Since the pandemic began there's been an ongoing debate about the link between a patient's vitamin D levels and how badly the virus affects them. 

The problem is that, scientifically speaking, correlation and causation are not the same – and health authorities demand causal proof before recommending new treatments.

However, the evidence of a correlation between vitamin D and better patient outcomes is growing all the time and now a new review of the evidence has been ordered by the UK's health secretary. 

Medical researcher Gareth Davies and consultant endocrinologist Richard Quinton tell RAZOR's Neil Cairns how much vitamin D we should be taking – and why it can change from case to case.

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