Improvement of vitamin D status through consumption of either fortified food products or supplement pills increased hemoglobin concentration in adult subjects: Analysis of pooled data from two randomized clinical trials.

Background: It is documented that vitamin D may have a role in erythropoiesis as its deficiency is accompanied by an increased risk of anemia. Aim: This study aimed to examine whether improvement of vitamin D status through daily consumption of either fortified foods or supplements could impinge on certain hematologic parameters in adults. Methods: We pooled data from our two separate clinical trials and made five experimental groups. As part of their usual diet, one group consumed 500 mL/day of yogurt drink fortified with 1000 IU of vitamin D (D-yogurt, n = 27) whereas one group consumed 500 mL/day of the plain yogurt drink (P-yogurt, n = 27). In addition three other groups consumed either 50 g/day bread fortified with 1000 IU of vitamin D (D-bread) or supplement containing 1000 IU vitamin D (D-supplement, n = 27) or placebo (placebo, n = 27). Biochemical measurements were performed before and after the intervention. Results: In all three vitamin D-supplemented groups, serum 25(OH)D concentration increased after the intervention period, which was interestingly accompanied by a significant increment of hemoglobin (D-yogurt, p < 0.001, D-bread, p = 0.003, D-supplement, p < 0.001). Analyses indicated that among participants in vitamin D-intervention groups, being in D-yogurt group was more favourable predictor of improvement in hemoglobin concentrations compared with the placebo (p < 0.001), D-bread (p = 0.045) and P-yogurt (p = 0.001). Conclusion: Improvement of vitamin D status via regular intake of either vitamin D-fortified food products or supplements can result in a significant increment of hemoglobin in adult subjects. This finding has very important clinical as well as public health implications.

Daily intake of yogurt drink fortified either with vitamin D alone or in combination with added calcium causes a thyroid-independent increase of resting metabolic rate in adults with type 2 diabetes: a randomized, double-blind, clinical trial.

We investigated the effect of daily intake of yogurt drink fortified with either vitamin D alone or with added calcium on resting metabolic rate (RMR), thyroid hormones and homeostatic model assessment for insulin resistance in subjects with type 2 diabetes (T2D). A total of 75 adult subjects with T2D were randomly assigned to 1 of the 3 groups to receive either D-fortified yogurt drink (DY; 1000 IU vitamin D/day), Ca-D-fortified yogurt drink (CDY; 1000 IU vitamin D plus 500 mg calcium), or plain yogurt drink for 12 weeks. All assessments were done at the baseline and after the intervention. The concentrations of anti-thyroid peroxidase antibody (anti-TPO-Ab), intact parathyroid hormone (iPTH) and thyroid stimulating hormone (TSH) had declined significantly compared with baseline values only in the CDY group. The mean RMR increased in both DY and CDY groups (p < 0.001 for both). Also, changes of serum concentrations of 25-hydroxycalciferol (B = 2.96, 95% confidence interval (CI) = 1.3 to 4.6, p = 0.001) and iPTH (B = -2.41, 95% CI = -4.5 to -0.31, p = 0.025) remained significant predictors of RMR changes even after adjustment for changes of serum concentrations of TSH (B = -18.2, 95% CI = -61.7 to 25.2, p = 0.406). Daily intake of vitamin D together with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Also, vitamin D with or without added calcium causes a significant thyroid-independent increase in RMR in euthyroid subjects with T2D. Registered at clinicaltrials.gov as NCT01229891. Novelty: Daily intake of vitamin D with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Vitamin D with or without added calcium causes a thyroid-independent increase in RMR in euthyroid subjects with T2D.

Effect of latitude on seasonal variations of vitamin D and some cardiometabolic risk factors: national food and nutrition surveillance.

BACKGROUND: Despite a remarkable reduction in the occurrence of many micronutrient deficiencies in most countries, vitamin D deficiency has remained a global problem. Age-adjusted disability-adjusted life years lost due to cardiovascular disease in the Eastern Mediterranean Region, including in the Islamic Republic of Iran, are higher than the global average. AIMS: To assess the effects of latitude and season on vitamin D status in the Iranian population and the association between vitamin D status and certain cardiometabolic risk factors. METHODS: A sample of 1111 participants aged 19-65 years was randomly selected from 6 regions with latitudes ranging from 29º.0 N to 37.5º N. All anthropometric and biochemical assessments were performed twice a year, summer and winter during 2013 to 2014. RESULTS: Overall mean 25(OH)D concentration was 26.9 [standard deviation (SD) 17.8] nmol/L in winter and 43.4 (SD 32.9 nmol/L in summer (P < 0.001). Poor vitamin D status was noticeable in both seasons (90.1% and 69.2%, respectively). Being male (B, 7.6; 95% CI: 4.3 to 10.8; P < 0.001) and living at a latitude higher than 33 ° were positive predictors, and serum 25(OH)D concentration in winter (B, -0.2; 95% CI: -2.9 to -0.11; P < 0.001) was a negative predictor of changes of 25(OH)D concentrations. CONCLUSION: We found a high prevalence of suboptimal vitamin D status in Iranian adults throughout the year, irrespective of latitude and season. Improvement of mean circulating 25(OH)D concentrations in the community to 50+ nmol/L through a fortification programme is likely to engender healthy cardiometabolic changes.

Vitamin D-fortified cooking oil is an effective way to improve vitamin D status: an institutional efficacy trial.

PURPOSE: High prevalence of vitamin D deficiency (VDD) justifies a cost-effective and sustainable strategy to combat VDD in the community. This study was undertaken for the first time to evaluate the efficacy of daily consumption of vitamin D fortified sunflower oil with a meal. METHODS: This single-blind trial was conducted in two separate institutions: one as intervention (D-fortified sunflower oil) group (DO, n1 = 39) and the other as control (unfortified sunflower oil) group (SO, n2 = 33). Participants consumed their lunches cooked either with D-fortified or unfortified cooking sunflower oil (500 IU/30 g) for 12 weeks. Dietary, anthropometric and biochemical assessments were done for all participants before and after the intervention. RESULTS: A total of 65 subjects from both sexes aged 32.5 ± 4 years completed the intervention period. Serum 25(OH)D showed a significant increase in DO and a decrease in SO group (8.8 ± 9.3 vs. - 7.4 ± 6.4 ng/mL, p < 0.001). The rise in serum 25(OH)D in DO group was accompanied by a significant decrease in iPTH (DO: - 10.2 ± 29.4 vs. SO: + 9.2 ± 29.5 pg/mL; p = 0.009). A significant reduction in weight (p = 0.004), BMI (p = 0.029), waist girth (p < 0.001), serum total cholesterol (p = 0.0290) and LDL-C (p = 0.010) was observed in DO, as compared with SO group. CONCLUSIONS: Cooking oil can be considered as an efficacious vehicle for mass fortification program to combat VDD. The improvement of vitamin D status may bring about betterment of certain cardiometabolic risk factors. REGISTRATION NUMBER: Clinicaltrials.gov: NCT03826654.

Efficacy of Vitamin D Supplementation in Physical Performance of Iranian Elite Athletes.

BACKGROUND: There has been no report of the vitamin D status of the professional athletes from Iran to date. This study was performed to evaluate the efficacy of weekly vitamin D supplementation on athletic performance in Iranian athletes expedited to Asian competition in Taipei, China, 2015. METHODS: This study was a randomized controlled clinical trial. Seventy subjects were enrolled in the study. The athletes were randomly divided into two groups: vitamin D supplement (D; received 50,000 IU of vitamin D supplement weekly) and control (P, received a placebo weekly). Duration of the study was 8 weeks. Anthropometric, dietary, athletic performance, and biochemical evaluations were performed for all subjects in the beginning and in the end of the intervention period. RESULTS: A significant rise in circulating 25(OH)D concentration was observed in D group (17.3 ± 16.9 ng/mL, P < 0.001), whereas in P group, there was a statistically significant decrement (-3.1 ± 8.4 ng/mL, P = 0.040). There were no either within- or between-group significant differences in Ergo jump, vertical jump, and agility tests. In strength leg press tests, both groups showed a significant improvement. However, comparisons of changes revealed that the improvement in D group was significantly higher than in P group (P = 0.034). Moreover, in sprint test (one repetition-Max, 1RM), only D group had a significant within-group improvement (P = 0.030). CONCLUSIONS: Weekly supplementation with 50,000 IU vitamin D resulted in nearly 17 ng/mL increment in circulating calcidiol. This increase was associated with significant improvement of power leg press and sprint tests in D-supplemented group.

Vitamin D-Fortified Bread Is as Effective as Supplement in Improving Vitamin D Status: A Randomized Clinical Trial.

CONTEXT: Bread can potentially be a suitable vehicle for fortification with vitamin D. OBJECTIVE: This study was undertaken to evaluate the following: 1) the bioavailability of vitamin D from the fortified Iranian bread and 2) the possible effects of daily consumption of the fortified bread on certain health aspects. DESIGN, SETTING, AND PARTICIPANTS: This was a randomized, double-blind, placebo-controlled trial conducted over 8 weeks in 90 healthy subjects aged 20-60 years. INTERVENTION: Subjects were randomly allocated to one of three groups: 1) fortified bread (FP; 50 g bread fortified with 25 µg vitamin D3 plus placebo daily; n = 30); 2) supplement (SP; 50 g plain bread plus 25 µg vitamin D supplement daily; n = 30); and 3) control (CP; 50 g plain bread plus placebo daily; n = 30). OUTCOME MEASURES: Initial and final anthropometric and biochemical assessments were performed. RESULTS: The within-group changes of serum 25-hydroxyvitamin D concentrations were 39.0 ± 22.6 (P < .001), 28.9 ± 31.2 (P < .001), and -9.2 ± 12.3 nmol/L in the FP, SP, and CP groups, respectively. Only in FP and SP groups, serum intact PTH concentrations decreased approximately 13.5% and 14.5%, respectively. Visceral fat also showed a significant decrement in FP (-1.05% ± 1.4%; P ≤ .001) and SP (-0.96% ± 1.7%; P = .006). Serum low-density lipoprotein cholesterol concentration showed a within-group reduction in FP (-10.4 ± 11.2 mg/dL; P < .001) and an insignificant decrement in SP (-6.6 ± 20.2 mg/dL; P = .083). Serum high-density lipoprotein increased in both vitamin D-supplemented groups (FP: 9.7 ± 7.6 vs SP: 5.7 ± 6.7 mg/dL; P < .001). CONCLUSION: Vitamin D-fortified bread could be potentially effective in raising circulating 25-hydroxyvitamin D levels of the population to nearly adequate levels.

A Vitamin D-Calcium-Fortified Yogurt Drink Decreased Serum PTH but did not Affect Osteocalcin in Subjects with Type 2 Diabetes.

INTRODUCTION: There is sparse evidence of the effect of vitamin D on bone biomarkers in diabetic patients, and therefore, in a randomized clinical trial, we evaluated the effects of the daily intake of vitamin D, either with or without extra calcium, on selected bone biomarkers. MATERIALS AND METHODS: Ninety women and men aged 30 - 50 years old with type 2 diabetes were randomly divided into three groups in a double-blind manner. Group 1 (PD), the control group, received a plain yogurt drink. Groups 2 (DD) and 3 (CDD) received 1000 IU vitamin D3, and 1000 IU vitamin D3 plus 500 mg calcium, respectively, via drinking two 250 mL bottles a day of a fortified yogurt drink for twelve weeks. Anthropometric and biochemical assessments were made, including 25(OH), intact parathyroid hormone (iPTH), osteocalcin, and calcium. RESULTS: Although the time and time × group interaction effects on the bone biomarkers were not statistically significant, there was a modest decrease in iPTH concentrations in both DD and CDD groups over twelve weeks. The subgroups with initial vitamin D deficiency/insufficiency in the CDD group had greater and significant decrease in serum iPTH concentrations after twelve weeks of treatment compared to the PD group (- 9.0 ± 21.2 v.s 8.6 ± 21.8 pg/mL, p = 0.042). CONCLUSION: The improvement in vitamin D status following the daily intake of fortified doogh for twelve weeks was accompanied by a decrement in iPTH, mostly in those subjects with poor initial vitamin D status.

Regular consumption of both vitamin D- and calcium- and vitamin D-fortified yogurt drink is equally accompanied by lowered blood lipoprotein (a) and elevated apoprotein A1 in subjects with type 2 diabetes: a randomized clinical trial.

OBJECTIVE: Cardiovascular disease (CVD) is the major morbidity and cause of death in diabetic subjects. Observational studies have shown the association of low vitamin D status with poor glycemic control, atherogenic lipid profile, and CVD. However, the possible link between circulating 25-hydroxycholecalciferol and apoproteins (Apo A1 and B) and the atherogenic lipoprotein (a) [Lp(a)] has not been documented to date. METHODS: Ninety subjects with type 2 diabetes (T2D) aged 30-60 years from both sexes were randomly allocated to one of the 3 groups to receive 2 bottles a day of either (1) plain doogh (PD; containing 150 mg calcium and no detectable vitamin D/250 mL); (2) vitamin D-fortified doogh (DD; containing 150 mg calcium and 500 IU vitamin D/250 mL); or (3) calcium- and vitamin D-fortified doogh (CDD; containing 250 mg calcium and 500 IU vitamin D/250 mL) for 12 weeks. Anthropometric, dietary, and laboratory assessments, including Apo A1, Apo B, and Lp(a), were done. RESULTS: Improvement of vitamin D status in DD and CDD groups, compared to PD, resulted in a significant increase in Apo A1 (mean changes 0.22 ± 0.38, 0.20 ± 0.27 and 0.01 ± 0.35 g/L, respectively, p = 0.047) and a significant decrease in serum Lp(a) (mean changes -0.08 ± 0.30, -0.08 ± 0.31, and 0.14 ± 0.25 µmol/L, respectively, p = 0.011). There was no significant difference between DD and CDD groups. Serum Apo B did not change significantly in any of the groups. CONCLUSIONS: Significant amelioration of serum Apo A1 and Lp(a) following improvement of vitamin D status in T2D subjects may have preventive implications against long-term diabetic complications, notably CVD. This trial was registered at ClinicalTrials.gov as NTC01229891.

Improvement of vitamin D status via daily intake of fortified yogurt drink either with or without extra calcium ameliorates systemic inflammatory biomarkers, including adipokines, in the subjects with type 2 diabetes.

CONTEXT: Systemic inflammation is thought to have a central role in diabetic long-term complications. OBJECTIVE: The aim of this study was to investigate the effects of vitamin D either with or without extra calcium on certain inflammatory biomarkers in the subjects with type 2 diabetes (T2D). DESIGN, SETTING, AND PARTICIPANTS: This was a double-blind, randomized, controlled trial conducted over 12 wk in 90 T2D subjects aged 30-60 yr from both sexes. INTERVENTION: Subjects were randomly allocated to one of three groups to receive two 250-ml bottles a day of plain Persian yogurt drink or doogh (PD, containing 150 mg calcium and no detectable vitamin D(3)/250 ml), vitamin D-fortified doogh (DD, containing 500 IU vitamin D(3) and 150 mg calcium/250 ml), or calcium + vitamin D(3)-fortified doogh (CDD, containing 500 IU vitamin D(3) and 250 mg calcium/250 ml). OUTCOME MEASURES: The changes in inflammatory markers were evaluated. RESULTS: Compared to the baseline values, highly sensitive C-reactive protein, IL-1ß, IL-6, fibrinogen, and retinol binding protein-4 concentrations significantly decreased in both the DD and CDD groups. Although the decrement in highly sensitive C-reactive protein and fibrinogen was more in CDD compared to DD (-4.0 ± 8.5 vs. -1.3 ± 2.8 mg/liter, and -0.40 ± 0.74 and -0.20 ± 0.52 mg/liter, respectively), the differences were not significant. There was a significant increase in serum adiponectin in both the DD and CDD groups (51.3 ± 65.3 vs. 57.1 ± 33.8 µg/liter; P < 0.05). Mean adiponectin changes in CDD were significantly higher than in PD (P = 0.021). CONCLUSIONS: Daily intake of vitamin D-fortified doogh improved inflammatory markers in T2D subjects, and extra calcium conferred additional benefit only for the antiinflammatory adipokine, i.e. adiponectin.

Regular consumption of vitamin D-fortified yogurt drink (Doogh) improved endothelial biomarkers in subjects with type 2 diabetes: a randomized double-blind clinical trial.

BACKGROUND: Endothelial dysfunction has been proposed as the underlying cause of diabetic angiopathy that eventually leads to cardiovascular disease, the major cause of death in diabetes. We recently demonstrated the ameliorating effect of regular vitamin D intake on the glycemic status of patients with type 2 diabetes (T2D). In this study, the effects of improvement of vitamin D status on glycemic status, lipid profile and endothelial biomarkers in T2D subjects were investigated. METHODS: Subjects with T2D were randomly allocated to one of the two groups to receive either plain yogurt drink (PYD; containing 170 mg calcium and no vitamin D/250 mL, n1 = 50) or vitamin D3-fortified yogurt drink (FYD; containing 170 mg calcium and 500 IU/250 mL, n2 = 50) twice a day for 12 weeks. Anthropometric measures, glycemic status, lipid profile, body fat mass (FM) and endothelial biomarkers including serum endothelin-1, E-selectin and matrix metalloproteinase (MMP)-9 were evaluated at the beginning and after the 12-week intervention period. RESULTS: The intervention resulted in a significant improvement in fasting glucose, the Quantitative Insulin Check Index (QUICKI), glycated hemoglobin (HbA1c), triacylglycerols, high-density lipoprotein cholesterol (HDL-C), endothelin-1, E-selectin and MMP-9 in FYD compared to PYD (P < 0.05, for all). Interestingly, difference in changes of endothelin-1, E-selectin and MMP-9 concentrations in FYD compared to PYD (-0.35 ± 0.63 versus -0.03 ± 0.55, P = 0.028; -3.8 ± 7.3 versus 0.95 ± 8.3, P = 0.003 and -2.3 ± 3.7 versus 0.44 ± 7.1 ng/mL, respectively, P < 0.05 for all), even after controlling for changes of QUICKI, FM and waist circumference, remained significant for endothelin-1 and MMP-9 (P = 0.009 and P = 0.005, respectively) but disappeared for E-selectin (P = 0.092). On the contrary, after controlling for serum 25(OH)D, the differences disappeared for endothelin-1(P = 0.066) and MMP-9 (P = 0.277) but still remained significant for E-selectin (P = 0.011). CONCLUSIONS: Ameliorated vitamin D status was accompanied by improved glycemic status, lipid profile and endothelial biomarkers in T2D subjects. Our findings suggest both direct and indirect ameliorating effects of vitamin D on the endothelial biomarkers. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01236846.

Daily consumption of vitamin D- or vitamin D + calcium-fortified yogurt drink improved glycemic control in patients with type 2 diabetes: a randomized clinical trial.

BACKGROUND: Low serum concentrations of 25-hydroxyvitamin D [25(OH)D] have been associated with impaired glucose tolerance and diabetes. OBJECTIVE: This study aimed to compare the effects of daily intake of vitamin D- or vitamin D(3) + calcium-fortified yogurt drink on glycemic status in subjects with type 2 diabetes (T2D). DESIGN: Ninety diabetic subjects were randomly allocated to 3 groups to consume plain yogurt drink (PY; containing no vitamin D and 150 mg Ca/250 mL), vitamin D-fortified yogurt drink (DY; containing 500 IU vitamin D(3) and 150 mg Ca/250 mL), or vitamin D + calcium-fortified yogurt drink (DCY; containing 500 IU vitamin D(3) and 250 mg Ca/250 mL) twice per day for 12 wk. Fasting serum glucose (FSG), glycated hemoglobin (Hb A(1c)), homeostasis model assessment of insulin resistance (HOMA-IR), serum lipid profile, and percentage fat mass (FM) were assessed before (baseline) and after the intervention. RESULTS: In both the DY and DCY groups, mean serum 25(OH)D(3) improved (+32.8 ± 28.4 and +28.8 ± 16.1 nmol/L, respectively; P < 0.001 for both), but FSG [-12.9 ± 33.7 mg/dL (P = 0.015) and -9.6 ± 46.9 mg/dL (P = 0.035)], Hb A(1c) [-0.4 ± 1.2% (P < 0.001) and -0.4 ± 1.9% (P < 0.001)], HOMA-IR [-0.6 ± 1.4 (P = 0.001) and -0.6 ± 3.2 (P < 0.001)], waist circumference (-3.6 ± 2.7 and -2.9 ± 3.3; P < 0.001 for both), and body mass index [in kg/m(2); -0.9 ± 0.6 (P < 0.001) and -0.4 ± 0.7 (P = 0.005)] decreased significantly more than in the PY group. An inverse correlation was observed between changes in serum 25(OH)D(3) and FSG (r = -0.208, P = 0.049), FM (r = -0.219, P = 0.038), and HOMA-IR (r = -0.219, P = 0.005). CONCLUSION: Daily intake of a vitamin D-fortified yogurt drink, either with or without added calcium, improved glycemic status in T2D patients. This trial was registered at clinicaltrials.gov as NCT01229891.