The BMJ
['Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data.', 'High doses of vitamin D to reduce exacerbations in chronic obstructive pulmonary disease: a randomized trial.', 'Iwona Stelmach', 'The BMJ', 'Creative Commons Attribution', 'Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data.']