Best Way to Take Your Vitamin D Supplement

  • Rajni Sarma MBBS, MD from North-Eastern Hill University, India

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Are you taking your vitamin D supplement correctly? The COVID-19 pandemic has turned people’s focus to improving their health and well-being. As a result, immune-boosting vitamins like vitamin D and C have become increasingly popular. 

In this article, we will discuss the health benefits of taking vitamin D, the best ways to enhance its absorption by the body, and the factors that influence vitamin D uptake. So, take advantage of this chance to gain knowledge and insight to benefit you and your family's health.

Understanding vitamin D

What is vitamin D?

Vitamin D is a fat-soluble vitamin that regulates bone metabolism and the immune system. It’s two major forms are:1

  • Vitamin D3 - Primarily present in sunlight and foods of animal origin
  • Vitamin D2 - Commonly found in plant-based food and fortified food

Vitamin D3 is the chief source of vitamin D. Although both forms are essential, vitamin D3 is more effective in maintaining the serum vitamin D level in our body than vitamin D2.2

Sources of vitamin D

The short and simple answer is from sunlight, food, and supplements.

Did you know that your skin can synthesise as much as 80% of its vitamin D using ultraviolet (UV) light?Therefore, the easiest way to get vitamin D is by regularly exposing yourself to sunlight. 

Unlike other vitamins and minerals, vitamin D is limited in food sources. However, here is a list of common sources of vitamin D3 that you can add to your diet:2

  • Salmon, mackerel, tuna, sardines
  • Cod liver oil
  • Beef liver
  • Egg yolk
  • Mushrooms
  • Milk, cheese, orange juice, cereals, and other fortified food products

Do we really need vitamin D supplements?

Not everyone will require vitamin D supplements.  If you enjoy good health, eat a diet rich in vitamin D, and do outdoor activities, then you should not worry about your vitamin D level.

Who needs supplements?

Let's take a closer look and find out who needs vitamin D supplements:1,2

  • Children between 1 and 4 need a daily dose of vitamin D supplements.
  • Pregnant women
  • Breastfeeding mother
  • Anybody, especially in the winter when there is less exposure to sunlight
  • People wearing full clothes make less vitamin D
  • Housebound and frail individuals with limited mobility
  • If you spend very little time outdoors
  • Those with obesity
  • If you adopt a vegan diet
  • Dark skin individual
  • Medical conditions that affect vitamin D absorption, such as Crohn's disease, celiac disease or cystic fibrosis.

Benefits of taking Vitamin D supplements: What does the research say?

Vitamin D is one of the few extensively researched vitamins.  This section discusses the benefits of vitamin D on a wide range of diseases:

Skeletal system

Various studies have revealed its use in the extra-skeletal system, such as preventing or reducing the risk of cancer, infections, and autoimmune diseases.3,4

  • Vitamin D aids the absorption of calcium and phosphorus in the gut, which is required for healthy bones and teeth.
  • Vitamin D deficiency  can cause rickets and dental caries in children and osteoporosis in adults


Vitamin D may play a role in lowering the risk of colorectal cancer and, to a lesser extent, bladder cancer. 

Reproductive health

Intake of vitamin D supplementations by pregnant women reduces the risk of gestational diabetes, pre-eclampsia, preterm delivery, and delivery of low-birth-weight babies. 5

Infectious diseases

  • Vitamin D modulates both anti-bacterial and anti-viral immune responses
  • Vitamin D reduces the critical course of disease in infections such as tuberculosis, COVID-19, and HIV.3

Autoimmune diseases

  • Vitamin D has anti-inflammatory and immunomodulatory properties
  • It suppresses and prevents the progression of autoimmune diseases such as inflammatory bowel disease, inflammatory myopathies, rheumatoid arthritis, and multiple sclerosis4

Heart diseases

It keeps the heart healthy and reduces the risk of stroke, ischaemic heart diseases and myocardial infarction. 


It could help in preventing or delaying dementia and lowering the cognitive dysfunction of older people.6

Are vitamin D supplements over-rated?

Vitamin D deficiency is a significant public health concern worldwide and in all age groups.7 Modern lifestyles have limited outdoor activities due to increased indoor and online opportunities, compounded by the pandemic and remote work.

Some studies question vitamin D supplements' benefits, but they are not overrated in the current scenario, especially after the recent COVID-19 outbreak.

When and how do you take vitamin D supplements? 

It is a fat-soluble vitamin that works well with fat-containing food. One study suggests that consuming large, healthy, fat-containing meals can help increase blood vitamin D absorption by 50%.8

Does the timing of vitamin D supplement matter?

You should follow a strict routine if you take supplements for a deficiency. Otherwise, you can make it flexible and take vitamin D at any convenient time, depending on your daily schedule.

In the morning

If you love to start your day with a heavy breakfast, consider taking vitamin D in the morning.

In the afternoon

Most of us enjoy heavy meals at lunch or frequently attend lunch meetings, making it an ideal time to take this supplement.

At bedtime

It is recommended to avoid taking vitamin D supplements at night if you have a light dinner.

Tips for making vitamin D supplements work for you

If you want to make vitamin D supplements work for you, there are some steps you can take:

  • Be patient and create a consistent schedule that helps in maintaining the daily dose
  • Check your serum vitamin D level regularly so that the doctor can help you tailor the dose as per your need
  • Choose vitamin D supplements from the market that suit you the best
  • Add vitamin D-rich food to your daily diet 1
  • Take supplements with your meal for better absorption 8
  • Consider lifestyle modifications that include more outdoor activities and exposure to sunlight1
  • Avoid interfering agents or medicines that inhibit absorption 1,9

Vitamin D supplements: Interactions and potential side effects

Interactions of vitamin D 

Are you mixing your vitamin D with other vitamins? Nowadays, there are tons of supplements available in the market. Knowing the interaction between various supplements helps you make informed decisions.

For example, when you take calcium supplements with vitamin D, it helps in better absorption of calcium and keeps your bones healthy.1 Further, vitamin D works well with other fat-soluble vitamins, such as vitamin K, according to a study.9

Similarly, there is no harm if you take vitamin D with any water-soluble vitamins but water-soluble vitamins can work better without fatty food. Water-soluble vitamins do not require food to be absorbed and are not stored in the body like fat-soluble vitamins. Therefore, taking your daily supplements of vitamin D and water-soluble vitamins at different times could give better results.

There are a few medications that could interfere with vitamin D absorption. The most common are antiobesity drugs, orlistat and olestra, which are known to reduce vitamin D absorption in our body.1 Therefore, if you are taking medication, it is important to consult your doctor before starting vitamin D supplements.

Potential risks of excess vitamin D supplement

Excess of vitamin D intake can hinder your health. The side effects of vitamin D are mainly due to raised serum calcium levels. Here is the list of possible side-effects that you must know:7

  • Lethargy
  • Dehydration
  • Vomiting
  • Constipation
  • Renal stones
  • Frequent urination
  • Colicky pain from the passage of renal stones.
  • Confusion and coma
  • Cardiovascular issues


Is milk a good source of vitamin D?

Milk is not a good source of vitamin D. Unlike in countries like the USA and Canada, milk fortification is not practiced  in the UK.

Why do individuals with darker skin produce less vitamin D?

Melanin, present in dark skin, limits the ability to make vitamin D by the skin from sunlight. Therefore, dark-skinned people have a higher incidence of vitamin D deficiency compared to  white people.

Can sunlight entering my room produce vitamin D?

Ultraviolet B radiation from sunlight does not penetrate glass, so sunshine through a window cannot produce vitamin D.

How much time does vitamin D take to get absorbed?

It takes around 24 hours to reach peak concentration in the blood.7 However, vitamin D absorption is influenced by innumerable factors that may prevent or slow down its absorption in the gut.

Does a fibre-rich diet interfere with vitamin D?

Fibre-rich diets reduce vitamin D bioavailability, but fibre is as important as vitamin D in the diet.1 Hence, you should not lower your daily fibre intake in your food. Your body will regulate vitamin D absorption as per its needs.


  • Vitamin D is essential for maintaining bone metabolism and the immune system
  • This fat-soluble vitamin is found mainly in sunlight and in some foods
  • Supplements are often needed if you don't get enough vitamin D or if you have any underlying medical condition 
  • As well as healthy teeth, bones, and muscles, vitamin D could help lower the risk of cancer, infections, and autoimmune diseases.
  • To make vitamin D supplements work for you, take it with heavy meals and avoid interfering agents or medicines that inhibit absorption.
  • You can take vitamin D at any time of the day, but make sure to make it your daily routine
  • Excess intake of vitamin D can cause side effects
  • Supplements cannot replace food and sunlight; they should be taken judiciously.


  1. Borel P, Caillaud D, Cano NJ. Vitamin D bioavailability: State of the art. Crit Rev Food Sci Nutr [Internet]. 2015;55(9):1193–205. Available from:
  2. Pfotenhauer KM, Shubrook JH. Vitamin D deficiency, its role in health and disease, and current supplementation recommendations. Journal of Osteopathic Medicine [Internet]. 2017;117(5):301–5. Available from:
  3. Taha R, Abureesh S, Alghamdi S, Hassan RY, Cheikh MM, Bagabir RA, et al. The relationship between vitamin D and infections including COVID-19: Any hopes? Int J Gen Med [Internet]. 2021;14:3849–70. Available from:
  4. Athanassiou L, Kostoglou-Athanassiou I, Koutsilieris M, Shoenfeld Y. Vitamin D and autoimmune rheumatic diseases. Biomolecules [Internet]. 2023;13(4):709. Available from: 
  5. Palacios C, Kostiuk LK, Peña-Rosas JP. Vitamin D supplementation for women during pregnancy. Cochrane Libr [Internet]. 2019; Available from: 
  6. Sultan S, Taimuri U, Basnan SA, Ai-Orabi WK, Awadallah A, Almowald F, et al. Low vitamin D and its association with cognitive impairment and dementia. J Aging Res [Internet]. 2020;2020:1–10. Available from:
  7. Ramasamy I. Vitamin D metabolism and guidelines for vitamin D supplementation. Clinical Biochemist Reviews [Internet]. 2020;41(3):103–26. Available from:
  8. Mulligan GB, Licata A. Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D. J Bone Miner Res [Internet]. 2010;25(4):928–30. Available from:
  9. Masterjohn C. Vitamin D toxicity redefined: Vitamin K and the molecular mechanism. Med Hypotheses [Internet]. 2007;68(5):1026–34. Available from:

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Rajni Sarma

MBBS, MD from North-Eastern Hill University, India
MSc in Molecular Pathology of Cancer, Queen's University, Belfast, UK

I worked as a medical doctor for almost eight years before applying to Queen’s University Belfast for MSc in Molecular Pathology of Cancer. My outstanding verbal and demonstrative skills have helped me to get distinction in my master’s program.

However, I found my true passion in medical writing. Therefore, after I graduated from Queen’s University, I decided not to join any laboratory but to restart my career as a medical writer.

The topics that intrigue me are haematology, oncology, rare diseases, immunology, gynaecology, molecular pathology, targeted therapy, and precision medicine. I am currently an intern at Klarity and a volunteer medical writer for a health and wellness website. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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