Doses of 400 international units per day or lower did not reduce the risk of either fracture type. A greater reduction in risk was also seen among trial participants whose blood levels of 25-hydroxyvitamin D (a commonly used measure of blood vitamin D levels) achieved a greater increase.

Among individuals taking high doses of vitamin D, additional calcium did not appear to have any further protective effect against fractures. "Physiologically, the calcium-sparing effect of vitamin D may explain why we did not see an additional benefit of calcium supplementation at a higher dose of vitamin D," the authors write.

"The greater fracture reduction with a higher received dose or higher achieved 25-hydroxyvitamin D levels for both non-vertebral fractures and hip fractures suggests that higher doses of vitamin D should be explored in future research to optimize anti-fracture efficacy," they conclude.

"Also, it is possible that greater benefits may be achieved with earlier initiation of vitamin D supplementation and longer duration of use. Our results do not support use of low-dose vitamin D with or without calcium in the prevention of fractures among older individuals."

-- Click for more news in Tech Max >>

Editor:Liu Fang