Characterization of the metabolic and physiologic response to chromium supplementation in subjects with type 2 diabetes mellitus

Investigation of extracellular medium osmolality depending on zinc application and incubation time on A549 cancer cells

Changes in the osmolality of the extracellular medium (ECM) affect cell volume and cellular processes such as cell migration and proliferation. Not only may high concentrations of zinc (Zn) lead to cell death by apoptosis, but Zn is also a physiological suppressor of apoptosis. The aim of our study was to examine whether Zn and regulation of extracellular osmolality had an effect on the lung cancer cell line (A549) and how to be changed in ECM according to elements and osmolality depending on incubation time and Zn application. Our study consisted of four groups: cell-free medium, ECM of cancer cell after 24 h incubation (24hECM), ECM of cancer cell after 48 h incubation (48hECM), and ECM of cancer cell after 48 h incubation with ZnCl₂ (48hECM + Zn). ECM osmolality was measured by using osmometer, and the levels of chromium (Cr), iron (Fe), and magnesium (Mg) elements were analyzed using ICP-OES device for all groups. According to the result of the analysis, a statistically significant difference was found when osmolality and element values of ECM of 24hECM and 48hECM groups were compared with the values of the 48hECM + Zn group. It was observed that there was a decrease in the levels of Cr, Fe, and Mg with Zn application and incubation period in ECM. The regulation of ECM osmolality is a promising method due to biophysical effects on cancer cells. In our study, we speculated that the understanding of the effects of Zn and osmolality with the relationship between ECM and cancer cell might lead to the discovery of biophysical approaches as a novel therapeutic strategy.

Cr (VI) induces abnormalities in glucose and lipid metabolism through ROS/Nrf2 signaling

The hexavalent form of chromium, Cr (VI), has been associated with various diseases in humans. In this study, we examined the mechanisms underlying the effect of Cr (VI) on glucose and lipid metabolism in vivo and in vitro. We found that Cr (VI) induced abnormal liver function, increased fasting blood glucose (FBG), as well as glucose and insulin intolerance in mice. Furthermore, Cr (VI) decreased glucose-6-phosphate (G6P) level and glucose transporter-2 (GLUT2) expression, increased the levels of triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), reduced high-density lipoprotein-cholesterol (HDL-C), and increased sterol regulatory element-binding proteins 1 (SREBP1) and fat synthase (FAS) in vitro and in vivo. Moreover, Cr (VI) promoted intracellular ROS production in vitro, and induced reduction of antioxidant enzyme level and Nrf2/HO-1 expression in vitro and in vivo. Also, N-acetyl cysteine (NAC, effective antioxidant and free radical scavenger) pretreatment inhibited the production of intracellular ROS, significantly suppressed Cr (VI)-induced oxidative stress, lipid accumulation, decreased G6P and GLUT2, and improved impaired glucose tolerance and glucose and insulin intolerance caused by Cr (VI) in mice. Dh404 activated expression of Nrf2 decreased ROS level, increased HO-1 expression, ameliorated activity of the antioxidant enzyme, inhibited Cr (VI) increase of SREBP1, FAS level, and reduction of G6P and GLUT2. To sum up, these data suggest that dysregulation of ROS/Nrf2/HO-1 has an important role in Cr (VI)-induced glucose/lipid metabolic disorder.

Effect of a New Formulation of Nutraceuticals as an Add-On to Metformin Monotherapy for Patients with Type 2 Diabetes and Suboptimal Glycemic Control: A Randomized Controlled Trial

The aim of the study was to evaluate the overall biohumoral and metabolic effects of a 12-week add-on therapy consisting of a new nutraceutical formulation (BHC) based on berberine, hesperidin, and chromium picolinate in type 2 diabetes mellitus (T2D) patients with suboptimal glycemic compensation receiving metformin. After 12 weeks, participants in the group receiving metformin plus BHC, compared to the group receiving metformin only, saw a significant improvement in their glucose profile, in terms of both glycated hemoglobin (HbA1c) and fasting blood glucose (FBG). Their FBG dropped from 145 ± 20 mg/dL to 128 ± 23 mg/dL (p < 0.01), a decrease of 11.7% compared with the baseline. This decrease differed significantly from the situation in the control arm (p < 0.05). HbA1c decreased by 7.5% from the baseline, from 53.5 ± 4.3 mmol/mol to 49.5 ± 5.1 mmol/mol (p < 0.01), in the group given BHC, while no difference was seen in the control group. Advanced glycation end products (AGEs) and malondialdehyde (MDA) were found to be significantly reduced (p < 0.01) only in the BHC group, from 9.34 ± 7.61 μg/mL to 6.75 ± 6.13 μg/mL, and from 1.7 ± 0.15 μmol/L to 1.4 ± 0.25 μmol/L, respectively. In patients with T2D taking metformin with suboptimal glycemic compensation, adding BHC for 3 months significantly improved glucose control in terms of FBG and HbA1c, and had a positive effect on the lipid peroxidation profile, as indicated by a decrease in AGEs and MDA.

Effects of chromium supplementation on blood pressure, body mass index, liver function enzymes and malondialdehyde in patients with type 2 diabetes: A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND

Several studies reported beneficial effects of chromium supplementation for management of type 2 diabetes mellitus (T2DM). The present study aimed to provide a systematic review and meta-analysis of randomized controlled trials (RCTs) examining the effects of chromium supplementation on blood pressure, body mass index (BMI), liver function enzymes and malondialdehyde (MDA) in patients with T2DM.

METHODS

PubMed, Scopus, and Embase were searched up to 15 November 2020 with no language and time restriction. RCTs that reported the effects of chromium supplementation on blood pressure, BMI, liver function enzymes and MDA in patients with T2DM were included. A random-effects model was used to compute weighted mean differences (WMDs) with 95 % confidence intervals (CIs). Between-study heterogeneity was assessed by Cochran's Q test and quantified by I² statistic.

RESULTS

Of 3586 publications, 15 RCTs were included for the meta-analysis. Pooled effect sizes indicated that chromium significantly reduced diastolic blood pressure (DBP) (WMD): -2.36 mmHg, 95 % CI: -4.14, -0.60; P = 0.008), and MDA (WMD: -0.55 umol/l, 95 % CI: -0.96, -0.14; P = 0.008). However, chromium supplementation did not significantly affect BMI, systolic blood pressure (SBP), alanine aminotransferase (ALT), aspartate aminotransferase (AST). Meta-regression analysis did not show significant linear relationship between dose of chromium and change in BMI (p = 0.412), SBP (p = 0. 319), DBP (p = 0.102), ALT (p = 0.923), AST (p = 0.986) and MDA (p = 0.055).

CONCLUSION

The present systematic review and meta-analysis shows that supplementation with chromium at dose of 200-1000 μg/day may reduce DBP and MDA in T2DM patients.

The effect of the high-fat diet supplemented with various forms of chromium on rats body composition, liver metabolism and organ histology Cr in liver metabolism and histology of selected organs

BACKGROUND

In the present study, we hypothesized that feeding rats a high-fat diet negatively affects liver metabolism and function and disturbs the histology of some internal organs. We also postulated that there is a form of chromium whose administration alleviates the negative effects of a high-fat diet in rats.

METHODS

To verify the hypotheses, we tested the effect of various forms of chrome (picolinate - Cr-Pic, Chromium(III)-methionine complex - Cr-Met, and chrome nanoparticles - Cr-NPs) applied in the recommended amount of 0.3 mg/kg of BW on growth parameters, body fat, liver metabolism and functional disorders, and histological parameters of selected internal organs in rats fed a standard (S) or high-fat diet (F). The experiment was conducted on 56 male outbred Wistar rats (Rattus norvegicus. Cmdb:WI) randomly divided into eight experimental groups. For eight weeks the rats received a standard or high-fat diet, without Cr or with Cr at 0.3 mg/kg diet in the form of Cr-Pic, Cr-Met or Cr-NPs.

RESULTS AND CONCLUSION

The use of a F diet disrupted the lipid-carbohydrate profile, worsened liver metabolism and function, reduced the expression of hepatic PPAR-α and leaded to negative changes in the histological image of internal organs - liver, kidneys and pancreas. The 8-week use of an chromium supplement in a F diet, regardless of the form used, did not improve the ratio of fat tissue to lean tissue, worsened liver function and negatively affected on the histological image of the liver, kidneys and pancreas. However, the most negative changes in lipid-carbohydrate metabolism and liver functioning were observed with CrNPs supplementation.

Insulin-like and mimetic molecules from non-mammalian organisms: potential relevance for drug discovery

Insulin was first discovered in extracts of vertebrate pancreas during a focused search for a therapy for diabetes. Subsequent efforts to discover and isolate a similar active principle from yeast and plants driven by the hope to identify insulin-like/mimetic molecules with critical advantages in the pharmacokinetic profile and expenditure of production compared to authentic human insulin were not successful. As a consequence, it has generally been assumed that hormones evolved exclusively during course of the evolution of vertebrate endocrine organs, implying a rather recent origin. Concomitantly, the existence and physiological role of vertebrate hormones in lower multi- and unicellular eukaryotes have remained a rather controversial subject over decades, albeit there is some evidence that hormones and hormone-binding proteins resembling those of vertebrates are expressed in fungi and yeast. Past and recent findings on the existence of insulin-like and mimetic materials, such as the glucose tolerance factor, in lower eukaryotes, in particular Neurospora crassa and yeast, will be presented. These data provide further evidence for the provocative view that the evolutionary roots of the vertebrate endocrine system may be far more ancient than is generally believed and that the identification and characterisation of insulin-like/mimetic molecules from lower eukaryotes may be useful for future drug discovery efforts.

Effects of chromium supplementation on glycemic control in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

We aimed to investigate the effect of chromium supplementation on glycemic control indices in patients with type 2 diabetes (T2DM).

METHODS

Randomized controlled trials examining the effect of chromium supplementation on glycemic control indices and published before February 2020 were detected by searching online databases, including PubMed, Scopus, Embase, Web of sciences and The Cochrane Library, using a combination of suitable keywords. Mean change and standard deviation (SD) of the outcome measures were used to estimate the mean difference between the supplementation group and the control group at follow-up.

RESULTS

Twenty-eight studies reported fasting plasma glucose (FPG), insulin, hemoglobin A1C (HbA1C) and homeostatic model assessment for insulin resistance (HOMA-IR) as an outcome measure. Results revealed significant reduction in FPG (weighted mean difference (WMD): -19.00 mg/dl, 95% CI: -36.15, -1.85, P = 0.030; I²: 99.8%, p < 0.001), insulin level (WMD: -12.35 pmol/l, 95% CI: -17.86, -6.83, P < 0.001), HbA1C (WMD: -0.71 %, 95% CI: -1.19, -0.23, P = 0.004) and HOMA-IR (WMD: -1.53, 95% CI: -2.35, -0.72, P < 0.001; I²: 89.9%, p < 0.001) after chromium supplementation.

CONCLUSION

The results of the current meta-analysis study might support the use of chromium supplementation for the improvement of glycemic control indices in T2DM patients.

Role of Minerals and Trace Elements in Diabetes and Insulin Resistance

Minerals and trace elements are micronutrients that are essential to the human body but present only in traceable amounts. Nonetheless, they exhibit well-defined biochemical functions. Deficiencies in these micronutrients are related to widespread human health problems. This review article is focused on some of these minerals and trace element deficiencies and their consequences in diabetes and insulin resistance. The levels of trace elements vary considerably among different populations, contingent on the composition of the diet. In several Asian countries, large proportions of the population are affected by a number of micronutrient deficiencies. Local differences in selenium, zinc, copper, iron, chromium and iodine in the diet occur in both developed and developing countries, largely due to malnutrition and dependence on indigenous nutrition. These overall deficiencies and, in a few cases, excess of essential trace elements may lead to imbalances in glucose homeostasis and insulin resistance. The most extensive problems affecting one billion people or more worldwide are associated with inadequate supply of a number of minerals and trace elements including iodine, selenium, zinc, calcium, chromium, cobalt, iron, boron and magnesium. This review comprises various randomized controlled trials, cohort and case-controlled studies, and observational and laboratory-based studies with substantial outcomes of micronutrient deficiencies on diabetes and insulin resistance in diverse racial inhabitants from parts of Asia, Africa, and North America. Changes in these micronutrient levels in the serum and urine of subjects may indicate the trajectory toward metabolic changes, oxidative stress and provide disease-relevant information.

Magnesium, Calcium, Potassium, Sodium, Phosphorus, Selenium, Zinc, and Chromium Levels in Alcohol Use Disorder: A Review

Macronutrients and trace elements are important components of living tissues that have different metabolic properties and functions. Trace elements participate in the regulation of immunity through humoral and cellular mechanisms, nerve conduction, muscle spasms, membrane potential regulation as well as mitochondrial activity and enzymatic reactions. Excessive alcohol consumption disrupts the concentrations of crucial trace elements, also increasing the risk of enhanced oxidative stress and alcohol-related liver diseases. In this review, we present the status of selected macroelements and trace elements in the serum and plasma of people chronically consuming alcohol. Such knowledge helps to understand the mechanisms of chronic alcohol-use disorder and to progress and prevent withdrawal effects, also improving treatment strategies.

Effects of Chromium Picolinate Supplementation on Cardiometabolic Biomarkers in Patients with Type 2 Diabetes Mellitus: a Randomized Clinical Trial

Type 2 diabetes mellitus (T2DM) is a serious public health problem accompanies with several complications. This study was conducted to evaluate the effects of chromium picolinate (CrPic) supplementation on the glycemic status and lipid profile in patients with T2DM. The patients with T2DM (n = 52) were randomly allocated into 2 groups. One group received 400 µg CrPic per day and the other group took placebo; the intervention duration was 8 weeks. Anthropometric indices and metabolic factors were measured at the beginning, and at end of the study. The patients were recommended not to change their normal diet, life style and medication. No significant changes were observed for weight, body mass index, and fasting blood glucose (FBG) in both groups; while intra-groups changes in homeostatic model assessment for insulin resistance (HOMA-IR) value was significant (p < 0.05). Results of analysis of covariance showed that there were significance differences between groups in total cholesterol, low density lipoprotein cholesterol and HOMA-IR at the end of the intervention adjusting for baseline levels (p = 0.035, 0.030 and < 0.001, respectively). In this study, oral supplementation with 400 µg CrPic for eight weeks did not alter FBG concentration as well as anthropometric parameters in individuals with T2DM. However, the modest beneficial effects of chromium supplementation on insulin resistance as indicated by HOMA-IR and lipid profile were found.

The Effect of Chromium Nanoparticles and Chromium Picolinate in the Diet of Chickens on Levels of Selected Hormones and Tissue Antioxidant Status

Simple Summary

We have postulated that supplementation with Cr can increase serotonin levels and improve the antioxidant status of chickens, with no adverse effect on the secretion of other hormones. Obtaining such results may be beneficial in high-density rearing of poultry exposed to many stressors. The studies compared the effects of two forms of Cr (Cr-Pic and Cr-NP) found at two doses 3 and 6 mg/kg. It was found that at the dose of 3 mg/kg, the expected beneficial results can be obtained (increase in serotonin and decrease in norepinephrine level), however, due to the deterioration of the antioxidative system, these studies should be continued to verify these results. Due to the adverse effect of Cr at 3 mg/kg on the antioxidant status of chickens, this level of Cr should not be considered in both forms Cr-Pic and Cr-NP as a feed additive for broiler chickens. In the future, studies on the potential beneficial effects of Cr on the organism should take into account doses lower than 3 mg/kg.

Abstract

We have postulated that supplementation with Cr can increase serotonin levels and improve the antioxidant status of chickens, with no adverse effect on the secretion of other hormones. The study aimed to determine what form and dose of Cr more favorably affect the level of selected hormones (insulin, glucagon, serotonin, dopamine, noradrenaline, histamine, T3 and T4) and the antioxidant status (level of malondialdehyde and lipid peroxides, activity of superoxide dismutase and catalase) of chicken tissues. The experiment was carried out on chickens randomly divided into five treatment groups. The basal diets (control group) were supplemented with two levels of Cr (3 and 6 mg/kg) and two Cr sources: Cr-picolinate (Cr-Pic) and Cr-nano (Cr-NP) to obtain four experimental diets: 3 mg/kg Cr-Pic, 6.0 mg/kg Cr-Pic, 3.0 mg/kg Cr-NP. and 6.0 mg/kg Cr-NP. The addition of Cr in both forms increased the level of serotonin at a dose of 3 mg/kg and, at the same time, reduced the level of noradrenaline. The addition of Cr at 3 mg/kg, irrespective of the form used, regulated the level of hormones of carbohydrate metabolism (increasing insulin levels and reducing glucagon levels) and had an adverse effect on the antioxidant status of the liver and breast muscle. Due to the adverse effect of Cr at 3 mg/kg on the antioxidant status of chickens, this level of Cr should not be considered in both forms Cr-Pic and Cr-NP as a feed additive for broiler chickens. In the future, studies on the potential beneficial effects of Cr on the organism should take into account doses lower than 3 mg/kg.

Potential roles of chromium on inflammatory biomarkers in diabetes: A Systematic

Diabetes, as a low-grade chronic inflammatory disease, causes disruption in proper function of immune and metabolic system. Chromium is an important element required for normal lipid and glucose metabolism. Chromium deficiency is correlated with elevation in cardiometabolic risk, which results from increased inflammation. This systematic review was conducted to discover the potential roles of chromium on inflammatory biomarkers. Eligible studies were all in vitro, animal and human studies published in English-language journals from inception until October 2018. PubMed, Scopus, Embase, ProQuest and Google Scholar databases were searched to fined interventional studies from the effects of chromium on inflammatory biomarkers such as tumour necrosis factor a (TNF-a), C-reactive protein (CRP), interleukins, monocyte chemoattractant protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1) and adipocytokines in hyperglycaemia and diabetes. Out of 647 articles found in the search, only 14 articles were eligible for analysis, three in vitro studies, eight animal studies and three human studies. Twelve of the 14 studies included in this review, chromium significantly decreased inflammatory factors. The findings of this review indicate, based on in vitro and in vivo studies, that chromium might have potential anti-inflammatory properties, but some of the studies did not show anti-inflammatory effects for chromium (two studies). There are only three studies in humans with controversial results. Therefore, more consistent randomized double-blind controlled trials are needed to reach relevant clinical recommendations, as well as to determine the precise mechanism, of chromium on inflammation in diabetes.

A meta-analysis of the effect of chromium supplementation on anthropometric indices of subjects with overweight or obesity

The role of chromium as a weight loss agent remains questionable, and although previous meta-analyses findings have reported small reductions in body weight in individuals with overweight/obesity following chromium supplementation, there have been significant limitations with these findings. The objective of this meta-analysis was to evaluate the current evidence for the efficacy of oral chromium supplementation in individuals with overweight/obesity from randomized controlled trials. Studies were identified by a search of electronic databases from inception to November 2018 and combined and stratified analyses were used. Twenty-one trials from 19 studies were identified which met all inclusion criteria which were suitable for statistical pooling, and data from 1316 participants were included. Pooled analysis showed significant reductions in anthropometric indices associated with body composition; for weight loss (weighted mean difference [WMD]: -0.75 kg, 95% confidence interval [CI], -1.04, -0.45, P < 0.001), body mass index (WMD: -0.40, 95% CI, -0.66, -0.13, P = 0.003 and body fat percentage (WMD: -0.68%, 95% CI, -1.32, -0.03, P = 0.04) in individuals with overweight/obesity. No changes were detected in controls. Subgroup analysis showed significant improvements in weight loss and body fat percentage, particularly for study durations ≤12 weeks and doses ≤400 μg/d. Chromium supplementation was associated with some improvements in body composition in subjects with obesity/overweight. The effect size was medium and the clinical relevance of chromium as a weight loss aid remains uncertain. Further investigation from larger and well-designed randomized controlled studies, especially in patients with diabetes, is warranted.

The safety and effectiveness of commonly-marketed natural supplements for weight loss in populations with obesity: A critical review of the literature from 2006 to 2016

Objective: To evaluate the evidence published from 2006 to 2016 on the effectiveness and safety of commonly used natural supplements for weight loss in individuals with obesity.Methods: Amazon and Google were searched for names of mono-agent natural supplements marketed for weight loss and a list of the 10 supplements was created. Google Scholar, Pubmed, Science Direct, and the Cochrane Library were searched for articles that met inclusion.Results: At least one article was published on the effectiveness or safety of bitter orange, capsinoid, carnitine, chromium picolinate, Coleus forskohlii, conjugated linoleic acid, glucomannan, green tea and psyllium for weight loss in populations with obesity from 2006 to 2016. There was insufficient evidence to suggest that the natural supplements examined contribute to significant weight loss, with the exception of perhaps glucomannan in the form of PGX. In general, the majority of side-effects reported were minor to moderate, and gastrointestinal-related. However, in some cases extreme side-effects such as liver and kidney failure were observed.Conclusion: Contrary to popular belief, results of this review suggest that the use of natural supplements for weight loss are unlikely to contribute to meaningful weight loss and in some cases may contribute to harm.

Concentration of chromium in whole blood and erythrocytes showed different relationships with serum apolipoprotein levels in Cr(VI) exposed subjects

OBJECTIVE

To explore the effects of hexavalent chromium [Cr(VI)] on apolipoprotein(Apo) metabolism.

METHODS

One hundred and six long-term Cr(VI) exposed subjects and fifty five non-exposed individuals were recruited. The blood metals, glucose and lipid parameters were measured to evaluate the effects of hexavalent chromium on the apolipoproteins.

RESULTS

The quantity and homeostasis of multi-elements were significantly different between Cr(VI)exposed subjects and the controls(P < 0.05). The levels of serum TG, FPG, LDL-C, Apo AI, AII, CII, CIII, E and Lp(a) also changed significantly (P < 0.05). Concentration of chromium in whole blood and erythrocytes had different relationships with serum apolipoprotein levels in Cr(VI)exposed subjects.

CONCLUSIONS

Exposure of hexavalent chromium could significantly change the homeostasis of multi-elements as well as the levels of serum apolipoproteins. Cr(III) and Cr(VI)may have different effects on the apolipoproteins.

Aerobic training reduces oxidative stress in skeletal muscle of rats exposed to air pollution and supplemented with chromium picolinate

Objective: The purpose of this study was to investigate the effects of chromium picolinate (CrPic) supplementation associated with aerobic exercise using measures of oxidative stress in rats exposed to air pollution.

Methods: Sixty-one male Wistar rats were divided into eight groups: residual oil fly ash (ROFA) exposure and sedentary (ROFA-SED); ROFA exposure, sedentary and supplemented (ROFA-SED-CrPic); ROFA exposure and trained (ROFA-AT); ROFA exposure, supplemented and trained (ROFA-AT-CrPic); sedentary (Sal-SED); sedentary and supplemented (Sal-SED-CrPic); trained (Sal-AT); and supplemented and trained (Sal-AT-CrPic). Rats exposed to ROFA (air pollution) received 50 µg of ROFA daily via intranasal instillation. Supplemented rats received CrPic (1 mg/kg/day) daily by oral gavage. Exercise training was performed on a rat treadmill (5×/week). Oxidative parameters were evaluated at the end of protocols.

Results: Trained groups demonstrated lower gain of body mass (P < .001) and increased exercise tolerance (P < .0001). In the gastrocnemius, trained groups demonstrated increased SOD activity (P < .0001) and decrease levels of TBARS (P = .0014), although CAT activity did not differ among groups (P = .4487).

Conclusion: Air pollution exposure did not lead to alterations in oxidative markers in lungs and heart, and exercise training was responsible for decreasing oxidative stress of the gastrocnemius.

Effects of zinc, magnesium, and chromium supplementation on cardiometabolic risk in adults with metabolic syndrome: A double-blind, placebo-controlled randomised trial

The prevalence of metabolic syndrome (MetS) has been increasing rapidly worldwide. The activities of zinc, magnesium and chromium have a potential association with MetS; therefore, we investigated the effects of zinc, magnesium and chromium supplements on metabolic risk factors in adults with MetS. In this double-blind, placebo controlled randomised study, 32 adults with MetS were included in the zinc, magnesium, and chromium-administered group (n = 16) or the placebo group (n = 16) and received either 300 mg magnesium, 600 μg chromium and 36 mg zinc per day or placebo over a 24-week period. The primary endpoint was the change in the MetS components, including serum glucose, triglyceride and high-density lipoprotein cholesterol levels, blood pressure and waist circumference. Data were analysed using repeated-measures analysis of variance. The metabolic risk factors did not change post-intervention, but the serum C-reactive protein level decreased in the mineral-supplemented group compared with that in the placebo group. Further studies with stricter inclusion criteria are needed to better evaluate the potential for zinc, magnesium and chromium to improve metabolic risk in adults with MetS.

Isoproterenol exacerbates hyperglycemia and modulates chromium distribution in mice fed with a high fat diet

BACKGROUND AND PURPOSE

Isoproterenol (ISO), a nonselective β-adrenoceptor agonist for treating bradycardia and asthma, has been proposed to raise blood glucose level. Little is known regarding the relationship between ISO treatment, the induced chromium (Cr) redistribution, and changes in glucose metabolism. We aimed to characterize the effects of a single dose of ISO on glucose homeostasis and Cr level changes in an obesity mouse model.

METHODS

Mice (C57BL6/j strain) were first fed for a continuous period of 12 weeks with either a high fat diet (HFD), to develop an obesity animal model, or a standard diet (SD), to develop a lean animal model as controls. These groups were each separated into two subgroups to receive either a single dose of ISO or saline (control). We measured in vivo their metabolic parameters, fasting glucose level, area under the curve (AUC) for glucose level time profile, insulin level time profile, insulin sensitivity index, and chromium distribution.

RESULTS

After a single dose of ISO, the SD-fed mice had slightly higher blood glucose levels compared with the SD controls, when the level was measured 30 and 60min after injection. By contrast, the ISO-treated HFD-fed mice had significantly higher blood glucose levels and AUC during the entire 120min following one administration compared with the HFD control group. Additionally, they had a substantially lower HOMA-IR index, whereas insulin levels remained unchanged. The Cr level in their bones and liver was decreased, and loss of Cr through urinary excretion was elevated.

CONCLUSION

The results demonstrated that ISO exacerbated hyperglycemic syndrome in the obesity animal model. ISO induced a net negative Cr balance as a result of increased urinary excretion, leading to Cr mobilization that was not desirable to overcome the hyperglycemia.

Chromium supplementation for adjuvant treatment of type 2 diabetes mellitus: Results from a pooled analysis

SCOPE

We conducted a pooled analysis of randomized controlled trials to evaluate the effects of chromium supplementation on clinically relevant metabolic biomarkers in type 2 diabetes mellitus (T2DM) patients.

METHODS AND RESULTS

Electronic searches were conducted and the bibliographies of located articles were searched, and 28 studies were suitable for statistical pooling. Endpoints were calculated as weighted mean differences (WMDs) with 95% confidence intervals (CIs) by using fixed-effects or random-effects models. Statistical heterogeneity, publication bias, subgroup analyses, sensitivity analysis and meta-regression assessments were also assessed. Chromium reduced levels of fasting plasma glucose (WMD, -0.99 mmol/L; 95% CI, -1.72 to -0.25; p = 0.008), hemoglobin A1c (WMD, -0.54 %; 95% CI, -0.82 to -0.25; p = 0.0002), triglycerides (WMD, -11.71 mg/dL; 95% CI, -18.38 to -5.04; p = 0.0006). Chromium also increased levels of high-density lipoprotein cholesterol (WMD, 1.73 mg/dL; 95% CI, 0.50 to 2.96; p = 0.006). These results were robust in sensitivity analysis and were not dependent on the chromium dose and duration of supplementation. Subgroup analyses indicated that these notably favorable effects were presented in T2DM subjects ingesting chromium chloride and chromium picolinate formulations.

CONCLUSION

Our pooled analysis suggested that chromium supplementation might be a candidate as an adjunct to pharmacological management in patients with T2DM.

Selenium, Vanadium, and Chromium as Micronutrients to Improve Metabolic Syndrome

Trace metals play an important role in the proper functioning of carbohydrate and lipid metabolism. Some of the trace metals are thus essential for maintaining homeostasis, while deficiency of these trace metals can cause disorders with metabolic and physiological imbalances. This article concentrates on three trace metals (selenium, vanadium, and chromium) that may play crucial roles in controlling blood glucose concentrations possibly through their insulin-mimetic effects. For these trace metals, the level of evidence available for their health effects as supplements is weak. Thus, their potential is not fully exploited for the target of metabolic syndrome, a constellation that increases the risk for cardiovascular disease and type 2 diabetes. Given that the prevalence of metabolic syndrome is increasing throughout the world, a simpler option of interventions with food supplemented with well-studied trace metals could serve as an answer to this problem. The oxidation state and coordination chemistry play crucial roles in defining the responses to these trace metals, so further research is warranted to understand fully their metabolic and cardiovascular effects in human metabolic syndrome.

Pioglitazone-induced improvements in insulin sensitivity occur without concomitant changes in muscle mitochondrial function

AIMS

Pioglitazone (Pio) is known to improve insulin sensitivity in skeletal muscle. However, the role of Pio in skeletal muscle lipid metabolism and skeletal muscle oxidative capacity is not clear. The aim of this study was to determine the effects of chronic Pio treatment on skeletal muscle mitochondrial activity in individuals with type 2 diabetes (T2D).

MATERIALS AND METHODS

Twenty-four participants with T2D (13M/11F 53.38±2.1years; BMI 36.47±1.1kg/m²) were randomized to either a placebo (CON, n=8) or a pioglitazone (PIO, n=16) group. Following 12weeks of treatment, we measured insulin sensitivity by hyperinsulinemic-euglycemic clamp (clamp), metabolic flexibility by calculating the change in respiratory quotient (ΔRQ) during the steady state of the clamp, intra- and extra-myocellular lipid content (IMCL and EMCL, respectively) by ¹H magnetic resonance spectroscopy (¹H-MRS) and muscle maximal ATP synthetic capacity (ATPmax) by ³¹P-MRS.

RESULTS

Following 12weeks of PIO treatment, insulin sensitivity (p<0.0005 vs. baseline) and metabolic flexibility (p<0.05 vs. CON) significantly increased. PIO treatment significantly decreased IMCL content and increased EMCL content in gastrocnemius, soleus and tibialis anterior muscles. ATPmax was unaffected by PIO treatment.

CONCLUSIONS

These results suggest that 12weeks of pioglitazone treatment improves insulin sensitivity, metabolic flexibility and myocellular lipid distribution without any effect on maximal ATP synthetic capacity in skeletal muscle. Consequently, pioglitazone-induced enhancements in insulin responsiveness and fuel utilization are independent of mitochondrial function.

Profile of Trace Elements in Selected Medicinal Plants Used for the Treatment of Diabetes in Eritrea

This study was designed to investigate the profile of certain trace elements having therapeutic properties related to diabetes mellitus. The investigated plants were Aloe camperi, Meriandra dianthera, Lepidium sativum, Brassica nigra, and Nigella sativa. These plants are traditionally used in the management of diabetes in Eritrea. The elemental analysis was conducted using inductively coupled plasma optical emission spectrometry (ICP-OES) and flame atomic absorption spectroscopy (FAAS) techniques. The accuracy of the methods was verified using in-house reference materials (CRMs) and no significant differences were observed between the measured and certified values. The analysis displayed variable concentrations of the different trace elements including Zn, Cr, V, Mn, and Se in the plants. Moreover, the levels of major elements, such as Mg, Ca, K, Na, and Ba, and heavy metals, such as Fe, Cu, Ni, Co, As, and Pb, were determined and found to be in the permissible limit defined by WHO. Among the plants, Meriandra dianthera showed the highest levels of Mn, Cr, V, and other elements and the values were significantly different (P < 0.05).

Controlling type-2 diabetes by inclusion of Cr-enriched yeast bread in the daily dietary pattern: a randomized clinical trial

PURPOSE

Chromium (Cr)-enriched yeast supplementation to whole wheat bread (WWCrB) has been shown to ameliorate postprandial glycemic response in healthy subjects. The present study investigates the long-term benefit of WWCrB consumption for patients with type-2 diabetes mellitus (T2DM).

METHODS

Thirty patients with T2DM were randomly assigned to a group receiving WWCrB or the plain whole wheat bread (WWB) group. Plasma glucose, insulin, glycosylated hemoglobin (HbA_1c) and insulin resistance were determined, and oral glucose tolerance test (OGTT) was performed at the beginning and the end of the dietary intervention, which lasted for 12 weeks. Biochemical parameters related to the disease, markers of inflammation as well as body weight and energy balance were examined.

RESULTS

At the end of the study, subjects of WWCrB group exerted lower levels of glucose, insulin and HbA_1c and improved insulin resistance (P < 0.05 against before treatment). Area under the glucose curve attained during OGTT decreased after the intervention (28,117.5 ± 1266.4 vs. 31,588.5 ± 1187.5 mg min/dL before treatment, P < 0.05) with significantly lower values of glucose concentration at 0 and 60 min. A significant reduction in body weight and systolic blood pressure (SBP) was observed (P < 0.05 against before treatment). Markers of inflammation and lipid profiles were not affected by WWCrB consumption.

CONCLUSIONS

Inclusion of WWCrB in the daily dietary pattern of diabetic patients resulted in improvement of glucose tolerance and insulin resistance, significant reduction in HbA_1c, weight loss and lower SBP. Patients with inadequate glycemic control may benefit from the consumption of WWCrB.

Chromium supplements for glycemic control in type 2 diabetes: limited evidence of effectiveness

Some adults with type 2 diabetes mellitus (T2DM) believe that chromium-containing supplements will help control their disease, but the evidence is mixed. This narrative review examines the efficacy of chromium supplements for improving glycemic control as measured by decreases in fasting plasma glucose (FPG) or hemoglobin A1c (HbA1c). Using systematic search criteria, 20 randomized controlled trials of chromium supplementation in T2DM patients were identified. Clinically meaningful treatment goals were defined as an FPG of ≤7.2 mmol/dL, a decline in HbA1c to ≤7%, or a decrease of ≥0.5% in HbA1c. In only a few randomized controlled trials did FPG (5 of 20), HbA1c (3 of 14), or both (1 of 14) reach the treatment goals with chromium supplementation. HbA1c declined by ≥0.5% in 5 of 14 studies. On the basis of the low strength of existing evidence, chromium supplements have limited effectiveness, and there is little rationale to recommend their use for glycemic control in patients with existing T2DM. Future meta-analyses should include only high-quality studies with similar forms of chromium and comparable inclusion/exclusion criteria to provide scientifically sound recommendations for clinicians.

Effect of chromium supplementation on the glucose homeostasis and anthropometry of type 2 diabetic patients: Double blind, randomized clinical trial: Chromium, glucose homeostasis and anthropometry

OBJECTIVE

To evaluate the effect of chromium supplementation on the glucose homeostasis and anthropometry of type 2 diabetic patients.

MATERIAL AND METHODS

Fifty-six individuals with type 2 Diabetes were randomized on a double blind clinical trial into three groups: placebo (NC0), 50μg (NC50) and 200μg (NC200) of chromium nicotinate. Glucose homeostasis, anthropometry and physical activity intensity were evaluated at the beginning, at day 45 and at day 90. Energy intake was evaluated at the beginning, between the beginning and 45 days, and between days 45 and 90 of the study.

RESULTS

There were no differences within or between groups for HOMA-IR, waist circumference, body fat percentage, lean body mass percentage and total energy intake during the trial. There was an increase of the HOMA-β in group NC0 (p=0.0349) and a decrease of 1.08kg in group NC50 (p=0.0048) at 90 days. The relation between body mass index, body fat percentage and insulin sensitivity did not change in the placebo and supplemented groups (p>0.05). In the effect of the intervention, for each 1cm increase in waist circumference there was an increase of 1.90±0.63 in HOMA-IR (p=0.0087) and 16.31±5.27% in HOMA-β (p=0.0073) in group NC200. No difference was seen in the intensity of physical activity within the groups and in the comparison between the supplemented groups (NC50 and NC200) and placebo (NC0) at 90 days. There was an increase in energy expenditure in physical activity at 90days (p=0.0371) of intervention in the group subjects NC50. As for total energy intake, there were no differences within or between the groups during the study.

CONCLUSION

50μg and 200μg supplementation with chromium nicotinate for 90days did not promote improvements in glucose homeostasis and anthropometry in individuals with type 2 diabetes mellitus.

Risk of Type 2 Diabetes Is Lower in US Adults Taking Chromium-Containing Supplements

BACKGROUND

Dietary supplement use is widespread in the United States. Although it has been suggested in both in vitro and small in vivo human studies that chromium has potentially beneficial effects in type 2 diabetes (T2D), chromium supplementation in diabetes has not been investigated at the population level.

OBJECTIVE

The objective of this study was to examine the use and potential benefits of chromium supplementation in T2D by examining NHANES data.

METHODS

An individual was defined as having diabetes if he or she had a glycated hemoglobin (HbA1c) value of ≥6.5%, or reported having been diagnosed with diabetes. Data on all consumed dietary supplements from the NHANES database were analyzed, with the OR of having diabetes as the main outcome of interest based on chromium supplement use.

RESULTS

The NHANES for the years 1999-2010 included information on 62,160 individuals. After filtering the database for the required covariates (gender, ethnicity, socioeconomic status, body mass index, diabetes diagnosis, supplement usage, and laboratory HbA1c values), and when restricted to adults, the study cohort included 28,539 people. A total of 58.3% of people reported consuming a dietary supplement in the previous 30 d, 28.8% reported consuming a dietary supplement that contained chromium, and 0.7% consumed supplements that had "chromium" in the title. Compared with nonusers, the odds of having T2D (HbA1c ≥6.5%) were lower in persons who consumed chromium-containing supplements within the previous 30 d than in those who did not (OR: 0.73; 95% CI: 0.62, 0.86; P = 0.001). Supplement use alone (without chromium) did not influence the odds of having T2D (OR: 0.89; 95% CI: 0.77, 1.03; P = 0.11).

CONCLUSIONS

Over one-half the adult US population consumes nutritional supplements, and over one-quarter consumes supplemental chromium. The odds of having T2D were lower in those who, in the previous 30 d, had consumed supplements containing chromium. Given the magnitude of exposure, studies on safety and efficacy are warranted.

The Potential of Cr3 [Triaqua-μ3 -Oxo-Hexa-μ-Propionatotrichromium(III) Chloride] to Reduce Birth Defects in the Offspring of Diabetic CD-1 Mice

Diabetes mellitus is a growing concern worldwide and leads to multiple complications during pregnancy. Pharmacologic doses of chromium (Cr) have been linked with improving insulin sensitivity and other positive benefits in the treatment of diabetes in animal models. By using streptozotocin induced hyperglycemia in female CD-1 mice, reproductive outcomes of diabetic and chromium-dosed diabetic females were examined. After dosing 10 mg/kg Cr in the form of triaqua-μ3 -oxo-hexa-μ-propionatotrichromium(III) chloride or Cr3 during gestation days 8-16 (GD8-GD16), all females were sacrificed on gestation day 17 (GD17) and examined for maternal weight gain. The fetuses were examined for gross malformations and for skeletal malformations. The offspring of Cr3-dosed females tended to have a reduction in the incidence of supernumerary ribs. While hyperglycemia still had negative impacts on the health of dams and their offspring, administration of Cr led to an apparent trend in the reduction in the number of malformations and incidence of supernumerary ribs compared to those of untreated diabetic mothers.

Dietary chromium supplementation for targeted treatment of diabetes patients with comorbid depression and binge eating

Dietary chromium supplementation for the treatment of diabetes remains controversial. The prevailing view that chromium supplementation for glucose regulation is unjustified has been based upon prior studies showing mixed, modest-sized effects in patients with type 2 diabetes (T2DM). Based on chromium's potential to improve insulin, dopamine, and serotonin function, we hypothesize that chromium has a greater glucoregulatory effect in individuals who have concurrent disturbances in dopamine and serotonin function--that is, complex patients with comorbid diabetes, depression, and binge eating. We propose, as suggested by the collective data to date, the need to go beyond the "one size fits all" approach to chromium supplementation and put forth a series of experiments designed to link physiological and neurobehavioral processes in the chromium response phenotype.

Anti-diabetic potential of chromium histidinate in diabetic retinopathy rats

BACKGROUND

Chromium (Cr) is commonly used as a complementary medicine for diabetes mellitus. Several studies suggest that Cr intakes may improve glucose metabolism and decrease oxidative stress. Therefore, we aimed to assess the effects of chromium histidinate (CrHis) supplementation using a range of reliable biomarkers of oxidative damage and histopathological changes in rats with diabetic retinopathy.

METHODS

Diabetes was induced with streptozotocin [(STZ), 55 mg/kg] by intraperitoneal injection in male Long-Evans rats. Three weeks after STZ injection, rats were divided into four groups, namely, untreated normal controls, normal rats receiving CrHis (110 μg/kg/day); untreated diabetics and diabetics treated with CrHis (110 μg/kg/day) orally for 12 weeks.

RESULTS

In the untreated diabetic group, levels of serum glucose, glycosylated haemoglobin (HbA1c), total cholesterol (TC) and retina malondialdehyde (MDA) were significantly increased, while expressions of retina insulin, and glucose transporter 1 (GLUT 1) and glucose transporter 3 (GLUT3) and level of serum insulin were decreased. CrHis supplementation was found to reduce the levels of glucose, HbA1c, total cholesterol and MDA and to improve the GLUT1, GLUT3 and insulin expressions in STZ-induced diabetic rats. CrHis prevents the changes in the expressions of GLUT1, GLUT3 and insulin and the level of MDA in the retina tissue, confirming the protective effect of CrHis supplementation against the retinopathy caused by STZ. Histopathologic findings suggest that the CrHis-treated diabetic group had normal retinal tissue appearance compared with the untreated diabetic group.

CONCLUSIONS

These results verify that CrHis has critical beneficial effects against retinal complications. Although detailed studies are required for the evaluation of the exact mechanism of the ameliorative effects of CrHis against diabetic complications, these preliminary experimental findings demonstrate that CrHis exhibits antidiabetic effects in a rat model of diabetic retinopathy by regulating the glucose metabolism and suppressing retinal tissue damage.

pH-metric chemical speciation modeling and studies of in vitro antidiabetic effects of bis[(imidazolyl)carboxylato]oxidovanadium(IV) complexes

A range of bidentate N,O-donor ligands of the imidazolyl-carboxylate moiety, which partially mimic naturally occurring bioligands, were prepared and reacted with the oxidovanadium(IV) ion to form the corresponding bis-coordinated oxidovanadium(IV) complexes. The aqueous pH-metric chemical speciation was investigated using glass electrode potentiometry, which allowed for the determination of protonation and stability constants of the ligands and complexes, respectively. The species distribution diagrams generated from this information gave evidence that the bis[(imidazolyl)carboxylato]oxovanadium(IV) complexes possess a broad pH-metric stability. The complexes improved glucose uptake in cell cultures using 3T3-L1 adipocytes, C2C12 muscle cells and Chang liver cells. The PTP inhibition studies indicated that the mechanism underlying insulin-stimulated glucose uptake was possibly via the protein tyrosine phosphorylation through the inhibition of the protein tyrosine phosphatase 1B (PTP 1B). The vanadium compounds also demonstrated the inhibition of D-dimer formation, suggesting that these compounds could potentially relieve a hypercoagulative state in diabetic patients.

Chromium level in prediction of diabetes in pre-diabetic patients

BACKGROUND

Chromium supplementations (Cr) have been shown to exert beneficial effects in the management of type-2 diabetes. Prevalence of Cr deficiency in pre-diabetic patients is not well-understood, therefore, the aim of this study was to evaluate the extent of this prevalence.

MATERIALS AND METHODS

In this cross-sectional descriptive study, 132 pre-diabetic patients were recruited. The participants were randomly selected from those who referred to the Shariati Hospital in Isfahan, Iran. Blood samples are collected for measurement of Cr, insulin, fasting blood sugar (FBS), and two-hour post-load plasma glucose. The body mass index (BMI) was calculated. Determination of Cr was carried out by atomic absorption spectrometry.

RESULTS

Thirty-four (31.5%) patients had Cr deficiency and 74 (68.5%) patients had normal Cr. There was no significant difference between sex, age groups (<50 years and ≥50 years) and between patients with and without a family history of diabetes in both the groups. No significant differences in age, BMI, FBS or insulin were observed between two groups. In the group with a normal level of Cr, there was a significant reversed correlation between the Cr level and age, but no significant correlation existed between the Cr level and other factors in both groups.

CONCLUSION

The levels of Cr deficiency are relatively common in patients with pre-diabetes, and it is necessary to screen patients with diabetes and pre-diabetes according to the American Diabetes Association guidelines, with regard to the Cr level and action should be taken to eliminate the Cr deficiency in these patients.

Is chromium pharmacologically relevant?

Recent research, combined with reanalysis of previous results, has revealed that chromium can no longer be considered an essential trace element. Clinical studies are ambiguous at best as to whether Cr has a pharmacological effect in humans. Observed effects of Cr on rodent models of insulin resistance and diabetes are best interpreted in terms of a pharmacological role for Cr. Studies on the effects of Cr on rat models of diabetes are reviewed herein and suggest Cr increases insulin sensitivity in peripheral tissues of the rodent models. The lack of effects in human studies may stem from humans receiving a comparably smaller dose than the rodent models. However, given the different responses to Cr in the rodent models, humans could potentially have different responses to Cr.

Chromium

Chromium is ubiquitous in the environment as Cr(III) and Cr(VI) oxidation states, which interconvert under environmentally and biologically relevant conditions (although Cr(III) usually predominates). While Cr(VI) is an established human carcinogen and a major occupational and environmental hazard, Cr(III) has long been regarded as an essential human micronutrient, although recent literature has cast serious doubts on the validity of this postulate. Despite five decades of research, no functional Cr-containing enzymes or cofactors have been characterized conclusively, and several hypotheses on their possible structures have been refuted. Gastrointestinal absorption pathways for both Cr(III) and Cr(VI) are apparent and whole-blood speciation can involve Cr(VI) uptake and reduction by red blood cells, as well as Cr(III) binding to both proteins and low-molecular-mass ligands in the plasma. DNA-damaging effects of Cr(VI) and anti-diabetic activities of Cr(III) are likely to arise from common mechanistic pathways that involve reactive Cr(VI/V/IV) intermediates and kinetically inert Cr(III)-protein and Cr(III)-DNA adducts. Both Cr(III) and Cr(VI) are toxic to plants and microorganisms, particularly Cr(VI) due to its higher bioavailability and redox chemistry. Some bacteria reduce Cr(VI) to Cr(III) without the formation of toxic Cr(V) intermediates and these bacteria are being considered for use in the bioremediation of Cr(VI)-polluted environments.

Chromium nicotinate has no effect on insulin sensitivity, glycemic control, and lipid profile in subjects with type 2 diabetes

OBJECTIVE

To investigate the effect of chromium nicotinate supplementation on insulin sensitivity, glycemic control, and lipid profile in subjects with type 2 diabetes.

MATERIALS AND METHODS

In a double-blind clinical trial, 56 overweight individuals with type 2 diabetes were randomized into 3 groups: placebo (NC0), 50 μg (NC50), and 200 μg (NC200) of chromium as chromium nicotinate. Chromium status, sensitivity to insulin, glycemic control, and lipid profile were assessed at the beginning of the study and 45 days and 90 days after.

RESULTS

In the beginning, most subjects showed low concentrations of serum chromium (71.88%), regular levels of urinary chromium (80.65%), and insulin resistance (73.80%). The serum chromium concentrations did not differ among the groups over time (p = 0.2549). The changes in serum chromium and urine concentrations did not relate to changes in fasting glucose (p > 0.05). At 90 days of intervention, there was no significant difference between groups in fasting glucose, glycosylated hemoglobin, homeostasis model assessment insulin resistance (HOMA-IR), total cholesterol, and low-density lipoprotein (LDL); there was increase in homeostasis model assessment β-cell function (HOMA-β; p = 0.0349) and high-density lipoprotein (HDL; p = 0.0425) in the NC0 group and a reduction of triglycerides in the NC0 (p = 0.0177) and NC50 (p = 0.0336) groups.

CONCLUSION

Supplementation at 50 and 200 μg of chromium as chromium nicotinate did not promote glycemic control, increase insulin sensitivity, or change the lipid profile of subjects with diabetes.

Systematic review and meta-analysis of the efficacy and safety of chromium supplementation in diabetes

WHAT IS KNOWN AND OBJECTIVE

Chromium is an essential mineral for carbohydrate and lipid metabolism. Results of previous systematic reviews and meta-analyses of chromium supplementation and metabolic profiles in diabetes have been inconsistent. Recently, several published trials have emerged. We conducted a systematic review and meta-analysis to assess the effects on metabolic profiles and safety of chromium supplementation in diabetes mellitus.

METHODS

Clinical trials were identified through MEDLINE, the Cochrane library, CINAHL, Web of Science, Scopus and www.clinicaltrial.gov up to May 2013. Historical search of reference lists of related articles was also conducted. Studies were included if they (i) were randomized controlled trials comparing chromium mono- or combined supplementation against placebo, (ii) reported HbA1c or fasting plasma glucose and (iii) were of at least 3 weeks when reporting fasting plasma glucose, or of at least 8 weeks if HbA1c was reported. No language restriction was imposed. Treatment effect and adverse events were estimated with mean difference and odds ratio, respectively.

RESULTS AND DISCUSSION

Twenty-five randomized controlled trials met the inclusion criteria. Of these, 22 studies evaluated chromium monosupplementation. One study evaluated chromium yeast combined with vitamins C and E, and two others evaluated chromium picolinate plus biotin (CPB). Overall, chromium mono- and combined supplementation significantly improved glycaemic control (mean difference for HbA1c -0·55%; 95% CI -0·88 to -0·22%; P = 0·001, mean difference for FPG -1·15 mm; 95% CI -1·84 to -0·47 mm; P = 0·001). In particular, chromium monotherapy significantly reduced triglycerides and increased HDL-C levels. The effects on glucose and triglycerides levels were shown especially with chromium picolinate. Glycaemic control may improve with chromium monosupplementation of more than 200 μg daily. HbA1c and FPG also improved in patients with inadequate glycaemic control at baseline. The risk of adverse events did not differ between chromium and placebo.

WHAT IS NEW AND CONCLUSIONS

The available evidence suggests favourable effects of chromium supplementation on glycaemic control in patients with diabetes. Chromium monosupplement may additionally improve triglycerides and HDL-C levels. Chromium supplementation at usual doses does not increase the risk of adverse events compared with placebo. Data on chromium combined supplementation are limited and inconclusive. Long-term benefit and safety of chromium supplementation remain to be further investigated.

The effect of chromium picolinate supplementation on the pancreas and macroangiopathy in type II diabetes mellitus rats

PURPOSE

The aim was to explore the effect of the chromium picolinate (CrPic) administration on the pancreas and macroangiopathy of type II diabetes mellitus rats.

METHODS

The type II diabetes mellitus (T2DM) rat model was induced by low-dose streptozotocin (STZ). The rats were randomly divided into 5 groups (ten rats in each group). After supplementing CrPic for 15 weeks, the histopathological examination was performed by hematoxylin-eosin (HE) staining. Serum insulin and NO level were determined by radioimmunoassay and colorimetry, respectively. Serum glycosylated hemoglobin (HbA1C), adiponectin (APN), advanced glycation end products (AGES), and apelin were measured by ELISA. Real-time reverse transcription polymerase chain reaction (RT-PCR) was applied for detecting the mRNA expression of APN and apelin.

RESULTS

After CrPic treatment, compared with the T2DM control group (group 2), pancreas sections stained with HE showed the completed pancreatic cells structure and no inflammatory infiltration in groups 4 and 5. In addition, the levels of serum NO and insulin were significantly increased and the serum levels of HbA1C, AGES, APN, and apelin were significantly decreased in groups 4 and 5 compared with group 2. The mRNA expression of APN and apelin in groups 4 and 5 was also recovered to the normal level.

CONCLUSION

CrPic can recover the function of Β-cells and alleviate macroangiopathy in STZ-induced T2DM rats.

Improved meta-analytic methods show no effect of chromium supplements on fasting glucose

The trace mineral chromium has been extensively researched over the years in its role in glucose metabolism. Dietary supplement companies have attempted to make claims that chromium may be able to treat or prevent diabetes. Previous meta-analyses/systematic reviews have indicated that chromium supplementation results in a significant lowering of fasting glucose in diabetics but not in nondiabetics. A meta-analysis was conducted using an alternative measure of effect size, d(ppc2) in order to account for changes in the control group as well as the chromium group. The literature search included MEDLINE, the Cochrane Controlled Trials Register, and previously published article reviews, systematic reviews, and meta-analyses. Included studies were randomized, placebo-controlled trials in the English language with subjects that were nonpregnant adults, both with and without diabetes. Sixteen studies with 809 participants (440 diabetics and 369 nondiabetics) were included in the analysis. Screening for publication bias indicated symmetry of the data. Tests of heterogeneity indicated the use of a fixed-effect model (I² = 0 %). The analysis indicated that there was no significant effect of chromium supplementation in diabetics or nondiabetics, with a weighted average effect size of 0.02 (SE = 0.07), p = 0.787, CI 95 % = -0.12 to 0.16. Chromium supplementation appears to provide no benefits to populations where chromium deficiency is unlikely.

Brewer's Yeast Improves Glycemic Indices in Type 2 Diabetes Mellitus

BACKGROUND

Brewer's yeast may have beneficial effects on insulin receptors because of itsglucose tolerance factor in diabetic patients. This study was conducted to investigate the effects of brewer's yeast supplementation on glycemic indices in patients with type 2 diabetes mellitus.

METHODS

In a randomized double-blind controlled clinical trial, 84 adults (21 men and 63 women) aged 46.3 ± 6.1 years old with type 2 diabetes mellitus were recruited and divided randomly into two groups: Supplement group receiving brewer's yeast (six 300mg tablets/day, total 1800 mg) and control group receiving placebo (six 300mg tablets/day) for 12 weeks. Body weight, height, body mass index, food consumption (based on 24h food record), fasting blood sugar (FBS), glycosylated hemoglobin, insulin sensitivity, and insulin resistance were measured before and after the intervention. Data analysis was performed using the Statistical Package for Social Sciences (version 18.0).

RESULTS

The changes in FBS, glycosylated hemoglobin, and insulin sensitivity were significantly different between the two groups during the study (respectively P < 0.001, P < 0.001, P = 0.02 independent sample t-test). There was a significant difference in FBS, glycosylated hemoglobin, and insulin sensitivity at the end of the study between the two groups after removing the effects of baseline values (respectively P = 0.002, P < 0.001, P = 0.02, analysis of covariance). Changes in body mass index, 24h food record, insulin resistance were not significant.

CONCLUSIONS

Dietary supplementation with brewer›s yeast besides the usual treatment of diabetes can ameliorate blood glucose variables in type 2 diabetes mellitus.

Nutritional supplements for diabetes sold on the internet: business or health promotion?

Background

Diabetes is one of the most widespread chronic disease. Although many medications are available for the treatment and prevention of diabetes, many people turn to nutritional supplements (NSs). In these years, the online sales have contributed to the growth of use of nutritional supplement. The aim of the research was to investigate the type of information provided by sales websites on NSs, and analyse the existence of scientific evidence about some of the most common ingredients found in available NSs for diabetes.

Methods

A web search was conducted in April 2012 to identify web sites selling NSs in the treatment of diabetes using Google, Yahoo and Bing! and the key word used was “diabetes nutritional supplements”. Website content was evaluated for the quality of information available to consumers and for the presence of a complete list of ingredients in the first NS suggested by the site. Subsequently, in order to analyze the scientific evidence on the efficacy of these supplements a PubMed search was carried out on the ingredients that were shared in at least 3 nutritional supplements.

Results

A total of 10 websites selling NSs were selected. Only half of the websites had a Food and Drug Administration disclaimer and 40% declared clearly that the NS offered was not a substitute for proper medication. A total of 10 NS ingredients were searched for on PubMed. Systematic reviews, meta-analyses or randomized control trials were present for all the ingredients except one. Most of the studies, however, were of poor quality and/or the results were conflicting.

Conclusions

Easy internet access to NSs lacking in adequate medical information and strong scientific evidence is a matter of public health concern, mainly considering that a misleading information could lead to an improper prevention both in healthy people and people suffering from diabetes. There is a clear need for more trials to assess the efficacy and safety of these NSs, better quality control of websites, more informed physicians and greater public awareness of these widely used products.

A double-blind, randomized pilot trial of chromium picolinate for binge eating disorder: results of the Binge Eating and Chromium (BEACh) study

OBJECTIVE

Chromium treatment has been shown to improve mood, appetite, and glucose regulation in various psychiatric and medical patient populations. The authors propose that chromium may be useful in the treatment of binge eating disorder (BED).

METHOD

Twenty-four overweight adults with BED were enrolled in a 6-month double-blind placebo-controlled trial and randomly assigned to receive either 1000mcg chromium/day ("high dose"; n=8) or 600mcg chromium/day ("moderate dose"; n=9) as chromium picolinate or placebo (n=7). Mixed linear regression models were used to estimate mean change in binge frequency and related psychopathology, weight, symptoms of depression, and fasting glucose.

RESULTS

Fasting glucose was significantly reduced in both chromium groups compared to the placebo group; similarly, numerically, but not significantly, greater reductions in binge frequency, weight, and symptoms of depression were observed in those treated with chromium versus placebo, although statistical power was limited in this pilot trial. For fasting glucose, the findings suggest a dose response with larger effects in the high dose compared to moderate dose group.

CONCLUSION

These initial findings support further larger trials to determine chromium's efficacy in maintaining normal glucose regulation, reducing binge eating and related psychopathology, promoting modest weight loss, and reducing symptoms of depression in individuals with BED. Studies designed to link the clinical effects of chromium with changes in underlying insulin, serotonin, and dopamine pathways may be especially informative. If efficacious, chromium supplementation may provide a useful, low-cost alternative to or augmentation strategy for selective serotonin reuptake inhibitors, which have partial efficacy in BED. ClinicalTrials.gov NCT00904306.

Chromium supplementation in overweight and obesity: a systematic review and meta-analysis of randomized clinical trials

The increased prevalence of obesity has made the use of dietary supplements as weight reducing agents highly popular, but their efficacy has not been proven. One such supplement is chromium. The purpose of this review was to evaluate the evidence for or against the efficacy of chromium supplementation in overweight and obese individuals. Electronic searches were conducted in Medline, Embase, Amed and The Cochrane Library. The bibliographies of located articles were also searched. No age, gender or language restrictions were imposed. The reporting quality of identified randomized clinical trials (RCTs) was assessed using a methodological checklist adapted from the Consolidated Standard of Reporting Trials Statement and Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Thirty-nine trials were identified and 20 were included. There were variations in reporting quality of included studies. A meta-analysis of 11 studies showed a statistically significant difference in weight loss favouring chromium over placebo (mean difference (MD): -0.50 kg; 95% confidence interval (CI): -0.97, -0.03). There was a high statistical heterogeneity. Adverse events included watery stools, vertigo, headaches and urticaria. The evidence from available RCTs shows that chromium supplementation generates statistically significant reductions in body weight. The magnitude of the effect is small, and the clinical relevance is uncertain. Future trials should last at least 16 weeks and greater uniformity in the measuring and assessment tools for body composition is recommended.