As the days get shorter in the Northern hemisphere, concerns tend to arise about the lack of sunlight – and possible vitamin D deficiency,  according to internet. For many, a go-to fix is to take supplements.

The supplement, after all, has been touted as a near-miracle. Both vitamin D2 and D3 supplements are available over-the-counter without a prescription and have been linked to improving immunity, tiredness and muscle weakness, bone pain, and depression. They’ve also been said to help stave off cancer and the consequences of ageing.

It may be little wonder that, according to research by market analysis company Mintel, a third of adults in the UK who take vitamin supplements count vitamin D among them.