Vitamin D status in Kancheepuram District, Tamil Nadu, India.
ABSTRACT: BACKGROUND:Vitamin D has multifarious roles in maintenance of health and prevention of disease. The present study was undertaken to assess the vitamin D status of a rural adult south Indian population and to identify its associations with socioeconomic status and cultural practices. METHODS:Between June 2015 and July 2016, 424 healthy adults residing in Kattankulathur block in Tamil Nadu, India, provided venous blood samples and answered questions by personal interview. 25-hydroxy vitamin D was estimated by ELISA. RESULTS:Fifty nine (13.9%) of the 424 participants had 25OHD levels below 12?ng/mL (vitamin D deficient) and 175 (41.3%) had 25OHD levels between 12 to 20?ng/mL (vitamin D insufficiency). In univariate analysis, demographic factors associated with vitamin D status included education, occupation, socioeconomic class, and birthplace; lifestyle factors included sun exposure time, skin surface exposed to sunlight, use of sunscreen, awareness of vitamin D, and consumption of fish; and hygiene related factors included source of drinking water, availability of tap water at home, and closed toilet at home. In ordinal logistic regression, the following variables were found to be independently associated with vitamin D sufficiency: Duration of daily sun exposure below 30?min (Odds ratio 0.31, 95% confidence intervals 0.14-0.71, P?=?0.006), sun exposure 30-60?min (OR 0.49, 95% CI 0.30-0.80, P?=?0.004), male gender (OR 2.00, 95% CI 1.30-3.09, P?=?0.002), higher level of education (OR 0.80, 95% CI 0.69-0.94, P?=?0.005), non-consumption of fatty fish (OR 0.48, 95% CI 0.24-0.85, P?=?0.035) and presence of closed toilet system at home (OR 0.59, 95% CI 0.37-0.93). CONCLUSION:VDD and VDI are highly prevalent in this rural Indian community. The study identifies socioeconomic and behavior patterns that negatively impact vitamin D sufficiency, thus providing a basis for targeted intervention.
Project description:Multiple sclerosis (MS) incidence and serum 25-hydroxyvitamin D (25OHD) levels vary by race/ethnicity. We examined the consistency of beneficial effects of 25OHD and/or sun exposure for MS risk across multiple racial/ethnic groups. We recruited incident MS cases and controls (blacks 116 cases/131 controls; Hispanics 183/197; whites 247/267) from the membership of Kaiser Permanente Southern California into the MS Sunshine Study to simultaneously examine sun exposure and 25OHD, accounting for genetic ancestry and other factors. Higher lifetime ultraviolet radiation exposure (a rigorous measure of sun exposure) was associated with a lower risk of MS independent of serum 25OHD levels in blacks (adjusted OR = 0.53, 95% CI = 0.31-0.83; p = 0.007) and whites (OR = 0.68, 95% CI = 0.48-0.94; p = 0.020) with a similar magnitude of effect that did not reach statistical significance in Hispanics (OR = 0.66, 95% CI = 0.42-1.04; p = 0.071). Higher serum 25OHD levels were associated with a lower risk of MS only in whites. No association was found in Hispanics or blacks regardless of how 25OHD was modeled. Lifetime sun exposure appears to reduce the risk of MS regardless of race/ethnicity. In contrast, serum 25OHD levels are not associated with MS risk in blacks or Hispanics. Our findings challenge the biological plausibility of vitamin D deficiency as causal for MS and call into question the targeting of specific serum 25OHD levels to achieve health benefits, particularly in blacks and Hispanics.
Project description:Observational studies have demonstrated an association between decreased vitamin D level and risk of multiple sclerosis (MS); however, it remains unclear whether this relationship is causal. We undertook a Mendelian randomization (MR) study to evaluate whether genetically lowered vitamin D level influences the risk of MS.We identified single nucleotide polymorphisms (SNPs) associated with 25-hydroxyvitamin D (25OHD) level from SUNLIGHT, the largest (n = 33,996) genome-wide association study to date for vitamin D. Four SNPs were genome-wide significant for 25OHD level (p-values ranging from 6 × 10-10 to 2 × 10-109), and all four SNPs lay in, or near, genes strongly implicated in separate mechanisms influencing 25OHD. We then ascertained their effect on 25OHD level in 2,347 participants from a population-based cohort, the Canadian Multicentre Osteoporosis Study, and tested the extent to which the 25OHD-decreasing alleles explained variation in 25OHD level. We found that the count of 25OHD-decreasing alleles across these four SNPs was strongly associated with lower 25OHD level (n = 2,347, F-test statistic = 49.7, p = 2.4 × 10-12). Next, we conducted an MR study to describe the effect of genetically lowered 25OHD on the odds of MS in the International Multiple Sclerosis Genetics Consortium study, the largest genetic association study to date for MS (including up to 14,498 cases and 24,091 healthy controls). Alleles were weighted by their relative effect on 25OHD level, and sensitivity analyses were performed to test MR assumptions. MR analyses found that each genetically determined one-standard-deviation decrease in log-transformed 25OHD level conferred a 2.0-fold increase in the odds of MS (95% CI: 1.7-2.5; p = 7.7 × 10-12; I2 = 63%, 95% CI: 0%-88%). This result persisted in sensitivity analyses excluding SNPs possibly influenced by population stratification or pleiotropy (odds ratio [OR] = 1.7, 95% CI: 1.3-2.2; p = 2.3 × 10-5; I2 = 47%, 95% CI: 0%-85%) and including only SNPs involved in 25OHD synthesis or metabolism (ORsynthesis = 2.1, 95% CI: 1.6-2.6, p = 1 × 10-9; ORmetabolism = 1.9, 95% CI: 1.3-2.7, p = 0.002). While these sensitivity analyses decreased the possibility that pleiotropy may have biased the results, residual pleiotropy is difficult to exclude entirely.A genetically lowered 25OHD level is strongly associated with increased susceptibility to MS. Whether vitamin D sufficiency can delay, or prevent, MS onset merits further investigation in long-term randomized controlled trials.
Project description:Trials in school-aged children suggest vitamin D supplementation reduces asthma exacerbations. Primary aim: to examine whether vitamin D3 (100,000 IU) rapidly raises serum 25-hydroxyvitamin D (25OHD) ≥75 nmol/L in asthmatic preschoolers.In a double-blind, randomised, placebo-controlled trial, preschool-aged children with asthma received 100,000 IU vitamin D3 (intervention) or placebo (control), followed by 400 IU vitamin D3 daily for 6 months. Serum 25OHD was measured at baseline, 10 days, 3 and 6 months. Outcomes included the group difference in 25OHD change from baseline at 3 months (Δ25OHD); the proportion of children with 25OHD ≥75 nmol/L at 3 months; the pattern in serum vitamin D over 6 months; the proportion of children with hypercalciuria at any time point (safety); and group rates for oral corticosteroids. Continuous outcomes were analysed using generalised linear mixed models and group rate ratios of events per child were assessed using a Poisson distribution model.Twenty-two children were randomised (intervention:11; control:11) during winter. At 3 months, the group difference in Δ25OHD (7.2 nmol/L; 95 % CI: -13.7, 28.1) was not significant; yet, 100 % versus 54.5 % (intervention versus control) had serum 25OHD ≥75 nmol/L. There was a significant group difference in Δ25OHD at 10 days (110.3 nmol/L; 95 % CI: 64.0, 156.6). One child in each group had transient hypercalciuria at 10 days. Group oral corticosteroids rates were 0.82 and 1.18/child, intervention versus control (rate ratio = 0.68; 95 % CI: 0.30, 1.62; non-significant).Following 100,000 IU vitamin D3, all children reached serum 25OHD ≥75 nmol/L, compared with half who received placebo. Daily supplementation, sun exposure and insufficient power may explain the absence of a significant 3-month group difference in Δ25OHD. No clinically important alterations in bone metabolism biomarkers occurred. Group oral corticosteroid rates will inform sample size calculations for the larger trial. ( NCT01999907 , 25 November 2013).
Project description:BACKGROUND:Vitamin D deficiency is pandemic while resources available to measure 25-hydroxyvitamin D (25OHD) are limited. The present study aimed to verify whether sun exposure measured by a structured questionnaire could predict serum 25OHD concentrations in healthy Caucasian individuals living in a tropical area. METHODS:A cross-sectional study was carried out in subjects living in the greater São Paulo area, Brazil. Two groups of 50 young (20 to 40 years old) and 50 older (60 to 80 years old) subjects (N =?200) answered a structured questionnaire on sun exposure and had blood samples drawn for serum 25OHD concentration measurement during both summer and winter. Anthropometric data were also recorded. Correlation between the questionnaire variables (duration of sun exposure, amount of exposed skin, total sun exposure score - TSES and other data) and serum 25OHD concentration was evaluated. RESULTS:Mean serum 25OHD concentration was 17.60?±?7.3 ng/mL with no difference between age groups (p =?0.293). TSES weakly correlated with serum 25OHD levels (r =?0.264; p <?0.001). Separate analyzes by age groups demonstrated that TSES correlated significantly with serum 25OHD concentration only in the older subjects during summer (r =?0.322; p =?0.023). Using linear regression analyses, TSES and body mass index (BMI) were significantly associated with serum 25OHD levels. On the other hand, Receiver operating characteristic (ROC) analysis for TSES showed no significance as a screening tool for vitamin D deficiency (p =?0.172). CONCLUSION:Sun exposure questionnaire associated with BMI correlates with serum 25OHD concentration with very low accuracy. The use of the questionnaire does not discriminate between vitamin D sufficient and deficient individuals.
Project description:Our study is aimed to 1) clarify the vitamin D status in Uygur and Kazak ethnic populations and 2) elucidate the relationship between 14 SNPs (in 5 vitamin D-related genes) and vitamin D deficiency in these 2 ethnic populations.A multistage-cluster sampling survey was carried out for residents with Uygur or Kazak ethnicity in Xinjiang, China. Anthropometric measurements were taken and the concentrations of 25OHD were measured. Fourteen common variants in VDR, GC, CYP2R1, CYP27B1, and DHCR7/NADSYN1 were genotyped by using multiple SNaPshot assay. Logistic regression analysis was performed to identify the possible risk factors for vitamin D deficiency, after adjusting for several environmental and biological factors. The pattern of SNP associations was distinct between Uygurs and Kazaks.Anthropometric measurements and the concentrations of 25OHD were obtained from 1873 participants (945 Uygur ethnic and 928 Kazak ethnic). The genotypes of 14 SNPs were measured for 300 Uygurs and 300 Kazaks. The median 25OHD concentration was as low as 10.4 ng/ml in Uygurs and 16.2 ng/ml in Kazaks. In Uygurs, the prevalence of vitamin D deficiency, in-sufficiency, and sufficiency was 91.2%, 5.8%, and 3.0%, respectively. CYP2R1-rs10766197 was significantly associated with the presence of vitamin D deficiency in the Uygur ethnic population (P=0.019, OR=6.533, 95%C.I.: 361-31.357), while DHCR7/NADSYN1-rs12785878 was significantly associated with the presence of vitamin D deficiency in the Kazak ethnic population (P=0.011, OR=2.442, 95%C.I.: 1.224-4.873). Of 10 SNPs in VDR and GC genes, none was associated with vitamin D status in these 2 ethnic populations.Vitamin D insufficiency is highly prevalent in Uygurs and Kazaks living in Xinjiang, China. Polymorphisms in CYP2R1-rs10766197 and DHCR7/NADSYN1-rs12785878 are associated with vitamin D deficiency in Uygur and Kazak ethnic populations.
Project description:To assess vitamin D status and the influences of race, sun exposure and dietary vitamin D intake on vitamin D levels, and to evaluate two vitamin D repletion regimens in extremely obese patients awaiting bariatric surgery.A cross-sectional analysis of dietary vitamin D, sun exposure, PTH [intact (iPTH) and PTH(1-84)] and 25-hydroxyvitamin D (25OHD; differentiated 25OHD2 and 25OHD3) in 56 obese [body mass index (BMI) > 35 kg/m(2)] men and women (age 20-64 years). In a pilot clinical trial, 27 subjects with 25OHD levels < 62 nmol/l were randomized to receive ergocalciferol or cholecalciferol for 8 weeks.Serum 25OHD was low (mean 45 +/- 22 nmol/l) and was inversely associated with BMI (r = -0.36, P < 0.01). Each BMI increase of 1 kg/m(2) was associated with a 1.3 nmol/l decrease in 25OHD (P < 0.01). BMI, sun exposure, African American race and PTH predicted 40% of the variance in 25OHD (P < 0.0001). Serum 25OHD significantly increased at 4 and 8 weeks in both treatment groups (P < 0.001), whereas PTH(1-84) declined significantly in subjects treated with cholecalciferol (P < 0.007) and tended to decrease following ergocalciferol (P < 0.09).In severely obese individuals, those who are African American, have higher BMI and limited sunlight exposure are at greatest risk for vitamin D insufficiency. These demographic factors can help to identify at-risk patients who require vitamin D repletion prior to bariatric surgery. Commonly prescribed doses of ergocalciferol and cholecalciferol are effective in raising 25OHD. Further investigation is needed to evaluate whether these regimens have differential effects on PTH, and to determine the optimal regimen for vitamin D repletion in the extremely obese patient.
Project description:The risk of metabolic syndrome can be influenced by inadequate vitamin D levels, and exposure to sunlight is the main external source of vitamin D. The present study assessed the influence of environmental, biological, and nutritional factors in relation to seasonal 25-hydroxyvitamin D (25OHD) concentration in individuals with metabolic syndrome.This cross-sectional study enrolled 180 individuals with metabolic syndrome aged between 18 and 80 years. The 25OHD concentration was considered the dependent variable; independent variables included age, sex, skin color, use of sunscreen, skin type, sun exposure score, ultraviolet radiation index, geographic location, season, body mass index, waist:hip ratio, waist circumference, parathyroid hormone level, total serum calcium level, and calcium and vitamin D intake.The average vitamin D in individuals evaluated in summer 32?±?10 ng/mL was greater than in the winter 26?±?8 ng/mL (p?<?0.017). HDL-cholesterol was the only component of the MetS that differed significantly between the seasons (p?<?0.001), showing higher concentrations in autumn 45?±?8 mg/dL than in summer 35?±?8 mg/dL. In the multiple regression model, gender, WHR, sun exposure score, and winter vs. summer explained 10% of the variation in 25OHD concentration (p?=?0.004).Sex, waist:hip ratio, sun exposure, and summer season were predictors of 25OHD status among individuals with metabolic syndrome. HDL-cholesterol was the only component of metabolic syndrome that differed significantly between the seasons.
Project description:A possible role of vitamin D in depression has received considerable attention, especially given the significant disability, mortality, and healthcare costs associated to depression and the high prevalence of vitamin D deficiency.We investigated the cross-sectional associations between serum 25-hydroxyvitamin D (25OHD) levels and depressive symptoms (CES-D) in 5,607 older adults from the English Longitudinal Study of Ageing (ELSA).Overall, there was a significant association between low 25OHD levels and elevated depressive symptoms (odds ratio [OR] = 1.58, 95% confidence interval [CI] = 1.20-2.07 for the lowest quartile; OR = 1.45, 95% CI = 1.15-1.83 for <30 nmol/L cut-off and OR = 1.34, 95% CI = 1.10-1.62 for the ?50 nmol/L cut-off) after adjustment for a wide range of covariates of clinical significance. Fully adjusted models showed that women in the lowest (OR = 1.67, 95% CI = 1.20-2.34) and second lowest (OR = 1.68, 95% CI = 1.20-2.35) quartiles of 25OHD as well as those with 25OHD levels <30 nmol/L (OR = 1.40, 95% CI = 1.06-1.86) and ?50 nmol/L (OR = 1.35, 95% CI = 1.07-1.72) were more likely to report elevated depressive symptoms. For men, however, this association only remained significant for those with 25OHD levels of <30 nmol/L (OR = 1.60, 95% CI = 1.06-2.42) in the fully adjusted models.The independent and inverse association found between low 25OHD levels and elevated depressive symptoms suggests that vitamin D deficiency may be a risk factor for late-life depression, particularly among women. Whether our findings have any clinical meaning or not, additional data are needed from well-designed randomized controlled trials of vitamin D for the prevention and treatment of late-life depression.
Project description:Vitamin D is hypothesized to suppress inflammation. We tested total and free vitamin D metabolites and their association with inflammatory markers. Interleukin-6 levels were lower with higher 25-hydroxyvitamin D. 1,25-dihydroxyvitamin D and free 25OHD associations mirrored those of 25OHD. However, associations for the two metabolites diverged for tumor necrosis factor alpha (TNF-?) soluble receptors.Vitamin D is hypothesized to suppress inflammation, and circulating 25-hydroxyvitamin D (25OHD) and inflammatory markers are inversely correlated. However, total serum 25OHD may not be the best indicator of biologically active vitamin D.We tested serum total 25OHD, total 1,25(OH)2D, vitamin D binding protein (DBP), and estimated free 25OHD and free 1,25(OH)2D associations with inflammatory markers serum interleukin-6 (IL-6), TNF-? and their soluble receptors, interleukin-10 (IL-10), and C-reactive protein (CRP) as continuous outcomes and the presence of ?2 inflammatory markers in the highest quartile as a dichotomous outcome, in a random subcohort of 679 men in the Osteoporotic Fractures in Men (MrOS) study.IL-6 was lower in men with higher 25OHD (-0.23 ?g/mL per standard deviation (SD) increase in 25OHD, 95 % confidence intervals (CI) -0.07 to -0.38 ?g/mL) and with higher 1,25(OH)2D (-0.20 ?g/mL, 95 % CI -0.0004 to -0.39 ?g/mL); free D associations were slightly stronger. 25OHD and DBP, but not 1,25(OH)2D, were independently associated with IL-6. TNF-? soluble receptors were inversely associated with 1,25(OH)2D but positively associated with 25OHD, and each had independent effects. The strongest association with ?2 inflammatory markers in the highest quartile was for free 1,25(OH)2D (odds ratios (OR) 0.70, 95 % CI 0.54 to 0.89 per SD increase in free 1,25(OH)2D).Associations of 1,25(OH)2D and free 25OHD with IL-6 mirrored those of 25OHD, suggesting that 1,25(OH)2D and free D do not improve upon 25OHD in population-based IL-6 studies. However, associations for the two metabolites diverged for TNF-? soluble receptor, warranting examination of both metabolites in studies of TNF-? and its antagonists.
Project description:BACKGROUND:Vitamin D has been linked with improved cancer outcome. This systematic review and meta-analysis investigates the relationship between cancer outcomes and both vitamin D-related genetic variation and circulating 25-hydroxyvitamin D (25OHD) concentration. METHODS:A systematic review and meta-analysis of papers until November 2016 on PubMed, EMBASE and Web of Science pertaining to association between circulating vitamin D level, functionally relevant vitamin D receptor genetic variants and variants within vitamin D pathway genes and cancer survival or disease progression was performed. RESULTS:A total of 44?165 cases from 64 studies were included in meta-analyses. Higher 25OHD was associated with better overall survival (hazard ratio (HR=0.74, 95% CI: 0.66-0.82) and progression-free survival (HR=0.84, 95% CI: 0.77-0.91). The rs1544410 (BsmI) variant was associated with overall survival (HR=1.40, 95% CI: 1.05-1.75) and rs7975232 (ApaI) with progression-free survival (HR=1.29, 95% CI: 1.02-1.56). The rs2228570 (FokI) variant was associated with overall survival in lung cancer patients (HR=1.29, 95% CI: 1.0-1.57), with a suggestive association across all cancers (HR=1.26, 95% CI: 0.96-1.56). CONCLUSIONS:Higher 25OHD concentration is associated with better cancer outcome, and the observed association of functional variants in vitamin D pathway genes with outcome supports a causal link. This analysis provides powerful background rationale to instigate clinical trials to investigate the potential beneficial effect of vitamin D in the context of stratification by genotype.