Vitamin D3: Benefits, Side Effects, Sources & More

Written by Salma Younas | Last updated on August 4, 2023

In this article, we will explore the incredible power of vitamin D beyond just keeping our bones healthy. Together, we will learn how it affects our immune system, mental well-being, and even our risk of getting sick. 

We'll also talk about how sunlight, diet, and supplements play a role in maintaining optimal vitamin D levels. 


Meet vitamin D3, the "sunshine vitamin" that plays a vital role in your body. Found naturally in foods like eggs, fish, and beef liver, this fat-soluble vitamin can also be produced when your skin is exposed to sunlight.

One notable advocate of vitamin D3 is David Sinclair, a renowned scientist and longevity expert, who recognizes the importance of this supplement in his own health regimen.

David Sinclair, a professor of genetics at Harvard Medical School, is well-known for his research on aging and longevity.

He has emphasized the significance of vitamin D3 supplementation as part of his anti-aging protocol. Sinclair believes that vitamin D3 is not only essential for maintaining strong bones, but it also has potential anti-aging benefits by supporting overall health and disease prevention.

But why should you care?

Well, not only does vitamin D3 help your body absorb calcium and phosphorus for sturdy bones, it also defends against bone disorders, fights inflammation, and may even protect you from diseases like cancer and cardiovascular issues.

Research suggests that maintaining optimal vitamin D3 levels, as recognized by experts like David Sinclair, is crucial for overall health and well-being.

Don't miss out on the wonders of vitamin D3 – discover why it's a key nutrient for your health and well-being.

What is Vitamin D3? 

Vitamin D has two major types known as vitamin D2 and vitamin D3.

Vitamin D3 also known as cholecalciferol is a fat-soluble vitamin that is available in dietary supplements as well as in some foods. It is produced endogenously in response to ultraviolet rays from sunlight. 

Vitamin D3 absorbs calcium and phosphorus which help to keep your body strong. It is one of the most important vitamins for the proper growth and development of your bones.

Vitamin D3 maintains the right amount of calcium and phosphorus that your body needs to keep you healthy and prevent certain diseases. 

Uses of Vitamin D3

Vitamin D is one of the most important hormones in your body. It is essential for your good health. 

Vitamin D3 has many uses in your body five of them are mentioned below:

  • Absorbs calcium and helps prevent many bone diseases such as rickets, osteoporosis, and osteomyelitis. 
  • Vitamin D3 is one of the most essential nutrients for building and keeping your bone strong. 
  • Works as an antioxidant and helps to remove all the toxins from your body. 
  • Your muscles need vitamin D3 to move and your immune system needs it to fight against the foreign bacteria.
  • Vitamin D3 is required in people with underactive parathyroid. Vitamin D3 is effective in increasing the blood levels of calcium in people with low parathyroid hormones. 

Health benefits of vitamin D3

Vitamin D3 carries considerable health benefits. As we know that vitamin d3 is a crucial nutrient for your bone health. It absorbs calcium and phosphorus and helps prevent bone diseases. 

Vitamin D3 prevents the risk of bone fractures, especially in older men and women. Your muscle also needs vitamin D3 for proper functioning as it provides strength to your muscles. 

Without vitamin D3, your body can not absorb enough calcium and phosphorus which results in weak bone. 

Vitamin D3 also has antioxidant properties.  It helps to protect your skin and improve hydration of your skin hence preventing the premature aging of your skin. 

Having an adequate amount of Vitamin D3 levels in your body helps to regulate the antioxidants that in return combat oxidative stress and promotes graceful aging. 

In addition to the primary function of vitamin D3, it also plays an important role in many other health benefits. It helps to reduce the risk of heart disease. A low level of vitamin D3 increases the risk of hypertension which eventually results in heart failure and stroke.

Vitamin D3 improves your immune function and help to prevent the risk of serious illness such as autoimmune diseases, diabetes, and rheumatoid arthritis. 

Some studies have shown that vitamin D3 may also regulate your mood and decrease the signs of depression, and anxiety, especially in new mums.

Possible side effects of Vitamin D3

While vitamin D3 is a superstar nutrient, it's important to tread cautiously and avoid overindulgence. Let's dive into the intriguing realm of potential side effects when vitamin D3 goes into superhero mode!

  • May cause toxicity:  Excessive vitamin D3 can stir up a tempest in your stomach, causing discomfort, headaches, loss of appetite, dizziness, and even nausea.
  • Hypercalcemia symptoms:  Excess of vitamin D3 can lead to hypercalcemia symptoms, including vomiting, nausea, stomach pain, kidney stones, high blood pressure, and even heart diseases.
  • Connection to artery adventures: Scientist have discovered a mysterious link between high vitamin D3 levels and the hardening of arteries, also known as atherosclerosis.

Vitamin D3 deficiency 

  1. Lack of sun exposure and poor dietary intake: Vitamin D3 deficiency usually results from the lack of sun exposure and poor dietary intake.
  1. Weakening of bones: Deficiency of vitamin D3 can result in the weakening of your bones, causing them to become brittle and thin.
  1. Impaired immune system: Vitamin D3 plays an important role in regulating your immune system. Deficiency reduces the activity of the immune system and the cells responsible for addressing infections, potentially leading to frequent illnesses.
  1. Fatigue, bone and lower back pain, depression, and anxiety: A deficiency of vitamin D3 is also a potential cause of fatigue, bone and lower back pain, depression, and anxiety.
  2. Weight gain and obesity: Vitamin D3 deficiency is associated with weight gain and is one of the most common risk factors for obesity.
  1. Risk factors for deficiency: Dark skin tones, elderly individuals, overweight individuals, and those who do not consume much fish and dairy are at higher risk of vitamin D3 deficiency.
  1. Impact of certain health conditions: People with Crohn's disease and celiac disease may have vitamin D3 deficiency due to the impact of these conditions on nutrient absorption.

Vitamin D2 vs D3

Vitamin D has two major types: Vitamin D2 and Vitamin D3. 

Vitamin D2


  • Found in plant-based sources such as mushrooms and fortified foods.
  • Produced when plants are exposed to sunlight.


  • Less effective in raising blood levels of vitamin D compared to vitamin D3.
  • Produces a lower amount of calcifediol, the main circulating form of vitamin D, compared to vitamin D3.


  • Suitable for individuals following a vegetarian or vegan diet.
  • Can be a supplement option for those who are unable to consume animal-based sources of vitamin D3.

Vitamin D3


  • Found in animal-sourced foods like fish oil, liver, and eggs.
  • Produced when the skin is exposed to sunlight.


  • Limited plant-based dietary sources.
  • Animal-based sources may not be suitable for individuals with dietary restrictions or ethical considerations.


  • More effective in raising blood levels of vitamin D compared to vitamin D2.
  • Commonly used in supplements to address vitamin D deficiency.
  • Preferred option for individuals who can consume animal-based sources and require higher levels of vitamin D supplementation.

Assessing vitamin D3 levels

It is important to assess vitamin d3 levels inside the body, how much level of vitamin d3 is present in our body, and how much is needed.

Therefore it is important to assess vitamin d3 levels in our body and test if the vitamin D levels are too high or too low.

The 25(OH)D level test is used to assess the level of vitamin D3 in the body. If you are having pain in bones and muscles without doing any heavy exercise then you should check your vitamin d3 level. 

It is the most activated form of vitamin D and usually, your health care provider will assess the level of vitamin d3 in the body to check if there is any deficiency of vitamin d3. The test to check for vitamin d3 levels is called the cholecalciferol test.

Recommended dosage

Get ready to soak up the sun-kissed goodness of Vitamin D3!

For most individuals, a recommended daily dose of 600 IU. But if you're looking to add some extra energy to your bones, consider upping the dosage to 800-1000 IU, especially if you're 70 years or older.  

It is also advised to consult a healthcare professional who can guide you on the perfect dosage tailored just for you. It's time to dance under the Vitamin D3 spotlight and let your radiance shine through!

Sources of vitamin D3

Different sources of vitamin d3 can be taken to maintain the level inside our body. 

These sources can be

Natural food sources

  • Egg yolks
  • Beef liver
  • Cheese
  • Trout
  • Tuna
  • Milk
  • Butter
  • Cereal.


When you are not getting enough vitamin D3 from your diet then you should take vitamin D3 in supplement form, which is available in the form of gummies, capsules, soft gels, and liquid drops. 

These doses must be in greater dosage than normal dosage because some is stored by the body and the rest is passed out from the body. Dosage must be decided by your health care provider according to your medical history and age. 


Unlike vitamin D2, vitamin D3 can be absorbed by sunlight. An organic compound called 7-dehydrocholesterol is activated in the skin when exposed to sunlight and starts churning out vitamin D3. Therefore it is important to take in sunlight.

What to look for in vitamin D3 supplements

Vitamin D3 is very important for our immune system, and brain health, helps to lose weight, it also lowers the risk of type 2 diabetes. 

While taking vitamin D3 supplements, the dosage must be known because if vitamin d3 is taken in a higher dosage than recommended then it can be harmful to the body. The dosage of vitamin D3 also differs according to age. 

Therefore it is important to tell your healthcare provider about any supplements you are taking other than vitamin D3 supplements.

Similar supplements to vitamin D3

In addition to vitamin D3 supplements which are abundantly available in pharmacies, there are several alternative sources that can help fulfill your body's need for this essential nutrient. 

These alternatives provide natural ways to increase your vitamin D3 levels without solely relying on supplements. Some of these are:

  • Fish oil, derived from fatty fish, contains vitamin D3 and can be consumed as a supplement. 
  • Cod liver oil, another natural source, is rich in vitamin D3 as well as omega-3 fatty acids. 
  • Certain types of mushrooms, when exposed to sunlight, can synthesize vitamin D, making them a valuable dietary source.
  • Lastly, the sun itself is a powerful source of vitamin D3, as our bodies naturally produce it when exposed to sunlight. By exploring these alternative sources, you can find effective ways to maintain optimal levels of vitamin D3 and support your overall well-being. 

Frequently Asked Questions

What does vitamin D3 do for you?

Vitamin D3 cholecalciferol a fat-soluble vitamin helps your body to absorb calcium and phosphorus from the intestines which increases blood calcium levels and transports it to bones and teeth to make our skeletal system strong and have healthy bones.

Does D3 affect blood pressure?

Taking vitamin D3 orally has no significant effect on the blood pressure of a person who is deficient in D3, it reduces the systolic and diastolic blood pressure of people older than 50 years who are experiencing this vitamin deficiency and have hypertension.

Who needs to take vitamin D3?

People who are extremely deficient in vitamin D3 and children having age under 1 to 4 years and all babies should take vitamin D3. if one is not having adequate sun exposure or has any other skin medical condition or dark skin or if someone is lactose intolerant should take supplements.

What are signs you need vitamin D3?

There can be many signs which show someone requires vitamin D3. A few common symptoms are not sleeping well, fatigue, pain in bones, muscle weakness, and hair loss.

It is quite possible to get sick more easily due to a weak immune state and loss of appetite.

How do you know you need vitamin D3? 

If you feel exhausted and fatigued, easily experience bone aches, mood changes, and irregular sleep, and have muscle weakness this could be a warning for D3 deficiency.

Should I take vitamin D3 in the morning or at night?

Vitamin D3 is best to take with meals as it's a fat-soluble vitamin that gets absorbed well with food

As with vitamin D3, it is good to take in the morning because it can interfere with melatonin production if taken during the nighttime.


In conclusion, vitamin D3 plays a crucial role in maintaining our overall health and well-being.

From its essential function in promoting calcium absorption and bone health to its impact on the immune system, cardiovascular health, and mental well-being, this vital nutrient has far-reaching effects throughout the body.

Research suggests that a significant portion of the population may be deficient in vitamin D3, particularly in regions with limited sun exposure or in certain high-risk groups.

Consequently, supplementation or increased sun exposure, when safe and appropriate, may be necessary to achieve optimal vitamin D3 levels.

It is important to note that while vitamin D3 offers numerous potential benefits, it is not a magic cure-all. It should be approached as part of a comprehensive and balanced approach to overall health, including a nutritious diet, regular physical activity, and other lifestyle factors.

By prioritizing the maintenance of adequate vitamin D3 levels and adopting a holistic approach to health, we can optimize our well-being and strive for a healthier, more vibrant life.


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  5. Overview of vitamin d3. Retrieved from

About the author 

Salma is an experienced community pharmacist who's worked at multiple well-known pharmaceutical companies including Dynatis Limited and Medipak Limited

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