Winter warmth from Cochrane

At this time of year, when the sun makes its briefest appearance, maintaining vitamin D intake is a priority, but what evidence is there that vitamin D helps prevent fractures? An updated review now includes 53 studies involving more than 90 000 men and women aged over 65 years from community, hospital and nursing home settings. It found that taking vitamin D on its own is unlikely to prevent fractures, but when taken with calcium supplements it slightly reduces the likelihood of hip and other types of fracture (doi: 10.1002/14651858.CD000227.pub4).

A small chink of sunshine for people with osteoarthritis comes with an updated review of oral herbal therapies. Forty-five new studies have been added to the original four, involving nearly 6000 participants. With over 30 medicinal plant products included, the results focus on the two with multiple studies: Boswellia serrata and avocado-soyabean unsaponifiables. For both, the evidence points towards slight reductions in pain and improvements in function, with more definitive evidence in favour of B. serrata. Evidence on side effects is uncertain (doi: 10.1002/14651858.CD002947.pub2).

The outlook is patchier in a new review of interventions to improve control of modifiable risk factors in the secondary prevention of stroke. The review included 26 studies, most lasting between 3 and 12 months, and looked at patient-level behavioural interventions and predominantly organisational ones. As one might expect with such a multifactorial issue, deciphering the results is no easy task. What emerges is that changes to the organisation of services, such as establishing integrated stroke units, are more effective at modifying risk factors, especially blood pressure and body mass index, than only addressing patient education or behaviour. For anything more substantive, such as the effects on recurrent cardiovascular events, the evidence is equivocal (doi: 10.1002/14651858.CD009103.pub2).

For those looking to indoor pursuits to keep active during the cooler months, new reviews find low-quality evidence pointing towards the benefits of yoga for primary prevention of cardiovascular disease (doi: 10.1002/14651858.CD010072.pub2), but insufficient evidence to make any claims for tai chi (doi: 10.1002/14651858.CD010366.pub2). Either way, keeping active and clear of daily distractions can't be a bad thing.

For more fireside reading on these and other reviews, check out The Cochrane Library at www.thecochranelibrary.com.