Randomization
Participants were randomly assigned (1:1) into two groups by using block randomization with a block size of 4 using a computer program. Packets containing the two interventions were prepared in accordance with the randomization numbers and were arranged serially, and then distributed consecutively to participants according to their entry into the trial. Both the groups received standard DOTS ATT as per RNTCP guidelines, according to which they received Isoniazid, Rifampicin, Pyrazinamide and Ethambutol thrice a week on alternate days for 2 months- designated as the Intensive phase, which was followed by the Continuation phase where they received Isoniazid, Rifampicin thrice a week on alternate days for 4 months). However, after 1 year of study initiation, patients were provided with daily Isoniazid, Rifampicin, Pyrazinamide and Ethambutol for 2 months during the Intensive Phase followed by daily Rifampicin, Isoniazid and Ethambutol for 4 months during the Continuation Phase, in accordance with the changes proposed by the RNTCP (8). Those with persistent sputum AFB smear positive at two months of therapy were provided an extra month of intensive therapy The intervention group received supplemental dose of oral vitamin D3 (60,000 IU/sachet every week for first two months, then every fortnight for next four months and then every month for next 18 months), and the control received only placebo with an identical schedule. The vitamin D and placebo sachets were identical in terms of their taste and physical appearance.