How much Vitamin D do I need ?

Posted by Rufus Greenbaum on

Vitamin D | How much Vitamin D do I need? | Greenvits

What is the problem with Vitamin D ?

Doctors have known and accepted for many years that you need enough Vitamin D to help your bones grow and give you strong muscles. If you don't get sun on your skin - then you may develop weak bones and your muscles may ache and become weak, and if you are older you may be more likely to fall.

This document gives you suggestions for what you can do to overcome these problems - and maybe help you with information about a lot more illnesses where lack of Vitamin D may play a part.

To see if any of your health problems may be due to a deficiency of Vitamin D, check the 100 illnesses listed at You can read and search the website in more than 70 different languages !
Then come back here to see which type and strength of Vitamin D is best for you !


What do I need - & why ?

  • The UK Department of Health says that Vitamin D Deficiency is when your blood serum level of Vitamin D 25(OH)D is less than 25 nmol/L ( nanomols per Litre )

( 25 nmol/L = 10 ng/mL ( nanograms per millilitre ) in the American scale )

  • The USA Institute of Medicine has set their definition of Vitamin D Deficiency at 50 nmol/L (20 ng/mL)
  • Many experts say that there are biomarkers for bone quality that change just above 75 nmol/L (30ng/mL), so they suggest that the level should be set there.
  • Professor Robert Heaney, who was a world expert in Osteoporosis, said that Vitamin D "enables the body to absorb calcium" and that the level should be set at 100 nmol/L (40ng/mL)
  • Dr John Cannell, of in his book Athlete's Edge, says that there is "extreme substrate deprivation" below 125 nmol/L (50ng/mL)
  • Professor Bruce Hollis, who is a world expert in Vitamin D for pregnant women and their babies, says that the baby takes nutrients from the mother and that pregnant women should have 125 nmol/L (50ng/mL)

The causal link between severe vitamin D deficiency and rickets or the bone disease of osteomalacia is overwhelming, while the link between vitamin D insuffiency and osteoporosis with associated decreased muscle strength and increased risk of falls in osteoporotic humans is well documented by evidence based intervention studies.

There are newly appreciated associations between vitamin D insufficiency and many other diseases, including tuberculosis, psoriasis, multiple sclerosis, inflammatory bowel disease, type-1 diabetes, high blood pressure, increased heart failure, myopathy, breast and other cancers which are believed to be linked to the non-calcemic actions of the parent vitamin D and its daughter steroid hormone.

Based on the evidence we now have at hand, action is urgent.

It is projected that the incidence of many of these diseases could be reduced by 20%-50% or more, if the occurrence of vitamin D deficiency and insufficiency were eradicated by increasing vitamin D intakes through increased UVB exposure, fortified foods or supplements. The appropriate intake of vitamin D required to effect a significant disease reduction depends on the individual's age, race, lifestyle, and latitude of residence.

Download the "Call-To-Action" here: Call To Action

You can watch videos about this at: or

So, you choose your expert and you set your own levels !

I am following the 40 eminent experts and have set my personal target at 100-150 nmol/L (40-60ng/mL)


What do I have already ?

The only reliable way to know is to have a blood test for 25-hydroxyVitaminD or 25(OH)D

 The options are:

  • Ask your doctor for a test.
  • Have the test done privately

Many doctors are under pressure to save the cost of testing, or they have been told that they are only allowed one test per year for each patient.

If your doctor does do a test, ask them for a copy of the result and file it carefully away for comparison with later tests.

There is a simple way to test yourself for Vitamin D deficiency:

Vitamin D | How much Vitamin D do I need? | Greenvits Press as hard as you can on the lowest bone in your ribs (Sternum)
Vitamin D | How much Vitamin D do I need? | Greenvits Press as hard as you can on both your shins (Tibia)

If you feel pain, Mayo Clinic says that it is most likely that your Vitamin D is low
Read more about this here: Vitamin D Self-Test

If you want to have a full blood test done privately there is an NHS hospital in Birmingham UK that offers the test direct to the public for £28 (=$42). Check out or phone +44 (0)121 507 4278

You can also order a Vitamin D test at: This is more expensive, but you are contributing your results to their database of a world-wide intervention trial. Doctors and other health professionals who would like to enter batches of results from multiple tests done locally in their practice are invited to contact Grass Roots Health.

In the UK  you can get a Vitamin D blood test from: They have a mobile phlebotomist who can visit you at home if you live near London. and provide testing services, but they need a referral from a health professional, like a doctor, dietitian or qualified nutritionist.


How do I add to what I already have ?

When you have received the results of your Vitamin D blood test you will have a number that probably ranges from 10 nmol/L to 300 nmol/L (4-120ng/mL), plus an opinion from the testing laboratory of how your result compares to their target.

If you compare that to the new target that you and your doctor want to set, which will hopefully be at least 75 nmol/L (30ng/mL) and could be between 100-150 nmol/L (40-60ng/mL), you will probably find that there is a difference.

A rough rule of thumb is that you will need to take 25 micrograms ( = 1,000 IU ) of Vitamin D3 every day for 3 months to raise your level by 25 nmol/L (10ng/mL). This guide works well when you are below 100 nmol/L, but you will need increasingly large amounts above 100 nmol/L, as the body self-regulates.

Here are some examples:

Result ( nmol/L )                   25        50        25        50

Target ( nmol/L )                    75        75      100      150

Requirement ( IU / day )   2,000   1,000    3,000   4,000

( Micrograms per day )          50        25        75      100

I have been taking 5,000 IU ( 125 micrograms ) each day for the past 5 years and my level was 143 nmol/L when it was last tested.

Vitamin D can be taken weekly or 2-weekly or even monthly, since the half-life of Vitamin D in the body is 30-60 days. Multiply the daily amount by 7 and take approximately that amount once a week.

If you take a single capsule of 1250 micrograms (50,000 IU) of Vitamin D:

  • 1 a week will give you 180 micrograms (7,000IU) each day
  • 1 every 2 weeks will give you 90 micrograms (3,500IU) each day

Alternatively, once a week you could take

  • 4 of the 125 microgram (5,000IU) capsules
  • 2 of the 250 microgram (10,000IU) capsules

This would be equivalent to 70 micrograms (2,800IU) each day

The European Food Safety Agency has issued an official Opinion which allows any adult over 18 to take 100 micrograms ( 4,000IU ) a day and 250 micrograms ( 10,000 IU ) a day under special circumstances. Read the EFSA Opinion here: EFSA Opinion


If you take high doses of Vitamin D each day ( more than 50 micrograms = 2,000IU ) then you should also consider taking Vitamin K, which helps direct the Vitamin D to the bones and muscles. Read more here: Co-factors

Here is a suitable product: D3-K2

There are a very few people who have a genetic problem with Vitamin D, such as sufferers from Thyroid problems or Sarcoidosis (too sensitive) or Coeliac or Crohn's disease (not sensitive enough) You will need detailed advice from your doctor or specialist.

The current advice for pregnant women from the NHS is to take only 10 micrograms ( 400 IU ) a day. Vitamin D in pregnancy and be more informed to discuss this subject with your midwife, doctor or other health professional.

What can I eat or take ?

It is very difficult to get enough Vitamin D from food. For example, you would have to eat about 300-500grams of mackerel or salmon  to get 25 micrograms of Vitamin D. The best result of Vitamin D from food that I have heard of is a lady from Bangladesh who was eating 3 pieces of sun-dried fish from Bangladesh each day.

The other alternative is to expose your body, without sunscreen, to direct sunlight – but only when your shadow is shorter than your height. This is only possible in the UK between April and September and between about 10:00am and 4:00pm. Do not burn your body and cover up if your body begins to become pink. A white skinned person will receive 20,000 IU within 15 minutes, but an Asian person might need 30-60 minutes and an African person might need 1-2 hours in the direct sun.

In his book Athlete's Edge, Dr John Cannell of describes how his daughter has fair skin and used to burn easily. He suggested that she took 10,000 IU of Vitamin D3 a day for a month before she went into the sun, and she then found that she was not as sensitive to the sun as she used to be.

You can buy 25 micrograms ( 1,000 IU ) of Vitamin D3 over-the-counter from a chemist or supermarket.

You can buy anything from 1,000 IU to 50,000 IU from most Health Stores

Of course, you can also buy all of these variants here at GreenVits ! ! !


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