Plasma 25-Hydroxyvitamin D Concentration and Risk of Incident Type 2 Diabetes in Women

OBJECTIVE — To determine the association between 25-hydroxyvitamin D (25-OHD) con-centration and risk of incident type 2 diabetes. RESEARCH DESIGN AND METHODS — In a nested case-control study conducted among 608 women with newly diagnosed type 2 diabetes and 559 control subjects in the Nurses’ Health Study, we measured the association between baseline plasma 25-OHD concentration and risk of incident diabetes. RESULTS — After adjusting for matching factors and diabetes risk factors, including BMI, higher levels of plasma 25-OHD were associated with a lower risk for type 2 diabetes. The odds ratio for incident type 2 diabetes in the top (median 25-OHD, 33.4 ng/ml) versus the bottom (median 25-OHD, 14.4 ng/ml) quartile was 0.52 (95 % CI 0.33–0.83). The associations were consistent across subgroups of baseline BMI, age, and calcium intake. CONCLUSIONS — Plasma 25-OHD concentration was associated with lower risk of inci-dent type 2 diabetes in women. Diabetes Care 33:2021–2023, 2010 G rowing evidence indicates that sub-optimal vitamin D status may play arole in the development of type 2 diabetes (1). Results from longitudinal observational studies support the hypoth-esis that low vitamin D status is associated with development of type 2 diabetes; however, only one study has examined the association between blood 25-hydroxyvitamin D (25-OHD) concentra-tion and incident type 2 diabetes, and there was no significant association among women (2,3). We examined pro-spectively the association between plasma 25-OHD concentration and risk of inci-dent type 2 diabetes among women in a case-control study nested within th

Effect of body composition methodology on heritability estimation of body fatness

Heritability estimates of human body fatness vary widely and the contribution of body composition methodology to this variability is unknown. The effect of body composition methodology on estimations of genetic and environmental contributions to body fatness variation was examined in 78 adult male and female monozygotic twin pairs reared apart or together. Body composition was assessed by six methods - body mass index (BMI), dual energy x-ray absorptiometry (DXA), underwater weighing (UWW), total body water (TBW), bioelectric impedance (BIA), and skinfold thickness. Body fatness was expressed as percent body fat, fat mass, and fat mass/height2 to assess the effect of body fatness expression on heritability estimates. Model-fitting multivariate analyses were used to assess the genetic and environmental components of variance. Mean BMI was 24.5 kg/m2 (range of 17.8-43.4 kg/m2). There was a significant effect of body composition methodology (p<0.001) on heritability estimates, with UWW giving the highest estimate (69%) and BIA giving the lowest estimate (47%) for fat mass/height2. Expression of body fatness as percent body fat resulted in significantly higher heritability estimates (on average 10.3% higher) compared to expression as fat mass/height2 (p=0.015). DXA and TBW methods expressing body fatness as fat mass/height2 gave the least biased heritability assessments, based on the small contribution of specific genetic factors to their genetic variance. A model combining DXA and TBW methods resulted in a relatively low FM/ht2 heritability estimate of 60%, and significant contributions of common and unique environmental factors (22% and 18%, respectively). The body fatness heritability estimate of 60% indicates a smaller contribution of genetic variance to total variance than many previous studies using less powerful research designs have indicated. The results also highlight the importance of environmental factors and possibly genotype by environmental interactions in the etiology of weight gain and the obesity epidemic.R01 AR046124 - NIAMS NIH HHS; R01 MH065322 - NIMH NIH HHS; T32 HL069772 - NHLBI NIH HHS; R21 DK078867 - NIDDK NIH HHS; R37 DA018673 - NIDA NIH HHS; R01 DK076092 - NIDDK NIH HHS; R01 DK079003 - NIDDK NIH HHS; F32 DK009747 - NIDDK NIH HHS; R01 DA018673 - NIDA NIH HH

Baseline Characteristics of the Vitamin D and Type 2 Diabetes (D2d) Study: A Contemporary Prediabetes Cohort That Will Inform Diabetes Prevention Efforts

© 2018 by the American Diabetes Association. OBJECTIVE: To describe baseline characteristics of the Vitamin D and Type 2 Diabetes (D2d) study, the first large U.S. diabetes prevention clinical trial to apply current American Diabetes Association (ADA) criteria for prediabetes.RESEARCH DESIGN AND METHODS: This is a multicenter (n = 22 sites), randomized, double-blind, placebo-controlled, primary prevention clinical trial testing effects of oral daily 4,000 IU cholecalciferol (D3) compared with placebo on incident diabetes in U.S. adults at risk for diabetes. Eligible participants were at risk for diabetes, defined as not meeting criteria for diabetes but meeting at least two 2010 ADA glycemic criteria for prediabetes: fasting plasma glucose (FPG) 100-125 mg/dL, 2-h postload glucose (2hPG) after a 75-g oral glucose load 140-199 mg/dL, and/or a hemoglobin A1c (HbA1c) 5.7-6.4% (39-46 mmol/mol).RESULTS: A total of 2,423 participants (45% of whom were women and 33% nonwhite) were randomized to cholecalciferol or placebo. Mean (SD) age was 59 (9.9) years and BMI 32 (4.5) kg/m2. Thirty-five percent met all three prediabetes criteria, 49% met the FPG/HbA1c criteria only, 9.5% met the 2hPG/FPG criteria only, and 6.3% met the 2hPG/HbA1c criteria only. Black participants had the highest mean HbA1c and lowest FPG concentration compared with white, Asian, and other races (P \u3c 0.01); 2hPG concentration did not differ among racial groups. When compared with previous prediabetes cohorts, the D2d cohort had lower mean 2hPG concentration but similar HbA1c and FPG concentrations.CONCLUSIONS: D2d will establish whether vitamin D supplementation lowers risk of diabetes and will inform about the natural history of prediabetes per contemporary ADA criteria

Dairy attentuates oxidative and inflammatory stress in metabolic syndrome123

Background: Oxidative and inflammatory stress are elevated in obesity and are further augmented in metabolic syndrome. We showed previously that dairy components suppress the adipocyte- and macrophage-mediated generation of reactive oxygen species and inflammatory cytokines and systemic oxidative and inflammatory biomarkers in obesity

Dairy consumption and cardiometabolic diseases: systematic review and updated meta-analyses of prospective cohort studies

Purpose of Review Dairy products contain both beneficial and harmful nutrients in relation to cardiometabolic diseases. Here, we provide the latest scientific evidence regarding the relationship between dairy products and cardiometabolic diseases by reviewing the literature and updating meta-analyses of observational studies. Recent Findings We updated our previous meta-analyses of cohort studies on type 2 diabetes, coronary heart disease (CHD), and stroke with nine studies and confirmed previous results. Total dairy and low-fat dairy (per 200 g/d) were inversely associated with a 3–4% lower risk of diabetes. Yogurt was non-linearly inversely associatedwith diabetes (RR = 0.86, 95%CI: 0.83–0.90 at 80 g/ d). Total dairy and milk were not associated with CHD (RR~1.0). An increment of 200 g of daily milk intake was associated with an 8% lower risk of stroke. Summary The latest scientific evidence confirmed neutral or beneficial associations between dairy products and risk of cardiometabolic diseases

Eating Fish and Risk of Type 2 Diabetes: A population-based, prospective follow-up study

Objective: To investigate the relation between total fish, type of fish (lean and fatty), and EPA&DHA intake and risk of type 2 diabetes in a population-based cohort. Research design and methods: The analysis included 4,472 Dutch participants aged =55 years without diabetes at baseline. Dietary intake was assessed with a semi-quantitative food frequency questionnaire. Hazard ratios (RR) with 95% confidence intervals (95% CI) were used to examine risk associations adjusted for age, sex, lifestyle, and nutritional factors. Results: After 15 years of follow-up, 463 participants developed type 2 diabetes. Median fish intake, mainly lean fish (81% ), was 10 g/d. Total fish intake was associated positively with risk of type 2 diabetes; the RR was 1.32 (95% CI 1.02, 1.70) in the highest total fish group (=28 g/d) compared with non-fish eaters (p for trend= 0.04). Correspondingly, lean fish intake tended to be associated positively with type 2 diabetes (RR highest group (=23 g/d): 1.30 (95% CI 1.01, 1.68), p for trend= 0.06), but fatty fish was not. No association was observed between EPA&DHA intake and type 2 diabetes (RR highest group (=149.4 mg/d): 1.22 (95% CI 0.97, 1.53)). When additionally adjusted for intake of selenium, cholesterol, and vitamin D this RR decreased to 1.05 (95% CI 0.80, 1.38) (p for trend= 0.77). Conclusion: The findings do not support a beneficial effect of total fish, type of fish, or EPA&DHA intake on the risk of type 2 diabetes. Alternatively, other dietary components, like selenium, and unmeasured contaminants present in fish might explain our result

Effects of vitamin D supplementation on endothelial function:a systematic review and meta-analysis of randomised clinical trials

Background: In addition to regulating calcium homoeostasis and bone health, vitamin D influences vascular and metabolic processes including endothelial function (EF) and insulin signalling. This systematic review and meta-analysis of randomised clinical trials (RCTs) were conducted to investigate the effect of vitamin D supplementation on EF and to examine whether the effect size was modified by health status, study duration, dose, route of vitamin D administration, vitamin D status (baseline and post-intervention), body mass index (BMI), age and type of vitamin D.  Methods: We searched the Medline, Embase, Cochrane Library and Scopus databases from inception until March 2015 for studies meeting the following criteria: (1) RCT with adult participants, (2) vitamin D administration alone, (3) studies that quantified EF using commonly applied methods including ultrasound, plethysmography, applanation tonometry and laser Doppler.  Results: Sixteen articles reporting data for 1177 participants were included. Study duration ranged from 4 to 52 weeks. The effect of vitamin D on EF was not significant (SMD: 0.08, 95 % CI −0.06, 0.22, p = 0.28). Subgroup analysis showed a significant improvement of EF in diabetic subjects (SMD: 0.31, 95 % CI 0.05, 0.57, p = 0.02). A non-significant trend was found for diastolic blood pressure (β = 0.02; p = 0.07) and BMI (β = 0.05; p = 0.06).  Conclusions: Vitamin D supplementation did not improve EF. The significant effect of vitamin D in diabetics and a tendency for an association with BMI may indicate a role of excess adiposity and insulin resistance in modulating the effects of vitamin D on vascular function. This remains to be tested in future studies