Another disappointing result for Vitamin D supplements. A large study, with school-aged children randomly assigned to either a vitamin D supplement group or no supplement, found that vitamin D supplementation had no effect on the number of fractures that occurred in the children. Vitamin D3 supplementation did not prevent fractures or have an effect on bone strength.
Most children were vitamin D deficient at the beginning of the 3 year study (but none had rickets, for which vitamin D is prescribed). The vitamin D supplement (14,000 IU/week for 3 years) group soon had normal levels while the other group stayed at low levels. And yet there were no differences in the percentage getting fractures (6% in both groups) over time.
From Science Daily: Vitamin D supplements do not prevent bone fractures in children
A major clinical trial led by Queen Mary University of London and the Harvard T.H. Chan School of Public Health has found that vitamin D supplements do not increase bone strength or prevent bone fractures in children with vitamin D deficiency. The findings challenge widely held perceptions relating to the effects of vitamin D on bone health.
Around one-third of children have at least one fracture before the age of 18. This is a major global health issue, as childhood fractures can lead to life years of disability and/or poor quality of life.
The potential for vitamin D supplements to improve bone strength has attracted growing interest in recent years, based on vitamin D's role in promoting bone mineralisation.
Working with partners in Mongolia, a setting with a particularly high fracture burden and where vitamin D deficiency is highly prevalent, researchers from Queen Mary and Harvard conducted a clinical trial to determine if vitamin D supplementation would decrease risk of bone fractures or increase bone strength in schoolchildren.
Over the course of three years, 8,851 schoolchildren aged 6-13 living in Mongolia received a weekly oral dose of vitamin D supplementation. 95.5% of participants had vitamin D deficiency at baseline, and study supplements were highly effective in boosting vitamin D levels into the normal range.
However, they had no effect on fracture risk or on bone strength, measured in a subset of 1,438 participants using quantitative ultrasound.
The trial findings are likely to prompt scientists, doctors and public health specialists to re-consider the effects of vitamin D supplements on bone health.
Professor Adrian Martineau, Lead of the Centre for Immunobiology at Queen Mary University of London, added:
"It is also important to note that children who were found to have rickets during screening for the trial were excluded from participation, as it would not have been ethical to offer them placebo (dummy medication). Thus, our findings only have relevance for children with low vitamin D status who have not developed bone complications. The importance of adequate vitamin D intake for prevention of rickets should not be ignored, and UK government guidance recommending a daily intake of 400 IU vitamin D remains important and should still be followed."