The Daily Requirement of Vitamin D

The Daily Requirement of Vitamin D

Feb 22, 2023
Vitamin D, the sunshine hormone is produced naturally by the body when you expose your skin to the sun. You can also obtain it from foods, sources of Vitamin D include oily fish, fortified cereals, mushrooms, egg yolks, meat and milk and of course supplements (1). 


Everyone believes that its main role is bone health, but it has many other functions. Recent research has even shown its ability to assist in weight loss.  


Vitamin D helps your body absorb calcium and phosphate (8). It contributes to the normal functioning of the immune system, maintenance of normal bones and teeth and normal muscle function and plays a role in the process of cell division.  


It is a fat-soluble vitamin which comes in two forms: Vitamin D2 (ergocalciferol) and D3 (cholecalciferol) (5). This means excess Vitamin D is stored in the fat cells of the body. 


Therefore, it is best to consume during or after a meal as absorption is much more efficient when consumed with healthy dietary fats such as avocados, nuts and seeds.


Water-soluble vitamins are excreted in the urine when excess is consumed so it is unlikely to overdose on them and they do not need to be consumed with dietary fats. 



Did you Know? 

1 in 5 people have insufficient vitamin D levels! (4). 

The average diet provides only 3-4ug of Vitamin D per day (5). 

Wearing sunscreen and air pollution can affect your Vitamin D production (2). 



Many people are deficient because of the lack of sunshine in colder countries and even in sunnier countries, many are deficient because they do not expose their skin to the sun. 

Even when individuals do expose their skin to the sun, it is hard to catch the correct ‘type’ of sun rays, at the correct time, for the right amount of time (2).  

If you are deficient, you may experience symptoms such as bone and joint aches, hair loss, fatigue and frequent colds (3). 

Deficiency can eventually lead to osteoporosis, heart disease, high blood pressure, cancer, autoimmune diseases, depression, insomnia, arthritis, diabetes, asthma, chronic pain and infectious diseases (7). 

Those who are even more at risk of a deficiency include babies and young children, pregnant and breastfeeding individuals, those over 65, those who spend less time outside or do not expose their skin, those further away from the equator and those in high air polluted areas. 

Individuals with dark skin are also at risk of developing deficiency because of their higher levels of melanin, which protects against ultraviolet radiation exposure, reducing the production of vitamin D (4).  


Recommended Daily Intake 

  • Babies up to the age of one need 8.5-10ug per day.
  • From one upwards (and adults) we need 10ug per day.

However, this is the nutrient reference value (NRV) or recommended daily intake (RDI) for a healthy adult. It does not take into consideration deficiency, existing health problems or lifestyle factors etc. 

The upper safe limit is 100ug (4,000iu) (9). Although, if you are deficient a higher dose is needed to bring your serum (blood) level up, such as 10,000iu for at least three months and then 4,000iu daily, as a safe maintenance dose (10). 


Microgram or IU? 

Many brands advertise their supplements in ‘IU’ units which can be confusing as the RDI is in micrograms (ug).  1 microgram = 40 IU, which means 10 micrograms is equal to 400 IU (4). 


25 Hydroxy Test  

The 25 Hydroxy test, is a blood test that tests for the presence of Vitamin D in your blood. It is used to determine deficiency or toxicity, depending on your result. 

A “normal” result is considered between 20 and 50 ng/mL, however, many professionals argue this should be raised to 30 - 40 ng/mL (11). 



Too much can result in abdominal pain, vomiting, nausea and confusion. However, Vitamin D toxicity is rare, and you would most likely need to consume a high dose, such as 50,000 daily for a long period (6). 


Magnesium and Vitamin K 

Magnesium supplements should always be taken with Vitamin D supplements, as taking them alone can cause magnesium deficiency. Magnesium intake also helps convert Vitamin D into its active form, so it is more easily absorbed by the body. 

Vitamin K2 can also direct Vitamin D to the correct place, reducing the risk of calcification (hardening) of the organs and soft tissue (10). This is why many supplement formulations also include Vitamin K2.  


Related Articles 



  1. Your Quick Guide to Vitamin D — Nutravita
  2. It’s Vitamin D-day. — Nutravita
  3. Low Vitamin D Symptoms | Promote The Calcium | Nutravita
  5. All About Vitamin D3 (
  6. Vitamin D3 Benefits, Uses, Foods, Deficiency, Side Effects - Dr. Axe (
  7. How Much Vitamin D Per Day Should I Take? - Dr. Axe (
  8. Vitamin D - Consumer (
  9. Vitamin D - NHS (
  11. Vitamin D 25 Hydroxy Test: Purpose, Procedure, Results - Dr. Axe (


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Any information or product suggested on this website is not intended to diagnose, treat, cure, or prevent any medical condition. Never disregard medical advice or delay in seeking it because of something you have read on this website. Consult your primary healthcare physician before using any supplements or making any changes to your regime. 

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