The global Vitamin D supplement market is worth billions, and doctors prescribe the pills for everything from back ache to depression – yet superstar scientist Prof Tim Spector, co-creator of the Zoe Covid Study tracker app, says there’s little evidence taking it does anything at all for our health. The Medical Minefield team speak to him and Bolton-based Vitamin D advocate GP Dr Jane Wilcock, who often tells her patients they need a dose of the sunshine vitamin.