Improving the health of people in the UK with Vitamin D

How much Vitamin D ?

There are 4 parts to this:

  • What do I need ?
  • What do I have already ?
  • How do I add to what I have already ?
  • What can I eat or take ?

What do I need ?

The UK Department of Health says that 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 ( IOM ) set the equivalent level at 50 nmol/L in their report issued in November 2010

Many experts say that there are biomarkers that change just above 75 nmol/L, so they suggest that the level should be set there.

Professor Robert Heaney, who is a world expert in Osteoporosis, says that Vitamin D “enables the body to absorb calcium” and that the level should be set at 100 nmol/L

Dr John Cannell, of in his book Athlete’s Edge, says that there is “extreme substrate deprivation” below 125 nmol/L

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

A group of 40 eminent experts at have issued a “Call-To-Action” calling for optimum blood serum levels to be between 100-150 nmol/L

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

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.

If you want to have the test done privately there is an NHS hospital in Birmingham that offers the test direct to the public.

Check out or phone +44 (0)121 507 4278 provide a direct-to-the public testing service

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. 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 200 nmol/L, 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 and could be between 100-150 nmol/L, 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 per day for 3 months to raise your level by 25 nmol/L.  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 2 years and my level was 143 nmol/L when it was last tested in August 2011.

Vitamin D can be taken once a week, since the half-life of Vitamin D in the body is 14-30 days.  Multiply the daily amount by 7 and take approximately that amount once a week.


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.  Please read other sections of this site and then you can 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 300-500g 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 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 10,000 IU from most Health Stores or online from eBay, Amazon or other specialist supplier of Vitamins and supplements.

You can take tablets, capsules, sprays or drops.

Doctors can prescribe 500 micrograms ( 20,000 IU ) of Vitamin D3 for weekly use, but these are “specials” which may cause problems in sourcing or payment via the NHS.

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