Authorities in the UK have started encouraging people to take vitamin D rather than merely advising it. Photograph: Alamy The link between vitamin D and Covid is being kept under review by the UK health secretary as more studies suggest that having low levels of the “sunshine hormone” raises the risk of death. Matt Hancock has asked the National Institute for Health and Care Excellence (Nice), which sets NHS England clinical guidelines, and Public Health England (PHE) to keep researching emerging evidence, after the authorities began “encouraging” people to take vitamin D supplements rather than merely “advising” it. Nice has twice said there was not sufficient causal evidence to support the use of vitamin D in high doses in hospitals to treat or prevent the respiratory illness.