Vitamin D3: Usage, Health Benefits & Side Effects

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Vitamin D3 is also known as the sunshine vitamin [1] because it is activated in the body when we are exposed to the sun.

But let’s face it, for many of us, there is more concrete than sunshine in our day-to-day. Are you getting enough vitamin D3? What are the signs that you have a vitamin D3 deficiency?

What other sources of vitamin D3 other than sunlight are available? Is there such a thing as too much vitamin D3?

And if you are past the age of getting rickets do you really need it? In this article, we tackle all these questions and more leaving you empowered to take the next step.

What is Vitamin D3?

Vitamin D3 is one of the many vitamins your body needs to fully function and maintain health. The body tissues cannot make vitamins so they are ingested through eating vitamin-rich foods.

Vitamin D3 is one of the Vitamin D’s (there is 1,2 and of course 3).

Also known as cholecalciferol, vitamin D3 is special because it occurs naturally on the skin as a type of hormone. It is activated when our skin is exposed to the sun.

Vitamin D3 is quite rare in food sources and only occurs in egg yolks and oily fish. Even then, the vitamin D3 from these food sources is rendered ineffective until one is exposed to sunlight.

Vitamin D3 is mainly known for building and maintaining stronger bones and teeth. But there is more to this special vitamin than just bones including boosting the immune system and hormone creation.

Let us take a closer look at the science behind the functions of vitamin D3.

How does Vitamin D3 Work?

Once-over your skin is exposed to the sun’s rays, the hormone cholecalciferol is converted to vitamin D. The vitamin D makes two pit stops; first in the liver, then in the kidneys, before it is converted to the active form that is useful for the body.

In the liver, it picks up an oxygen molecule and a hydrogen molecule and is then transformed to 25-hydroxyvitamin D. The new element, 25-hydroxyvitamin D, is then taken to the kidneys where it picks up one more oxygen and one more hydrogen molecules respectively.

It is then transformed to 1,25 dihydroxyvitamin D which is the active form of vitamin D (it’s like upgrading your gaming avatar).

So now the active form of vitamin D3 is put to work. It is circulated in the body to help with the absorption of calcium and phosphorus.

Calcium and phosphorus are necessary compounds for healthy strong bones. Vitamin D stimulates the intestines to absorb more calcium and phosphorus before they are broken down by the kidneys.

Vitamin D increases absorption by up to between 30% and 40%. When vitamin D reserves are below the required levels the absorption level is only between 10%-15%.

Up to 99% of all the vitamin D in the body goes into making stronger bones and teeth. Vitamin D was discovered by a doctor’s appointment in the 1900s researching on rickets and other nutritional deficiency diseases.

Evidence from more current research suggests that vitamin D has way more to offer the body than just strong teeth and bones.

Strong teeth and bones are pretty important making vitamin D vital. Insufficient vitamin D3 has dire consequences on health.

Vitamin D Deficiency

The risk of experiencing vitamin D deficiency is greater today because of the concrete jungle lifestyle where people spend more time facing walls and gadget screens than they do in the sun.

Certain groups of people are at a higher risk of vitamin D deficiency. These are:

  • People of color because while their skin pigmentation protects them from UV rays, it takes them longer for vitamin D to be activated.
  • People with malabsorption issues that inhibit the absorption of calcium and phosphorus into the bloodstream.
  • Those with kidney and liver disease that may inhibit the conversion of vitamin D to its active form
  • People who wear sunscreen all the time
  • Those with advanced age

Vitamin D deficiency can have long term effects on both children and adults as it increases the risk of bone diseases. Growing children who have vitamin D may develop rickets while adults may develop osteomalacia or osteoporosis.

The previously stated conditions result from advanced cases of vitamin D deficiency. Simpler symptoms that you can look out for in order to arrest the situation include:

  • Bone and back pain
  • Fatigue
  • Muscle pain
  • Impaired wound healing

If you experience these symptoms visit a doctor and get tested for vitamin D deficiency.

Is Vitamin D Safe?

Obviously, the best source of vitamin D is some good old sunshine. Life constraints such as job schedule, geographical location and weather patterns may limit how much sun we are exposed to.

And so we may have to turn to diet and supplements.

Natural sources of vitamin D [2] include oily fish, egg yolks, mushrooms, liver, cheese, fortified yogurt, and cereals. Given their natural state, these sources are safe to consume.

Supplements are another matter altogether. There are plenty of vitamin D supplements in capsule, chewable tablet, and even liquid form.

It would be presumptuous to generalize that all vitamin D supplements are either safe or unsafe to consume. Depending on individual anatomy some people, like with any other supplements, may experience mild symptoms while others might not.

Just to be safe, conduct some due diligence on the brand of supplements you intend to buy.

Also, consult your doctor prior to taking any supplements and stick to the dosage as instructed. We have a more comprehensive list of precautions later on in the article.

Health Benefits of Vitamin D

Health Benefits of Vitamin D3

Recent research shows that vitamin D is vital for more than just muscles and bones. It can tackle and prevent the following health issues.

  • Healthy bones [3] – this is the most significant role of vitamin D3. The vitamin helps in maintaining phosphorus in the body and regulates calcium. All these processes are vital for the formation of healthy bones.
  • Depression – Vitamin D aids in the production of the hormone serotonin, also known as the “feel-good” hormone. Serotonin is what is released in the brain when you do what you love, like let’s say eat something super delicious, I love food. Low levels of serotonin may present the onset of mood disorders and ultimately clinical depression.
  • Respiratory infections – Some recent researches have shown vitamin D supplements to reduce the risk of flu and other respiratory infections by up to 12% [4,5].
  • Boosts the immune system by enhancing anti-micro bacterial responses by the body
  • Better nerve and muscle function.
  • Cellular growth, healing, and remodeling.
  • May help prevent preeclampsia in pregnant women [6].

While there is no shred of doubt on the importance of vitamin D, there is research that goes beyond the classic Vitamin D for bones. However, some claims are yet to be linked directly to vitamin D through credible research and case studies.

If you have a pre-existing condition, you may want to check with your doctor or physician prior to taking vitamin D supplements.

Vitamin D Side Effects

People react differently to different substances. Some people have experienced mild symptoms to vitamin D supplements, others none at all, and others have had allergic reactions.

As long as you follow instructions, you should be fine. In extreme situations like in case of allergies, the following symptoms may occur:

  • Chest pains
  • Shortness of breath
  • Swelling of the face
  • Difficulty breathing
  • Swelling of the throat.

In case of any of these symptoms, stop taking the vitamin D3 supplements and visit a doctor immediately.

Vitamin D Usage and Dosing Consideration

One critical factor to consider when it comes to taking vitamin D supplements is that you need to be tested and diagnosed with vitamin D deficiency. Unlike other vitamin supplements, too much vitamin D in the body may lead to a vitamin D overdose.

The consequences of an overdose are not pretty and should be avoided at all cost.

Vitamin D supplements come in all forms, from capsules to liquid medicine, chewable tablets, and vitamin D water. Follow the prescription to the letter; don’t get creative.

Ensure you ingest all the medicine as instructed. For instance, if it’s a chewable tablet, please chew it before swallowing.

The dosage and the duration over which to take the supplements will depend on your level of deficiency. This is why we discourage self-medication.

Consult a doctor and follow up with them to ensure the medication is working.

You may take vitamin D supplements with or without food, there is no “best time” to take the supplements, just follow your prescription.

Food is another way of getting vitamin D although it will take a lot of it. Your doctor may suggest specific foods to take along with the supplements.

The best way to take in vitamin D is, of course, the sun. Basking in the midday sun for about 30 minutes two times a week should work [7].

But please try and avoid the scorching afternoon sun.

It’s easy and straightforward unless it’s winter. You can turn to supplements during winter.

Sunscreen proponents however completely refute any basking suggesting that direct exposure to UV rays may cause skin cancer and premature aging. It’s never that serious.

You can also check out the research-backed dosage guideline [8].

Risks and Precautions

Vitamin D is relatively safe when taken within the recommended dose per day. However, too much of anything is always a mess.

Taking too much vitamin D can lead to an overdose which has the following long term side effects:

  • Hypercalcemia– this is when there is too much calcium in the bloodstream. It can cause calcification of the blood vessels, where calcium cakes itself to artery and vein walls limiting blood flow and causing an irregular heartbeat [9].
  • Tissue damage– excess calcium may bind with phosphates and form crystals that deposit on soft tissues like the kidneys and liver. If unchecked, the crystals could lead to organ damage.
  • Brittle bones– High calcium ratio compared to the blood agent that binds it to the bones may cause it not to bond correctly making the bones brittle and prone to fractures [10].

Although the above can occur in extreme cases of vitamin D overdose, there is no harm in taking precautions. Take note of the following:

  • Do not take any vitamin D supplements if you are allergic to vitamin D, have high vitamin D levels already, have hypercalcemia, or have malabsorption issues that will hinder vitamin D absorption into the bloodstream.
  • If you have a pre-existing condition or previously had liver disease, please disclose this information to your doctor and seek advice.
  • Vitamin D supplements may contain ingredients like peanut oil, you may want to vet the ingredients in case of allergies.
  • If you are pregnant or breastfeeding, consult a doctor before using vitamin D supplements.
  • Do not give vitamin D supplements to children without consulting a doctor because their age, weight, and diet influence the dosage
  • Check ingredients if you are vegan too
  • Consult your doctor if you experience a combination of any of the following symptoms of vitamin D overdose; exhaustion, dehydration and frequent urination, loss of appetite, continuous headaches, nausea slow reflexes, irregular heartbeat, or weak muscles


Can I take Vitamin D every day?

The dosage and duration over which you take vitamin D will depend on what your doctor prescribed

Can I take vitamin D on an empty stomach?

You can take it with or without food, but follow the prescription

When is the best time to take Vitamin D?

There is no best time for maximum effects, just follow the prescription

Is Vitamin D good for your skin?

There are currently no studies depicting any correlation between vitamin D and rejuvenated skin, but is not bad for your skin either.

Can vitamin D hurt your kidneys?

Too much vitamin D can result in an overdose, which may cause tissue damage on soft organs like the kidney and if untreated organ damage. But these are very extreme cases and as long as you consult your doctor and follow instructions, you have nothing to worry about.

Is vitamin D good for arthritis?

Some studies suggest that vitamin D deficiency may be among the causes of rheumatoid arthritis, but for further clarification, consult a doctor.


Vitamin D is essential for strong bones, muscles, immunity just to name a few functions. The sun is the most effective source of vitamin D; it’s easy to administer and better yet it’s free.

Unfortunately, life’s demands may not allow us the luxury of basking under the sun so supplements we must take.

Vitamin D supplements are relatively safe, just don’t get carried away, and most importantly, always consult a doctor and follow instructions.

Cases of vitamin D overdose from food sources and sunlight are non-existent. Regardless of the source, we all need vitamin D. Pick a source or sources that will compliment your lifestyle and stay healthy.



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