Neither latitude , region of the world , nor laboratory methodology were found to be associated with the prevalence of hypovitaminosis
BACKGROUND Hypovitaminosis D is considered a global public health issue .
Knowledge of its true dimensions will allow us to design interventions and plan preventive measures that can have a significant impact on human health .
OBJECTIVES The aim of this study was to evaluate the prevalence of hypovitaminosis D , defined as a serum 25-hydroxyvitamin D concentration < 30 ng/ml , in postmenopausal women around the world , as well as to identify the potential associated factors .
Vitamin D supplementation increases calcium absorption without a threshold effect.
BACKGROUND The maximal calcium absorption in response to vitamin D has been proposed as a biomarker for vitamin D sufficiency . OBJECTIVE The objective was to determine whether there is a threshold beyond which increasing doses of vitamin D , or concentrations of serum 25-hydroxyvitamin D [ 25(OH)D ] , no longer increase calcium absorption . DESIGN This was a placebo-controlled , dose-response , r and omized , double-blind study of the effect of vitamin D on calcium absorption in healthy postmenopausal women . Seventy-six healthy postmenopausal women were r and omly assigned to placebo or 800 IU ( 20 μg ) , 2000 IU ( 50 μg ) , or 4000 IU ( 100 μg ) vitamin D₃ for 8 wk . The technique of dual isotopes of stable calcium was used with a calcium carrier to measure calcium absorption at baseline and after 8 wk . RESULTS Seventy-one women with a mean ± SD age of 58.8 ± 4.9 y completed the study . The mean calcium intake was 1142 ± 509 mg/d and serum 25(OH)D was 63 ± 14 nmol/L at baseline . A statistically significant linear trend of an increase in calcium absorption adjusted for age and body mass index with increasing vitamin D₃ dose or serum 25(OH)D concentration was observed . A 6.7 % absolute increase in calcium absorption was found in the highest vitamin D₃ group ( 100 μg ) . No evidence of nonlinearity was observed in the dose-response curve . CONCLUSIONS No evidence of a threshold of calcium absorption was found with a serum 25(OH)D range from 40 to 130 nmol/L. Calcium absorption in this range is not a useful biomarker to determine nutritional recommendations for vitamin
Neither latitude , region of the world , nor laboratory methodology were found to be associated with the prevalence of hypovitaminosis
BACKGROUND Hypovitaminosis D is considered a global public health issue .
Knowledge of its true dimensions will allow us to design interventions and plan preventive measures that can have a significant impact on human health .
OBJECTIVES The aim of this study was to evaluate the prevalence of hypovitaminosis D , defined as a serum 25-hydroxyvitamin D concentration < 30 ng/ml , in postmenopausal women around the world , as well as to identify the potential associated factors .