Table 1 Changes to the registered protocol

2

Addition of new questionnaires including on level of sun exposure, frequency of eating food containing vitamin D, key service contacts, Fitzpatrick skin type, levels of physical activity (IPAQ) and duration of untreated psychosis.

3

Addition of second questionnaire assessing physical activity (SIMPAQ).

Addition of PANSS assessment at month 3.

4

Changes to all study documents for clarification and to include site-specific information and logos.

5

The definition of the first episode of psychosis was changed from “6 months post-first presentation to services” to “3 years post-first presentation to services”.

6

Change in inclusion criteria to allow patients to take up to 400 IU per day of vitamin D in view of new Public Health England recommendations.

7

Change to inclusion criteria to allow patients aged up to 65 years to participate. Removal of anticonvulsants as an exclusion criterion. Remove hospitalisation due to a deterioration in mental health from the definition of a serious adverse event. Blood test for beta human chorionic gonadotropin was included if a urine test was not possible. Clarification for permitted dosing windows.

Total study duration was reduced from 12 to 6 months.

8

Removal of exclusion criteria regarding anaemia, sickle cell anaemia and thalassemia.

9.1*

Clarification of outcome measures. Time between doses to be a minimum of 24 days. Clarification of window for collection of final assessment. Pregnancy test not required if participant is medically sterile or post-menopause. Vitamin D levels will be sent to GP at the end of the study. Phase II designation (not Phase IV).

9.2

Change in study end date to December 2019.

10.1*

Discontinuation of RNA sample collection. Increase in participant reimbursement. Clarifications to existing procedures regarding safety of the iPTH test, service contact form use, collection of adverse event details and attempts to contact participants for the follow-up.