Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

The BEST-D study was a single centre pilot study to establish the optimum dose of vitamin D to assess in a future large randomised trial. Between September 2012 and March 2013, 305 participants were randomised to either 4000 IU D3 (n=102), 2000 IU vitamin D3 tablets  (n=102), or matching placebo (n=101) daily and were followed for one year. The primary endpoints were the mean plasma levels of 25(OH)D and the proportion of participants achieving levels greater than 90nmol/L at one year.   A variety of other secondary and tertiary endpoints were assessed.

The BEST-D study has shown that:

  • Allocation to 2000 IU vitamin D daily increases 25(OH)D on average by 50 nmol/L and 75% of participants achieved levels >90nmol/L and 4000 IU nmol/L raised levels by about 80 nmol/L and 88% of participants achieved plasma levels of 25(OH)D >90 nmol/L.  
  • Both 4000 IU and 2000 IU doses were safe with no new cases of hypercalcaemia or any other safety concerns

The main results of BEST-D have been published and indicate that 4000 IU (100 µg)  daily is required to ensure that most people attain blood levels of 25(OH)D which are associated with the lowest risk of vascular and non-vascular mortality and fractures in observational studies.

The BEST-D trial was funded by a grant to Oxford University from the British Heart Foundation (PG/12/32/29544) and British Heart Foundation Centre for Research Excellence provided partial funding.  Tischcon Corporation (Westbury, New York, USA), donated the active and placebo vitamin D capsules.


Further information:

Our team

Related research themes