TUESDAY, March 24 (HealthDay News) -- About three out of four American adolescents and adults currently have insufficient levels of vitamin D, though oral vitamin D supplementation is effective in preventing fractures among older adults, according to two studies published in the March 23 issue of the Archives of Internal Medicine.
In one study, Adit A. Ginde, M.D., from the University of Colorado Denver School of Medicine in Aurora, and colleagues compared serum 25-hydroxyvitamin D (25[OH]D) levels using data from the National Health and Nutrition Examination Survey of 18,883 participants in 1988 to 1994 and 13,369 individuals in 2001 to 2004. They found that the mean 25(OH)D level fell from 30 ng/mL to 24 ng/mL during this period. The percentage of individuals with very low 25(OH)D levels (less than 10 ng/mL) increased from 2 to 6 percent, while the percentage of individuals with normal 25(OH)D levels (30 ng/mL or more) fell from 45 to 23 percent.
In the other study, Heike A. Bischoff-Ferrari, of University Hospital in Zurich, Switzerland, and colleagues performed a meta-analysis on the efficacy of oral supplemental vitamin D in preventing hip and non-vertebral fractures among individuals aged 65 and older. The analysis included 12 trials for non-vertebral fractures involving 42,279 subjects and eight trials for hip fractures involving 40,886 subjects. The researchers found that the pooled relative risk for the prevention of hip fractures was 0.91 and the pooled relative risk for prevention of non-vertebral fractures was 0.86.
"Non-vertebral fracture prevention with vitamin D is dose-dependent, and a higher dose should reduce fractures by at least 20 percent for individuals aged 65 years or older," Bischoff-Ferrari and colleagues write.
Abstract - Ginde
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Abstract - Bischoff-Ferrari
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