The growing evidence on vitamin D and Covid

The argument that vitamin D deficiency may contribute to more severe cases of Covid is gaining ground. It is now reaching the point where it is surprising that we are not hearing from leading medical officials and politicians that people should consider taking supplements to ensure they have sufficient vitamin D.

This is not the same as arguing that vitamin D is a magic bullet that will cure the disease. Vitamins are not medication, the taking of which will have positive effects on everybody. They are top-ups: things that hurt you when you don’t have enough of them in your system but do no extra good when you have enough. Indeed, with many vitamins, including D, taking too much can be toxic.

However, it is true that many people are deficient in vitamin D, especially at the end of winter. That is because, uniquely, vitamin D is a substance manufactured by ultraviolet light falling on your skin.