Association of vitamin D status with metabolic syndrome and its components: A cross-sectional study in a population of high educated Iranian adults

Relationship between Circulating 25-Hydroxyvitamin D and Metabolic Syndrome in Chinese Adults: A Large Nationwide Longitudinal Study

OBJECTIVE

This study investigated the association of circulating levels of 25-hydroxyvitamin D (25[OH]D) with the risk of metabolic syndrome (MetS) and its components in adults.

METHODS

This nationwide cohort involved 23,810 Chinese adults attending annual health evaluations. Serum 25(OH)D levels, MetS status, and covariates were determined at each examination. Among them, 8146, 3310, and 1971 completed two, three, and more than three evaluations, respectively. A hybrid mixed-effects and Cox regression model was employed to determine the cross-sectional and longitudinal relationships.

RESULTS

The odds ratios (ORs) and 95% confidence intervals (CIs) of MetS were significantly lower in individuals within quartile 4 (vs. 1) of serum 25(OH)D for both between-individual (0.43 [0.35, 0.52]) and within-individual comparisons (0.60 [0.50, 0.73]), respectively (all p-trends < 0.001). Among the MetS components, the corresponding ORs (95% CI) in between- and within-individual comparisons were 0.40 (0.29, 0.54) and 0.26 (0.19, 0.36) for abdominal obesity, 0.49 (0.41, 0.58) and 0.78 (0.66, 0.93) for high triglycerides, 0.70 (0.59, 0.82) and 0.75 (0.64, 0.87) for hypertriglyceridemia, 0.48 (0.39, 0.59) and 0.87 (0.71, 1.07) for low HDL cholesterol, and 0.92 (0.76, 1.12) and 0.49 (0.41, 0.59) for hypertension, respectively. Decreased hazard ratios (95% CIs) in quartile 4 (vs. 1) of 25(OH)D were found for MetS (0.80 [0.65, 1.00]), high triglycerides (0.76 [0.62, 0.92]), abdominal obesity (0.77 [0.63, 0.96]), and low HDL cholesterol (0.64 [0.50, 0.81]).

CONCLUSIONS

Decreased concentrations of serum 25(OH)D correlate significantly to a heightened MetS risk and specific components. Our findings underscore the potential preventive function of circulating vitamin D concerning metabolic disorders.

Vitamin D and Metabolic Syndrome in Working Age Subjects from an Obesity Clinic

Serum vitamin D (VitD) levels have been inversely related with metabolic syndrome (MetS), although the direct impact of VitD is still debated. This study examined 879 subjects of working age from an obesity and occupational clinic in Milan, Italy. Among these participants, 316 had MetS, while 563 did not. A multiple logistic regression analysis was conducted to determine the odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) for MetS in relation to serum VitD levels. After controlling for age, sex, leisure time physical activity, and body mass index (BMI), individuals with VitD levels between 20 and 29.9 ng/dL, or at least 30 ng/dL, had approximately half the risk of developing MetS (OR: 0.52, 95% CI: 0.32-0.86 and OR: 0.50, 95% CI: 0.25-0.99, respectively) compared to those with VitD levels below 10 ng/dL. This study presents further evidence of the beneficial effect of adequate VitD levels on the risk of MetS in a population of overweight/obese workers, even after adjusting for BMI. This study supports the importance of testing for and-if required-supplementing VitD in individuals with metabolic risk factors.

Association between Serum Vitamin D and Metabolic Syndrome in a Sample of Adults in Lebanon

The evidence on the association between vitamin D and metabolic syndrome (MetS) is inconclusive. This was a cross-sectional study to explore the relationship between vitamin D serum levels and MetS in a sample of Lebanese adults (n = 230), free of diseases that affect vitamin D metabolism, recruited from an urban large university and neighboring community. MetS was diagnosed according to the International Diabetes Federation criteria. A logistic regression analysis was performed taking MetS as the dependent variable, and vitamin D was forced into the model as an independent variable. The covariates included sociodemographic, dietary, and lifestyle variables. The mean (SD) serum vitamin D was 17.53 (12.40) ng/mL, and the prevalence of MetS was 44.3%. Serum vitamin D was not associated with MetS (OR = 0.99 (95% CI: 0.96, 1.02), p < 0.757), whereas the male sex, compared with the female sex and older age, was associated with higher odds of having MetS (OR = 5.92 (95% CI: 2.44, 14.33), p < 0.001 and OR = 1.08 (95% CI: 1.04, 1.11), p < 0.001, respectively). This result adds to the controversy in this field. Future interventional studies are warranted to better understand the relationship between vitamin D and MetS and metabolic abnormalities.

Comparative effects of vitamin and mineral supplements in the management of type 2 diabetes in primary care: A systematic review and network meta-analysis of randomized controlled trials

Medical nutrition treatment can manage diabetes and slow or prevent its complications. The comparative effects of micronutrient supplements, however, have not yet been well established. We aimed at evaluating the comparative effects of vitamin and mineral supplements on managing glycemic control and lipid metabolism for type 2 diabetes mellitus (T2DM) to inform clinical practice. Electronic and hand searches for randomized controlled trials (RCTs) were performed until June 1, 2022. We selected RCTs enrolling patients with T2DM who were treated with vitamin supplements, mineral supplements, or placebo/no treatment. Data were pooled via frequentist random-effects network meta-analyses. A total of 170 eligible trials and 14223 participants were included. Low to very low certainty evidence established chromium supplements as the most effective in reducing fasting blood glucose levels and homeostasis model assessment of insulin resistance (SUCRAs: 90.4% and 78.3%, respectively). Vitamin K supplements ranked best in reducing glycated hemoglobin A1c and fasting insulin levels (SUCRAs: 97.0% and 82.3%, respectively), with moderate to very low certainty evidence. Vanadium supplements ranked best in lowering total cholesterol levels with very low evidence certainty (SUCRAs:100%). Niacin supplements ranked best in triglyceride reductions and increasing high-density lipoprotein cholesterol levels with low to very low evidence certainty (SUCRAs:93.7% and 94.6%, respectively). Vitamin E supplements ranked best in reducing low-density lipoprotein cholesterol levels with very low evidence certainty (SUCRAs:80.0%). Our analyses indicated that micronutrient supplements, especially chromium, vitamin E, vitamin K, vanadium, and niacin supplements, may be more efficacious in managing T2DM than other micronutrients. Considering the clinical importance of these findings, new research is needed to get better insight into this issue.

Nutrient Patterns and Its Association and Metabolic Syndrome among Chinese Children and Adolescents Aged 7-17

This study was designed to explore the associations between nutrient patterns (NPs) and metabolic syndrome (MetS) and its five components among Chinese children and adolescents aged 7-17. The required data of participants were collected from the China National Nutrition and Health Surveillance of Children and Lactating Mothers in 2016-2017. Ultimately, 13,071 participants were included. Nutrient patterns were obtained by means of factor analysis. Multivariate logistic regression analysis was conducted to evaluate the association between nutrient patterns with MetS and its components. After adjusting covariates, the results of logistic regression models revealed that high-carbohydrate patterns were associated with the presence of abdominal obesity. The high-animal protein pattern was negatively associated with high triglyceride (TG) and low high-density lipoprotein cholesterol (HDL-C). The high-sodium-and-fat pattern had a negative relationship with elevated blood pressure (BP) and was positively associated with low HDL-C. The high-Vitamin D-and-Vitamin B₁₂ pattern had protective effects on MetS, high TG, and low HDL-C. Further large-scale longitudinal investigations are necessary in the future.

Serum 25-hydroxyvitamin D levels and dyslipidemia: a systematic review and dose-response meta-analysis of epidemiologic studies

CONTEXT

Findings of previous observational studies that examined the association between circulating vitamin D levels and lipid profiles have been inconsistent.

OBJECTIVE

A dose-response meta-analysis of epidemiologic studies was conducted to investigate the relationship between serum 25-hydroxyvitamin D levels and dyslipidemia in adults.

DATA SOURCES

Electronic databases were searched systematically for articles published up to June 2021.

DATA EXTRACTION

Fifty-seven observational studies and 2 cohort studies that reported odds ratios (ORs) or relative risks (RRs) with 95%CIs for dyslipidemia in relation to serum 25-hydroxyvitamin D levels in adults were included.

DATA ANALYSIS

A high level, vs a low level, of serum 25-hydroxyvitamin D was related to a significant 19% decrease in the odds of hypertriglyceridemia (OR 0.81; 95%CI, 0.74-0.89), an 18% reduction in low high-density lipoprotein cholesterol (HDL-C) (OR 0.82; 95%CI, 0.76-0.89), and an 18% reduction in dyslipidemia (OR 0.82; 95%CI, 0.75-0.91). No significant association was found between a high vs a low level of serum 25-hydroxyvitamin D and risk of high low-density lipoprotein cholesterol (LDL-C) levels (OR 0.86; 95%CI, 0.62-1.19) or hypercholesterolemia (OR 1.03; 95%CI, 0.93-1.15). Dose-response analyses demonstrated that each 10 ng/mL increase in the serum 25-hydroxyvitamin D level was linked, respectively, to a 7% (OR 0.93;95%CI, 0.85-1.02), a 3% (OR 0.97; 95%CI, 0.90-1.05), and a 4% (OR 0.96; 95%CI, 0.92-1.00) marginally significant decrease in the odds of hypertriglyceridemia, low HDL-C, and dyslipidemia.

CONCLUSION

Higher serum 25-hydroxyvitamin D levels are associated with significant reductions in the odds of hypertriglyceridemia, low HDL-C, and dyslipidemia in a dose-response trend.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021219484.

Vitamin D status and prevalence of metabolic syndrome by race and Hispanic origin in US adults: findings from the 2007-2014 NHANES

BACKGROUND

Vitamin D status has been found to be inversely associated with metabolic syndrome (MetS) in some studies. Vitamin D status varies by race and ethnicity, and the association of MetS with vitamin D status in US adults and by race and Hispanic origin has not been evaluated extensively.

OBJECTIVES

We aimed to examine the associations between vitamin D status and MetS overall, and across race and Hispanic origin groups, in a nationally representative sample of US adults who participated in the NHANES from 2007 to 2014.

METHODS

The total sample included 8639 adults, ≥20 y of age. Serum vitamin D was measured using a standardized LC-tandem MS method and was categorized using data-driven tertiles. MetS was defined using measured waist circumference, triglycerides, HDL cholesterol, blood pressure, and fasting glucose. Multivariable logistic regression models were fitted [accounting for sociodemographic and lifestyle factors, dietary supplement use, and BMI (in kg/m2)] to examine the associations of serum vitamin D with MetS among adults overall, and by race and Hispanic origin.

RESULTS

Serum vitamin D in the lowest tertile (≤56 nmol/L) was significantly associated with increased odds of MetS compared with the highest tertile (>77.9 nmol/L) (fully adjusted model OR: 1.85; 95% CI: 1.51, 2.27). Inverse associations were noted for all race-Hispanic origin groups: non-Hispanic white (NHW) (OR: 2.24; 95% CI: 1.67, 3.01), non-Hispanic black (OR: 1.56; 95% CI: 1.06, 2.29), and Hispanic (OR: 1.48; 95% CI: 1.03, 2.14) adults.

CONCLUSIONS

Lower vitamin D status was significantly associated with MetS among US adults after adjusting for sociodemographic and lifestyle factors, dietary supplement use, and BMI. This finding was noted across all race and Hispanic origin groups, although the strength of the association varied, being strongest for NHW adults.

The impacts of vitamin D supplementation in adults with metabolic syndrome: A systematic review and meta-analysis of randomized controlled trials

Background: Studies have shown the association of vitamin D status with the development of metabolic syndrome (MetS), which has attracted an extensive research interest with inconsistent results. Therefore, we hypothesized that vitamin D supplementation (VDS) will benefit adults with MetS.

Aims: To test our hypothesis, we performed a meta-analysis to evaluate the effect of VDS on MetS in adults using relevant biomarkers such as anthropometric parameters, blood pressure, blood lipid profile, glycemia, oxidative stress and vitamin D toxicity (VDT).

Methods: Randomized controlled trials published in PubMed, Web of Science, embase and the Cochrane Library between 2012 and 2022 on the effect of VDS on MetS in adults were searched. The language was limited to English. A meta-analysis performed using RevMan 5.4 and Stata 14.0 software, sensitivity analysis, and evaluation of the risk of bias and general quality of the resulting evidence were conducted.

Results: Eventually, 13 articles were included in this meta-analysis. Overall, VDS significantly increased the endline serum 25-hydroxyvitamin D levels as compared to the control [MD:17.41, 95% CI (14.09, 20.73), p < 0.00001]. VDS did not affect waist circumference, body mass index, body fat percentage and VDT biomarkers, but decreased waist-to-hip ratio and blood pressure (p < 0.01). VDS significantly decreased fasting plasma glucose (FPG) [MD: 3.78; 95% CI (−6.52, −1.03), p = 0.007], but did not affect the levels of blood high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglyceride (TG). Pooled estimate of nine papers indicated a significant reduction of fasting insulin (FI) (p = 0.006), and homeostasis model assessment of insulin resistance (p = 0.0001). The quantitative insulin check index levels were moderately increased (p = 0.007) without any impact on the glycosylated hemoglobin type A1C (HbA1c). For the oxidative stress parameters, VDS significantly lowered the levels of malondialdehyde and hypersensitive C-reactive protein (p < 0.05).

Conclusion: Results of this meta-analysis demonstrate that VDS only reduces insulin resistance and hypertension but not the blood lipid profile and HbA1c. It appears that the evidence for the benefit of VDS in adults with MetS is inconclusive. Further clinical studies are still needed.

Occurrence of metabolic syndrome components in northerners

The metabolic syndrome is currently becoming more common. It is a significant public health concern as it is epidemic affecting populations in many regions of the world. In Magadan region no research has been carried out to study the frequency of components of the metabolic syndrome among northerners. This survey was performed to assess the occurrence of the main and additional components of the metabolic syndrome among 17 to 74 year old residents of the Northern region. Two hundred and forty north born Caucasians participated in the study: male subjects at their young age, working age, and retirement age, all belonging to the territory of Magadan region. We used photometric, immunochemiluminescent research methods, as well as standard methods for assessing body mass index and cardiovascular system. The metabolic syndrome factors were determined in accordance with the criteria of the National Cholesterol Education Program (NCEP), the Adult Treatment Program III (ATP III), the International Diabetes Federation (IDF), and the Consensus of International Experts in Cardiology and Endocrinology. We analyzed five main components of the metabolic syndrome (overweight, carbohydrate metabolic impairments hypertension, hypertriglyceridemia, hypoalphacholesterolemia) and three additional components (presence of insulin resistance, purine metabolism disorder, deficient and insufficient concentrations of vitamin D). Combinations of the components were also studied through the examined age groups. According to the ATP III, NCEP and IDF criteria, the metabolic syndrome was more common in elderly subjects (47%) than in working age (21%) or young examinees (3%). Older males tended to exhibit higher frequency of both the main and additional factors of metabolic syndrome. The total index of the occurrence of metabolic syndrome factors in the group of young men was 101%; in the group of men of working age - 180%, and in men of retirement age - 274%. The results on occurrence of the metabolic syndrome components observed in the surveyed groups of northerners can make an information data base, which we assume can be applied when planning and carrying out scientifically grounded preventive measures, which will improve subjective quality of life and its expectancy under the North conditions.

Transcriptome and metabolome changes induced by bitter melon (Momordica charantia)- intake in a high-fat diet induced obesity model

Background and aim

Metabolic syndrome (MetS) is a complex disease of physiological imbalances interrelated to abnormal metabolic conditions, such as abdominal obesity, type II diabetes, dyslipidemia and hypertension. In the present pilot study, we investigated the nutraceutical bitter melon (Momordica charantia L) -intake induced transcriptome and metabolome changes and the converging metabolic signaling networks underpinning its inhibitory effects against MetS-associated risk factors.

Experimental procedure

Metabolic effects of lyophilized bitter melon juice (BMJ) extract (oral gavage 200 mg/kg/body weight-daily for 40 days) intake were evaluated in diet-induced obese C57BL/6J male mice [fed-high fat diet (HFD), 60 kcal% fat]. Changes in a) serum levels of biochemical parameters, b) gene expression in the hepatic transcriptome (microarray analysis using Affymetrix Mouse Exon 1.0 ST arrays), and c) metabolite abundance levels in lipid-phase plasma [liquid chromatography mass spectrometry (LC-MS)-based metabolomics] after BMJ intervention were assessed.

Results and conclusion

BMJ-mediated changes showed a positive trend towards enhanced glucose homeostasis, vitamin D metabolism and suppression of glycerophospholipid metabolism. In the liver, nuclear peroxisome proliferator-activated receptor (PPAR) and circadian rhythm signaling, as well as bile acid biosynthesis and glycogen metabolism targets were modulated by BMJ (p < 0.05). Thus, our in-depth transcriptomics and metabolomics analysis suggests that BMJ-intake lowers susceptibility to the onset of high-fat diet associated MetS risk factors partly through modulation of PPAR signaling and its downstream targets in circadian rhythm processes to prevent excessive lipogenesis, maintain glucose homeostasis and modify immune responses signaling.

Effect of supplementation with Chlorella vulgaris on lipid profile in adults: A systematic review and dose-response meta-analysis of randomized controlled trials

OBJECTIVE

To summarize available findings on the effect of Chlorella vulgaris supplementation on lipid profile in adults.

DESIGN

Systematic review and meta-analysis of randomized controlled trials (RCTs).

SETTING

This study followed 2020 PRISMA guideline. We performed a systematic search in the online databases to identify relevant articles and then, extracted required data from each paper for the meta-analysis. Random-effects models were used to obtain overall mean difference (MD) comparing Chlorella vulgaris supplementation with a control group.

MAIN OUTCOME MEASURES

Blood lipids including triglyceride (TG), total cholesterol (TC), LDL-C, and HDL-C.

RESULTS

In total, 10 RCTs with a total sample size of 539 adults (264 in the Chlorella vulgaris group and 275 in the control group) were included. Of the 10 RCTs, four had a low risk of bias for all aspects of the Cochrane risk of bias tool. Also, only two studies determined the chlorella content, purity, potency, and contamination of the supplements used in the intervention. Combining results from these studies showed a summary MD of -2.11 mg/dL (95% CI: -7.28 to 3.06) for TG, -7.47 mg/dL (95% CI: -12.98 to -1.96) for TC, -7.71 mg/dL (95% CI: -14.05 to -1.37) for LDL-C, and -0.45 mg/dL (95% CI: -0.67 to 1.57) for HDL-C, indicating a beneficial effect of Chlorella vulgaris supplementation on TC and LDL-C levels. Based on the dose-response analysis, the reducing effect of Chlorella vulgaris supplementation on LDL-C levels was seen at the dosages between zero and 1500 mg/d (P for non-linearity= 0.01), whereas in higher amounts, this effect was not significant.

CONCLUSION

We found that Chlorella vulgaris supplementation had a beneficial effect on TC and LDL-C levels with no significant effect on TG and HDL-C levels.

Serum Vitamin D Levels in Relation to Hypertension and Pre-hypertension in Adults: A Systematic Review and Dose–Response Meta-Analysis of Epidemiologic Studies

Background

Findings of observational studies that evaluated the association of serum vitamin D status and high blood pressure were contradictory. This meta-analysis of epidemiologic studies assessed the relation of serum vitamin D levels to hypertension (HTN) and pre-hypertension in adults.

Methods

We conducted a systematic search of all published articles up to March 2021, in four electronic databases (MEDLINE (PubMed), Web of Science (ISI), Embase and Scopus), and Google scholar. Seventy epidemiologic studies (10 prospective cohort, one nested case–control, and 59 cross-sectional investigations) that reported relative risks (RRs), odds ratios (ORs), hazard ratios, or prevalence ratios with 95% CIs for HTN or pre-hypertension in relation to serum vitamin D concentrations in adults were included in the analysis.

Results

In prospective studies, a 16% decrease in risk of hypertension was observed in participants with high levels of serum vitamin D compared to low levels (RR: 0.84; 95%CI: 0.73, 0.96; 12 effect sizes). Dose–response analysis in prospective studies revealed that each 25 nmol/L increase in serum vitamin D concentrations resulted in 5% reduced risk of HTN (RR: 0.95; 95% CI: 0.90, 1.00). Also, a significant nonlinear relationship between serum vitamin D levels and HTN was found (P_nonlinearity < 0.001). In cross-sectional investigations, highest vs. lowest level of serum vitamin D was related to reduced odds of HTN (OR: 0.84; 95%CI: 0.79, 0.90; 66 effect sizes) and pre-hypertension (OR: 0.75; 0.95%CI: 0.68, 0.83; 9 effect sizes). Dose–response analysis in these studies showed that each 25 nmol/L increase in serum vitamin D levels was related to a significant 6% reduction in odds of hypertension in all populations (RR: 0.94; 95%CI: 0.90, 0.99) and 3% in studies with representative populations (RR: 0.97; 95%CI: 0.95, 0.99).

Conclusion

This meta-analysis of epidemiologic studies disclosed that serum vitamin D concentrations were inversely related to the risk of HTN in adults, in a dose–response manner in both prospective cohort and cross-sectional studies.

Systematic Review Registration:http://www.crd.york.ac.uk/Prospero, identifier: CRD42021251513.

Nutrient pattern analysis of mineral based, simple sugar based, and fat based diets and risk of metabolic syndrome: a comparative nutrient panel

BACKGROUND

Although there is growing evidence on the association between nutrient patterns and metabolic risk factors, very little is known about the relationship between nutrient patterns and metabolic syndrome (MetS). The aim of this study was to examine the associations of nutrient patterns with MetS among apparently healthy obese adults living in Tabriz, Iran.

METHODS

Three hundred and forty-seven apparently healthy obese (BMI ≥ 30 kg/m²) adults aged 20-50 years were included in this cross-sectional study. Dietary intake of 38 nutrients was assessed by a validated semi-quantitative food frequency questionnaire (FFQ) of 132 food items. Nutrient patterns were determined using factor analysis. The MetS was defined based on the guidelines of the National Cholesterol Education Program Adult Treatment Panel III (ATP III).

RESULTS

Three major nutrient patterns were extracted: "Mineral based pattern", "Simple sugar based pattern" and "Fat based pattern". There was no significant association between nutrient patterns and MetS, in the crude model even after adjusting for confounders. There was a significant difference between quartiles in the mineral based pattern for free mass (FFM), diastolic blood pressure (DBP), large Waist circumference (WC) and Waist-to-hip ratio (WHR). In the simple sugar based pattern, we observed a significant association for SBP, DBP, and triglyceride (TG) levels. In addition, the fat based pattern was positively associated with BMI, and weight.

CONCLUSIONS

We did not observe any significant association of nutrient patterns with the risk of MetS amongst the apparently healthy obese adult's population. Whereas we confirmed the deleterious effect of the simple sugar and fat based patterns on several metabolic risk factors, our findings also showed that the mineral based pattern is related to healthier metabolic factors in an Iranian population. These results should be approved by future studies to recognize any causal relationship between adherence to specific nutrient patterns and MetS.

Insuficiência de vitamina D e fatores associados: um estudo com idosos assistidos por serviços de atenção básica à saúde

Resumo O objetivo deste artigo é analisar a insuficiência de vitamina D e fatores associados em idosos assistidos na atenção primária à saúde. Trata-se de um estudo transversal que avaliou 533 idosos (≥ 60 anos) em três cidades do estado de São Paulo, Brasil. Foi avaliada a 25-hidroxivitamina D (25 OH D) sérica por quimioluminescência. Os fatores avaliados foram condições sociodemográficas (sexo, faixa etária, etnia, escolaridade, renda, estado civil), de saúde (doenças referidas), composição corporal (IMC, circunferência da cintura), estilo de vida (atividade física e tabagismo) e exposição solar (finalidade, duração, frequência e horário de exposição, partes expostas, uso de protetor solar, tipo de pele). A prevalência de insuficiência foi de 64,5%, com associação para sexo feminino, etnia não brancos/não declarados, baixo peso, circunferência da cintura elevada (risco para DCV) e inatividade física. Houve associação negativa para exposição solar habitual de mãos, braços e pernas, durante atividade de lazer, deslocamentos diários e atividade física e entre as 9h e 15h. Os achados mostram a relevância de fatores como sexo, etnia, composição corporal, atividade física e hábitos de exposição solar na alta prevalência de níveis inadequados de vitamina D em idosos.

Vitamin D and Calcium Status Among Adolescents with Morbid Obesity Undergoing Bariatric Surgery

PURPOSE

Obesity is very prevalent among children and adolescents these days. Obese children are at increased risk of vitamin D and other micronutrient deficiencies. This risk is even higher in children and adolescents with morbid obesity who are candidates for bariatric surgery. Although multiple studies have studied the prevalence of vitamin D deficiency in adults undergoing bariatric surgery, studies are limited concerning adolescents in this regard. We aimed to study the prevalence of vitamin D deficiency and insufficiency and calcium status among morbidly obese children and adolescents.

MATERIALS AND METHODS

A number of 96 adolescents (20 years old and younger) with morbid obesity (BMI ≥ 99% percentile), who were candidates for bariatric surgery, were enrolled in this study (from 2016 to 2018), and their serum vitamin D and calcium levels were measured.

RESULTS

Sixty-four percent of the patients were vitamin D-deficient and 15.7% of them had insufficient levels of serum vitamin D. Only 20.2% of the children had sufficient serum vitamin D levels. Serum calcium levels were within the normal range among all of the patients. There was no significant relationship between age and sex with vitamin D levels.

CONCLUSION

Vitamin D deficiency is of very high prevalence among adolescents with morbid obesity.

Serum and Dietary Vitamin D in Individuals with Class II and III Obesity: Prevalence and Association with Metabolic Syndrome

The association between vitamin D deficiency and metabolic syndrome (MS) in severe obesity is unclear and controversial. We analyzed serum and dietary vitamin D and their association with MS in 150 adults with class II and III obesity (BMI ≥ 35 kg/m²) from the DieTBra Trial (NCT02463435). MS parameters were high fasting blood glucose, low HDL cholesterol, high triglycerides, elevated waist circumference, and hypertension. Vitamin D deficiency was considered as a level < 20 ng/mL. We performed multivariate Poisson regression adjusted for sociodemographic and lifestyle variables. The prevalence of serum vitamin D deficiency was 13.3% (mean 29.9 ± 9.4 ng/mL) and dietary vitamin D median was 51.3 IU/day. There were no significant associations between vitamin D, serum, and diet and sociodemographic variables, lifestyle, and class of obesity. Serum vitamin D deficiency was associated with age ≥ 50 years (p = 0.034). After a fully adjusted multivariate Poisson regression, MS and its parameters were not associated with serum or dietary vitamin D, except for lower HDL, which was associated with serum vitamin D deficiency (PR = 0.71, 95% CI 0.52–0.97; p = 0.029). Severe obese individuals had a low prevalence of vitamin D deficiency, which was not associated with MS.

Fruit and vegetable consumption in relation to primary headaches: the MEPHASOUS study

BACKGROUND

Fruit and vegetable consumption may beneficially affect the odds of primary headaches due to their antioxidant contents. However, no study has examined the association between fruit and vegetable consumption and primary headaches among university students.

AIM

To assess the relation between fruit and vegetable intakes and primary headaches among Iranian university students.

METHODS

Overall, 83,214 university students with an age range of ≥ 18 years participated in the present study. Dietary intakes and also data on confounding variables were collected using validated questionnaires. Data on dietary intakes were collected using a validated dietary habits questionnaire. We used the International Classification of Headache Disorders-3 (ICHD-3) criteria to define primary headaches.

RESULTS

Fruit consumption was negatively associated with primary headaches; such that after controlling for potential confounders, greater intake of fruits was associated with 30% lower odds of primary headaches (OR: 0.70, 95% CI 0.58-0.84). Such an inverse association was also found for vegetable consumption. In the fully adjusted model, students in the top category of vegetable consumption were 16% less likely to have primary headaches compared with those in the bottom category (OR: 0.84, 95% CI 0.74-0.95). Subgroup analysis revealed that fruit consumption was inversely associated with primary headaches in females, unlike males, and vegetable consumption was inversely associated with these headaches in males, as opposed to females. Moreover, fruit and vegetable consumption was related to lower odds of primary headaches in normal-weight students.

CONCLUSION

Fruit and vegetable intakes were associated with reduced odds of primary headaches.

LEVEL OF EVIDENCE

Level III, cross-sectional analytic studies.

Role of Vitamin D in the Metabolic Syndrome

The prevalence of hypovitaminosis D has risen in developed countries over the past few years in association with lifestyle changes and an increase in unhealthy habits. Vitamin D deficiency has been implicated in various diseases, including metabolic syndrome (MetS), which is clinically defined by a set of metabolic and vascular disorders. The objective of this study was to review scientific evidence on the relationship between MetS and vitamin D deficiency to support the development of prevention strategies and health education programs. An inverse relationship has been reported between plasma vitamin D concentrations and the features that define MetS, i.e., elevated serum concentrations of glucose, total cholesterol, low-density lipoproteins, triglycerides, glycosylated hemoglobin, and a high body mass index. Numerous studies have described the benefits of vitamin D supplementation to improve outcomes in individuals with MetS. Interventions to maintain optimal vitamin D concentrations are proposed as a preventive strategy against MetS.

The association of serum levels of zinc and vitamin D with wasting among Iranian pre-school children

PURPOSE

Wasting is a main indicator of Child's undernutrition that is associated with several non-communicable diseases and child mortality. This is the first population-based study which evaluated the association of serum zinc and vitamin D levels with wasting in a Middle East region. We also reported the prevalence of vitamin D and zinc deficiencies among Iranian pre-school children aged 6 years.

METHODS

This was a multicenter cross-sectional study that included 425 children aged between 5 and 7 years (on average 6 years) with BMI-for-age Z-scores of < - 1 SD resident in urban and rural areas of Iran in the spring of 2012 as part of the National Integrated Micronutrient Survey 2 (NIMS-2). Anthropometric measurements and blood sampling were obtained. The prevalence of vitamin D and zinc deficiencies together with the correlations of these variables with the increase of BMI-for-age Z-scores were evaluated.

RESULTS

The prevalence of vitamin D and zinc deficiencies was 18.8% and 12.7%, respectively. In addition, 31.1% of children were wasted. Children in the second tertile of 25(OH)D levels were less likely to have wasting compared with those in the first tertile in both crude and adjusted models (OR 0.47, 95% CI 0.27-0.83). A significant inverse association was found between serum levels of zinc and wasting (OR 0.57, 95% CI 0.34-0.96); such that after adjusting for confounders, children in the highest tertile of serum zinc had 47% less odds of wasting compared with those in the first tertile (OR 0.53, 95% CI 0.31-0.91).

CONCLUSION

The prevalence of vitamin D and zinc deficiencies among Iranian pre-school children aged 6 years was 18.8 and 12.7%, respectively. Serum levels of vitamin D and zinc were inversely associated with wasting either before or after controlling for confounders.

LEVEL OF EVIDENCE

Level III, case-control analytic studies.

Serum vitamin D levels in relation to abdominal obesity: A systematic review and dose-response meta-analysis of epidemiologic studies

Although several observational studies have investigated the relationship between vitamin D deficiency and risk of central obesity, the results were inconsistent. We performed a dose-response meta-analysis on epidemiologic studies that evaluated the association of vitamin D status and abdominal obesity in adults. A systematic search was carried out of all published articles, up to May 2020, in five electronic databases, including MEDLINE (Pubmed), EMBASE, Institute for Scientific Information (ISI) (Web of science), Scopus and Google scholar. Forty-one observational studies 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 included in the analysis. Using a random effects model, the overall effect size was calculated. Combining 44 effect sizes from 36 cross-sectional studies with 257,699 participants revealed that the highest versus the lowest serum vitamin D level was significantly associated with a 23% decreased odds of abdominal obesity (OR: 0.77; 95% CI [0.71, 0.83]). This inverse association was significant in almost all subgroups based on different covariates. Dose-response analysis showed that each 25 nmol/L increase in serum vitamin D was related to 8% reduced risk of abdominal obesity (OR: 0.92; 95% CI [0.85, 0.99]). When we confined the analysis to 23 effect sizes from 17 studies with representative population (242,135 participants), the same results were obtained (OR: 0.79; 95% CI [0.71, 0.87]). Dose-response analysis indicated that each 25 nmol/L increase in blood vitamin D levels was linked to 10% decreased central adiposity risk in representative populations (OR: 0.90; 95% CI [0.82, 0.99]). This meta-analysis of epidemiologic studies revealed that serum vitamin D level was inversely associated with risk of abdominal obesity in adults, in a dose-response manner. The same findings were obtained in representative populations. Further prospective studies are required to examine the causal association between serum vitamin D levels and abdominal obesity.

Comparison of dietary micronutrient intake in PCOS patients with and without metabolic syndrome

BACKGROUND

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder in reproductive-age women. It is one of the risk factors of metabolic syndrome (MetS). These two syndromes have an inflammatory etiologic foundation along with oxidative stress. The present study aimed to compare the dietary intake of antioxidant micronutrients in PCOS women with and without MetS.

MATERIALS AND METHODS

Overall, 42 participants eligible for this nested case control study were selected by the convenience sampling method. The case group included 14 PCOS patients with MetS and the control group included 28 PCOS patients without MetS. The dietary intake assessment of selenium, chromium, zinc, carotenoids, vitamin D and vitamin E was carried out by a 147-item Food Frequency Questionnaire (FFQ). PCOS and MetS were diagnosed using the Rotterdam criteria and NCEP ATP III, respectively. Statistical analysis was performed using SPSS16 software, T-test and Mann Whitney. Significant P-value was considered 0.05.

RESULTS

Dietary intake of antioxidant micronutrients (selenium, zinc, chromium, carotenoids and vitamin E) was significantly lower in the PCOS women with MetS than in the control group (P < 0.05).

CONCLUSION

Since the PCOS patients without MetS had more intake of the aforementioned micronutrients than those with MetS, it is assumed that the dietary intake of these nutrients could probably have a protective effect on MetS.

Sugar-sweetened beverages consumption in relation to hypertension among Iranian university students: the MEPHASOUS study

PURPOSE

This study aimed to assess the link between sugar-sweetened beverages (SSBs) consumption and hypertension among a large population in the Middle East.

METHODS

In this cross-sectional study (a part of Mental and Physical Health Assessment of University Student: MEPHASOUS study), 66,634 university students from all provinces of Iran, aged ≥ 18 years, were included. A self-administered dietary habits questionnaire was used to assess SSBs consumption as well as other dietary intakes. Participants were categorized based on three levels of SSB consumption: < 1 time/wk, 1-3 times/wk, and ≤ 3 times/wk. Hypertension was defined as systolic blood pressure (SBP) of ≥ 140 and diastolic blood pressure of ≥ 90.

RESULTS

Compared with those in the bottom category, students in the top category of SSBs consumption were more likely to have hypertension (OR 1.71, 95% CI 1.54-1.90). This association remained significant even after adjusting for confounding variables; such that participants in the highest category of SSBs consumption had 2.17 times greater odds of hypertension compared with those in the lowest category (OR 2.17, 95% CI 1.91-2.47). Stratified analysis based on gender and BMI status revealed such significant association in men (OR 2.12, 95% CI 1.79-2.50) and women (OR 2.03, 95% CI 1.67-2.48), and in all categories of BMI including students with underweight (OR 2.53, 95% CI 1.81-3.52), normal-weight (OR 2.13, 95% CI 1.81-2.51), overweight (OR 2.14, 95% CI 1.58-2.89) and obesity (OR 1.59, 95% CI 1.00-2.53).

CONCLUSION

Our results support previous findings indicating a significant positive association between SSBs consumption and hypertension.

LEVEL OF EVIDENCE

Level III, cross-sectional analytic studies.

Effects of zinc supplementation on lipid profile in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Findings on the effects of zinc supplementation on the lipid profile in patients with type 2 diabetes mellitus (T2DM) are conflicting. The current comprehensive systematic review and meta-analysis aimed to summarize available evidence in this regard.

METHODS AND RESULTS

After a systematic search in the online databases, we included the randomized controlled trials (RCTs) investigating the effect of zinc supplementation on lipid profile [total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG)] in patients with T2DM. Altogether, 9 studies with a total sample size of 424 patients with T2DM were included in the analysis. Combining 9 effect sizes from 9 RCTs, we found a significant lowering effect of zinc supplementation on serum levels of TG (weighted mean difference (WMD): -17.08, 95% CI: -30.59, -3.58 mg/dL, P = 0.01) and TC (WMD: -26.16, 95% CI: -49.69, -2.62 mg/dL, P = 0.02). Although the overall effect of zinc supplementation on LDL-C levels was not significant, a beneficial effect was seen in studies that administered <100 mg/d zinc. Based on the non-linear dose-response analysis, a greater reduction in serum levels of TC and LDL-C following zinc supplementation was seen at <12 weeks' duration of intervention. Unlike the overall effect size, we found a significant increasing effect of zinc supplementation on serum HDL-C concentrations in most subgroups of RCTs according to the subgroup analyses.

CONCLUSION

We found that zinc supplementation may beneficially influence lipid profile in patients with T2DM.

The association between nutrient patterns and metabolic syndrome among Iranian adults: cross-sectional analysis of Shahedieh cohort study

OBJECTIVE

To assess the association between patterns of nutrient intake and metabolic syndrome (MetS) in a large sample of Iranian adults.

DESIGN

Baseline data from the Shahedieh cohort study were used in the current cross-sectional study. Dietary intakes were assessed through the use of a validated semi-quantitative FFQ. Nutrient patterns (NP) were derived using factor analysis. The MetS was defined according to criteria introduced from the National Cholesterol Education Program Adult Treatment Panel III, modified for Iranian adults.

SETTING

Yazd, Iran.

PARTICIPANTS

A total of 7325 Iranian adults aged between 30 and 75 years.

RESULTS

Three NP were identified. A significant positive association was found between adherence to semi-plant NP (characterised by the high intakes of P; vitamins B1, B3, B6 and B5; Se; Mg; Fe; protein; Cr; Cu; fibre; biotin; Mn; Zn and Na) and odds of MetS (OR 1·68, 95 % CI 1·43, 1·98). However, after adjusting for potential confounders, this association became non-significant. In addition, after taking potential confounders into account, individuals in the highest quintile of the semi-animal NP, rich in Ca; K; vitamins B2, B12, A, D, K and C; SFA; dietary cholesterol and trans-fatty acid, were 26 % more likely to have MetS compared with those in the lowest quintile (OR 1·26, 95 % CI 1·05, 1·51). No significant association was seen between adherence to the high-carbohydrate/low-fat NP and odds of MetS.

CONCLUSIONS

We found that adherence to a semi-animal NP was associated with increased odds of MetS.

Dairy Consumption in Relation to Hypertension Among a Large Population of University Students: The MEPHASOUS Study

BACKGROUND

Hypertension is a chronic condition that its prevalence is increasing at an alarming rate. Findings on the association between dairy consumption and hypertension are conflicting and few data are available in the Middle East.

AIM

To assess the association between dairy consumption and hypertension among a large population of university students.

MATERIALS AND METHODS

The current study was performed in the framework of the Mental and Physical Health Assessment of University Student (MEPHASOUS) project. Overall, 67,011 university students with complete information were included in the statistical analysis. To assess dairy consumption, a self-administered dietary habits questionnaire was employed. Blood pressure was measured using a standard protocol. The systolic/diastolic blood pressure of ≥140/90 mmHg was considered hypertension.

RESULTS

Hypertension was prevalent among 6.9% of students. A significant inverse association was found between dairy consumption and the odds of hypertension; such that after taking potential confounders into account, individuals in the highest levels of dairy consumption had 85% lower odds for having hypertension compared with those in the lowest levels (odds ratio (OR): 0.15, 95% confidence interval (CI): 0.13-0.18). Such an inverse association was also seen among males (OR: 0.14, 95% CI: 0.11-0.18) and females (OR: 0.16, 95% CI: 0.12-0.21), normal-weight students (OR: 0.15, 95% CI: 0.12-0.18) and those with overweight or obesity (OR: 0.15, 95% CI: 0.11-0.21), and individuals with (OR: 0.13, 95% CI: 0.11-0.16) and without (OR: 0.24, 95% CI: 0.17-0.35) family history of hypertension.

CONCLUSION

Our results support the previous findings on the inverse association between dairy consumption and hypertension among university students.

Association of vitamin D, retinol and zinc deficiencies with stunting in toddlers: findings from a national study in Iran

OBJECTIVE

The objective of this study was to investigate the association of serum levels of 25(OH)D₃ (vitamin D), retinol (vitamin A) and zinc with stunting in a large sample of Iranian toddlers.

STUDY DESIGN

This was a cross-sectional study.

METHODS

A total of 4261 children, aged 10-36 months, who had Iranian birth certificates were included in the present study. Weight and height were measured by experienced professionals in accordance with standard protocols. Stunting was defined as a height-for-age z-score of <-1 standard deviation (SD) based on the World Health Organization (WHO) criteria (the WHO Child Growth Standards median). Serum levels of 25(OH)D₃, retinol and zinc were examined based on standard methods.

RESULTS

The mean age of the study participants was 19.2 ± 8.4 months. A significant inverse association was found between serum retinol concentrations and the odds of stunting such that after controlling for potential confounders, toddlers in the highest quartile of serum retinol levels had 29% lower odds of stunting than those in the lowest quartile (odds ratio [OR]: 0.71, 95% confidence interval [CI]: 0.53-0.97). Furthermore, a significant inverse association was found between serum levels of retinol and stunting in girls (OR: 0.57, 95% CI: 0.34-0.94), urban toddlers (OR: 0.66, 95% CI: 0.44-0.99) and those who did not use nutritional supplements (OR: 0.70, 95% CI: 0.52-0.95). Although serum 25(OH)D₃ levels were not significantly associated with stunting in the overall study population, we found a positive association among toddlers who used nutritional supplements. No significant association was found between serum levels of zinc and stunting.

CONCLUSION

We found a significant inverse association between serum levels of retinol and stunting in toddlers aged 10-36 months.

The prevalence of metabolic syndrome among Iranian bakers

BACKGROUND

Metabolic syndrome (MetS) is a group of risk factors that are associated with increased risk for atherosclerotic cardiovascular disease.

OBJECTIVE

The objective of this study was to determine the prevalence of metabolic syndrome and its individual components among Iranian bakery workers.

METHODS

A cross-sectional study enrolling 163 randomly selected bakery workers from Semnan province (Northeast Iran), was conducted in 2017. A standard questionnaire was used for data collection. Analyses were performed using t-test, one-way ANOVA and Latent Class Analysis (LCA) in R software.

RESULTS

The prevalence of MetS was 19.8% among bakery workers. More bakery workers with MetS had no regular exercise (p = 0.001) and worked more than eight hours a day (p = 0.001). In this study, the International Diabetes Federation (IDF) diagnostic criteria had more agreement with the American Heart Association (AHA) (49.1%) than the World Health Organization (WHO) and Adult Treatment Panel (ATP) criteria. Also, the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATPIII) had the highest sensitivity for diagnosing MetS. The sensitivity of the four diagnostic methods, WHO, IDF, ATP and AHA, were 45.2%, 61.7%, 67.9% and 64.8%; and their specificity were 98.2%, 100%, 100% and 100%, respectively.

CONCLUSION

The prevalence of MetS is high among bakery workers in Iran. Increased physical activity and intake of fruit and vegetables are recommended for the prevention of MetS.

Vitamin D deficiency in relation to general and abdominal obesity among high educated adults

PURPOSE

To assess the association of vitamin D deficiency with general and abdominal obesity among high educated Iranian adults.

METHODS

Current cross-sectional study was done on 500 Iranian professors aged 35 years or more. Complete data on general and abdominal obesity as well as serum 25(OH)D concentrations were available for 352 persons. Obesity was considered as body mass index ≥ 30, and abdominal obesity as waist circumference ≥ 80 cm for women and ≥ 94 cm for men. Furthermore, vitamin D deficiency was defined as serum 25(OH)D < 30 ng/ml.

RESULTS

Mean age of study population was 53.03 ± 7.15 years. Compared with those in the first quartile of serum 25(OH)D, participants in the fourth quartile were less likely to be generally obese (OR 0.46, 65% CI 0.22-0.99). Such finding was also seen even after taking potential confounders into account. Furthermore, we found an inverse association between serum 25(OH)D and abdominal obesity in fully adjusted model (OR 0.44, 95% CI 0.22-0.86). In addition, a significant positive association was found between vitamin D deficiency and obesity; such that after controlling for potential confounders, participants with vitamin D deficiency had 2.16 and 2.04 times greater odds for having general (OR 2.16, 95% CI 1.05-4.45) and abdominal obesity (OR 2.04, 95% CI 1.16-3.60), respectively, than those with normal levels of vitamin D.

CONCLUSION

Serum 25(OH)D concentrations were inversely associated with general and abdominal obesity. In addition, vitamin D deficiency was positively associated with both general and abdominal obesity.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study.

The GC2 haplotype of the vitamin D binding protein is a risk factor for a low plasma 25-hydroxyvitamin D concentration in a Han Chinese population

Background

The GC haplotype of the vitamin D binding protein (encoded by the GC gene) might be a risk factor to the vitamin D (VD) nutritional status for many populations, while evidences from the Chinese Han population are sparse. We test the association between vitamin D binding protein genotypes and VD status as well as the metabolic parameters of glucose and lipids in a Han Chinese population.

Methods

In a cross-sectional study conducted at a health examination centre (registered in ClinicalTrials.gov as QLS2013), 2641 adults were included and grouped according to their plasma 25-hydroxyvitamin D (25OHD) concentrations as VD deficient (VDD), insufficient (VDI), or sufficient (VDS). The rs7041 and rs4588 genotypes were analysed with a molecular beacon-based qPCR method using blood samples.

Results

Plasma 25OHD concentrations were lower in the GC2/2, rs7041T/T, and rs4588A/A genotypes than the GC1f/1s, rs7041G/T, and rs4588C/C genotypes (P <  0.05). After adjusting for confounders, the GC2 haplotype increased the risk of low VD status (P <  0.05) in both genders. More genotypic models revealed the negative contributions of rs4588A than rs7041T to low VD status (P <  0.05). The combined rates of VDD and VDI were 80.2% in males and 86.1% in females. Compared with VDI, VDS, or both, VDD showed higher plasma concentrations of fasting blood glucose, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and triglycerides in males (P <  0.05); however, no significant differences were found with regard to these parameters between the subgroups defined by the GC genotypes (P > 0.05).

Conclusions

In a Han Chinese population, the GC2 haplotype or more exactly rs4588A is a risk factor for low VD status but is not associated with glucose and lipid metabolic disorders, which are inversely correlated with the circulating 25OHD concentration in males.

Trial registration

The study was retrospectively registered in January 2018 as NCT03406234 in the ClinicalTrials.gov online system.

Electronic supplementary material

The online version of this article (10.1186/s12986-019-0332-0) contains supplementary material, which is available to authorized users.