Vitamin D status in a multi-ethnic population of northern Norway: the SAMINOR 2 Clinical Survey.

OBJECTIVE: To investigate serum 25-hydroxyvitamin D (S-25(OH)D) concentration in a multi-ethnic population of northern Norway and determine predictors of S-25(OH)D, including Sami ethnicity. DESIGN: Cross-sectional data from the second survey of the Population-based Study on Health and Living Conditions in Regions with Sami and Norwegian Populations (the SAMINOR 2 Clinical Survey, 2012-2014). S-25(OH)D was measured by the IDS-iSYS 25-Hydroxy Vitamin DË¢ assay. Daily dietary intake was assessed using an FFQ. BMI was calculated using weight and height measurements. SETTING: Ten municipalities of northern Norway (latitude 68°-70°N). PARTICIPANTS: Males (n 2041) and females (n 2424) aged 40-69 years. RESULTS: Mean S-25(OH)D in the study sample was 64·0 nmol/l and median vitamin D intake was 10·3 µg/d. The prevalence of S-25(OH)D<30 nmol/l was 1·9 % and <50 nmol/l was 24·7 %. In sex-specific multivariable linear regression models, older age, blood sample collection in September-October, solarium use, sunbathing holiday, higher alcohol intake (in females), use of cod-liver oil/fish oil supplements, use of vitamin/mineral supplements and higher intakes of vitamin D were significantly associated with higher S-25(OH)D, whereas being a current smoker and obesity were associated with lower S-25(OH)D. These factors explained 21-23 % of the variation in S-25(OH)D. CONCLUSIONS: There were many modifiable risk factors related to S-25(OH)D, however no clear ethnic differences were found. Even in winter, the low prevalence of vitamin D deficiency found among participants with non-Sami, multi-ethnic Sami and Sami self-perceived ethnicity was likely due to adequate vitamin D intake.

Evidence of a significant vitamin D deficiency among 9-13-year-old Polish children: results of a multicentre study.

PURPOSE: To evaluate the extent to which the population of Polish preadolescents is vitamin D deficient and to assess seasonal variations in vitamin D status. PARTICIPANTS AND METHODS: A total of 720 healthy children aged 9-13 years (409 girls, 311 boys) residing in 6 representative geographical locations in Poland were studied. A parental-assisted questionnaire provided data on nutritional habits, vitamin D supplements and sun exposure. Serum concentration of 25-hydroxyvitamin was determined twice, after the winter in March and after the summer in October. RESULTS: In March, vitamin D deficiency (25-50 nmol/L) was found in 64%, and severe deficiency (< 25 nmol/L) in 20.2% of children. In October, the deficiency and severe deficiency were still noticed in 25.9 and 0.1% of children, respectively. The mean serum concentration of 25-OHD was 52% higher in October (55.4 ± 14.0 nmol/L) than in March (36.4 ± 13.5 nmol/L), (p < 0.01). In children with 25-OHD < 50 nmol/L in March, their 25-OHD concentration increased by 64% through March to October (32.5 ± 8.2 vs. 53.2 ± 7.9 nmol/L, p < 0.01). An association was found between 25-OHD concentration and regular consumption of vitamin D supplements, cod-liver oil and fish. CONCLUSIONS: The majority of preadolescent Polish boys and girls show vitamin D deficiency after the winter period, although a distinct amelioration over summertime is found in this age group. There is a need to implement effective prevention and intervention strategies in the management of vitamin D deficiency among schoolchildren in Poland, with the supplementation throughout the entire year.

Season, dietary factors, and physical activity modify 25-hydroxyvitamin D concentration during pregnancy.

PURPOSE: The objectives of this cross-sectional study were to define maternal and umbilical cord blood (UCB) 25-hydroxyvitamin D (25(OH)D) to characterize maternal factors modifying 25(OH)D during pregnancy and predict UCB 25(OH)D in two subgroups with Declined [Δ25(OH)D <0 nmol/l] and Increased [Δ25(OH)D >0 nmol/l] 25(OH)D concentration. METHODS: A complete dataset was available from 584 women. 25(OH)D was determined at gestational weeks 6-13 and in UCB. Baseline characteristics were collected retrospectively using questionnaires. Δ25(OH)D was calculated as UCB 25(OH)D-early pregnancy 25(OH)D. Dietary patterns were generated with principal component analysis. Multivariate regression models were applied. RESULTS: Vitamin D deficiency was scarce, since only 1% had 25(OH)D concentration <50 nmol/l both in early pregnancy and in UCB. Shared positive predictors of UCB 25(OH)D in the subgroups of Declined and Increased, were early pregnancy 25(OH)D (P < 0.001) and supplemental vitamin D intake (P < 0.04). For the Increased subgroup summer season at delivery (P = 0.001) and "sandwich and dairy" dietary pattern characterized with frequent consumption of vitamin D fortified margarine and milk products (P = 0.009) were positive predictors of UCB 25(OH)D. Physical activity (P = 0.041) and maternal education (P = 0.004) were additional positive predictors in the Declined group CONCLUSIONS: Maternal and newborn vitamin D status was sufficient, thus public health policies in Finland have been successful. The key modifiable maternal determinants for 25(OH)D during pregnancy, and of the newborn, were supplemental vitamin D intake, frequent consumption of vitamin D fortified foods, and physical activity.

Vitamin D deficiency and C-reactive protein: a bidirectional Mendelian randomization study.

BACKGROUND: Low vitamin D status is often associated with systemic low-grade inflammation as reflected by elevated C-reactive protein (CRP) levels. We investigated the causality and direction of the association between vitamin D status and CRP using linear and non-linear Mendelian randomization (MR) analyses. METHODS: MR analyses were conducted using data from 294 970 unrelated participants of White-British ancestry from the UK Biobank. Serum 25-hydroxyvitamin D [25(OH)D] and CRP concentrations were instrumented using 35 and 46 genome-wide significant variants, respectively. RESULTS: In non-linear MR analysis, genetically predicted serum 25(OH)D had an L-shaped association with serum CRP, where CRP levels decreased sharply with increasing 25(OH)D concentration for participants within the deficiency range (<25 nmol/L) and levelled off at ∼50 nmol/L of 25(OH)D (Pnon-linear = 1.49E-4). Analyses using several pleiotropy-robust methods provided consistent results in stratified MR analyses, confirming the inverse association between 25(OH)D and CRP in the deficiency range (P = 1.10E-05) but not with higher concentrations. Neither linear or non-linear MR analysis supported a causal effect of serum CRP level on 25(OH)D concentration (Plinear = 0.32 and Pnon-linear = 0.76). CONCLUSION: The observed association between 25(OH)D and CRP is likely to be caused by vitamin D deficiency. Correction of low vitamin D status may reduce chronic inflammation.

U-Shaped Association of Standardized Serum 25-Hydroxyvitamin D with Risk of Low Muscle Mass: A Population-Based Cross-Sectional Study.

Background: In the United States (U.S.) general population, the association between standardized serum 25-hydroxyvitamin D (25(OH)D) concentration and risk of low muscle mass (LMM) remains unclear. Our research aimed to determine whether or not there was a relationship between serum 25(OH)D concentration and risk of LMM. Methods: We analyzed the cross-sectional data of the US population that participated in the National Health and Nutrition Examination Survey between 2011 and 2014. The relationship between serum 25(OH)D concentration and LMM risk was evaluated using restricted cubic spline (RCS) with multivariate logistic regression model and subgroup analysis. Results: In all, we included 10,256 people in our analysis. The RCS plot demonstrated a U-shaped relationship between serum 25(OH)D concentration and risk of LMM (P for nonlinearity <0.05). At a Vitamin D concentration of 38.5 nmol/L, LMM risk was at its lowest. Based on analyses stratified by age, sex, hypertension, and diabetes mellitus (DM), serum 25(OH)D concentration and risk of LMM were U-curve correlated for those age 40 or older, male, with hypertension, or without DM. However, LMM risk was positively related to serum 25(OH)D concentration in those younger than age 40 or in women. Conclusion: There is a U-shaped relationship between serum 25(OH)D concentration and the risk of LMM in the general U.S. population. Careful monitoring and appropriate Vitamin D supplementation might lessen the risk of LMM.

Necessity of daily 1000-IU vitamin D supplementation for maintaining a sufficient vitamin D status.

The changes in the serum 25-hydroxyvitamin D (25(OH)D) concentrations after daily 1000-IU vitamin D intake for 3 months (3-month-VD), 6 months (6-month-VD) and then 6-month cessation of vitamin D in-take (6-month-VD cessation) were examined. The serum 25(OH)D levels in 11 male and 16 female subjects were 12.1±3.5 ng/mL at baseline, increased to 27.1±4.7 ng/mL at 3-month-VD, 28.5±5.1 ng/mL at 6-month-VD and decreased to 16.4±4.0 ng/mL at 6-month-VD cessation. The present study suggested that a vitamin D intake of 1000 IU/day is required to maintain the 25(OH) D concentration at 30 ng/mL or higher without vitamin D intoxication. J. Med. Invest. 69 : 135-140, February, 2022.

Low Maternal Serum 25-Hydroxyvitamin D Concentration Is Associated With Postpartum Hemorrhage: A Retrospective Observational Study.

Objective: The primary aim of this study is to investigate the relationship between vitamin D serum level and the incidence of postpartum hemorrhage (PPH). The secondary objective is to determine the relative risk of low vitamin D associated with PPH. Methods: This was a retrospective observational study. A total of 600 women who had delivered their babies in a single tertiary teaching hospital were enrolled. Serum blood test for 25(OH)D was performed at 35 + 0 to 36 + 6 weeks of pregnancy to measure vitamin D. A 25(OH)D level < 20 ng/mL was defined as vitamin D deficient, and a level 21-29 ng/mL as insufficient. Results: Vitamin D levels were deficient in 145 (24.1%) and insufficient in 254 (42.3%) of the women tested. Women with deficient and insufficient vitamin D levels were significantly younger than those with sufficient vitamin D levels (p < 0.001). The overall rates of PPH in the deficient and insufficient groups were 6.9% (10/145) and 6.7% (17/254), respectively, and were significantly higher than the rate of the normal vitamin D group (1.5%, p = 0.009). Women with sufficient vitamin D levels had significantly higher hemoglobin levels than those with low vitamin D levels. Higher vitamin D levels were associated with a significantly low risk of PPH (AOR: 0.93, CI: 0.89-0.98, p = 0.006). Conclusion: Our results suggest that a low vitamin D level is a risk factor for PPH. Low vitamin D also related to high risk of low hemoglobin before delivery. Thus, antepartum care should include vitamin D supplements for all women if possible.

Vitamin d deficiency and metabolic syndrome: The joint effect on cardiovascular and all-cause mortality in the United States adults.

BACKGROUND: The long-term impact of vitamin D deficiency and metabolic syndrome (MetS) on cardiovascular disease (CVD) and all-cause mortality are still a matter of debate. AIM: To test the hypotheses that lower serum 25 hydroxyvitamin D [25(OH)D] concentrations (a marker of vitamin D level) and MetS have a long-term impact on the risk of CVD and all-cause mortality, and individuals with vitamin D deficiency can be identified by multiple factors. METHODS: A sample of 9094 adults, 20 to 90 years of age, who participated in the Third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1994) were followed through December 2015 was analyzed. The associations of serum 25(OH)D concentrations and MetS with CVD and all-cause mortality were analyzed longitudinally using Cox regression models. Classification and regression tree (CART) for machine learning was applied to classify individuals with vitamin D deficiency. RESULTS: Of 9094 participants, 30% had serum 25(OH)D concentrations < 20 ng/mL (defined as vitamin D deficiency), 39% had serum 25(OH)D concentrations between 20 to 29 ng/mL (insufficiency), and 31% had serum 25(OH)D concentrations ≥30 ng/mL (sufficiency). Prevalence of MetS was 28.4%. During a mean of 18 years follow-up, vitamin D deficiency and MetS were significantly associated with increased risk of CVD and all-cause mortality. Subjects with both vitamin D deficiency and MetS had the highest risk of CVD mortality (HR = 1.77, 95%CI: 1.22-2.58) and all-cause mortality (HR = 1.62, 95%CI: 1.26-2.09), followed by those with both vitamin D insufficiency and MetS for CVD mortality (HR = 1.59, 95%CI: 1.12-2.24), and all-cause mortality (HR = 1.41, 95%CI: 1.08-1.85). Meanwhile, vitamin D sufficiency significantly decreased the risk of CVD and all-cause mortality for those who even had MetS. Among the total study sample, CART analysis suggests that being non-Hispanic Black, having lower serum folate level, and being female were the first three predictors for those with serum 25(OH)D deficiency. CONCLUSION: Vitamin D deficiency and MetS were significantly associated with increased risk of CVD and all-cause mortality. There was a significant joint effect of vitamin D deficiency and MetS on the risk of mortality. Findings of the CART analysis may be useful to identify individuals positioned to benefit from interventions to reduce the risk of CVD and all-cause mortality.

Welfare receipt and the risk of vitamin D deficiency in Japanese patients on maintenance hemodialysis: a cross-sectional, retrospective study.

BACKGROUND: Vitamin D deficiency is often observed in patients undergoing maintenance hemodialysis and is associated with significantly increased risk of overall mortality. Despite reports of poor nutrition/intake, vitamin D status among patients on maintenance hemodialysis receiving welfare remains unknown. This study investigated the vitamin D status in welfare recipients undergoing maintenance hemodialysis. METHODS: This cross-sectional study investigated vitamin D status among 106 outpatients undergoing maintenance hemodialysis at two medical facilities in Japan. Patients were divided into welfare and non-welfare groups based on their status as of September 2018. Patients were divided into two categories: serum vitamin D deficiency, defined as serum 25(OH)D concentrations < 12 ng/mL, or non-deficiency. Vitamin D deficiency was used as a dependent variable, while welfare receipt was used as the main predictor variable. RESULTS: Mean [± standard deviation] patient age, median [interquartile range] body mass index, and hemodialysis duration were 66.9 [± 10.8] years, 21.5 [19.6, 24.3] kg/m2, and 7.9 [2.9, 12.3] years, respectively. Among 106 patients, 45 were women (42.5%) and 16 (15.1%) were receiving welfare. The welfare group had a higher diabetes prevalence (P = 0.003) and significantly lower median serum 25-hydroxyvitamin D concentrations (11.5 [8.7, 14.0] vs. 14.8 [11.2, 19.9] ng/mL, P = 0.005). Multiple logistic regression analysis revealed that welfare receipt was a significant risk factor for vitamin D deficiency (odds ratio [95% confidence interval], 4.41 [1.08, 18.07]). CONCLUSIONS: Welfare recipients undergoing maintenance hemodialysis are at significantly increased risks of vitamin D deficiency compared with patients not receiving welfare.