Vitamin D supplements 'don't improve bone strength'
11th October 2013 - Taking vitamin D supplements to improve bone mineral density and guard against osteoporosis is unjustified, a new study has found.
The New Zealand study of 4,082 adults - most of them women - did not find any evidence of improvements in almost any part of the body as a result of taking the supplements over almost 2 years.
"Most healthy adults do not need vitamin D supplements”, explains study leader Professor Ian Reid from the University of Auckland in a statement. "Our data suggest that the targeting of low-dose vitamin D supplements only to individuals who are likely to be deficient could free up substantial resources that could be better used elsewhere in healthcare."
Europe and the US
To reach their conclusion, Professor Reid and his colleagues reviewed data from 23 studies of adults with an average age of 59 drawn from mainly Europe and the US.
However, the authors could not find any improvements in bone strength among people who took vitamin D for an average period of 23.5 months, apart from a small but statistically significant increase in bone density (0.8%) at the femoral neck (hip).
According to the authors, such a localised effect is unlikely to be clinically significant.
The research, which appears in The Lancet, concludes: "This systematic review provides very little evidence of an overall benefit of vitamin D supplementation on bone density...Continuing widespread use of vitamin D for osteoporosis prevention in community-dwelling adults without specific risk factors for vitamin D deficiency seems to be inappropriate."
Writing in a linked Comment article, Clifford Rosen from the Maine Medical Research Institute in the US discusses how recent improvements in our understanding of the role of vitamin D lends support to these findings. He says: "Supplementation to prevent osteoporosis in healthy adults is not warranted. However, maintenance of vitamin D stores in the elderly combined with sufficient dietary calcium intake (800-1200 mg per day) remains an effective approach for prevention of hip fractures."
Dr Claire Bowring, National Osteoporosis Society medical policy manager says in an emailed statement: "Vitamin D is essential for good bone health. This latest study supports what the National Osteoporosis Society has been saying for years: the best source for most people is safe summer sunlight exposure, and that only people at risk of vitamin D deficiency should take a supplement.
"The Department of Health identifies the following groups pregnant and breastfeeding women, under 5s, people with darker skin, older people aged 65 and over and those with low or no exposure to the sun as being at risk of vitamin D deficiency."