Efficacy of vitamin D3-fortified-yogurt drink on anthropometric, metabolic, inflammatory and oxidative stress biomarkers according to vitamin D receptor gene polymorphisms in type 2 diabetic patients: a study protocol for a randomized controlled clinical trial

Fortification of Staple Foods for Household Use with Vitamin D: An Overview of Systematic Reviews

Vitamin D deficiency is a global public health concern with significant implications for bone health and chronic disease prevention. Our aim was to summarize the evidence from Cochrane and other systematic reviews evaluating the benefits or harms of vitamin D fortification of staple foods for household use. In April 2023, we systematically searched Ovid MEDLINE, Embase, Epistemonikos and the Cochrane Database of Systematic Reviews for systematic reviews investigating the effects of vitamin D fortification of food in general populations of any age. We used Cochrane methodology and assessed the methodological quality of included studies using AMSTAR (A MeaSurement Tool to Assess Systematic Reviews). We assessed the degree of overlap among reviews. All outcomes included in systematic reviews were assessed. The protocol is registered in PROSPERO (registration number: CRD42023420991). We included 27 systematic reviews out of 5028 records for analysis. Overall, 11 out of 12 systematic reviews calculating pooled estimates reported a significant increase in serum 25(OH)D concentrations. The mean change in serum 25(OH)D concentrations per additional 100 units of vitamin D ranged from 0.7 to 10.8 nmol/L. Fortification of food with vitamin D showed a reduction in the prevalence of vitamin D deficiency based on high-certainty evidence. Parathormone (PTH) levels were described to decrease, bone mineral density to increase, while the effects on other bone turnover markers were inconsistent. Fortification did not significantly impact most anthropometric parameters, but it seemed to positively influence lipid profiles. In summary, fortification of food with vitamin D results in a reduction of vitamin D deficiency and might increase serum 25(OH)D concentrations, to varying extents depending on the fortified vehicle and population characteristics. Additionally, fortification may have a positive impact on bone turnover and lipid metabolism but may only have a limited effect on anthropometric parameters.

Attenuation of Oxidative Stress, Interleukin-6, High-Sensitivity C-Reactive Protein, Plasminogen Activator Inhibitor-1, and Fibrinogen with Oral Vitamin D Supplementation for Six Months in Patients with Type 2 Diabetes Mellitus having Vitamin D Deficiency

Objectives  Type 2 diabetes mellitus (T2DM) associated with oxidative stress and inflammation causes endothelial dysfunction, which promotes cardiovascular risk. Vitamin D with its pleiotropic effect is said to protect against cardiovascular risk. However, with vitamin D deficiency being more prevalent in T2DM, the cardiovascular risk may get compounded.

Materials and Methods  An interventional study was conducted on 100 patients with T2DM having vitamin D deficiency (vitamin D < 20 ng/mL), who were given oral supplementation of 2,000 IU/day of vitamin D for a period of 6 months. Serum vitamin D, biomarkers of oxidative stress, malondialdehyde (MDA), oxidized LDL (OxLDL), ferric reducing ability of plasma (FRAP), biomarkers of inflammation, high-sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), plasminogen activator inhibitor-1 (PAI-1), and fibrinogen were measured at baseline and at the end of the third and sixth month of vitamin D supplementation.

Statistical Analysis  Repeated measures analysis of variance (ANOVA) was applied for comparison between baseline and third- and sixth-month data after vitamin D supplementation. Linear regression by generalized estimating equations (GEE), which grouped repeated measures for each subject and accounted for correlations that may occur from multiple observations within subjects, was applied.

Results  Serum vitamin D levels reached normal levels with a significant decrease in OxLDL, hsCRP, IL-6, PAI-1, and fibrinogen levels, with a significant increase in FRAP ( p  = 0.001) levels at the end of 6 months of vitamin D supplementation. These changes were observed even after correction with glycemic control (HbA1c). However, a significant decrease in MDA was observed only at the end of the sixth month of vitamin D supplementation. Vitamin D levels showed a significant negative association with Ox-LDL, Hs-CRP, IL-6, PAI-1, and fibrinogen, even after adjusting for BMI and statin use ( p  = 0.001).

Conclusion  Supplementation of vitamin D for a period of 6 months in patients with T2DM having vitamin D deficiency is beneficial in the attenuation of oxidative stress and inflammation.

Relationship between BsmI polymorphism and VDR gene methylation profile, gender, metabolic profile, oxidative stress, and inflammation in adolescents

BACKGROUND

the biological activity of vitamin D depends on the activity of its receptor or VDR. On the other hand, the activity of this receptor is influenced by its state of methylation. The objective of this study was to verify if the BsmI polymorphism of the VDR gene influences its methylation profile in adolescents. Secondly, it was to verify if the status of some metabolic factors (oxidative stress, inflammation, lipid profile, and glycemia) in the serum, and gender-adjusted vitamin D levels are independent factors with an influence on the VDR methylation profile.

METHODS AND RESULTS

the study included 198 adolescents of both sexes, aged 15-19 years, who underwent testing for VDR gene methylation polymorphisms, serum vitamin D levels, and metabolic, oxidative stress, and systemic inflammation markers. It was observed that the BB genotype was less methylated than the other groups (26.1 % versus 30.3 %, and 29.3 % for Bb and bb, respectively), although without statistical differences between them. The odds ratio indicated a protection of 13 % (partially methylated) for vitamin D status, while alpha glycols increased the risk ratio (of being partially methylated) by 3 %. MDA was protective at a 28 % chance of risk that adolescents with higher levels of lipid peroxidation would be hypomethylated.

CONCLUSION

we conclude that the methylation profile of the VDR gene is not influenced by the different BsmI polymorphism genotypes, and that serum vitamin D and serum markers of oxidative stress and inflammation can modulate this profile.

A systematic review and meta-analysis of the effect of Vitamin D-fortified food on glycemic indices

Some reports indicated that Vitamin D may improve glycaemia indices in diabetic patients. The aim of this systematic and meta-analysis was to evaluate effects of Vitamin D fortification on indices of glycemic control. Six databases (PubMed/Medline, ISI Web of Knowledge, Cochrane Library, Science Direct, Scopus, and Google Scholar) were searched, for randomized controlled trials that were published up to September 2018 and that compared the effect of Vitamin D-fortified food versus regular diet in relation to glycemic control. Of the 4,379 studies originally found, 11 articles remained to be assessed for meta-analysis. Vitamin D fortification was associated with a significant improvement in fasting serum glucose (mean difference [MD]: -2.772; 95% confidence interval [CI]: -5.435 to -0.109) and fasting serum insulin (MD: -2.937; 95% CI: -4.695 to -1.178) in patients with Type 2 diabetes mellitus. A diet with food enriched with Vitamin D was associated with a significant improvement in homeostatic model assessment of insulin resistance (MD: -1.608; 95% CI: -3.138 to -0.079) but was not associated with a significant reduction in hemoglobin A1C (MD: 0.034; 95% CI: -0.655 to 0.069). This meta-analysis indicates that Vitamin D fortification improves indices of glycemic control. Hence, food fortified with Vitamin D may be of potential therapeutic value in diabetic patients, as an adjuvant therapy.

Comparing the effectiveness of vitamin D plus iron vs vitamin D on depression scores in anemic females: Randomized triple-masked trial

Background: Low levels of 25-hydroxyvitamin D (25(OH)D) have been related to depression and anxiety. It seems that anemia is associated with vitamin D deficiency. We aimed to evaluate the effects of iron-vitamin D co-supplementation versus vitamin D alone on depression scores in anemic females with low levels of serum 25-hydroxyvitamin D.

Methods: This randomized controlled trial was conducted on eighty premenopausal females who were recruited between May 2015 and October 2015 from primary health care centers. Women with anemia and low concentrations of 25(OH)D were randomized to either 1000 IU/d vitamin D plus 27 mg/d iron (D-Fe) or vitamin D plus placebo supplements (D-P) for 12 weeks. Depressive and anxious symptoms were evaluated with the Beck Depression Inventory (BDI) with subscales 1–13 and 14–21 and Beck Anxiety Inventory (BAI). To compare the groups, Mann–Whitney or chi-squared tests were used and within groups comparison was performed using Wilcoxon signed ranks test. The study was registered on www.clinicaltrial.org as NC 01876563.

Results: The serum concentrations of 25(OH)D were increased significantly in both groups at the end of the study. In both groups, there was a significant improvement in total BDI, the BDI subscale, and the BAI scores (p<0.001). No differences were found between groups (p>0.05).

Conclusion: Although the potential positive effect of vitamin D on mental health was evident, iron plus vitamin D co-supplementation did not demonstrate any significant benefits over vitamin D alone, neither in depression score reduction nor anxiety symptoms.

Vitamin D supplementation and non-alcoholic fatty liver disease: A critical and systematic review of clinical trials

Previous observational studies have found a relationship between vitamin D deficiency and non-alcoholic fatty liver disease (NAFLD). However, this type of study could not show the causal relationship between these two conditions. Therefore, we systematically and critically reviewed the available clinical trials to elucidate such relationship. We searched databases such as Medline, Scopus and Cochrane to identify the clinical trials that assessed the effects of vitamin D supplementation in adults with NAFLD. The outcome variables of interest were indicators of hepatic steatosis, liver enzymes, insulin resistance, inflammation and oxidative stress. A total of 6 studies were included in the qualitative analysis. Only in two studies the grade of hepatic steatosis decreased significantly after vitamin D supplementation. The changes in insulin resistance parameters were reported significant only in one. Of the 3 included studies that measured biomarkers of inflammation and oxidative stress, one revealed a significant decrease in these biomarkers after vitamin D supplementation. Findings from current review study provided new insight into the factors that could affect the therapeutic role of vitamin D in NAFLD. Factors such as gender differences, baseline serum status of vitamin D, co-supplementation with calcium and gene polymorphism should be considered when designing future clinical trials.

Oxidative stress, type 2 diabetes and vitamin D: past, present and future

Oxidative stress refers to an imbalance between potentially harmful free radicals and the body's mechanisms to efficiently detoxify them in favor of the free radicals. Consequently, excess free radicals can attack and damage a wide range of biomolecules including proteins, lipids and nucleic acids. Antioxidant mechanisms of the body are under the influence of genetic and environmental (including dietary) factors. Diabetes is one of the most common metabolic disorders around the world. A huge body of evidence indicates a role for oxidative stress in development of many human diseases including diabetes. In this article, the latest information on the possible links of oxidative stress with diabetes development, control and complications as well as the newest results of antioxidant supplementation trials is reviewed. In addition, the possible role of vitamin D, as a newly recognized antioxidant in diabetes is discussed. Finally, concluding remarks on pivotal issues and future studies are presented.

Vitamin D receptor Cdx-2-dependent response of central obesity to vitamin D intake in the subjects with type 2 diabetes: a randomised clinical trial

This study aimed to investigate the effects of daily intake of vitamin D-fortified yogurt drink (doogh) on central obesity indicators in subjects with type 2 diabetes (T2D) and the possible modulation of this effect by vitamin D receptor (VDR) Cdx-2 genotypes. A total of sixty T2D subjects were randomly allocated to two groups to receive either plain doogh (PD; n 29, containing 170 mg Ca and no vitamin D/250 ml) or vitamin D3-fortified doogh (FD; n 31, containing 170 mg Ca and 12·5 μg/250 ml) twice a day for 12 weeks. 25-hydroxyvitamin D (25(OH)D), glycaemic as well as adiposity indicators were evaluated before and after the intervention. VDR-Cdx-2 genotypes in extended number of T2D subjects in the FD group (n 60) were determined as AA, GA and GG. After 12 weeks, in FD compared with PD, serum 25(OH)D increased (+35·4 v. -4·8 nmol/l; P<0·001) and mean changes of waist circumference (WC; -1·3 v. +1·6 cm; P=0·02), body fat mass (FM; -1·9 v. +0·60 %; P=0·008), truncal fat (TF; -1·1 v. 0·13 %; P=0·003) and visceral adipose tissue (-0·80 v. +0·37 AU; P<0·001) decreased significantly. Circulating 25(OH)D was raised only in the AA group (34·8 nmo/l in AA group v. -6·4 nmol/l in AG and -1·6 nmol/l in GG groups; P<0·001), which was accompanied by a significant decrease in changes of WC (P=0·004), FM% (P=0·01) and TF% (P<0·001) in the AA genotype. Daily intake of vitamin D-FD for 12 weeks improved the central obesity indices in T2D subjects, and the improvement was more pronounced in the carriers of the AA genotype of VDR-Cdx-2.

Association between VDR polymorphisms and breast cancer: an updated and comparative meta-analysis of crude and adjusted odd ratios

There is a lot of debate on the relationship between vitamin D receptor polymorphisms and risk of breast cancer. Herein, we quantitatively analyzed the published case-control studies on this relationship by meta- analysis, performing a bibliographic search from Pubmed and CNKI up to July 31, 2013. The included case- control studies for Fok1, Bsm1, Taq1, Apa1, Cdx2 and Poly-A were 16, 19, 20, 10, 4, 6, respectively. Crude and adjusted odd ratios and 95% confidence intervals were calculated to present and compare the strength of any associations. The results of combined analyses indicated that Fok1, Bsm1, Apa1, Cdx2 and Poly-A were not significantly associated with the risk of breast cancer. In contrast, the tt genotype of Taq1 was a modest risk factor for breast cancer development (tt vs. TT: OR = 1.21, 95% CI: 1.01-1.44). To further confirm the above results, adjusted effects for the six polymorphisms were pooled based on adjusted ORs reported in the original studies. Adjusted ORs of Fok1, Apa1, Cdx2 and Poly-A were similar to the crude ORs. However, Bsm1 and Taq1 showed inconsistent results. For Bsm1, OR for BB vs. bb was 0.85, 95% CI: 0.74-0.98; for Taq1, OR for tt vs. TT was 1.03, 95% CI: 0.92-1.15, and not associated with risk. Subgroup analyses for crude ORs showed some association between Bsm1, Taq1 and breast cancer in Caucasians only, but for adjusted ORs, no associations were found. This meta-analysis suggests that the roles that Fok1, Apa1, Cdx2 and Poly-A polymorphisms play in breast cancer risk are negligible, with Bsm1 and Taq1 as possible exceptions. To be conservative, we still assumed that they may play a modest role in determining breast cancer risk. Further studies are needed to validate our findings.

Functional foods-based diet as a novel dietary approach for management of type 2 diabetes and its complications: A review

Type 2 diabetes is a complicated metabolic disorder with both short- and long-term undesirable complications. In recent years, there has been growing evidence that functional foods and their bioactive compounds, due to their biological properties, may be used as complementary treatment for type 2 diabetes mellitus. In this review, we have highlighted various functional foods as missing part of medical nutrition therapy in diabetic patients. Several in vitro, animal models and some human studies, have demonstrated that functional foods and nutraceuticals may improve postprandial hyperglycemia and adipose tissue metabolism modulate carbohydrate and lipid metabolism. Functional foods may also improve dyslipidemia and insulin resistance, and attenuate oxidative stress and inflammatory processes and subsequently could prevent the development of long-term diabetes complications including cardiovascular disease, neuropathy, nephropathy and retinopathy. In conclusion available data indicate that a functional foods-based diet may be a novel and comprehensive dietary approach for management of type 2 diabetes.

Vitamin D Receptor Fok-I polymorphism modulates diabetic host response to vitamin D intake: need for a nutrigenetic approach

OBJECTIVE

Interpopulation as well as interindividual variations in response to vitamin D intake commonly observed in subjects with type 2 diabetes may be related to genetic makeup. One of the candidate genes potentially responsible for this diversity is vitamin D receptor (VDR). This study aimed to investigate the interactive effect of VDR Fok-I polymorphism and vitamin D intake on diverse aspects of diabetic host response.

RESEARCH DESIGN AND METHODS

Glycemic status, lipid profiles, inflammatory biomarkers, and VDR Fok-I genotypes were determined in diabetic subjects (n = 140) who participated in a randomized controlled trial. Participants consumed two 250-mL bottles per day of yogurt drink (doogh) fortified with 500 IU vitamin D/250 mL for 12 weeks.

RESULTS

Mean serum 25(OH)D increased by ~30 nmol/L (P < 0.001). The time × intervention effect was significant for 25(OH)D (P = 0.030), HDL (P = 0.011), high-sensitivity C-reactive protein (hsCRP) (P < 0.001), interleukin (IL)-4 (P = 0.008), and IL-6 (P = 0.017) among the genotypic groups. The alleles were defined as ''F'' or ''f'' depending on the absence or presence of the restriction site, respectively. The least increment in 25(OH)D was in ff (23.0 ± 3.8 nmol/L) compared with Ff (31.2 ± 3.4 nmol/L) and FF (35.6 ± 2.7 nmol/L) (P for trend = 0.009), but only the difference between ff and FF was significant (P = 0.023). FF group had the largest decrement of both hsCRP and IL-6 compared with Ff (P < 0.001 and P = 0.038) and ff (P = 0.010 and P = 0.048), respectively.

CONCLUSIONS

We concluded that those of VDR ff genotype may be regarded as "low responders" to vitamin D intake in terms of response of circulating 25(OH)D and certain inflammatory biomarkers. A nutrigenetic approach may, therefore, be needed to protect diabetic patients from vitamin D deficiency.

Improvement of vitamin D status resulted in amelioration of biomarkers of systemic inflammation in the subjects with type 2 diabetes

BACKGROUND

Both vitamin D deficiency and inflammation have been linked to cardiovascular disease, the major cause of death in diabetes. In this study, the effects of daily intake of vitamin D-fortified yoghourt drink (doogh) on systemic inflammatory biomarkers in subjects with type 2 diabetes (T2D) were investigated.

SUBJECTS AND METHODS

In this 12-week randomized controlled trial, T2D subjects received either plain doogh (PD; containing 170 mg calcium and no detectable vitamin D/250 mL, n(1) = 50) or vitamin D3-fortified doogh (FD; containing 170 mg calcium and 500 IU/250 mL, n(2) = 50) twice a day. Glycemic status, body fat mass and systemic inflammatory biomarkers including serum highly sensitive C-reactive protein (hsCRP), serum amyloid A (SAA), interleukin(IL)-2, IL-6, IL-10 and tumour necrosis factor (TNF)-α were evaluated at the beginning and after the intervention. Data were expressed as either mean ± SD or median (interquartile range) whenever they had either normal or non-normal distribution, respectively.

RESULTS

In the patients receiving the vitamin D fortified drink, compared with those receiving the unfortified drink, a significant increase in serum 25(OH)D was accompanied by significant changes in TNF-α (-57.9 (-264.6) versus +106.3 (683.2), p = 0.044), IL-6 (-6.3 (-69.2), p = 0.002), hsCRP (-0.39 (-1.50) versus +0.8 (1.52), p < 0.001), SAA (-14.2 ± 44.5 versus +5.6 ± 37.5 mg/L, p = 0.022) and IL-10 (+38.7 ± 157.0 versus -51.9 ± 165.2 ng/L, p = 0.013). The between-group differences of hsCRP, SAA and IL-6 changes remained significant even after controlling for changes quantitative insulin check index (p < 0.001, p < 0.001 and p = 0.009, respectively).

CONCLUSIONS

Improvement of vitamin D status of T2D subjects resulted in amelioration of the systemic inflammatory markers. This may have preventive implications against cardiovascular disease and other diabetic complications.

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.