Impact of vitamin D supplementation on adiposity in African-Americans

Background:

African-Americans have higher rates of obesity-associated chronic diseases. Serum 25-hydroxyvitamin D (25(OH)D) shows an inverse association with obesity status. We investigated whether vitamin D supplementation changes body mass index (BMI).

Subjects:

In total, 328 overweight African-Americans were enrolled over three consecutive winter periods (2007–2010) into a randomized, double-blind, placebo-controlled trial to receive cholecalciferol supplementation (0, 1000 international units (IU), 2000 IU or 4000 IU per day) for 3 months. Plasma concentrations of 25(OH)D and anthropometric measurements were done at baseline, 3 and 6 months.

Results:

At 3 months, vitamin D supplementation in three dose groups (1000 IU, 2000 IU or 4000 IU per day) did not cause any significant changes in BMI as compared with placebo group 3-month change in BMI per 1000 IU per day estimate (SE): 0.01 (0.039); P=0.78.

Conclusions:

In overweight African-Americans, short-term high-dose vitamin D supplementation did not alter BMI.     

Independent association of severe vitamin D deficiency as a risk of acute myocardial infarction in Indians

Background

Association of vitamin D deficiency with coronary heart disease (CHD) has been widely reported. Emerging data has shown high prevalence of vitamin D deficiency among Indians. However, this association has not been studied in Indians.

Methods

A case-control study with 120 consecutive cases of first incident acute myocardial infarction (MI) and 120 age and gender matched healthy controls was conducted at All India Institute of Medical Sciences, New Delhi. The standard clinical and biochemical risk factors for MI were assessed for both cases and controls. Serum 25 (OH) vitamin D assay was performed from stored samples for cases and controls using radioimmunoassay.

Results

Vitamin D deficiency [25(OH) D < 30 ng/ml] was highly prevalent in cases and controls (98.3% and 95.8% respectively) with median levels lower in cases (6 ng/ml and 11.1 ng/ml respectively; p < 0.001). The cases were more likely to have diabetes, hypertension and consume tobacco and alcohol. They had higher waist hip ratio, total and LDL cholesterol. Multivariate logistic regression analysis revealed severe vitamin D deficiency [25(OH) vitamin D < 10 ng/ml] was associated with a risk of MI with an odds ratio of 4.5 (95% CI 2.2–9.2).

Conclusions

This study reveals high prevalence of vitamin D deficiency among cases of acute MI and controls from India, with levels of 25 (OH)D being significantly lower among cases. Despite rampant hypovitaminosis, severe vitamin D deficiency was associated with acute MI after adjusting for conventional risk factors. This association needs to be tested in larger studies in different regions of the country.     

Impact of Vitamin D Status on Cardiometabolic Complications among Children and Adolescents with Type 1 Diabetes Mellitus

Objective:

There is an ongoing interest in the relationship between vitamin D status and diabetes control and complications. However, data from Saudi Arabia are limited. To determine the impact of vitamin D status on glycemic control and cardiometabolic complications of children and adolescents with type 1 diabetes mellitus (T1DM) attending a tertiary care diabetes clinic in Saudi Arabia.

Methods:

Demographic, clinical, and laboratory data of 301 children and adolescent subjects with T1DM (53.5% females) of a mean age of 13.9 years attending King Abdulaziz Medical City-Jeddah during 2010-2013 were retrospectively collected. Relationships between vitamin D status and frequency of hypoglycemia, hemoglobin A1c (HbA1c) level, body mass index (BMI), blood pressure, and lipid profile were evaluated.

Results:

The mean duration of diabetes was 7.7±3.7 years. Mean BMI value was 21.1±4.5 kg/m2 and HbA1c was 9.6±1.9% in both genders. Only 26.2% of the patients had a satisfactory HbA1c level. The mean level of 25-hydroxyvitamin D [25(OH)D] was 35.15 and that of cholesterol was 4.75. Vitamin D deficiency [25(OH)D≤37.5 nmol/L] was detected in 63.6% of the male and 67.7% of the female subjects. In males, it was inversely associated with frequency of hypoglycemia (p<0.01), BMI (p<0.05), diastolic blood pressure (p<0.05), and triglyceride levels (p<0.01), while in females, it was inversely associated with current age (p<0.05), age at diagnosis (p<0.01), and triglyceride levels (p<0.01). No significant correlation between HbA1c and vitamin D deficiency was observed.

Conclusion:

Vitamin D deficiency was highly prevalent in our study sample and was found to be associated with frequency of hypoglycemic episodes and with adverse cardiometabolic control.     

Vitamin D and respiratory health in the Busselton Healthy Ageing Study

Background and objective

The relationship between vitamin D and respiratory disease was examined by cross‐sectional analysis of a large community‐based sample.

Methods

Serum 25‐hydroxyvitamin D (25OHD) and history of respiratory disease, symptoms (recorded by questionnaire) and spirometry were measured in 5011 adults aged 45–69 years. Adjustments were made for age, sex, season and smoking (Model A), plus body mass index (BMI) and physical activity level (Model B), plus history of chronic diseases (Model C).

Results

Mean (SD) age was 58 (SD 6) years with 45% males, 10% current smokers and 12% taking vitamin D supplements. The prevalence of 25OHD level <50 nmol/L was 8.0%. In all the three models, 25OHD <50 nmol/L was significantly associated with asthma (Model C: odds ratio (OR): 1.32; 95% CI: 1.00, 1.73), bronchitis (1.54; 1.17, 2.01), wheeze (1.37; 1.10, 1.71) and chest tightness (1.42; 1.10, 1.83). Participants with vitamin D level > 100 nmol/L had higher forced vital capacity (FVC) in all the three models (1.17% higher, compared with the 50–100 nmol/L group in Model C).

Conclusion

Low levels of serum 25OHD were independently associated with asthma, bronchitis, wheeze and chest tightness after three levels of adjustment for potential confounders. Higher vitamin D levels were associated with higher levels of lung function.

     

Vitamin D Deficiency in Children and Adolescents in Ba?c?lar, ?stanbul

Objective:

This study aimed to evaluate the frequency of seasonal 25-hydroxyvitamin D [25(OH)D] deficiency and insufficiency in children and adolescents living in Bağcılar, district of İstanbul city.

Methods:

Serum vitamin D levels of 280 children aged 3-17 years old were measured at the end of winter and at the end of summer. Of the total group, vitamin D levels were re-measured in 198 subjects. Vitamin D deficiency was defined as a serum 25(OH)D level less than 15 ng/mL and insufficiency-as levels between 15 and 20 ng/mL. Patients whose vitamin D levels were less than 15 ng/mL at the end of winter were treated with 2000 units/day of vitamin D for 3 months.

Results:

In the “end of winter” samples, 25(OH)D deficiency was present in 80.36% of the subjects and insufficiency in 11.79%. In the “end of summer” samples, vitamin D deficiency was detected in 3.44% and insufficiency in 27.75%. Vitamin D levels in the “end of winter” samples were not significantly different between boys and girls, while “end of summer” levels were significantly lower in girls (p=0.015). Sunlight exposure was significantly higher in boys (p=0.011). The group with sufficient dairy product consumption had significantly higher vitamin D levels in both “end of summer” and “end of winter” samples. Limb pain was frequently reported in children with low vitamin D levels in the “end of winter” samples (p=0.001). Negative correlations were observed between vitamin D levels and season and also between vitamin D levels and age.

Conclusion:

It is essential to provide supplemental vitamin D to children and adolescents to overcome the deficiency seen especially at the end of winter.     

Hypovitaminosis D in Chronic Kidney Disease

Background and objectives: Recent studies show high prevalence of suboptimal 25-hydroxyvitamin D levels in chronic kidney disease patients. This study sought to test the hypothesis that the prevalence of 25-hydroxyvitamin D deficiency is significantly higher in chronic kidney disease patients and, in diabetic nephropathy, low serum 25-hydroxyvitamin D is associated with abnormal serum parathyroid hormone, bone mineral density, and coronary artery calcification.Design, setting, participants, & measurements: Study A used data from the Third National Health and Nutrition Examination Survey. Study B was a post hoc analysis of an observational study of coronary artery calcification in non–dialysis-dependent diabetic nephropathy.Results: In study A, the adjusted odds for 25-hydroxyvitamin D deficiency were 32% higher in chronic kidney disease patients. This higher prevalence of 25-hydroxyvitamin D deficiency, however, could not be explained by differences in total vitamin D intakes. The consequences of suboptimal 25-hydroxyvitamin D levels were analyzed in 146 patients with diabetic nephropathy. The significant, inverse relationship between serum 25-hydroxyvitamin D and parathyroid hormone levels was attenuated to a nonsignificant level on multivariate adjustment. There was a significant, inverse relationship between bone mineral density and coronary artery calcification scores; neither was independently associated with serum 25-hydroxyvitamin D. The serum 25-hydroxyvitamin D levels declined modestly in 72 patients studied after 12.4 ± 0.4 mo.Conclusions: 25-Hydroxyvitamin D deficiency is more common in chronic kidney disease, but this higher prevalence is unlikely to be a result of lower vitamin D intakes. The consequences of suboptimal 25-hydroxyvitamin D levels remain to be definitively elucidated.Vitamin D is important for maintaining bone health and muscle function (1). Serum 25 hydroxyvitamin D (25OHD) levels are a sensitive marker of the total body vitamin D stores. Epidemiologic and interventional studies suggest that serum 25OHD levels of at least 30 ng/ml are probably necessary to ensure optimal bone health and muscle function (1,2). Using this threshold, a large proportion of elderly, nursing home residents, dark-skinned people, and individuals who require hospitalization are either vitamin D insufficient (15 to 30 ng/ml) or deficient (<15 ng/ml) (1,3,4). In the absence of data from individuals with chronic kidney disease (CKD), the Kidney Disease Outcomes Quality Initiative (KDOQI) workgroup extrapolated these data to make opinion-based recommendations to maintain serum 25OHD levels >30 ng/ml in patients with stage 3 or 4 CKD (5). Numerous studies have demonstrated that the vast majority of non–dialysis-dependent patients with CKD have suboptimal 25OHD levels (6–9); however, none of these studies included a sufficiently large sample of control subjects to determine whether CKD is independently associated with a higher prevalence of suboptimal 25OHD levels. Moreover, secondary hyperparathyroidism and reduced bone mineral density (BMD)—the most common consequences of suboptimal 25OHD levels in the general population—are often present in patients with CKD. There is a paucity of data evaluating the role of 25OHD in the reduced BMD in CKD.We undertook this study to test the hypothesis that CKD is an independent predictor of 25OHD deficiency in a random sample of community-dwelling individuals of the United States using the Third National Health and Nutrition Survey (NHANES III; study A); this may, in part, be accounted for by lower daily vitamin D intakes. Furthermore, in a cohort of patients with diabetes and diabetic nephropathy (DN), we sought to determine the effects of suboptimal 25OHD levels on bone health (elevated serum parathyroid hormone (PTH) levels and reduced BMD) and coronary artery calcification (CAC) scores (study B).     

Abnormal vitamin D metabolism in cirrhosis.

Vitamin D metabolism was investigated in 10 patients with cirrhosis. Mean plasma 25 hydroxycholecalciferol (25 OHD) centration in alcoholic cirrhosis was lower than in controls but the difference was not significant. In three patients restudied after the summer, plasma 25 OHD had risen. In contrast to the finding in normal subjects, the half-life of intravenously administered 3H cholecalciferol was short in cirrhotics and showed no correlation with plasma 25 OHD. Furthermore, the appearance of 3H 25 OHD from 3H cholecalciferol was reduced compared to the control group four hours after injection. Increased rate of metabolism of cholecalciferol and deficient production of 25 ohd contribute to vitamin D deficiency in liver disease.     

The effect of vitamin D supplementation on vitamin D status and parathyroid function in elderly subjects

Vitamin D deficiency is common in the elderly and may lead to secondary hyperparathyroidism, cortical bone loss, and hip fractures. The effect of vitamin D supplementation for 1 yr was studied in 72 people living in a nursing home and 70 people living in an aged people's home. The subjects were randomized into 3 groups: control, and 400 or 800 IU vitamin D3/day. The initial vitamin D status of each subject was classified as deficient or borderline [serum 25-hydroxyvitamin D (25OHD) less than 30 nmol/L] in 79% and adequate (serum 25OHD greater than or equal to 30 nmol/L) in 21%. Serum 25OHD concentrations increased about 3-fold in both groups receiving vitamin D supplementation. Serum 1,25-dihydroxyvitamin D [1,25-(OH)2D] concentrations increased slightly but significantly, and the increase was inversely related to the initial serum 25OHD concentration. Serum intact PTH-(1-84) concentrations decreased about 15% during supplementation in both nursing home and aged people's home residents, whereas serum osteocalcin significantly decreased in the nursing home residents only. We conclude that a vitamin D3 supplement of 400 IU/day adequately improves vitamin D status in elderly people and increases 1,25-(OH)2D concentrations in those with vitamin D deficiency. Supplementation decreases parathyroid function and may depress bone turnover to some degree.     

Vitamin D Deficiency and Hashimoto’s Thyroiditis in Children and Adolescents: a Critical Vitamin D Level for This Association?

Objective:

Vitamin D has been suggested to be active as an immunomodulator in autoimmune diseases such as Hashimoto’s thyroiditis (HT). The goal of the present study was to investigate the vitamin D status in HT patients.

Methods:

This prevalence case-control study was conducted on 90 patients with HT (of ages 12.32±2.87 years) and 79 age-matched healthy controls (11.85±2.28 years). Serum 25-hydroxyvitamin D3 [25(OH)D3] levels were measured in all 169 subjects.

Results:

The prevalence of vitamin D deficiency in HT patients (64 of 90; 71.1%) was significantly higher than that in the control group (41 of 79; 51.9%) (p=0.025). Mean serum 25(OH)D3 level in the HT group was significantly lower compared to the control group (16.67±11.65 vs. 20.99±9.86 ng/mL, p=0.001). HT was observed 2.28 times more frequently in individuals with 25(OH)D3 levels <20 ng/mL (OR: 2.28, CI: 1.21-4.3).

Conclusion:

Vitamin D deficiency is associated with HT in children and adolescents. Levels lower than 20 ng/mL seem to be critical. The mechanism for this association is not clear.     

Association between vitamin D status and physical performance: the InCHIANTI study

BACKGROUND: Vitamin D status has been hypothesized to play a role in musculoskeletal function. Using data from the InCHIANTI study, we examined the association between vitamin D status and physical performance. METHODS: A representative sample of 976 persons aged 65 years or older at study baseline were included. Physical performance was assessed using a short physical performance battery (SPPB) and handgrip strength. Multiple linear regression was used to examine the association between vitamin D (serum 25OHD), parathyroid hormone (PTH), and physical performance adjusting for sociodemographic variables, behavioral characteristics, body mass index, season, cognition, health conditions, creatinine, hemoglobin, and albumin. RESULTS: Approximately 28.8% of women and 13.6% of men had vitamin D levels indicative of deficiency (serum 25OHD < 25.0 nmol/L) and 74.9% of women and 51.0% of men had vitamin D levels indicative of vitamin D insufficiency (serum 25OHD < 50.0 nmol/L). Vitamin D levels were significantly associated with SPPB score in men (beta coefficient [standard error (SE)]: 0.38 [0.18], p =.04) and handgrip strength in men (2.44 [0.84], p =.004) and women (1.33 [0.53], p =.01). Men and women with serum 25OHD < 25.0 nmol/L had significantly lower SPPB scores whereas those with serum 25OHD < 50 nmol/L had significantly lower handgrip strength than those with serum 25OHD > or =25 and > or =50 nmol/L, respectively (p <.05). PTH was significantly associated with handgrip strength only (p =.01). CONCLUSIONS: Vitamin D status was inversely associated with poor physical performance. Given the high prevalence of vitamin D deficiency in older populations, additional studies examining the association between vitamin D status and physical function are needed.     

Decreased Conversion of 25-hydroxyvitamin D3 to 24,25-dihydroxyvitamin D3 Following Cholecalciferol Therapy in Patients with CKD

Background and objectives

Elevated concentrations of fibroblast growth factor 23 (FGF23) are postulated to promote 25-hydroxyvitamin D (25[OH]D) insufficiency in CKD by stimulating 24-hydroxylation of this metabolite, leading to its subsequent degradation; however, prospective human studies testing this relationship are lacking.

Design, setting, participants, & measurements

An open-label prospective study was conducted from October 2010 through July 2012 to compare the effect of 8 weeks of oral cholecalciferol therapy (50,000 IU twice weekly) on the production of 24,25(OH)₂D₃ in vitamin D–insufficient patients with CKD (n=15) and controls with normal kidney function (n=15). Vitamin D metabolites were comprehensively profiled at baseline and after treatment, along with FGF23 and other mineral metabolism parameters.

Results

Vitamin D₃ and 25(OH)D₃ concentrations increased equivalently in the CKD and control groups following cholecalciferol treatment (median D₃ change, 8.6 ng/ml [interquartile range, 3.9–25.6 ng/ml] for controls versus 12.6 ng/ml [6.9–41.2 ng/ml] for CKD [P=0.15]; 25(OH)D₃ change, 39.2 ng/ml [30.9–47.2 ng/ml] for controls versus 39.9 ng/ml [31.5–44.1 ng/ml] for CKD [P=0.58]). Likewise, the absolute increase in 1α,25(OH)₂D₃ was similar between CKD participants and controls (change, 111.2 pg/ml [64.3–141.6 pg/ml] for controls versus 101.1 pg/ml [74.2–123.1 pg/ml] for CKD; P=0.38). Baseline and post-treatment 24,25(OH)₂D₃ concentrations were lower in the CKD group; moreover, the absolute increase in 24,25(OH)₂D₃ after therapy was markedly smaller in patients with CKD (change, 2.8 ng/ml [2.3–3.5 ng/ml] for controls versus 1.2 ng/ml [0.6–1.9 ng/ml] for patients with CKD; P<0.001). Furthermore, higher baseline FGF23 concentrations were associated with smaller increments in 24,25(OH)₂D₃ for individuals with CKD; this association was negated after adjustment for eGFR by multivariate analysis.

Conclusions

Patients with CKD exhibit an altered ability to increase serum 24,25(OH)₂D₃ after cholecalciferol therapy, suggesting decreased 24-hydroxylase activity in CKD. The observed relationship between baseline FGF23 and increments in 24,25(OH)₂D₃ further refutes the idea that FGF23 directly contributes to 25(OH)D insufficiency in CKD through stimulation of 24-hydroxylase activity.     

Cardiorespiratory Fitness Is Independently Associated with 25-Hydroxyvitamin D in Chronic Kidney Disease

Summary

Background and objectives

Vitamin D is an established important contributor to muscle function and aerobic metabolism. Hypovitaminosis D is highly prevalent in CKD patients and is associated with increased cardiovascular (CV) mortality via unknown mechanisms. Because aerobic-exercise capacity strongly predicts future CV events, we hypothesized that vitamin D status could be linked to CV outcomes via an effect on maximum aerobic-exercise capacity in patients with CKD and that this effect may be mediated in part via its actions on muscle strength and functional ability.

Design, setting, participants, & measurements

Baseline demographic, anthropometric, and biochemical data were collected in a cross-sectional study of patients with moderate CKD. Peak aerobic capacity was determined during treadmill stress testing using metabolic equivalence of tasks. Physical activity was assessed using the Active Australia questionnaire, grip strength by dynamometer, and functional capacity by “Up & Go” testing.

Results

The study included 85 participants (age 59.5 ± 9.7 years, 60% male, 44% diabetic, 92% Caucasian; mean serum 25-hydroxyvitamin D [25-OHD] 78.4 ± 29.4 nmol/L). We demonstrated that 25-OHD status was independently associated with aerobic-exercise capacity (β = 0.2; P = 0.008). Aerobic-exercise capacity was also predicted by younger age, white race, smaller waist circumference, absence of a previous angina history, and increasing weekly physical activity. However, neither muscle strength nor functional ability were significantly associated with 25-OHD.

Conclusions

Vitamin D is independently associated with aerobic capacity in CKD patients, and this finding is not explained by changes in muscle strength or functional ability.     

Serum 25-Hydroxyvitamin D and Change in Estimated Glomerular Filtration Rate

Summary

Background and objectives

Mounting evidence suggests that 1,25-dihydroxyvitamin D prevents the progression of chronic kidney disease (CKD). It is not clear whether “nutritional” forms of vitamin D affect GFR.

Design, setting, participants, & measurements

We tested whether serum 25-hydroxyvitamin D concentration (25(OH)D), a measure of total vitamin D intake from cutaneous synthesis and dietary consumption, is associated with loss of estimated GFR among 1705 older adults with predominantly normal baseline kidney function participating in the Cardiovascular Health Study. Baseline 25(OH)D was measured by HPLC-tandem mass spectrometry. GFR was estimated at baseline and 4 years later using the CKD-EPI formula, with rapid GFR loss defined as 12 ml/min per 1.73 m² or more over 4 years.

Results

Rapid GFR loss was observed for 207 participants (12%). Each 10 ng/ml lower 25(OH)D was associated with a 25% greater risk of rapid GFR loss (95% confidence interval [CI] 5%, 49%, P = 0.01), adjusting for potential confounding characteristics. Compared with 25(OH)D ≥30 ng/ml, 25(OH)D concentrations 15 to 29 ng/ml and <15 ng/ml were associated with 29% (95% CI −13%, 91%) and 68% (95% CI 1%, 177%) greater adjusted risks of rapid GFR loss, respectively. Magnitudes of association were largest among participants with diabetes. Results were similar evaluating a composite outcome of rapid GFR loss, end stage renal disease, and death.

Conclusions

Insufficient 25(OH)D may be a modifiable risk factor for early GFR loss. We recommend clinical trials to determine whether vitamin D supplementation prevents the development and progression of CKD.     

Nutritional Vitamin D Supplementation in Dialysis: A Randomized Trial

Background and objectives

Vitamin D (25-hydroxyvitamin D; 25[OH]D) deficiency is common in patients initiating long-term hemodialysis, but the safety and efficacy of nutritional vitamin D supplementation in this population remain uncertain.

Design, setting, participants, & measurements

This randomized, placebo-controlled, parallel-group multicenter trial compared two doses of ergocalciferol with placebo between October 2009 and March 2013. Hemodialysis patients (n=105) with 25(OH)D levels ≤32 ng/ml from 32 centers in the Northeast United States were randomly assigned to oral ergocalciferol, 50,000 IU weekly (n=36) or monthly (n=33), or placebo (n=36) for a 12-week treatment period. The primary endpoint was the achievement of vitamin D sufficiency (25[OH]D >32 ng/ml) at the end of the 12-week treatment period. Survival was assessed through 1 year.

Results

Baseline characteristics were similar across all arms, with overall mean±SD 25(OH)D levels of 21.9±6.9 ng/ml. At 12 weeks, vitamin D sufficiency (25[OH]D >32 ng/ml) was achieved in 91% (weekly), 66% (monthly), and 35% (placebo) (P<0.001). Mean 25(OH)D was significantly higher in both the weekly (49.8±2.3 ng/ml; P<0.001) and monthly (38.3±2.4 ng/ml; P=0.001) arms compared with placebo (27.4±2.3 ng/ml). Calcium, phosphate, parathyroid hormone levels, and active vitamin D treatment did not differ between groups. All-cause and cause-specific hospitalizations and adverse events were similar between groups during the intervention period. Lower all-cause mortality among ergocalciferol-treated participants was not statistically significant (hazard ratio, 0.28; 95% confidence interval, 0.07 to 1.19).

Conclusions

Oral ergocalciferol can increase 25(OH)D levels in incident hemodialysis patients without significant alterations in blood calcium, phosphate, or parathyroid hormone during a 12-week period.     

Factors Influencing Serum Vitamin D Concentration in Turkish Children Residing in ?zmir: A Single-Center Experience

Objective:

The aim of this study was to examine the vitamin D status of children and to determine the factors influencing serum 25-hydroxyvitamin D [25(OH)D] concentration in Turkish infants living in İzmir.

Methods:

In this study, we examined the serum 25(OH)D levels of 100 infants aged 1 to 24 months and of 22 mothers from İzmir, Turkey. The study also included a questionnaire given to the mothers to acquire data on the demographic characteristics of the infants and their mothers as well as information on vitamin D supplementation, clothing habits, and sunlight exposure.

Results:

Vitamin D deficiency was present in 31% of infants and 81.8% of mothers. Twenty-four male (42.9%) and 7 female (15.9%) infants were found to be vitamin D deficient (<20 mg/dL); 9 male (16.1%) and 17 female (38.6%) infants to be vitamin D insufficient (20-30 mg/dL); and 23 male (41.1%) and 20 female (45.5%) infants were vitamin D sufficient (>30 mg/dL). Only 63% of the infants were receiving vitamin D supplementation and 52% were said to be having regular exposure to sunlight. Mean serum vitamin D levels were lower in infants whose mothers were dressed according to the culture of traditional covered clothing (44%) compared to those infants whose mothers’ dressing style provided more exposure to sunlight.

Conclusion:

We conclude that low exposure to sunlight, inadequate use of vitamin D supplementation, and large family size are factors influencing the vitamin D status of Turkish children living in the inner city of İzmir.     

Plasma Vitamin D Level and Change in Albuminuria and eGFR According to Sodium Intake

Background and objectives

Low circulating 25-hydroxyvitamin D [25(OH)D] and high sodium intake are both associated with progressive albuminuria and renal function loss in CKD. Both vitamin D and sodium intake interact with the renin-angiotensin-aldosterone system. We investigated whether plasma 25(OH)D or 1,25-dihydroxyvitamin D [1,25(OH)₂D] is associated with developing increased albuminuria or reduced renal function and whether these associations depend on sodium intake.

Design, setting, participants, & measurements

Baseline plasma 25(OH)D and 1,25(OH)₂D were measured by liquid chromatography tandem mass spectrometry, and sodium intake was assessed by 24-hour urine collections in the general population–based Prevention of Renal and Vascular End-Stage Disease cohort (n=5051). Two primary outcomes were development of urinary albumin excretion >30 mg/24 h and eGFR (creatinine/cystatin C–based CKD Epidemiology Collaboration) <60 ml/min per 1.73 m². Participants with CKD at baseline were excluded. In Cox regression analyses, we assessed associations of vitamin D with developing increased albuminuria or reduced eGFR and potential interaction with sodium intake.

Results

During a median follow-up of 10.4 (6.2–11.4) years, 641 (13%) participants developed increased albuminuria, and 268 (5%) participants developed reduced eGFR. Plasma 25(OH)D was inversely associated with increased albuminuria (fully adjusted hazard ratio [HR] per SD higher, 0.86; 95% confidence interval [95% CI], 0.78 to 0.95; P=0.003) but not reduced eGFR (HR, 0.99; 95% CI, 0.87 to 1.12; P=0.85). There was interaction between 25(OH)D and sodium intake for risk of developing increased albuminuria (P interaction =0.03). In participants with high sodium intake, risk of developing increased albuminuria was inversely associated with 25(OH)D (lowest versus highest quartile: adjusted HR, 1.81; 95% CI, 1.20 to 2.73, P<0.01), whereas this association was nonsignificant in participants with low sodium intake (HR, 1.29; 95% CI, 0.94 to 1.77; P=0.12). Plasma 1,25(OH)₂D was not significantly associated with increased albuminuria or reduced eGFR.

Conclusions

Low plasma 25(OH)D is associated with higher risk of developing increased albuminuria, particularly in individuals with high sodium intake, but not of developing reduced eGFR. Plasma 1,25(OH)2D is not associated with risk of developing increased albuminuria or reduced eGFR.     

Serum 25-Hydroxyvitamin D Level and Kidney Function Decline in a Swiss General Adult Population

Background and objectives

Molecular evidence suggests that levels of vitamin D are associated with kidney function loss. Still, population-based studies are limited and few have considered the potential confounding effect of baseline kidney function. This study evaluated the association of serum 25-hydroxyvitamin D with change in eGFR, rapid eGFR decline, and incidence of CKD and albuminuria.

Design, setting, participants, & measurements

Baseline (2003–2006) and 5.5-year follow-up data from a Swiss adult general population were used to evaluate the association of serum 25-hydroxyvitamin D with change in eGFR, rapid eGFR decline (annual loss >3 ml/min per 1.73 m²), and incidence of CKD and albuminuria. Serum 25-hydroxyvitamin D was measured at baseline using liquid chromatography–tandem mass spectrometry. eGFR and albuminuria were collected at baseline and follow-up. Multivariate linear and logistic regression models were used considering potential confounding factors.

Results

Among the 4280 people included in the analysis, the mean±SD annual eGFR change was −0.57±1.78 ml/min per 1.73 m², and 287 (6.7%) participants presented rapid eGFR decline. Before adjustment for baseline eGFR, baseline 25-hydroxyvitamin D level was associated with both mean annual eGFR change and risk of rapid eGFR decline, independently of baseline albuminuria. Once adjusted for baseline eGFR, associations were no longer significant. For every 10 ng/ml higher baseline 25-hydroxyvitamin D, the adjusted mean annual eGFR change was −0.005 ml/min per 1.73 m² (95% confidence interval, −0.063 to 0.053; P=0.87) and the risk of rapid eGFR decline was null (odds ratio, 0.93; 95% confidence interval, 0.79 to 1.08; P=0.33). Baseline 25-hydroxyvitamin D level was not associated with incidence of CKD or albuminuria.

Conclusions

The association of 25-hydroxyvitamin D with eGFR decline is confounded by baseline eGFR. Sufficient 25-hydroxyvitamin D levels do not seem to protect from eGFR decline independently from baseline eGFR.     

Vitamin D deficiency as a risk factor for cystic fibrosis-related diabetes in the Scandinavian Cystic Fibrosis Nutritional Study

Aims/hypothesis

Many cystic fibrosis patients are vitamin D-insufficient. Cystic fibrosis-related diabetes is a major complication of cystic fibrosis. The literature suggests that vitamin D might possess certain glucose-lowering properties. We aimed to assess the relationship between vitamin D and cystic fibrosis-related glucose intolerance.

Methods

We enrolled 898 cystic fibrosis patients from Sweden, Norway and Denmark. Vitamin D intake was assessed using a seven-day food record. Serum 25-hydroxyvitamin D (s25OHD) and HbA_1c were measured, and an OGTT was carried out. Multiple linear and logistic regressions were used for HbA_1c and cystic fibrosis-related diabetes/OGTT result as outcome variables, respectively. Each model was controlled for country, and for known cystic fibrosis-related diabetes risk factors: age, sex, genotype, liver dysfunction, long-term corticosteroid treatment, and lung and pancreatic function.

Results

Degree of vitamin D insufficiency (OR 1.36; p?=?0.032) and s25OHD?p?=?0.042) were significant risk factors for cystic fibrosis-related diabetes. Accordingly, HbA_1c value was positively associated with s25OHD?R ²?=?20.5% and p?1c value in paediatric patients (adjusted R ²?=?20.2%; p?=?0.017), but not in adults.

Conclusions/interpretation

Vitamin D status is associated with HbA_1c and diabetes in cystic fibrosis, particularly in children. The study justifies prospective studies on the proposed role of vitamin D deficiency in the pathophysiology of diabetes mellitus.     

Correlation between serum vitamin D status and immunological changes in children affected by gastrointestinal food allergy

Background

Low vitamin D status is linked to increased incidence of food allergy and intestinal inflammation. Whether vitamin D status is associated with immunological changes in children with gastrointestinal food allergy (GFA) remains unclear.

Negative Association of Plasma Levels of Vitamin D and miR-378 With Viral Load in Patients With Chronic Hepatitis B Infection

Background:

Chronic Hepatitis B (CHB) is accompanied by inflammation of liver because of infection with Hepatitis B Virus (HBV). Previous studies revealed an inverse association between vitamin D and HBV DNA levels.

Objectives:

The current study aimed to investigate the levels of 25 (OH) D3 (the steady form of vitamin D), miR-378 and HBV DNA in the patients with CHB.

Patients and Methods:

One hundred and seventy three patients with HBeAg negative CHB were recruited for the study. Plasma levels of HBVDNA and 25 (OH) D3 were quantified. The expression level of miR-378 in plasma was measured by a relative quantitative Real Time Polymerase Chain Reaction (qRT-PCR) assay.

Results:

In the pathway regression analysis, the plasma level of 25 (OH) D3 showed a significant inverse correlation with plasma levels of HBV DNA (-0.198, P = 0.008) and direct correlation with miR-378 (0.188, P = 0.013). Similarly plasma level of miR-378 had inverse association with HBV DNA level (-0.177, P = 0.020).

Conclusions:

These results suggest that vitamin D could involve in a miRNA- mediated regulatory pathway in control of HBV replication. Further studies are recommended to understand the effects of miR-378 and anti-infective action of vitamin D on Hepatitis B Virus.