Antioxidant micronutrients and cardiovascular risk in patients with diabetes: a systematic review

Vitamin D, Oxidative Stress and Glycaemic Control in Subjects with Type 2 Diabetes Mellitus: Systematic Review

Background:

Diabetes mellitus (DM) is a metabolic and chronic disorder which causes high blood glucose concentrations and dysfunctional pancreatic beta-cells characterized by decreased insulin secretion and signalling. Scientific evidence suggests that vitamin D supplementation may help patients with type 2 diabetes mellitus (T2DM) improve glycaemic control, increasing insulin secretion and decreasing HbA1c concentrations. Additionally, this supplementation improves antioxidant enzyme concentrations, such as superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT) and total antioxidant capacity (TAC). Finally, some studies have reported that supplementation decreases oxidative markers such as malondialdehyde (MDA).

Materials and methods:

This systematic review was conducted following Reporting Items for Systematic Reviews and Meta-Analyses framework (PRISMA) in terms of study selection, data collection, data analysis, and result reporting. Several databases were reviewed from 2013 to 2020: Google Scholar, REDALYC, Scielo, Scopus and PubMed, among others; word combinations and MeSH keywords were used to find scientific evidence on vitamin D supplementation in patients with T2DM and their relationship with oxidative stress.

Objective:

To review the effect of vitamin D supplementation on glycaemic control and oxidative stress markers in patients with T2DM. Inclusion criteria involved adult patients with T2DM, oral vitamin D supplementation with different dosages and undefined time. Studies in children or animals and with other pathology, were excluded.

Results:

After making a detailed selection of the studies according to its title and abstract, 120 articles were selected for reading the full text. Consequently, 21 studies and 1 report were included in this review including systematic review and meta-analysis.

Conclusion:

Supplementation with vitamin D may help decrease glucose, glycosylated haemoglobin and improve insulin secretion. Subjects with T2DM have higher oxidative stress concentrations and lower antioxidants than healthy subjects; vitamin D supplementation may help improve oxidative and antioxidant markers.

Dietary Composition and Cardiovascular Risk: A Mediator or a Bystander?

The role of nutrition in the pathogenesis of cardiovascular disease has long been debated. The established notion of the deleterious effects of fat is recently under question, with numerous studies demonstrating the benefits of low-carbohydrate, high-fat diets in terms of obesity, diabetes, dyslipidemia, and metabolic derangement. Monounsaturated and polyunsaturated fatty acids, especially n-3 PUFAs (polyunsaturated fatty acids), are the types of fat that favor metabolic markers and are key components of the Mediterranean Diet, which is considered an ideal dietary pattern with great cardioprotective effects. Except for macronutrients, however, micronutrients like polyphenols, carotenoids, and vitamins act on molecular pathways that affect oxidative stress, endothelial function, and lipid and glucose homeostasis. In relation to these metabolic markers, the human gut microbiome is constantly revealed, with its composition being altered by even small dietary changes and different microbial populations being associated with adverse cardiovascular outcomes, thus becoming the target for potential new treatment interventions. This review aims to present the most recent data concerning different dietary patterns at both the macro- and micronutrient level and their association with atherosclerosis, obesity, and other risk factors for cardiovascular disease.

Diets high in vegetables, fruits, cereals, and tubers as a protective factor for metabolic syndrome in bank employees

BACKGROUND

The prevalence of metabolic syndrome (MetS) is increasing, and its development may be related to westernized diets and working conditions.

PURPOSE

The purpose of this study was to evaluate the association of dietary patterns in bank employees with the presence of MetS, considering sociodemographic and behavioral factors as well as laboratory tests.

SUBJECTS AND METHODS

This was a cross-sectional study of 515 bankers. Sociodemographic, occupational, behavioral, and food consumption data were collected. Dietary patterns were determined by principal component analysis with orthogonal varimax rotation.

RESULTS

The dietary pattern of vegetables, fruits, cereals, and tubers was correlated with the presence of MetS and with waist circumference measurements and triglyceride levels. Individuals in the third and fifth quintiles of the pattern "vegetables, fruits, cereals, and tubers" presented with 3.28 and 2.24 times less chances of MetS when compared to individuals in the first quintile of this dietary pattern (OR 0.30, 95% CI 0.13-0.67, and OR 0.44, 95% CI 0.21-0.92, respectively). Subjects over 45 years of age were almost twice as likely to develop MetS (OR 1.95, 95% CI 1.01-3.77).

CONCLUSION

Healthy eating represented by the dietary pattern "vegetables, fruits, cereals, and tubers" was associated with better health among bank employees, especially when evaluating competing metabolic complications such as MetS.

Plasma metabolomics of children with aberrant serum lipids and inadequate micronutrient intake

Blood lipids have served as key biomarkers for cardiovascular disease (CVD) risk, yet emerging evidence indicates metabolite profiling might reveal a larger repertoire of small molecules that reflect altered metabolism, and which may be associated with early disease risk. Inadequate micronutrient status may also drive or exacerbate CVD risk factors that emerge during childhood. This study aimed to understand relationships between serum lipid levels, the plasma metabolome, and micronutrient status in 38 children (10 ± 0.8 years) at risk for CVD. Serum lipid levels were measured via autoanalyzer and average daily micronutrient intakes were calculated from 3-day food logs. Plasma metabolites were extracted using 80% methanol and analyzed via ultra-high-performance liquid chromatography-tandem mass spectrometry. Spearman's rank-order coefficients (rs) were computed for correlations between the following serum lipids [total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides (TG)], 805 plasma metabolites, and 17 essential micronutrients. Serum lipid levels in the children ranged from 128-255 mg/dL for total cholesterol, 67-198 mg/dL for LDL, 31-58 mg/dL for HDL, and 46-197 mg/dL for TG. The majority of children (71 to 100%) had levels lower than the Recommended Daily Allowance for vitamin E, calcium, magnesium, folate, vitamin D, and potassium. For sodium, 76% of children had levels above the Upper Limit of intake. Approximately 30% of the plasma metabolome (235 metabolites) were significantly correlated with serum lipids. As expected, plasma cholesterol was positively correlated with serum total cholesterol (rs = 0.6654; p<0.0001). Additionally, 27 plasma metabolites were strongly correlated with serum TG (rs ≥0.60; p≤0.0001), including alanine and diacylglycerols, which have previously been associated with cardiometabolic and atherosclerotic risk in adults and experimental animals. Plasma metabolite profiling alongside known modifiable risk factors for children merit continued investigation in epidemiological studies to assist with early CVD detection, mitigation, and prevention via lifestyle-based interventions.

Associations Between Dietary Antioxidant Intake and Markers of Atherosclerosis in Middle-Aged Women From North-Western Algeria

Background: The role of several dietary antioxidants in preventing the development and the progression of atherosclerosis has recently aroused considerable interest. Although they are not yet conclusive, most of the existing suggestions support this hypothesis.

Objective: The aim of the present work was to investigate the intake of dietary antioxidant nutrients in relation to atherogenic indices in a group of Algerian middle aged women with and without type 2 diabetes.

Methods: A cross-sectional study was conducted on a group of middle-aged women from the north western region of Algeria. Anthropometric and biochemical parameters were measured. Dietary intake was assessed using a validated 3-days food record. Atherogenic indices -total cholesterol-to-high-density lipoprotein cholesterol ratio (TC/HDL) and apolipoprotein (apo) B-to-apo A1 ratio, were calculated. Associations between antioxidants dietary intake and atherogenic indices were examined using logistic regressions.

Results: 95 women with type 2 diabetes were compared to 93 non-diabetic ones. Statistical differences (p < 0.05) were revealed for body weight, height, body mass index (BMI), glycosylated hemoglobin (HbA1c) and total cholesterol levels. Furthermore, significant differences were noted for vitamin C, E and copper dietary intakes. The TC/HDL ratio was significantly associated to the highest quartiles of vitamin C in all patients; 3.519[2.405–4.408], p = 0.009 and in non-diabetic women; 3.984[1.775–7.412], p = 0.020, respectively. The odd ratios of vitamin E intakes were about 2.425[2.017–5.715], p = 0.012 in all patients and 1.843[1.877–2.731], p = 0.019 in non-diabetic group, respectively. However, the Apo B/Apo A1 ratio was more correlated to the highest quartiles of zinc and copper in non-diabetic group; OR = 0.059[0.006–0.572], p = 0.015 and 0.192[0.048–0.766], p = 0.019, respectively.

Conclusion: The estimated risk of atherosclerosis measured through the TC/HDL ratio was correlated to vitamins antioxidant intake, while the probable risk assessed by the Apo B/Apo A1 ratio was more associated to the mineral profile.

Antioxidant effects of vitamins in type 2 diabetes: a meta-analysis of randomized controlled trials

BACKGROUND

Vitamins are essential micronutrients with antioxidant potential that may provide a complementary treatment for patients with chronic diseases. Our aim was to assess the effect of vitamin supplementation on the antioxidant status and glycemic index of type 2 diabetes mellitus patients.

METHODS

We performed a systematic review with meta-analyses. Electronic searches were conducted in PubMed, Scopus, and Web of Science (December 2017). Randomized controlled trials evaluating the effect of any vitamin or vitamin complex supplementation on antioxidant status as primary outcome were included. The outcomes considered were: reduction of malondialdehyde (MDA); augmentation of glutathione peroxidase (GPx); changes in total antioxidant capacity (TAC), enhance in superoxide dismutase enzyme-SOD, and thiobarbituric acid reactive substances (TBARS). Outcomes of glycemic control were also evaluated. Pairwise meta-analyses were performed using software Review Manager 5.3.

RESULTS

Thirty trials fulfilled the inclusion criteria, but only 12 could be included in the meta-analyses of antioxidant outcomes. The most commonly studied vitamins were B, C, D and E. Vitamin E was related to significant reduction of blood glucose as well as glycated hemoglobin compared to placebo, while both vitamins C and E were mainly associated with reducing MDA and TBARS and elevating GPx, SOD and TAC, compared to placebo. However, outcome reports in this field are still inconsistent (e.g. because of a lack of standard measures).

CONCLUSIONS

Supplementation of vitamin E may be a valuable strategy for controlling diabetes complications and enhancing antioxidant capacity. The effects of other micronutrients should be further investigated in larger and well-designed trials to properly place these complementary therapies in clinical practice.

Amelioration of altered serum, liver, and kidney antioxidant enzymes activities by sodium selenite in alloxan-induced diabetic rats

BACKGROUND

The aim of this study was to evaluate the possible protective effect of sodium selenite on serum, liver, and kidney antioxidant enzymes activities in alloxan-induced type 1 diabetic rats.

METHODS

Forty Sprague-Dawley male rats were randomly divided into four groups; Group one as control, Group two as sham-treated with sodium selenite by 1 mg/kg intraperitoneal (i.p.) injections daily, Group three as diabetic untreated, and Group four as diabetic treated with sodium selenite by 1 mg/kg i.p. injections daily .Diabetes was induced in the third and fourth groups by subcutaneous alloxan injections. After eight weeks the animals were euthanized and livers and kidneys were immediately removed and used fresh or kept frozen until analysis. Before the rats were killed blood samples were also collected to measure glutathione peroxidase (GPX) and catalase (CAT) activities in sera.

RESULTS

Glutathione peroxidase and CAT activities serum, liver, and kidney were all significantly less in the diabetic rats than in the controls. Sodium selenite treatment of the diabetic rats resulted in significant increases in GPX activity in the kidneys and livers, and CAT activity in the sera and livers.

CONCLUSIONS

Our results indicate that sodium selenite might be a potent antioxidant that exerts beneficial effects on both GPX and CAT activities in alloxan-induced type 1 diabetic rats.

Modulation of glucose metabolism by balanced deep-sea water ameliorates hyperglycemia and pancreatic function in streptozotocin-induced diabetic mice

The aim of this study was to determine the effects of balanced deep-sea water (BDSW) on hyperglycemia and glucose intolerance in streptozotocin (STZ)-induced diabetic mice. BDSW was prepared by mixing DSW mineral extracts and desalinated water to yield a final hardness of 1000–4000 ppm. Male ICR mice were assigned to 6 groups; mice in each group were given tap water (normal and STZ diabetic groups) or STZ with BDSW of varying hardness (0, 1000, 2000, and 4000 ppm) for 4 weeks. The STZ with BDSW group exhibited lowered fasting plasma glucose levels than the STZ-induced diabetic group. Oral glucose tolerance tests showed that BDSW improves impaired glucose tolerance in STZ-induced diabetic mice. Histopathological evaluation of the pancreas showed that BDSW restores the morphology of the pancreatic islets of Langerhans and increases the secretion of insulin in STZ-induced diabetic mice. Quantitative real-time PCR assay revealed that the expression of hepatic genes involved in gluconeogenesis, glucose oxidation, and glycogenolysis was suppressed, while the expression of the genes involved in glucose uptake, β-oxidation, and glucose oxidation in muscle were increased in the STZ with BDSW group. BDSW stimulated PI3-K, AMPK, and mTOR pathway-mediated glucose uptake in C₂C₁₂ myotubes. BDSW increased AMPK phosphorylation in C₂C₁₂ myotubes and improved impaired AMPK phosphorylation in the muscles of STZ-induced diabetic mice. Taken together, these results suggest that BDSW is a potential anti-diabetic agent, owing to its ability to suppress hyperglycemia and improve glucose intolerance by modulating glucose metabolism, recovering pancreatic islets of Langerhans and increasing glucose uptake.