Vitamin D is one of the few supplements that most national public health bodies are in agreement are worth taking,  Public Health England (PHE) in 2016 published guidance that we should all consider taking 10 microgram supplements during the autumn and winter,  to help keep bones, teeth and muscles healthly.  However a recent statistical analysis looking at all relevant studies on vitamin D and bone health published in the British Medical Journal concluded that there was no reduction in fractures in those taking the supplement.
Critics of the report pointed out that there exists widespread deficiency of Vitamin D in some parts of the population.  Some estimates put this figure as high as 25% in areas such as Scotland where sunlight levels are lower than in the south. The primarly source of vitamin D is via the action of sunlight on our skin, with other good sources being oily fish, dairy products and fortified food such as cereals. There is little evidence to suggest any negative impacts of supplementation at low levels. It would therefore seem sensible to encourage supplementation in at risk groups who are unlikely to be able to obtain sufficient vitamin D from sunlight exposure or dietary sources.