Ensuring Adequate Vitamin D intake for Bone Health and Muscle Strength during Adolescence
A high prevalence of vitamin D deficiency has been reported in healthy growing children and adolescents in a number of countries. Vitamin D deficiency is associated with an elevation of PTH concentration in blood and an increase in the blood concentration of markers for bone turnover. Such changes in growing children and adolescents suggest that there may be suboptimal bone mass growth.
Vitamin D deficiency rickets has been reemerging as a public health problem in some developed and developing countries. Persistent severe vitamin D deficiency causes rickets in children and osteomalacia in adults, whereas mild vitamin D deficiency may also be associated with hyperparathyroidism and increased bone turnover.
A cross-sectional study by researchers in Australia, China, and Malaysia investigated the influence of low-vitamin D status on bone mass, bone turnover, and muscle strength in 301 healthy Chinese adolescent girls in Beijing, China. The researchers measured the Blood plasma 25-hydroxyvitamin D [25(OH)D], the plasma and urine biomarkers of bone turnover; and the bone mineral content (BMC) and density and bone area for the whole body and the distal and proximal forearm
Vitamin D deficiency was defined as a serum 25(OH)D concentration of <=50 nmol/L. Severe
Deficiency was defined as <25 nmol/L. 58% of the adolescent girls were vitamin D deficient and 31% were severely deficient.
The study results showed that girls with adequate vitamin D status had higher size-adjusted BMC for the whole body, distal forearm, and proximal forearm than those with poorer vitamin D status. Similar results were also found for handgrip muscle strength.
Girls with adequate vitamin D status had significantly lower concentrations of biomarkers for bone resorption compared with those of the vitamin D-deficient girls, suggesting that low vitamin D status is associated with greater rates of bone remodeling.
Adolescent girls with adequate vitamin D status had significantly higher bone mass and muscle strength compared with those with poor vitamin D status. This may be attributed in part to a lower rate of bone remodeling with adequate vitamin D status.
These findings suggest that adequate vitamin D status during adolescence is important for optimizing bone mass, which may lead to higher peak bone mass at maturity. Poor vitamin D status also compromises forearm muscle strength.
In conclusion, adequate vitamin D status is important in enhancing muscle strength and in attaining higher peak bone mass. This effect on bone may in part be attributed to lower rates of bone remodeling when vitamin D status is adequate.
Source:
Leng Huat Foo et al. (2009) J. Nutr. 139: 1002–1007
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