Background The prevention of chronic diseases has always been a major focus in the medical field as a measure to improve public health. As a potential prevention to one of the most common chronic diseases, vitamin D was previously reported to show some signs of positive effect on the prevention of upper respiratory tract infections. Although trials were performed to demonstrate the association between the effectiveness of vitamin D and upper respiratory tract infections in the past few years, the number of randomized controlled trials was limited. Only one systematic review with meta-analysis was carried out to study the effect of vitamin D supplementation on prevention of respiratory tract infections (Charan et al., 2012). Aim A systematic review of the existing evidence was carried out with the aim to examine the effectiveness of vitamin D supplementation as an intervention in prevention of upper respiratory tract infections. Method Studies were selectively chosen based on the inclusion and exclusion criteria. Retrieval of studies was performed and identified from MEDLINE (Ovid) and PUBMED. MeSH terms of “Vitamin D” and “Upper respiratory tract infections” were applied in the search. Only randomized controlled trials were selected. Non-English publications, reviews, discussions, conference papers, and publications with outcomes being not incidence of URTI, were excluded. The quality of each study was evaluated using the Jadad scale (Jadad et al., 1996). Data from the trials was extracted into the meta-analysis, and odds ratios and confidence intervals were used as measures of the association between vitamin D supplementation and incidence of upper respiratory tract infections across studies. Result Five randomized controlled trials were included in this review. In this meta-analysis, the number of events of upper respiratory tract infections in vitamin D group was lower than that in the placebo group (OR=0.53), suggesting that a 47% lower odds of falling in vitamin D groups than in controls. The 95% confidence interval ranged from 0.30to 0.93and did not include 1, suggesting that the effect of vitamin D on prevention of upper respiratory tract infections was significant. However, when the trials were divided into children and adult groups, the results were significantly different. The result of the trials with two children gave an OR of 0.33(95%CI: 0.13, 0.83), meaning a positive effect of vitamin D could be observed in the vitamin D group, compared to the placebo group. Meanwhile, three trials on adults had an OR of 0.78 (95%CI: 0.56, 1.09), which was insufficient to suggest the two groups were different. Conclusion While the positive effect of vitamin D supplementation for the prevention of upper respiratory tract infections is evident on children in this review, it is much less significant on adults due to inconsistencies in the results. Therefore, more research and trials with improved methodologies would be required in the future to increase our understanding and provide more certainty on this matter. / published_or_final_version / Public Health / Master / Master of Public Health

Objective：Low vitamin D has been implicated in the development of type 2 diabetes. However, whether vitamin D continues to have a clinically significant effect in existing diabetes is unclear. The objective of this study was to examine the association of serum vitamin D with glycemic control in established type 2 diabetes. Methods: This was a retrospective analysis of medical records. Characteristics of 487 patients with type 2 diabetes were stratified by vitamin D status and serum glycosylated hemoglobin (HbA1c). Vitamin D deficiency among the subjects was studied. The relationship between vitamin D and glycemic control was explored by multiple linear regression, multivariate analysis of variance (MANOVA) and chi-square test. Patients were stratified into overweight and non-overweight group based on body mass index (BMI), and the association of serum vitamin D concentration with glycemic control was evaluated in each group. Insulin resistance and C-peptide as mediators between vitamin D and HbA1c was tested. The impact of vitamin D on cholesterol metabolism was also assessed. Results: (1) Vitamin D deficiency was highly prevalent, accounting for 88.3% of the study sample. (2) Serum vitamin D levels were significantly inversely associated with serum HbA1c. This correlation was stronger in overweight group than in non-overweight group. There was no significant relationship between serum vitamin D levels and fasting plasma glucose (FPG). HbA1c was significantly lower in vitamin D insufficiency group than in vitamin D severe deficiency group. (3) Insulin resistance partially mediated the association between vitamin D and HbA1c. (4) No significant association of Vitamin D with low density lipoprotein (LDL) or high density lipoprotein (HDL) was found in this study. Conclusions: There was an inverse association between serum vitamin D levels and HbA1c. The inverse correlation of serum vitamin D level and HbA1c was stronger in overweight group than in non-overweight group, which indicates patients with obesity might benefit more from vitamin D supplementation. / published_or_final_version / Public Health / Master / Master of Public Health

Improved insulin sensitivity and glucose tolerance may be attributable to vitamin D sufficiency. An experimental design was created to investigate the use of phototherapy to increase serum vitamin D levels and improve circulating blood glucose levels in pre-diabetics. Seven participants with a pre-diabetic condition were randomly allocated to either 3 months of phototherapy or no therapy. OGTT, HbA1c, and serum vitamin D levels were assessed before and after treatment. In 2 treatment participants, pre-diabetes status was reduced from combined IFG/IGT to iIFG in one and iIGT in the second, while 1 control participant developed combined IFG/IGT and another, type 2 diabetes. HbA1c values improved in the phototherapy group but not in the controls. Phototherapy also increased serum vitamin D levels in the treatment group but not in the controls. This pilot study suggests that the experimental protocol was effective and it should be implemented in a larger sample size to confirm those trends.

Ultraviolet B (UVB) radiation from the sun is the chief cause of skin cancer and is also involved in the development of Vitamin D in humans. This poses an interesting challenge, especially for people living in locations at mid to high latitudes. Through an integrative research review and controlled testing the amount of UVB humans receive in the landscape has been explored. Two existing computer models along with personal dosimeter badges were used to evaluate how much UVB students at a school in Waterloo, Ontario received under various conditions in February, 2013. Results showed that it is possible to get the equivalent of 1000 I.U. of vitamin D in February in Waterloo under ideal weather conditions, but not in most conditions. With this information, a guide has been created to optimize UVB for outdoor spaces in all seasons that children may use in northern climates. The design guide includes a summary of the geophysical variables that affect how much UVB reaches the earth’s surface and key concepts to understand including the difference between diffuse and direct radiation. This study provides evidence-based research in the area of climate responsive landscape architecture. / Landscape Architecture Canada Foundation

Omega-3 polyunsaturated fatty acids (PUFA) and vitamin D both have anti-cancer effects through common and unique pathways. The hypothesis of this thesis is that the combination of n-3 PUFA with 1,25(OH)2D3 will inhibit breast cancer cell growth in an additive or synergistic manner. A 3X3 factorial design was used to test the combinations of five PUFA treatments (α-linoleic acid (ALA, 18:3n3), eicosapentaenoic acid (EPA, 20:5n3) and docosahexaenoic acid (DHA, 22:6n3), γ-linolenic acid (GLA, 18:3n6) and arachidonic acid (AA, 20:4n6)) with 1,25(OH)2D3 on MCF-7, MDA-MB-231, and MCF-10A cell growth, and determine any potential synergism in combination treatments. MCF-7 and MCF-10A cells responded to PUFA and 1,25(OH)2D3 treatments, but combinations provided no potential synergism. MDA-MB-231 growth was not affected by 1,25(OH)2D3, while combinations treatments involving ALA, EPA, GLA, and AA caused potentially synergistic growth inhibition. This thesis presents the novel observation that PUFA are sensitizing MDA-MB-231 cells to 1,25(OH)2D3 treatment.

Background: Recent research indicates that inadequate vitamin D status may incur increased cancer risk, particularly for breast and colon cancer. Cutaneous generation of vitamin D through direct absorption of summer sunlight is considered the principal source of vitamin D; however, at latitudes above 40ºN, UVB rays are insufficient to permit cutaneous synthesis during winter. Vitamin D can also be obtained from natural and fortified dietary sources and through supplement use, although dietary reference intake values do not seem to compensate for restricted cutaneous synthesis in winter. Objectives: To determine the prevalence of vitamin D insufficiency post-winter and post-summer, to determine the seasonal variation in 25-hydroxyvitamin D (25(OH)D) levels, and to investigate determinants of 25(OH)D concentrations. Methods: A cross-sectional study of vitamin D status post-winter and post-summer was conducted among 49 premenopausal rotating shift nurses at Kingston General Hospital. In each season, vitamin D levels were measured using a radioimmunoassay to quantify serum 25(OH)D from fasting blood samples, and personal, lifestyle, and dietary factors potentially influencing vitamin D levels were assessed from a self-report questionnaire. Nurses were classified as vitamin D sufficient (>30ng/mL) or insufficient (≤30ng/mL). Results: A statistically significant difference was found between mean serum 25(OH)D concentrations post-winter (32.6ng/mL) and post-summer (42.5ng/mL) (p=0.0003). The prevalence of vitamin D insufficiency post-winter was 49% compared to 24% post-summer p=0.02). Tanning bed use was associated with significantly higher winter serum 25(OH)D levels was tanning bed, while controlling for age, BMI, and vitamin D-fortified yogurt consumption (R2=0.41, p=0.007). For summer, predictors of higher serum 25(OH)D levels were supplement use and tanning bed use in the past six months, while controlling for age, BMI, and beef/veal consumption (R2=0.53, p=0.001). Conclusions: Vitamin D insufficiency was prevalent both post-winter and post-summer, but with much higher prevalence post-winter. Controlling for age and BMI, tanning bed use was a determinant of serum 25(OH)D concentrations in both seasons, while fortified yogurt consumption also contributed in winter, and beef/veal consumption and supplement use contributed in summer. These findings support the need to improve vitamin D status among this population, and to increase the dietary reference intake values and supplement recommendations. / Thesis (Master, Community Health & Epidemiology) -- Queen's University, 2009-09-22 15:35:27.652

No description available.

Introduction: Vitamin D deficiency is prevalent among older adults in long-term care (LTC) contributing to increased risk of falls and fractures, and decreased quality of life. The primary factors include limited dietary sources containing vitamin D, poor dietary intake, and low sunlight exposure. Vitamin D supplementation is recommended in LTC; however this practice varies across Canada. Objectives: The objectives of this study were to 1) examine the perceptions of LTC health professionals, staff, and visitors (family and friends) regarding vitamin D supplementation in LTC facilities; and (2) determine what barriers exist in providing vitamin D supplementation to all residents in LTC facilities. Methods: The study was conducted in two phases. Phase 1: Five focus group sessions (9-12 health professionals per group) were conducted in 5 LTC facilities within a Manitoba Regional Health Authority. Each focus group session was audio recorded to assist in generating themes. Phase 2: A self-administered nutrition survey was completed by LTC staff, health professionals, and visitors (family and friends) in all five recruited LTC facilities. Descriptive statistical analyses were conducted. Results: Phase 1: A total of 51 individuals participated (mean age = 46.7 years ± 10.3; female = 90.2%). The majority of participants consisted of Registered Nurses, Health Care Aides, Clinical Dietitians, Pharmacists, Social Workers, Recreation Therapists, and Administrators. Phase 2: A total of 102 individuals participated with an average age of 48.4 ± 13.8 years and were predominately (87.3%) female. Eighty-five percent of participants were LTC health professionals and staff, and 14.7% were visitors (family or friend) of a LTC resident. The results from both phases found that perceptions were positive about providing vitamin D supplementation to residents. Eighty-two percent (phase 1) and 92.2% (phase 2) of participants thought that receiving a supplement would make a difference to the overall health of LTC residents. The major barriers to vitamin D supplementation were: cost (healthcare cost, cost of the supplement, and cost of laboratory tests for serum vitamin D levels), the complexity of residents due to swallowing problems and reluctance with taking medications, polypharmacy, physician resistance, and differences between participants’ knowledge and education on vitamin D. Conclusions: Providing vitamin D supplementation to LTC residents was deemed important and would improve their overall health, but more education is needed to prevent vitamin D deficiency in LTC.

No description available.

Access to abstract restricted until 05/2017. / Access to thesis restricted until 05/2017. / Department of Family and Consumer Sciences