The Relative Influence of Calcium Intake and Vitamin D Status on Serum Parathyroid Hormone and Bone Turnover Biomarkers in a Double-Blind, Placebo-Controlled Parallel Group, Longitudinal Factorial Design

Abstract

rienced increases in CES-D scores of 1.9 (P ϭ 0.01) and 1.1 (P ϭ 0.20) points higher at 3-and 6-yr follow-up. Men with low Vit-D tended to have higher risk of developing depressed mood (hazard ratio ϭ 1.6; 95% confidence interval ϭ 0.9 -2.8; P ϭ 0.1). Conclusion: Our findings suggest that hypovitaminosis D is a risk factor for the development of depressive symptoms in older persons. The strength of the prospective association is higher in women than in men. Understanding the potential causal pathway between Vit-D deficiency and depression requires further research. ABSTRACT Context: Brain-derived neurotrophic factor (BDNF) haploinsufficiency is associated with hyperphagia and obesity in both animals and humans. BDNF appears to function downstream of the leptin-melanocortin signaling pathway to control energy balance. The potential role of BDNF in the etiology of the severe hyperphagia associated with PWS has not been previously explored. Objective: The aim was to compare BDNF concentrations in subjects with PWS and obese controls (OC) and lean controls (LC). Design and Setting: We conducted a cross-sectional study at an outpatient clinical research center. Participants: We studied 13 subjects with PWS [five males and eight females; mean Ϯ SD: age, 11.0 Ϯ 4.1 yr; body mass index (BMI)-Z, 2.05 Ϯ 0.78], 13 OC (eight females, five males; age, 12.3 Ϯ 2.7 yr; BMI-Z, 2.18 Ϯ 0.61), and 13 LC (six females, seven males; age, 12.4 Ϯ 2.6 yr; BMI-Z, Ϫ0.57 Ϯ 0.73). Main Outcome Measure: BDNF was measured in serum and plasma by ELISA. Analysis of covariance adjusted for age, sex, and BMI-Z. Results: All groups were comparable for age (P ϭ 0.50) and sex distribution (P ϭ 0.49). BMI-Z was comparable between PWS and OC (P ϭ 0.89) and lower in LC (P Ͻ 0.001). Adjusted serum BDNF was comparable (P ϭ 0.35) in OC (mean Ϯ SEM: 13.5 Ϯ 1.2 ng/ml) and LC (19.2 Ϯ 1.3 ng/ml), but lower in PWS (8.3 Ϯ 1.2 ng/ml; P ϭ 0.01 vs. OC; P ϭ 0.03 vs. LC). Adjusted plasma BDNF in PWS (217 Ϯ 130 pg/ml) was lower than OC (422 Ϯ 126 pg/ml; P ϭ 0.02), but statistically comparable with LC (540 Ϯ 143 pg/ml; P ϭ 0.10). Conclusions: Lower BDNF in PWS suggests insufficient central BDNF production because BDNF in peripheral circulation is believed to reflect cerebral BDNF output. Decreased BDNF may be a potential cause for the disordered satiety and morbid obesity associated with PWS. Further studies are needed to confirm this preliminary pilot study in a larger cohort of patients with PWS. Objective: Our objective was to examine the influence of calcium intake and vitamin D exposure separately and their interaction on biomarkers of calcium sufficiency. Design: Healthy men and women, age 20 -80 yr, were randomly allocated to four groups: 1) double placebo, 2) calcium (1200 mg daily) plus placebo, 3) vitamin D 3 (100 g) plus placebo, and 4) vitamin D 3 and calcium. Fasting serum and urine as well as serum and urine 2 h after a calcium load (600 mg of calcium carbonate) were obtained at baseline and 3 months. Results: Ninety-nine participants were randomized; 78 ...

Effect of Vitamin D Repletion on Urinary Calcium Excretion among Kidney Stone Formers

“…Therefore, the lack of change in PTH could partly explain the lack of change in urinary calcium excretion. Interestingly, other studies of vitamin D repletion have also not consistently shown a decline in serum PTH (14). The lack of suppression of PTH in our study may have been influenced by the large proportion of Hispanic participants.…”

Vitamin D levels in a large Mediterranean cohort: reconsidering normal cut-off values

“…It is noteworthy that significant changes in biomarkers of bone turnover are not always evident, despite an observed increase in 25-(OH)D levels and concomitant decrease in PTH levels when administering supplementation with oral VitD. 76,77 As has been reported by others, 78,79 a negative correlation between 25-(OH)D levels and glucose, triglycerides and total cholesterol was apparent in our population, confirming that higher serum concentrations of 25-(OH)D tend to be associated with a more favorable lipid profile. Literature reports on the association between VitD and total cholesterol are often discrepant, even when extensive adjustments for confounding factors (particularly BMI) have been applied, 45,80,81 while the association between VitD and triglycerides is consistently reported as negative, 82 with two exceptions concerning adolescent girls.…”

Calcium supplementation in osteoporosis: useful or harmful?

“…For many years, a normal calcium balance together with normal vitamin D status has been considered crucial for maintaining well-balanced bone metabolism and in the prevention and treatment of osteoporosis (4,5). However, in recent years the usefulness of calcium supplementation (alone and with concomitant vitamin D supplementation) has been questioned, since some studies reported only weak efficacy of these supplementations in reducing fragility fracture risk (6)(7)(8).…”