Iranian Journal of

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Background: There are no available reports indicating the effects of Dietary Approaches to Stop Hypertension (DASH) eating plan on insulin resistance, inflammation and oxidative stress among pregnant women with gestational diabetes mellitus (GDM) We aimed to investigate the effects of DASH diet on insulin resistance, serum hs-CRP and biomarkers of oxidative stress among pregnant women with GDM. Methods: This randomized controlled clinical trial was performed among 32 pregnant women diagnosed with GDM at 24-28 weeks' gestation. Subjects were randomly assigned to consume either the control (n=16) or DASH diet (n=16) for 4 weeks. The DASH diet was rich in fruits, vegetables, whole grains, and low-fat dairy products and low in saturated fats, total fats, cholesterol, refined grains, and sweets, with a total of 2400 mg/d sodium. The control diet contained 40-55% of its energy as carbohydrates, 10-20% as proteins and 25-30% as total fats. Fasting blood samples were taken at baseline and after 4 weeks of intervention to measure fasting plasma glucose (FPG), serum insulin and hs-CRP, HOMA-IR, plasma total antioxidant capacity (TAC) and total glutathione levels (GSH). Results: Consumption of DASH diet, compared to the control diet, resulted in decreased FPG (-7.62 vs. 3.68 mg/dL P=0.02), serum insulin levels (-2.62 vs. 4.32 µIU/ml, P=0.03) and HOMA-IR score (-0.8 vs. 1.1 P=0.03). Increased concentrations of plasma TAC (45.2 vs. -159.2 mmol/L P<0.0001) and GSH (108.1 vs. -150.9 µmol/L P<0.0001) were also seen in the DASH group compared with control group. We failed to find a significant difference in mean changes of serum hs-CRP levels between the two diets. Within-group comparisons revealed a significant reduction in plasma TAC and GSH levels in the control diet, while a significant rise in these biomarkers in the DASH diet. Conclusion: In summary, consumption of DASH diet in pregnant women with GDM had beneficial effects on FPG, serum insulin levels, HOMA-IR score, plasma TAC and total GSH levels. The effects of this dietary pattern on pregnancy outcomes need to be investigated in future studies.

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Background: This study was designed to assess the effects of calcium and vitamin D supplementation on the metabolic status of pregnant women with gestational diabetes mellitus (GDM).

Methods: This randomized placebo-controlled trial was performed at maternity clinics affiliated to Kashan University of Medical Sciences, Kashan, Iran. Participants were 56 women with GDM at 24–28 weeks gestation (18 to 40 years of age). Subjects were randomly assigned to receive calcium plus vitamin D supplements or placebo. All study participants were blinded to group assignment. Individuals in the calcium–vita- min D group (n = 28) received 1,000 mg calcium per day and a 50,000 U vitamin D3  pearl twice during the study (at study baseline and on day 21 of the intervention), and those in the placebo group (n = 28) received two placebos at the mentioned times. Fasting blood samples were taken at study baseline and after 6 weeks of intervention.

Results: The study was completed by 51 participants (calcium–vitamin D n = 25, placebo n =26). However, as the analysis was based on an intention-to-treat approach, all 56 women with GDM (28 in each group) were included in the final analysis. After the administration of calcium plus vitamin D supplements, we observed a significant reduction in fasting plasma glucose (p < 0.001), serum insulin levels (p = 0.02) and HOMA-IR (p = 0.001) and a significant increase in QUICKI (p = 0.003) compared with placebo. In addition, a significant reduction in serum LDL-cholesterol (P=0.02) and total cholesterol: HDL-cholesterol ratio (p = 0.003) and a significant elevation in HDL-cholesterol levels (p = 0.01) was seen after intervention in the calcium–vitamin D group compared with placebo. In addition, calcium plus vitamin D supplementation resulted in a significant increase in GSH (p =0.03) and prevented a rise in MDA levels (p = 0.03) compared with placebo.

Conclusion: Calcium plus vitamin D supplementation in women with GDM had beneficial effects on their metabolic profile.

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Background: Although the relation of serum vitamin D levels with abdominal obesity has been investigated by previous observational studies, the results are inconsistent. In the current study, a dose-response meta-analysis was conducted on epidemiologic studies that evaluated this association in adults.
Methods: We performed a systematic search of all published articles, up to May 2020, in five electronic databases. A total of 41 observational studies that reported odds ratios (ORs) or relative risks (RRs) with 95% confidence intervals (CIs) for abdominal obesity in relation to serum vitamin D levels in adults were found.
Results: Meta-analysis on 36 cross-sectional studies (combining 44 effect sizes) with 257699 participants, illustrated that the highest serum vitamin D level in comparison with the lowest serum vitamin D level was significantly related to 23% decreased odds of central obesity (OR=0.77; 95%CI:0.71-0.83). This inverse association was also significant in almost all subgroups based on different covariates. Based on dose-response analysis, each 25 nmol/l increase in serum vitamin D levels, was related to 8% reduced risk of central obesity (OR=0.92;95%CI:0.85,0.99). After limiting the analysis to 23 effect sizes from 17 studies with representative population (242135 participants), the same results were obtained (OR=0.79; 95%CI: 0.71-0.87). Based on dose-response analysis on studies with representative populations, each 25 nmol/l increase in blood vitamin D levels was linked to 10% decreased central adiposity risk(OR=0.90; 95%CI: 0.82, 0.99).
Conclusion: In this meta-analysis of epidemiologic studies, we demonstrated an inverse significant relation between serum vitamin D levels and risk of central obesity in adults, in a dose-response manner. The same findings were obtained in representative populations.