1. NICE. Covid-19 rapid guideline: vitamin D. 17 December 2020. www.nice.org.uk/guidance/ng187.
2. Statement from PHE and NICE on vitamin D supplementation during winter. 28 November 2020. www.gov.uk/government/publications/vitamin-d-supplementation-during-winter-phe-and-nice-statement/statement-from-phe-and-nice-on-vitamin-d-supplementation-during-winter.
3. Scientific Advisory Commission on Nutrition. Rapid review: vitamin D and acute respiratory tract infections. June 2020. https://app.box.com/s/g0ldpth1upfd7fw763ew3aqa3c0pyvky.
4. Martineau AR, Jolliffe DA, Hooper RL et al. Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ 2017;356:i6583.
5. Evidence does not support vitamin D for reducing respiratory infections, reviews conclude