Older people, and especially women going through the menopause, should take vitamin D supplements to reduce their risk of bone fractures.
Overall, people should start supplementing with 400 IUs of vitamin D every day once they reach retirement age of 65, researchers from the University Hospital in Zurich say.
They conclude that there is strong evidence that the supplements reduce the risk of fracture by up to 20 per cent. Earlier studies that were inconclusive either tracked the wrong sort of supplement - such as D2 - or had people taking too low a dose.
The new study - a meta-analysis, or review of previous studies - involved 42,279 participants, with an average age of 78 years. The overall risk of fracture fell by 14 per cent for all fractures and 9 per cent for hip fractures, but when researchers looked only at the studies that involved higher doses of the supplement, the risks fell to 20 per cent and 18 per cent.
(Source: Archives of Internal Medicine, 2009; 169: 551).