Search

Objective Observational studies have suggested positive associations between serum 25-hydroxyvitamin D (25( OH)D) levels and muscular strength, balance and quality of life. Our aim was to examine whether high-dose vitamin D supplementation would improve these measures as compared to standard-dose vitamin D, as well as the possible muscular effects of single nucleotide polymorphisms ( SNPs) in genes encoding vitamin D-related enzymes. Design A 12-month randomized, double-blind, controlled trial where the participants received daily elemental calcium (1000 mg) plus vitamin D3 (800 IU). In addition, the participants were randomized to receive either capsules with vitamin D3 (20 000 IU) or matching placebos to be taken twice a week. Patients A total of 297 postmenopausal women with osteopenia or osteoporosis. Measurements Muscle strength (handgrip and knee extensor strength), balance (tandem test) and quality of life ( EQ-5D) were measured at baseline and after 12 months. The subjects were genotyped for SNPs related to vitamin D metabolism. Results Of the 297 included women, 275 completed the study. Mean serum 25( OH)D levels dramatically increased in the high-dose group (from 64.7 to 164.1 nmol/L; P<.01), while a more moderate increased was observed in the standard-dose group (from 64.1 to 81.8 nmol/L; P<.01). There was no significant difference between the groups in change in muscular strength, balance or quality of life over the intervention period. Polymorphisms in rs3829251 (located in the 7-dehydrocholesterol reductase gene) were associated with muscle strength and treatment effects. Conclusion One-year treatment with high-dose vitamin D had no effect on muscular strength, balance or quality of life in postmenopausal women with osteopenia or osteoporosis as compared to standard dose. The association between rs3829251 and muscle strength needs confirmation in other populations. [ABSTRACT FROM AUTHOR]

Purpose:   To study the associations between serum 25-hydroxy-vitamin D (25(OH)D) levels, vitamin D administration and intraocular pressure (IOP)., Methods:   The design of the study included a nested case-control study and a randomized controlled intervention trial. In the first part, healthy Caucasians with high or low serum 25(OH)D levels were recruited from a population-based study. IOP of the right eye was measured by the use of a rebound tonometer. In the second part, those with low serum 25(OH)D levels were randomized to receive either capsules of vitamin D3 20,000 IU twice per week or placebo for 6 months before IOP was measured again., Results:   Intraocular pressure in the 87 participants with low serum 25(OH)D levels (mean 40.1±12.9 nm) did not differ from IOP in the 42 participants with high serum 25(OH)D levels (mean 85.1±14.0 nm) (15.9±3.3 mmHg versus 15.6±3.1 mmHg, p= 0.56, independent t-test). After intervention, IOP decreased by -0.8± 2.1 mmHg (p = 0.017, paired t-test) in the vitamin D group (n= 39) and -0.8±2.5 mmHg (p= 0.059) in the placebo group (n= 39), but the change was not significantly different between the groups (p= 0.92, independent t-test)., Conclusion:   This study in healthy participants revealed no associations between serum 25(OH)D levels and IOP, and administration of vitamin D3 to participants with low levels of 25(OH)D did not affect IOP. These results do not support a role of vitamin D in the regulation of IOP., (© 2013 Acta Ophthalmologica Scandinavica Foundation. Published by Blackwell Publishing Ltd.)

A number of single nucleotide polymorphisms (SNPs) related to height have been detected. Calcium metabolism is important for the skeleton and accordingly also for adult height. Therefore, in the present study, nine SNPs related to the vitamin D receptor (VDR) gene and serum levels of 25-hydroxyvitamin D (25(OH)D), calcium, phosphate and parathyroid hormone (PTH) were related to height in 9471 subjects. Relation with height was evaluated with linear regression for trend across SNP genotypes with age and gender as covariates. After correcting for multiple testing, significant associations with height were found for two SNPs related to the VDR gene (rs1544410 (Bsml) and rs7975232 (Apal)), one SNP related to serum 25(OH)D (rs3829251 at the DHCR7/NADSYN1 gene), one SNP related to serum calcium (rs1459015 at the PTH gene) and one SNP related to serum phosphate (rs1697421 at the ALPL gene). For rs3829251, the mean differences in height between major and minor homozygotes were 1.5-2.0 cm (P < 0.01) and were seen in both genders and all age groups tested, whereas for the other SNPs, the differences were less than 1 cm. In conclusion, several SNPs related to calcium metabolism are associated with height, in particular rs3829251 at the DHCR7/NADSYN1 gene., (© 2012 The Authors Annals of Human Genetics © 2012 Blackwell Publishing Ltd/University College London.)