“The Effect of Vitamin D Supplement on the Score and Quality of Sleep in 20–50 Year-old People With Sleep Disorders Compared With Control Group”, Shahi et al 2017

2017-majid.pdf: “The effect of vitamin D supplement on the score and quality of sleep in 20–50 year-old people with sleep disorders compared with control group”⁠, Majid Mohammad Shahi, Ahmad Hosseini Seyed, Bizhan Helli, Mohammad Hosein Haghighi Zade, Mohammad Abolfathi et al (2017; sleep; backlinks; similar):

Objectives: Sleep quality may be directly related with vitamin D serum level. Some studies found that people with lower vitamin D serum level experienced a lower sleep quality. Consequently, this study aimed at determining the effect of vitamin D supplements on sleep score and quality in 20–50 year-old people with sleep disorders.

Methods: This double blind, clinical trial was performed in November 2015–February 2016 on 89 people with sleep disorders based on Petersburg’s Sleep Index. Patient samples were divided randomly into 2 groups: intervention and placebo. At the end of the study, the data on 89 subjects (44 in intervention group and 45 people in placebo group) were examined. Intervention group received a 50 000-unit vitamin D supplement, one in a fortnight for 8 weeks. Meanwhile, placebo group received placebo. Before and after intervention, Petersburg’s Sleep Quality Questionnaire, International Physical Activity Questionnaire, general information questionnaire, sun exposure, vitamin D serum level and 3-day food record questionnaire were assessed and recorded for all participants. To analyze data, t-test, chi square, ANCOVA, U-Mann-Whitney and Wilcoxon statistical tests were used.

Findings: Based on the results of the present study, at the end of the study sleep score (PSQI) reduced statistically-significantly in vitamin recipients as compared with placebo recipients (p < 0.05). This difference was statistically-significant even after modifying confounding variables (p < 0.05).

Conclusion: This study shows that the use of vitamin D supplement improves sleep quality, reduces sleep latency, raises sleep duration and improves subjective sleep quality in people of 20–50 year-old with sleep disorder.

[Keywords: Vitamin D supplement, serum vitamin D, sleep disorders]

“Vitamin D Status and Ill Health: a Systematic Review”, Autier et al 2014

2014-autier.pdf: “Vitamin D status and ill health: a systematic review”⁠, Philippe Autier, Mathieu Boniol, Cécile Pizot, Patrick Mullie (2014-01-01; longevity; backlinks)

“Extraskeletal Effects of Vitamin D in Older Adults: Cardiovascular Disease, Mortality, Mood, and Cognition”, MPH & MHS 2010

2010-barnard.pdf: “Extraskeletal effects of vitamin D in older adults: Cardiovascular disease, mortality, mood, and cognition”⁠, Karen Barnard MBBCh MPH, Cathleen Colón-Emeric MHS (2010-01-01; longevity; backlinks)

“Vitamin D and Calcium Supplementation Reduces Cancer Risk: Results of a Randomized Trial”, Lappe et al 2007

“Vitamin D and calcium supplementation reduces cancer risk: results of a randomized trial”⁠, Joan M. Lappe, Dianne Travers-Gustafson, K. Michael Davies, Robert R. Recker, Robert P. Heaney (2007-06-01; backlinks):

Background: Numerous observational studies have found supplemental calcium and vitamin D to be associated with reduced risk of common cancers. However, interventional studies to test this effect are lacking.

Objective: The purpose of this analysis was to determine the efficacy of calcium alone and calcium plus vitamin D in reducing incident cancer risk of all types.

Design: This was a 4-y, population-based, double-blind⁠, randomized placebo-controlled trial⁠. The primary outcome was fracture incidence, and the principal secondary outcome was cancer incidence. The subjects were 1,179 community-dwelling women randomly selected from the population of healthy postmenopausal women aged >55 y in a 9-county rural area of Nebraska centered at latitude 41.4°N. Subjects were randomly assigned to receive 1,400–1,500 mg supplemental calcium/​d alone (Ca-only), supplemental calcium plus 1,100 IU vitamin D₃/​d (Ca + D), or placebo.

Results: When analyzed by intention-to-treat⁠, cancer incidence was lower in the Ca + D women than in the placebo control subjects (p < 0.03). With the use of logistic regression⁠, the unadjusted relative risks (RR) of incident cancer in the Ca + D and Ca-only groups were 0.402 (p = 0.01) and 0.532 (p = 0.06), respectively. When analysis was confined to cancers diagnosed after the first 12 mo, RR for the Ca + D group fell to 0.232 (CI: 0.09, 0.60; p < 0.005) but did not change statistically-significantly for the Ca-only group. In multiple logistic regression models, both treatment and serum 25-hydroxyvitamin D concentrations were statistically-significant, independent predictors of cancer risk.

Conclusions: Improving calcium and vitamin D nutritional status substantially reduces all-cancer risk in postmenopausal women. This trial was registered at clinicaltrials.gov as NCT00352170⁠.

[Keywords: serum 25-hydroxyvitamin D, cancer, women, calcium and vitamin D₃ supplementation]