues of the kidney, they can cause nephrocalcinosis. It is a disorder that can lead to kidney failure. 

Heart Issues

Extreme hypercalcemia due to excess vitamin D can hamper the proper functioning of the cells present in the heart. As a result, it causes irregular heartbeat, leading to blockage and heart attack.

Lung Damage

High vitamin D levels can cause calcium and phosphate deposition in the tissues. These deposits of calcium and phosphate can impair lung functioning. It can result in chest pain, trouble breathing, and persistent coughing. Hence, a high dosage of vitamin D supplements can lead to significant lung damage.

Effect on Mental Health

Hypercalcemia can alter the mental status of a person. The primary cause of hypercalcemia is excess vitamin D intake. Therefore, a high intake of vitamin D supplements can lead to severe changes in mood and can cause depression.

Brittle Bones and Pain

With excessive calcium in the body, the bones’ minerals do not effectively bind with the hormones present. As a result, it can lead to aching bones, severe joint pain, and a stooped posture. The best way to avoid the side effects is to limit vitamin D supplements.

Sunlight: The Natural Source of Vitamin D

Vitamin D is referred to as the sunshine vitamin for a reason. When exposed to sunlight, your skin can produce vitamin D with the help of the cholesterol in the body. Morning between 9:30 am – 10:30 am and evening between 4:30 pm to 6:30 pm is the best time to get sunlight as the sun is at its highest point. Therefore, the body can efficiently synthesise vitamin D during midday. 

Melanin determines your skin colour. Dark-skinned people usually have more melanin than light-skinned ones. Your skin colour also affects your vitamin D production. For example, dark skin produces less vitamin D than light skin. It is because the excess melanin in dark skin blocks vitamin D absorption from the sunlight. Therefore, dark-skinned people need to spend more time in the sunlight than light-skinned people to get the same vitamin D.

People with dark skin and those who live in cold areas do not get enough exposure to the sun. Thus they rely on vitamin D foods and supplements to fulfil their vitamin D needs.

Foods Rich in Vitamin D

Prolonged exposure to the sun can cause sunburns and increase the risk of skin cancer. Therefore, you can not meet your needs through the sunlight alone. Although food accounts for just 10% of the total vitamin D present in our body, we can get some vitamin D through food. We can get the rest from sunlight and supplements.

Both vegetarian and non-vegetarian foods contain vitamin D. 

Vegetarian Food Sources

Vegetarians can opt for the following food sources to fulfil a part of the vitamin D requirements of the body.


Mushrooms are the only vegetable with high amounts of Vitamin D. It is due to the high sunlight exposure. One hundred grams of mushrooms contain 1136 IU of Vitamin D.

Fortified Orange Juice

Oranges are rich in antioxidants and help our bodies fight off infections. It also prevents damage to our cells. In addition, oranges are extremely rich in vitamin D. A glass of fortified orange juice has up to 137 IU of vitamin D.

Fortified Yoghurt

You can get up to 10 to 20% of the required vitamin D through fortified yoghurt. It provides 80-120 IU of vitamin D. Yoghurt is also beneficial for gut health.


Cheese contains high protein, vitamins, phosphorus, fat, and calcium content. A hundred grams of cheddar cheese contain up to 24 IU of vitamin D, swiss cheese comprises 20 IU of Vitamin D, and feta contains 16 IU. It is a good source of vitamin D and is also delicious.

Cow milk

Cow milk is also a rich source of vitamin D. A glass of milk has up to 100 IU of vitamin D.

Non-Vegetarian Food Sources

Along with vitamin D supplements, non-vegetarian people can also opt for the following vitamin D-rich foods to regulate their nutritional levels.


The egg yolk is highly nutritious and is an excellent source of vitamin D. One egg yolk contains up to 41 IU of vitamin D. Eggs are rich in calcium, zinc, proteins, and other essential minerals. 

Cod Liver Oil

Cod liver oil is an incredible source of vitamin D. It is also extremely rich in Vitamin A. One teaspoon of cod liver oil provides up to 113% of a person’s daily vitamin D requirements.


Salmon is rich in vitamin D. It is also a good source of omega-3 fatty acids and has high-quality lean protein. Cooked salmon has up to 447 IU of vitamin D.


Vitamin D, “the sunshine vitamin”, is an essential vitamin for the body. However, since we do not get enough vitamin D through natural sources, consuming vitamin D supplements can fulfil our requirements. These supplements help maintain optimum vitamin D levels and ensure calcium and phosphorus regulation in the small intestine. However, excess vitamin D in our body is also harmful and can cause hypercalcemia, further leading to kidney and lung damage. In addition, it may also impact your mental health. Therefore, if you decide to take supplements, consult a physician beforehand to choose a supplement that is best suited for your body. 

Vitamin D is easier to absorb with the fats present in our bodies. Therefore, it is better to take vitamin D supplements after the biggest meal of the day. It doesn’t matter whether that is breakfast, lunch, or dinner. Vitamin D supplements are available as liquids, capsules, gummies, or chewable tablets.

Frequently Asked Questions

Q. Is it OK to take vitamin D every day?

A. Yes. Our bodies require vitamin D to perform various functions. Therefore, we should ensure a regular vitamin D intake in our bodies. However, you should start taking vitamin D supplements only after consulting with a healthcare expert. 

Q. Is taking a vitamin D supplement safe?

A. When consumed in adequate amounts, vitamin D supplements are safe. However, excess consumption may lead to calcium buildup in the body, which can be harmful. It may lead to issues like hypercalcemia, lung and kidney damage.

Q. How much vitamin D should you take every day?

A. It depends on the age and gender of the individual. For adults, the daily requirements range between 600-800IU. You can refer to the detailed chart in the article to know your exact vitamin D requirements.

Q. What are the best vitamin D tablets?

A. The most commonly used tablets for vitamin D are vitamin D2 and D3 tablets. However, you should consume a tablet that your doctor prescribes. A doctor will know your requirements and your health conditions. As a result, they will recommend the tablets that best suit you. Moreover, you should never consume more than 4000IU of vitamin D unless your doctor recommends it.

Q. When should I take vitamin D morning or night?

A. You should always have your vitamin D supplements after your heaviest meal of the day. That is because your body absorbs vitamin D with the help of fats in your body. Therefore, have vitamin D after consuming a meal containing high fats. It can either be breakfast, lunch or dinner.

Q. How do you know if you’re low in vitamin D?

A. A doctor or physician may diagnose your vitamin D deficiency by performing a diagnostic test for blood glucose levels. However, if you frequently feel sleepy or tired, have back or joint pain, experience hair loss, mood disorders and headaches, you are more likely to have a vitamin D deficiency.

Q. How can I boost my vitamin D?

A. Sunlight is the natural source of vitamin D absorption. So, you can increase your vitamin D levels by spending some time out in the sun every day. You can also include dietary sources such as fish, mushrooms etc. However, the best way to boost your vitamin D intake is to consume supplements after consulting with your doctor.

Q. Is it better to take vitamin D every day or once a week?

A. You can include external sources of vitamin D such as sunlight and dietary sources such as fish and mushrooms daily. However, if you are consuming supplements, following the physician’s prescription and dosage is advisable. Generally, it is best to have supplements every day rather than weekly or monthly.

Q. Which fruit is high in vitamin D?

A. Several fruits are rich in vitamin D. However, as per the international units, orange has the highest vitamin D concentration among fruits. Therefore, fortified orange juice is the best way to fulfil your vitamin D requirements through fruits.

Q. What’s the difference between vitamin D and vitamin D3?

A. There are two sources of vitamin D in our bodies- vitamin D2 and D3. Both are forms of vitamin D. So there is no meaningful difference between the two. However, vitamin D3 is a more absorbable form of vitamin D.

Q. Should I take vitamin D or D3?

A. The right dose of vitamin is more important than the type of vitamin D you get. It will ensure your levels are in the suitable range to avoid deficiency. Most experts recommend 600 to 800 IUs of vitamin D per day. However, vitamin D3 is a better option for supplements because it is easy to absorb vitamin D.

Q. Who should not take vitamin D3?

A. It is advisable for people with kidney and heart problems to consult a physician before starting vitamin D supplements. In addition, people with kidney stones should limit vitamin D3 supplements as it may worsen stone formation.

Q. Does taking vitamin D have side effects?

A. When consumed in prescribed doses, vitamin D supplements are safe. However, excess consumption may result in side effects such as lung and kidney problems, hypercalcemia, mood disorders etc.

Q. What foods are highest in vitamin D?

A. Although foods make for only 10% of our body’s vitamin D, some fruits may help us fulfil our vitamin D requirements. For example, fortified orange juice, yoghurt and cheese, fish, cod liver oil, and salmon are vitamin D rich foods.

Q. Do bananas have vitamin D?

A. Bananas do not contain vitamin D. However, they contain magnesium which plays a vital role in activating vitamin D in the human body. 

Q. What is a quick source of vitamin D?

A. Sunlight is the most effective and quickest source of Vitamin D. Your skin absorbs vitamin D from sunlight and fulfils your vitamin D absorption.

Q. Do carrots have vitamin D?

A. No. Carrots do not contain vitamin D. However, they are a rich source of vitamin C and Vitamin A that provides several health benefits. For example, they help improve vision, prevent cancer, helps lose weight etc.

Q. Do Apples have vitamin D?

A. No, apples do not contain vitamin D. However, they are one of the most nutritious fruits that provide many health benefits. For example, they help boost immunity, lower blood pressure, aid digestion etc.

Q. Do Almonds have vitamin D?

A. No, almonds do not contain vitamin D. None of the nuts and seeds, such as almonds, walnuts, etc., have vitamin D.

Q. What drink has the most vitamin D?

A. Fortified orange juice is a rich source of vitamin D. A glass of fortified orange juice has up to 137 IU of vitamin D.

About the Author

Parul holds a Masters of Medical Science in Public Health Nutrition from the University of Glasgow, Scotland, and has worked across the globe from the U.K to New Zealand (NZ) gaining her License with the Health Professionals Council (HPC, UK) and the NZ Nutrition Council. From being a Gold medalist in Clinical Nutrition to being awarded an internship with World Health Organisation (WHO, Cairo, Egypt) and Contracts with CDC Parul has had a wide spectrum of work experiences. She is very passionate about Nutrition and Fitness and holds strong to her guiding mantras ‘ Move more’ and ‘Eat Food that your grandmother can recognize’!

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