This website is dedicated to the millions of thyroid patients who are being ignored and left to suffer unnecessarily, and to healthcare practitioners, who want to better serve those patients.

What dose of Vitamin D3 to take?

Conversion of Vitamin D quantities:

25 ?g = 1,000 IU
500 ?g = 20,000 IU
?g = micrograms
mg = milligrams

Note that a milligram is 1,000 times more than a microgram and that many milligrams of Vitamin D are rarely prescribed !

The UK measures blood level of Vitamin D in nmol/L ( nanomols per Litre )
The US measures blood level of Vitamin D in ng/mL ( nanograms per milliliter )

Conversion: 1 ng/mL = 25 nmol/L

The half-life of Vitamin D in the body is about 30 days

This means that it is acceptable to take 7 times the daily dose once a week

So taking 50,000 IU once a week is equivalent to taking about 7,000 IU once a day
Toxicity may only start if you take more than 30,000 IU per day for 90 days
Dr Robert Heaney has said that it is OK for an adult to take 300,000 IU in a month


If you have Thyroid problems or Sarcoidosis you should follow specific advice from your doctor, as you may be abnormally sensitive to Vitamin D.

Maybe start with a single dose of 1,000 IU and wait a week to see what happens
You can watch videos of 2 scientific talk about this:

Go to and search for: Heaney

Dr Robert Heaney links all the evidence across many short-term and long-term illnesses

and explains how Vitamin D interacts with & enables uptake of calcium

There is more online at: Search by illness General advice Search for the experts Call To Action Look for videos of scientific conferences Occasional comments about UK specific matters

I gave a talk at Nutricentre that you can watch online at:

Rufus Greenbaum


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