Role of chromium in human health and in diabetes

Chromium and diabetes

Chromium enhances glucose control and decreases insulin resistance in type 2 diabetes.

RCT evidence suggests that supplements are safe and will offer some benefit in glucose control for such patients. Further trials are needed to confirm this and to clarify in what dose and form chromium supplements are best given.

Metabolic syndrome: role of maternal undernutrition and fetal programming

Development of metabolic syndrome is attributed to genes, dietary intake, physical activity and environmental factors. Fetal programming due to maternal nutrition is also an important factor especially in developing countries where intrauterine growth retardation followed by excess nutrition postnatally is causing mismatch predisposing individuals to development of metabolic syndrome and its components. Several epidemiological and animal studies have provided evidence for the link between intrauterine growth retardation and adult metabolic diseases. Deficiency of macronutrients, protein and carbohydrates, during pregnancy and gestation results in lower infant birth weight, a surrogate marker of fetal growth and subsequently insulin resistance, glucose intolerance, hypertension and adiposity in adulthood. The role of micronutrients is less extensively studied but however gaining attention with several recent studies focusing on this aspect. Several mechanisms have been proposed to explain the developmental origin of adult diseases important among them being alteration of hypothalamic pituitary axis, epigenetic regulation of gene expression and oxidative stress. All of these mechanisms may be acting at different time during gestation and contributing to development of metabolic syndrome in adulthood.

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.

Chromium picolinate attenuates hyperglycemia-induced oxidative stress in streptozotocin-induced diabetic rats

Chromium picolinate is advocated as an anti-diabetic agent for impaired glycemic control. It is a transition metal that exists in various oxidation states and may thereby act as a pro-oxidant. The present study has been designed to examine the effect of chromium picolinate supplementation on hyperglycemia-induced oxidative stress. Diabetes was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin (50mg/kg body weight) and chromium was administered orally as chromium picolinate (1mg/kg body weight) daily for a period of four weeks after the induction of diabetes. As is characteristic of diabetic condition, hyperglycemia was associated with an increase in oxidative stress in liver in terms of increased lipid peroxidation and decreased glutathione levels. The activity of antioxidant enzymes like superoxide dismutase, catalase and glutathione reductase were significantly reduced in liver of diabetic animals. Levels of α-tocopherol and ascorbic acid were found to be considerably lower in plasma of diabetic rats. Chromium picolinate administration on the other hand was found to have beneficial effect in normalizing glucose levels, lipid peroxidation and antioxidant status. The results from the present study demonstrate potential of chromium picolinate to attenuate hyperglycemia-induced oxidative stress in experimental diabetes.

Anti-atherogenic effect of chromium picolinate in streptozotocin-induced experimental diabetes

BACKGROUND

Several studies have implicated changes in the levels of trace elements in diabetes. Chromium is one such element that seems to potentiate insulin action, thereby regulating carbohydrate and lipid metabolism. The aim of the present study was to evaluate the effect of chromium supplementation as chromium picolinate on the lipid profile of streptozotocin (STZ)-induced diabetic rats.

METHODS

Rats were rendered diabetic by a single injection of STZ (50 mg/kg, i.p.). Chromium picolinate (1 mg/kg per day, p.o.) was administered to rats for a period of 4 weeks. At the end of the treatment period, plasma total lipids, triglycerides, total cholesterol and lipoprotein levels were determined, as was hepatic glucose-6-phosphate dehydrogenase activity.

RESULTS

Total plasma lipids increased significantly in diabetic rats and this increase was ameliorated by chromium treatment for 4 weeks. Elevated total lipids in diabetic rats were due to increased plasma triglyceride and cholesterol levels. Chromium supplementation lowered plasma triglyceride and cholesterol levels to near normal. Chromium treatment also normalized low-density lipoprotein-cholesterol (LDL-C) and very low-density lipoprotein-cholesterol levels and improved the total cholesterol:high-density lipoprotein-cholesterol (HDL-C) and HDL-C:LDL-C ratios, suggesting an anti-atherogenic effect. In addition to improving the plasma lipid profile, chromium supplementation normalized liver glucose-6-phosphate dehydrogenase activity in diabetic rats.

CONCLUSIONS

These results provide evidence that chromium picolinate effectively attenuates the dyslipidemia associated with diabetes and thus can be used as an adjuvant therapy in the treatment of diabetes and its associated complications.

Purification and characterization of chromium-binding substances from high-chromium yeast

As a highly efficient and easily absorbable source of chromium, the identities of the chromium-binding substances in yeast remain unclear. In this study, a mild extraction procedure involving extraction with ammonia, three-gel filtration, and high-performance liquid chromatography was adopted to obtain two chromium-binding substances from high-chromium yeast. A low-molecular-weight chromium-binding substance was identified, with mass-to-charge ratios (m/z) of 769 and 712, which included glutamic acid, glycine, and cysteine in an approximate ratio of 1:1:1, as well as nicotinic acid and chromium(III). Furthermore, it significantly potentiated (by 51%) the action of insulin to stimulate the conversion of (14)C-glucose into lipid in adipocytes. A novel high-molecular-weight chromium-binding substance was also isolated: electrospray ionization tandem mass spectrometry tentatively identified it as HUB1 target protein-1, glyceraldehyde-3-phosphate dehydrogenase, or ribosomal protein L2A(L5A)(rp8)(YL6). This is the first report of a high-molecular-weight chromium-binding substance in yeast and merits further studies.

Chromium picolinate modulates serotonergic properties and carbohydrate metabolism in a rat model of diabetes

Chromium picolinate (CrPic) has shown both antidepressant and antidiabetic properties. In this study, the effects of CrPic on serotonergic properties and carbohydrate metabolism in diabetic rats were evaluated. Sixty male Sprague-Dawley rats were divided into four groups. (1) The control group received only standard diet (8 % fat). (2) The CrPic group was fed standard diet and CrPic (80 μg CrPic per kilogram body mass (b.m.)/day), for 10 weeks (microgram/kilogram b.m./day). (3) The HFD/STZ group fed a high-fat diet (HFD, 40 % fat) for 2 weeks and then received streptozotocin (STZ, 40 mg/kg, i.p.) (i.v.) HFD-STZ-CrPic group treated as the previous group and then were administered CrPic. CrPic administration to HFD/STZ-treated rats increased brain chromium levels and improved all measurements of carbohydrate metabolism and serotonergic properties (P<0.001). CrPic also significantly increased levels of insulin, tryptophan, and serotonin (P<0.001) in the serum and brain, and decreased cortisol levels in the serum (P<0.01). Except chromium levels, no significant effect of CrPic supplementation was detected on the overall measured parameters in the control group. CrPic administration was well tolerated without any adverse events. The results support the use of CrPic supplementation which improves serotonergic properties of brain in diabetes.

Chromium, zinc and magnesium concentrations in the pubic hair of obese and overweight women

The study addressed chromium, zinc and magnesium concentrations in the pubic hair of obese and overweight women. It was carried out on hair collected from 85 women at the age of 16-80 living in the Podkarpackie Voivodeship (southern Poland). The experimental and control groups consisted of 39 and 46 females, respectively. The pubic hair was prepared under a procedure established by the International Atomic Energy Agency, followed by wet digestion in a microwave oven. The concentration of the metals in the pubic hair and reference material was assayed with the flame (Mg, Zn) and flameless (Cr) atomic absorption spectrometry. The pubic hair of overweight and obese women from the experimental group revealed significantly higher chromium and magnesium concentrations and significantly lower concentrations of zinc than in the control group. An increase in BMI brought about an increase in chromium and magnesium concentrations while zinc concentration decreased with increasing BMI. The disturbances in the mineral balance of overweight and obese women were also demonstrated by significantly different ratios of the elements compared with the control group.

Effect of chromium dinicocysteinate supplementation on circulating levels of insulin, TNF-α, oxidative stress, and insulin resistance in type 2 diabetic subjects: randomized, double-blind, placebo-controlled study

SCOPE

Chromium and cysteine supplementation have been shown to improve glucose metabolism in animal studies. This study examined the hypothesis that chromium dinicocysteinate (CDNC), a complex of chromium and l-cysteine, is beneficial in lowering oxidative stress, vascular inflammation, and glycemia in type 2 diabetic subjects.

METHODS AND RESULTS

Type 2 diabetic subjects enrolled in this study were given placebo for 1 month for stabilization and then randomized into one of three groups: placebo (P), chromium picolinate (CP), or CDNC, after which they received daily oral supplementation for 3 months. Of the 100 patients enrolled in the study, 74 patients completed it. There were 25 patients in the P supplemented group, 25 in the CP supplemented and 24 in the CDNC supplemented group who completed the study. Blood markers of glycemia, vascular inflammation, HOMA insulin resistance, and oxidative stress were determined at randomization and after 3 months of supplementation with P, CP, or CDNC. There was a significant decrease at 3 months in insulin resistance (p = 0.02) and in the levels of protein oxidation (p = 0.02) and TNF-α (p = 0.01) in the CDNC supplemented cohort compared to baseline. However, there was no statistically significant change in these markers in the CP supplemented group compared to baseline. Insulin levels significantly decreased (p = 0.01) for subjects receiving CDNC but not CP. There was no significant impact of supplementation on HbA(1c) or glucose levels in either of the groups.

CONCLUSION

CDNC supplementation lowers insulin resistance by reducing blood levels of TNF-α, insulin, and oxidative stress in type 2 diabetic subjects. Therefore, CDNC supplementation has potential as an adjunct therapy for individuals with type 2 diabetes.

Favorable effects on metabolic risk factors with daily brewer's yeast in type 2 diabetic patients with hypercholesterolemia: a semi-experimental study

BACKGROUND

The aim of the present study was to investigate the effect of brewer's yeast on plasma glucose and lipid profiles in patients with type 2 diabetes (T2D).

METHODS

The present semi-experimental study was performed on 55 T2D patients with hypercholesterolemia. All patients received 12 tablets of 300 mg yeast per day for 8 weeks. Each tablet contained 1.2 μg chromium. Fasting plasma glucose, total cholesterol, high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), and triglyceride levels were measured at baseline and then again at Weeks 4 and 8.

RESULTS

Although there was a tendency for plasma glucose levels to decrease at Week 4, the difference failed to reach statistical significance (P = 0.065). However, after 8 weeks, the decrease in plasma glucose was significant (P = 0.043). Again, although there was a tendency for decreased plasma cholesterol at Week 8 compared with baseline, the difference failed to reach statistical significance (215 ± 29 vs 226 ± 37 mg/dL, respectively; P = 0.056). Brewer's yeast significantly decreased plasma triglyceride and LDL-C levels at Weeks 4 and 8. In contrast, plasma HDL-C levels were significantly increased at both 4 and 8 weeks compared with baseline (41.3 ± 8.8 and 43.3 ± 7.5 vs 36 ± 5 mg/dL, respectively; P < 0.01 and P < 0.01, respectively).

CONCLUSION

In conclusion, the consumption of brewer's yeast over a period of 8 weeks may improve cardiometabolic risk factors in T2D patients. However, these findings need to be confirmed in a large double-blind clinical trial.

Chromium supplementation can alleviate the negative effects of heat stress on growth performance, carcass traits, and meat lipid oxidation of broiler chicks without any adverse impacts on blood constituents

This study was conducted to determine the effects of dietary supplementation with Cr nicotinate and Cr chloride and their optimum inclusion rate on performance, carcass traits, meat oxidative stability, serum metabolites, hematological parameters, and liver chromium concentration in heat-stressed broilers. A total number of 420, 1-day-old male broiler chicks were randomly assigned to seven treatments with four replicates of 15 chicks. The dietary treatments consisted of the basal diet supplemented with 0 (control), 500, 1,000, and 1,500 μg/kg Cr in the form of Cr nicotinate and Cr chloride. Chicks were raised for 6 weeks in heat stress condition (33 ± 2°C). Supplements of organic and inorganic Cr particularly at 1,500 μg/kg incorporation increased feed consumption (P < 0.05) and body mass gain of broilers (P < 0.01). Cr supplementation increased carcass yield and decreased abdominal fat (P < 0.01). Supplementation of 1,500 μg/kg Cr nicotinate (P < 0.05) enhanced liver Cr concentration. Storage time increased lipid oxidation of meat (P < 0.01). Cr decreased lipid oxidation of breast and thigh muscles over 2 (P < 0.01) or 6 (P < 0.05) days of storage time. Birds fed 1,500 μg/kg Cr nicotinate, had lower concentration of serum glucose and triglyceride at 21 days (P < 0.05). Hematological parameters tested at 21 and 42 days, were not influenced. The results suggested that dietary Cr supplementation regardless of its source have a positive effect on productive, and carcass traits, also enhances oxidative stability of refrigerated meat in broilers reared under heat stress conditions.

Chromium picolinate and chromium histidinate protects against renal dysfunction by modulation of NF-κB pathway in high-fat diet fed and Streptozotocin-induced diabetic rats

Background

Diabetic nephropathy is one of major complications of diabetes mellitus. Although chromium is an essential element for carbohydrate and lipid metabolism, its effects on diabetic nephropathy are not well understood. The present study was conducted to investigate the effects of chromium picolinate (CrPic) and chromium histidinate (CrHis) on nuclear factor-kappa B (NF-κB) and nuclear factor-E2-related factor-2 (Nrf2) pathway in the rat kidney.

Methods

Male Wistar rats were divided into six groups. Group I received a standard diet (8% fat) and served as a control; Group II was fed with a standard diet and received CrPic; Group III was fed with a standard diet and received CrHis; Group IV received a high fat diet (HFD, 40% fat) for 2 weeks and then were injected with streptozotocin (STZ) (HFD/STZ); Group V was treated as group IV (HFD/STZ) but supplemented with CrPic for 12 weeks. Group VI was treated as group IV (HFD/STZ) but supplemented with CrHis.

Results

The increased NF-κβ p65 in the HFD/STZ group was inhibited by CrPic and CrHis supplementation (P < 0.05). In STZ-treated rats, a significant decrease in levels of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) was found in kidney tissues when compared to control rats (P < 0.05). A significant increase in the levels of IκBα was observed in CrPic- and CrHis-treated rats when compared with STZ-treated rats. Renal Nrf2 levels were significantly decreased in diabetic rats compared with the control rats. There was a higher tendency for increase of kidney Nrf2 level and decrease in kidney NFκBp65 levels and 4- hydroxyl nonenal (4-HNE) protein adducts (P < 0.05) in diabetic rats.

Conclusion

Our result show that in kidney tissue CrHis/CrPic increases Nrf2 level, parallelly decreases NF-κB and partially restores IκBα levels in HFD/STZ group, suggesting that CrPic and CrHis may play a role in antioxidant defense system via the Nrf2 pathway by reducing inflammation through NF-κβ p65 inhibition. Moreover, a greater reduction in NF-κB expression and greater increases in expressions of IκBα and Nrf2 in diabetic rats supplemented with CrHis than rats supplemented with CrPic suggest that CrHis has more favorable effects than CrPic.

The malnutrition of obesity: micronutrient deficiencies that promote diabetes

Obesity and diabetes are increasing in prevalence worldwide. Despite excessive dietary consumption, obese individuals have high rates of micronutrient deficiencies. Deficiencies of specific vitamins and minerals that play important roles in glucose metabolism and insulin signaling pathways may contribute to the development of diabetes in the obese population. This paper reviews the current evidence supporting this hypothesis.

Serum chromium levels in gestational diabetes mellitus

OBJECTIVE

To measure serum chromium level in women with gestational diabetes mellitus (GDM) from Chennai, South India.

MATERIALS AND METHODS

Thirty women with gestational diabetes, 60 age matched controls.

INCLUSION CRITERIA

Gestational age 22-28 weeks, age group 20-35 years.

EXCLUSION CRITERIA

Gestational age beyond 28 weeks, malnutrition or presence of infection. Serum chromium was measured using inductive couple plasma emission spectrometer.

RESULTS

Serum chromium levels of women with GDM, 1.59+/-0.02 ng/ml (range: 0.16-4.0 ng/ml) were lower than in controls (4.58+/-0.62 ng/ml; range 0.82-5.33 ng/ml) (P < 0.001). However, there were no significant differences among cases and controls when subdivided by parity.

CONCLUSIONS

Women with GDM from a South Indian city had lower levels of serum chromium compared to pregnant women without GDM. Studies may be done whether chromium supplementation is useful in this group of women.

Bacterial diversity in Cr(VI) and Cr(III)-contaminated industrial wastewaters

The bacterial community structure of a chromium water bath, a chromium drainage waste system, a chromium pretreatment tank, and a trivalent chromium precipitation tank from the Hellenic Aerospace Industry S.A. was assessed using 16S rRNA libraries and a high-density DNA microarray (PhyloChip). 16S rRNA libraries revealed a bacterial diversity consisting of 14 distinct operational taxonomic units belonging to five bacterial phyla: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, and Bacteroidetes. However, employing a novel microarray-based approach (PhyloChip), a high bacterial diversity consisting of 30 different phyla was revealed, with representatives of 181 different families. This made it possible to identify a core set of genera present in all wastewater treatment stages examined, consisting of members of Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Epsilonproteobacteria, and Bacteroidetes. In the chromium pretreatment tank, where the concentration of Cr(VI) is high (2.3 mg/l), we identified the presence of Pseudomonadales, Actinomycetales, and Enterobacteriales in abundance. In the chromium precipitation tank, where the concentration of Cr(III) is high, the dominant bacteria consortia were replaced by members of Rhodocyclales and Chloroflexi. The bacterial community structure changed significantly with changes in the chromium concentration. This in-depth analysis should prove useful for the design and development of improved bioremediation strategies.

Ameliorating effect of chromium administration on hepatic glucose metabolism in streptozotocin-induced experimental diabetes

Chromium has been recognized as an essential trace element that plays an important role in carbohydrate metabolism. However, the molecular mechanisms involved in its action are not clear. This study was undertaken to understand the mechanism of chromium action in experimental diabetes. Streptozotocin-induced diabetic animals were administered chromium as chromium picolinate (CrP) at a daily dose of 1 mg/kg body weight for a period of 4 weeks. It was observed that chromium complexed with picolinate was effective in lowering plasma glucose levels as well as was able to alleviate polyphagia, polydipsia, and weight loss in diabetic animals. Administration of chromium was also found to normalize glycogen content in liver of diabetic animals to near control levels. The reduction in plasma glucose levels by chromium was accompanied by increase in activity of glycolytic enzymes (e.g., glucokinase, phosphofructokinase, and pyruvate kinase) and by suppression in activity of gluconeogenic enzymes (e.g., glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) in liver. Hepatic glucose uptake was found to be increased by chromium supplementation as demonstrated by decrease in Km and increase in Vmax values in diabetic animals. Chromium levels were lower in the liver of diabetic rats when compared with that of control rats. A negative correlation was observed between plasma glucose and chromium concentration in patients with diabetes. The data suggests that chromium supplementation as CrP is beneficial in correcting hyperglycemia, implying that the modulation of the glucose metabolism by chromium may be therapeutically beneficial in the treatment of diabetes.

Renal distal tubule proliferation and increased aquaporin 2 level but decreased urine osmolality in db/db mouse: treatment with chromium picolinate

Hallmark features of type 2 diabetes mellitus include glucosuria and polyuria. Further, renal aquaporin 2 is pivotal to regulation of fluid excretion and urine osmolality. Accordingly, we tested the hypothesis that the db/db mouse displays increased glucosuria and fluid excretion but reduced urine osmolality in association with decreased renal aquaporin 2 level. In addition, we examined the effect of chromium picolinate (Cr(pic)3) which is purported to improve glycemic control. The db/db mice excreted more urine in association with marked glucose excretion but lower urine osmolality than db/m control group. Light microscopic examination of renal tissue revealed proliferation of tubular structures in db/db compared to the db/m mice, a feature validated with Ki67 immunostaining. Further, these tubules showed generally similar immunostaining intensity and pattern for aquaporin 2 indicating that proliferated tubules are of distal origin. On the other hand, renal aquaporin 2 protein level was significantly higher in the db/db than db/m group. Treatment of db/db mice with Cr(pic)3 reduced plasma glucose and hemoglobin A1c (~15-17%, p<0.05) and Ki67 positive cells but other parameters were similar to their untreated counterparts. Collectively, these findings suggest that proliferation of renal distal tubules and increased aquaporin 2 level likely represent an adaptive mechanism to regulate fluid excretion to prevent dehydration in the setting of marked glucosuria in the db/db mouse, features not affected by Cr(pic)3 treatment. These observations are of relevance to increasing interest in developing therapeutic agents that facilitate renal glucose elimination.

Renal and glycemic effects of high-dose chromium picolinate in db/db mice: assessment of DNA damage

This study examined renal and glycemic effects of chromium picolinate [Cr(pic)3] supplementation in the context of its purported potential for DNA damage. In preventional protocol, male obese diabetic db/db mice were fed diets either lacking or containing 5, 10 or 100 mg/kg chromium as Cr(pic)3 from 6 to 24 weeks of age; male lean nondiabetic db/m mice served as controls. Untreated db/db mice displayed increased plasma glucose and insulin, hemoglobin A1c, renal tissue advanced glycation end products, albuminuria, glomerular mesangial expansion, urinary 8-hydroxydeoxyguanosine (an index of oxidative DNA damage) and renal tissue immunostaining for γH2AX (a marker of double-strand DNA breaks) compared to db/m controls. Creatinine clearance was lower in untreated db/db mice than their db/m controls, while blood pressure was similar. High Cr(pic)3 intake (i.e., 100-mg/kg diet) mildly improved glycemic status and albuminuria without affecting blood pressure or creatinine clearance. Treatment with Cr(pic)3 did not increase DNA damage despite marked renal accumulation of chromium. In interventional protocol, effects of diets containing 0, 100 and 250 mg/kg supplemental chromium, from 12 to 24 weeks of age, were examined in db/db mice. The results generally revealed similar effects to those of the 100-mg/kg diet of the preventional protocol. In conclusion, the severely hyperglycemic db/db mouse displays renal structural and functional abnormalities in association with DNA damage. High-dose Cr(pic)3 treatment mildly improves glycemic control, and it causes moderate reduction in albuminuria, without affecting the histopathological appearance of the kidney and increasing the risk for DNA damage.

Insulin sensitizing effects of oligomannuronate-chromium (III) complexes in C2C12 skeletal muscle cells

Background

It was known that the insulin resistance in skeletal muscle is a major pathogenic factor in diabetes mellitus. Therefore prevention of metabolic disorder caused by insulin resistance and improvement of insulin sensitivity are very important for the therapy of type 2 diabetes. In the present study, we investigated the ability of marine oligosaccharides oligomannuronate and its chromium (III) complexes from brown alga to enhance insulin sensitivity in C2C12 skeletal muscle cells.

Methodology/Principal Findings

We demonstrated that oligomannuronate, especially its chromium (III) complexes, enhanced insulin-stimulated glucose uptake and increased the mRNA expression of glucose transporter 4 (GLUT4) and insulin receptor (IR) after their internalization into C2C12 skeletal muscle cells. Additionally, oligosaccharides treatment also significantly enhanced the phosphorylation of proteins involved in both AMP activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) and phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathways in C2C12 cells, indicating that the oligosaccharides activated both the insulin signal pathway and AMPK pathways as their mode of action. Moreover, oligosaccharides distributed to the mitochondria after internalization into C2C12 cells and increased the expression of transcriptional regulator peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), carnitine palmitoyl transferase-1 (CPT-1), and phosphorylated acetyl-CoA carboxylase (p-ACC), which suggested that the actions of these oligosaccharides might be associated with mitochondria through increasing energy expenditure. All of these effects of marine oligosaccharides were comparable to that of the established anti-diabetic drug, metformin. In addition, the treatment with oligosaccharides showed less toxicity than that of metformin.

Conclusions/Significance

Our findings indicate that oligomannuonate and its chromium (III) complexes improved insulin sensitivity in C2C12 skeletal muscle cells, and acted as a novel glucose uptake stimulator with low toxicity, and could be used as dietary supplementary or potential drug for type 2 diabetes mellitus.

Chromium and manganese levels in biological samples of Pakistani myocardial infarction patients at different stages as related to controls

It has been speculated that trace elements may play a role in the pathogenesis of heart diseases In the present study, we aimed to access the levels of chromium (Cr) and manganese (Mn) in biological samples (whole blood, urine, and scalp hair) of myocardial infarction (MI) patients of both gender age ranged (45-60 years) at first, second, and third heart attack (n = 130), hospitalized in cardiac ward of National Hospital of Hyderabad city (Pakistan). For comparison, healthy age-matched referent subjects (n = 61), of both gender were also selected. The Cr and Mn in biological samples were measured by electrothermal atomic absorption spectrometry, prior to microwave-assisted acid digestion. The validity of the methodology was checked by the biological certified reference materials. During this study, 78% of 32 registered patients of third MI attack (aged >50 years) were died. In these subjects the concentration of Cr and Mn were decreased by 24.7% and 19.8% in scalp hair, while in blood samples 17.9% and 12.4%, respectively, as compared to those who tolerated third MI attack (p = 0.063). Although these data do not prove a causal relationship, these results are consistent with the hypothesis that heart disease may cause deficiencies of certain essential trace elements. The excretion levels of Cr and Mn in urine samples of first MCI were higher than controls at p values (0.029 and 0.011), respectively, whereas the excretion rates of both elements were further enhance after second myocardial infarction attack. The Cr and Mn concentration was inversely associated with the risk of myocardial infarction attacks in both genders. These results add to an increasing body of evidence that, Cr and Mn are importance for cardiovascular health.

An assessment of the impact of chromium-amended sediment on a marine nematode assemblage using microcosm bioassays

Microcosms were used to assess the impact of chromium on free-living marine nematodes. Nematodes were exposed to three chromium concentrations (500 ppm (dm, dry mass), 800 ppm (dm) and 1,300 ppm (dm)), and effects were examined after 4 weeks. Results showed significant differences between univariate measures of control nematodes and those from medium- and high-chromium microcosms. Most, decreased significantly with increasing level of chromium contamination. The medium-chromium treatment seems to be the minimal concentration that could has a negative effect on nematodes. Results from multivariate analyses demonstrated that responses of nematode species to chromium treatments were varied: Leptonemella aphanothecae was eliminated at all doses tested and seemed to be intolerant species to chromium; Daptonema normandicum and Sabatieria longisetosa which significantly increased at 500 ppm chromium (dm) appeared to be "opportunistic" species at this dose whereas the two Bathylaimus species (Bathylaimus capacosus and Bathylaimus tenuicaudatus) which increased at all the doses tested seemed to be "chromium resistant". As we think such "opportunistic" and "resistant" species could be used as sensitive indicators of unsafe marine food. The use of microcosms has allowed the effects of the chromium on nematodes to be assessed individually, which was not possible in the field.

Beneficial effect of chromium supplementation on glucose, HbA1C and lipid variables in individuals with newly onset type-2 diabetes

PROJECT

Chromium is an essential nutrient involved in normal carbohydrate and lipid metabolism. It influences glucose metabolism by potentiating the action as taking part in insulin signal amplification mechanism. A placebo-controlled single blind, prospective study was carried out to investigate the effect of chromium supplementation on blood glucose, HbA(1)C and lipid profile in newly onset patients with type-2 diabetes.

PROCEDURE

Total 40 newly onset type-2 diabetics were selected and after 1 month stabilization further randomly divided into two groups viz. study group and placebo group. The study group received 9 g brewer's yeast (42 μg Cr) daily and the other placebo group received yeast devoid of chromium for 3 months. Subjects were instructed not to change their normal eating and living habits. Fasting blood glucose, HbA(1)C and lipid profile were analyzed at beginning and completion of the study.

RESULTS

Results revealed that fasting blood glucose level significantly reduced in the subjects consuming yeast supplemented with chromium (197.65±6.68 to 103.68±6.64 mg/dL; p<0.001). HbA(1)C values improved significantly from 9.51±0.26% to 6.86±0.28%; p<0.001 indicating better glycaemic control. In experimental group total cholesterol, TG and LDL levels were also significantly reduced from 199.66±3.11 to 189.26±3.01 mg/dL; p<0.02, 144.94±8.31 to 126.01±8.26; p<0.05 and 119.19±1.71 to 99.58±1.10; p<0.001 respectively.

CONCLUSIONS

These data demonstrate beneficial effect of chromium supplementation on glycaemic control and lipid variables in subjects with newly onset type-2 diabetes.

Competitive binding of Fe3+, Cr3+, and Ni2+ to transferrin

Competitive binding of Fe(3+), Cr(3+), and Ni(2+) to transferrin (Tf) was investigated at various physiological iron to Tf concentration ratios. Loading percentages for these metal ions are based on a two M(n+) to one Tf (i.e., 100% loading) stoichiometry and were determined using a particle beam/hollow cathode-optical emission spectroscopy (PB/HC-OES) method. Serum iron concentrations typically found in normal, iron-deficient, iron-deficient from chronic disease, iron-deficient from inflammation, and iron-overload conditions were used to determine the effects of iron concentration on iron loading into Tf. The PB/HC-OES method allows the monitoring of metal ions in competition with Fe(3+) for Tf binding. Iron-overload concentrations impeded the ability of chromium (15.0 μM) or nickel (10.3 μM) to load completely into Tf. Low Fe(3+) uptake by Tf under iron-deficient or chronic disease iron concentrations limited Ni(2+) loading into Tf. Competitive binding kinetic studies were performed with Fe(3+), Cr(3+), and Ni(2+) to determine percentages of metal ion uptake into Tf as a function of time. The initial rates of Fe(3+) loading increased in the presence of nickel or chromium, with maximal Fe(3+) loading into Tf in all cases reaching approximately 24%. Addition of Cr(3+) to 50% preloaded Fe(3+)-Tf showed that excess chromium (15.0 μM) displaced roughly 13% of Fe(3+) from Tf, resulting in 7.6 ± 1.3% Cr(3+) loading of Tf. The PB/HC-OES method provides the ability to monitor multiple metal ions competing for Tf binding and will help to understand metal competition for Tf binding.

Alternative and complementary treatments for metabolic syndrome

Metabolic syndrome is defined by a cluster of cardiovascular disease risk factors that are associated with insulin resistance. In recent years, a number of innovative nutritional strategies have been proposed as safe alternative treatments to reduce the morbidity as well as the cost of treating metabolic syndrome. Of these, dietary supplementation with chromium picolinate or cinnamon extract has been studied most extensively. These interventions may attenuate insulin resistance and reduce the cardiovascular risk factors that together comprise the metabolic syndrome. However, more clinical trials are needed to determine the dose and duration of such treatments to make specific recommendations for populations with metabolic syndrome.

The way of serum chromium utilization may contribute to cardiovascular risk factors in centrally obese persons

INTRODUCTION

Obesity-related disturbances are considered to be risk factors for cardiovascular disease (CVD). Chromium is shown to improve carbohydrate and lipid metabolism. Conflicting data on effects of chromium supplementation in humans are published. The aim of the study was to assess the concentrations of serum chromium during the 75-g oral glucose tolerance test (OGTT) in obese persons.

MATERIAL AND METHODS

Fourty-eight centrally obese Caucasians, apparently healthy, using neither special diet nor mineral supplementation, were enrolled in the study. During the OGTT, 0-min and 120-min concentrations of plasma glucose (G 0', G 120'), serum insulin (Ins 0', Ins 120') and chromium (Cr 0', Cr 120') were determined. Plasma lipids, apolipoproteins A and B, and serum uric acid were measured at 0 min only. For parameters assessed during the OGTT, the difference D = [(120' concentration) - (0' concentration)] was calculated. Contradictory tendencies of Cr 120' were observed; thus the difference of serum chromium concentrations, DCr = [(Cr 120') - (Cr 0')], was used to establish the positive DCr group with DCr > 0 (PosDCr: n= 24; 9 male/15 female) and the negative DCr group with DCr < 0 (NegDCr: n= 24; 8 male/16 female).

RESULTS

The studied groups were comparable as far as their metabolic parameters are concerned, except higher G 120' (p= 0.043) and DG (p = 0.048), and lower Cr 120' (p < 0.000), which were observed in the NegDCr group. The NegDCr persons showed inverse correlations between Cr 0' and systolic and diastolic blood pressure.

CONCLUSIONS

We suggest that the studied centrally obese persons differed in chromium metabolism. In subjects "consuming" Cr during the OGTT, chromium status may be associated with increased risk for CVD.

Chromium dinicocysteinate supplementation can lower blood glucose, CRP, MCP-1, ICAM-1, creatinine, apparently mediated by elevated blood vitamin C and adiponectin and inhibition of NFkappaB, Akt, and Glut-2 in livers of zucker diabetic fatty rats

Chromium and cysteine supplementation can improve glucose metabolism in animal studies. This study examined the hypothesis that a cysteinate complex of chromium is significantly beneficial than either of them in lowering blood glucose and vascular inflammation markers in Zucker diabetic fatty (ZDF) rats. Starting at the age of 6 wk, ZDF rats were supplemented orally (daily gavages for 8 more weeks) with saline-placebo (D) or chromium (400 microg Cr/Kg body weight) as chromium dinicocysteinate (CDNC), chromium dinicotinate (CDN) or chromium picolinate (CP) or equimolar L-cysteine (LC, img/Kg body weight), and fed Purina 5008 diet for 8 wk. ZDF rats of 6 wk age before any supplementations and onset of diabetes were considered as baseline. D rats showed elevated levels of fasting blood glucose, HbA(1), CRP, MCP-1, ICAM-1 and oxidative stress (lipid peroxidation) and lower adiponectin and vitamin C, when compared with baseline rats. In comparison to D group, CDNC group had significantly lower blood glucose, HbA(1), CRP, MCP-1, ICAM-1 and lipid peroxidation and increased vitamin C and adiponectin levels. CDN, CP or LC showed significantly less or no effect on these biomarkers. Only CDNC lowered blood creatinine levels in comparison to D. While CDN and CP had no effect, activation of NFkappaB, Akt and glucose transporter-2 levels were decreased, insulin receptor substrate 1 (IRS-1) activation increased in livers of CDNC-rats. CDNC effect on glycemia, NFkappaB, Akt and IRS-1 in liver was significantly greater compared with LC. Blood chromium levels did not differ between Cr-groups. Exogenous vitamin C supplementation significantly inhibited MCP-1 secretion in U937 monocytes cultured in high-glucose-medium. CDNC is a potent hypoglycemic compound with anti-inflammatory activity apparently mediated by elevated blood vitamin C and adiponectin and inhibition of NFkappaB, Akt, and Glut-2 and increased IRS-1 activation in livers of type 2 diabetic rats.

Effects of chromium picolinate on vascular reactivity and cardiac ischemia-reperfusion injury in spontaneously hypertensive rats

Chromium picolinate [Cr(pic)(3)] is a nutritional supplement widely promoted to exert beneficial metabolic effects in patients with type 2 diabetes/impaired glucose tolerance. Frequent comorbidities in these individuals include systemic hypertension, abnormal vascular function and ischemic heart disease, but information on the effects of the supplement on these aspects is sparse. Utilizing male spontaneously hypertensive rats (SHR), we examined the potential impact of Cr(pic)(3) on blood pressure, vascular reactivity and myocardial ischemia-reperfusion injury (IRI). Dietary Cr(pic)(3) supplementation (as 10 mg chromium/kg diet for six weeks) did not affect blood pressure of the SHR. Also, neither norepinephrine (NE) and potassium chloride (KCl)-induced contractility nor sodium nitroprusside (SNP)-induced relaxation of aortic smooth muscle from the SHR was altered by Cr(pic)(3) treatment. However, Cr(pic)(3) augmented endothelium-dependent relaxation of aortas, produced by acetylcholine (ACh), and this effect was abolished by N-nitro-L-arginine methyl ester (L-NAME), suggesting induction of nitric oxide (NO) production/release. Treatment with Cr(pic)(3) did not affect baseline coronary flow rate and rate-pressure-product (RPP) or infarct size following regional IRI. Nonetheless, Cr(pic)(3) treatment was associated with improved coronary flow and recovery of myocardial contractility and relaxation following ischemia-reperfusion insult. In conclusion, dietary Cr(pic)(3) treatment of SHR alters neither blood pressure nor vascular smooth muscle reactivity but causes enhancement of endothelium-dependent vasorelaxation associated with NO production/release. Additionally, while the treatment does not affect infarct size, it improves functional recovery of the viable portion of the myocardium following IRI.

Chromium-induced genotoxicity and interference in human lymphoblastoid cell (TK6) repair processes

Two model chromium (Cr) compounds, one hexavalent (sodium chromate) and one trivalent (chromium chloride), were investigated in a human lymphoblastoid cell line (TK6) to increase our knowledge regarding Cr-induced genotoxicity mechanisms. Both selected compounds were genotoxic using the comet assay, although the percentage of DNA in tail obtained after treatment with Cr(VI) was significantly higher than that obtained with Cr(III), at the higher concentrations tested. To determine the nature of the induced damage, enzymes recognizing oxidized bases were used. Treatments with formamidopyrimidine (FPG) and endonuclease III (EndoIII) displayed a greater degree of DNA damage, indicating that the induction of oxidized bases accounts for an important proportion of the damage induced by Cr compounds. In addition, the kinetic repair studies showed that generated DNA damage is removed in approximately 8 h, with the damage induced by Cr(III) being removed/repaired more rapidly than damage produced by Cr(VI). To detect Cr interferences with the repair process, a post-treatment was applied after exposure to 2 Gy gamma radiation. Post-treatment significantly delayed the repair kinetics of DNA damage induced by radiation. This interference effect induced by Cr(VI) was more pronounced. In conclusion, evidence indicates that a high proportion of the Cr-induced DNA damage is correlated with oxidative damage, and that both Cr compounds interfere with repair mechanisms involved in repair of DNA damage induced by gamma radiation.

Oral administration of the high-chromium yeast improve blood plasma variables and pancreatic islet tissue in diabetic mice

The in vivo effects of oral administration of the high-chromium yeast to healthy and diabetic mice are described. Given that these complexes are proposed to function by potentiating the actions of insulin and activating the insulin receptor kinase, changes in lipid and carbohydrate metabolism would be expected. After 15 weeks administration (500 μg Cr/kg body mass) to healthy mice, abnormal metabolism and pathological change were not observed. After 15 weeks of treatment (0-1,000 μg Cr/kg body mass) of diabetic mice, the effect of high-chromium yeast on blood lipids and blood glycosylated hemoglobin (GHb) of diabetes are not consistent. High-chromium yeast results in a lowering (P < 0.05) of GHb and triglyceride, lowering (P < 0.01) of total cholesterol, and restoration (P < 0.01) of insulin; these results are in stark contrast to those of diabetic mice of administration of normal yeast, which have no effect on these parameters and serve as control group. The histopathological analysis of pancreas islet shows that high-chromium yeast could profoundly protect the impaired pancreatic islet and β-cells from inflammatory infiltration and fibrosis.

A pilot study of chromium picolinate for weight loss

BACKGROUND

Chromium is an essential trace element and nutritional supplement that has garnered interest for use as a weight loss aid.

OBJECTIVE

This trial assesses the effects of chromium picolinate supplementation, alone and combined with nutritional education, on weight loss in apparently healthy overweight adults.

DESIGN

This was a randomized, double-blind, placebo-controlled trial of 80 otherwise healthy, overweight adults assessed at baseline for central adiposity measured by computerized tomography. Subjects were randomly assigned to daily ingestion of 1000 microg of chromium picolinate or placebo for 24 weeks. All subjects received passive nutritional education at the 12-week point in both the intervention and control groups. Outcomes include weight, height, blood pressure, percent body fat, serum, and urinary biomarkers.

RESULTS

At baseline, both the chromium and placebo groups had similar mean body mass index (BMI) (chromium = 36 +/- 6.7 kg/m(2) versus placebo = 36.1 +/- 7.6 kg/m(2); p = 0.98). After 12 weeks, no change was seen in BMI in the intervention as compared to placebo (chromium = 0.3 +/- 0.8 kg/m(2) versus placebo = 0.0 +/- 0.4 kg/m(2); p = 0.07). No change was seen in BMI after 24 weeks in the intervention as compared to placebo (chromium = 0.1 +/- 0.2 kg/m(2) versus placebo = 0.0 +/- 0.5 kg/m(2); p = 0.81). Variation in central adiposity did not affect any outcome measures.

CONCLUSIONS

Supplementation of 1000 microg of chromium picolinate alone, and in combination with nutritional education, did not affect weight loss in this population of overweight adults. Response to chromium did not vary with central adiposity.

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

The objective of the study was to provide a comprehensive evaluation of chromium (Cr) supplementation on metabolic parameters in a cohort of type 2 diabetes mellitus subjects representing a wide phenotype range and to evaluate changes in "responders" and "nonresponders." After preintervention testing to assess glycemia, insulin sensitivity (assessed by euglycemic clamps), Cr status, and body composition, subjects were randomized in a double-blind fashion to placebo or 1000 microg Cr. A substudy was performed to evaluate 24-hour energy balance/substrate oxidation and myocellular/intrahepatic lipid content. There was not a consistent effect of Cr supplementation to improve insulin action across all phenotypes. Insulin sensitivity was negatively correlated to soleus and tibialis muscle intramyocellular lipids and intrahepatic lipid content. Myocellular lipids were significantly lower in subjects randomized to Cr. At preintervention, responders, defined as insulin sensitivity change from baseline of at least 10% or greater, had significantly lower insulin sensitivity and higher fasting glucose and A(1c) when compared with placebo and nonresponders, that is, insulin sensitivity change from baseline of less than 10%. Clinical response was significantly correlated (P < .001) to the baseline insulin sensitivity, fasting glucose, and A(1c). There was no difference in Cr status between responder and nonresponders. Clinical response to Cr is more likely in insulin-resistant subjects who have more elevated fasting glucose and A(1c) levels. Chromium may reduce myocellular lipids and enhance insulin sensitivity in subjects with type 2 diabetes mellitus who do respond clinically independent of effects on weight or hepatic glucose production. Thus, modulation of lipid metabolism by Cr in peripheral tissues may represent a novel mechanism of action.

Current concepts about chromium supplementation in type 2 diabetes and insulin resistance

Chromium has been established to be an essential trace element in mammals in regard to maintenance of normal carbohydrate metabolism. Studies that provided chromium to human subjects in documented deficiency states noted improved glucose levels. However, controversy exists as to whether dietary supplementation with chromium should be routinely recommended in subjects without documented deficiencies. Over the recent past, several well-designed clinical trials have provided evidence in favor of and against a beneficial effect of chromium. It appears that across all subject phenotypes (eg, lean and obese, insulin sensitive and insulin resistant), a consistent significant and beneficial effect of chromium may not be observed. Specifically, recent data fail to demonstrate significant improvement in carbohydrate metabolism in individuals with metabolic syndrome, impaired glucose tolerance, or consistently in individuals with type 2 diabetes. However, patient selection may be an important factor in determining clinical response, as it was concluded that a clinical response to chromium (ie, decreased glucose and improved insulin sensitivity) may be more likely in insulin-resistant individuals with type 2 diabetes who have more elevated fasting glucose and hemoglobin A(1c) levels.

Effects of chromium picolinate on glycemic control and kidney of the obese Zucker rat

Background

Chromium picolinate (Cr(pic)3) is advocated as adjuvant therapy for impaired glycemic control, despite concerns for DNA damage. Potential toxicity of Cr(pic)3 should be greater for the kidney that accumulates chromium. Therefore, we tested the hypothesis that Cr(pic)3 treatment of obese Zucker rats (OZR) exacerbates renal abnormalities associated with dysglycemia.

Methods

Male OZR were treated with diets lacking or containing 5 and 10 mg/kg of chromium, as Cr(pic)3, for 20 weeks; lean Zucker rats (LZR) served as controls. Glycemic and renal effects of Cr(pic)3 were determined in the context of indices of oxidative stress and inflammation.

Results

The OZR displayed increased fasting plasma glucose and insulin in association with enlarged pancreatic islets exhibiting collagen and periodic acid Schiff-positive deposits compared to LZR; Cr(pic)3 treatment did not affect these parameters. The OZR, irrespective of Cr(pic)3, excreted more albumin than LZR. Also, other indices of renal function or histopathology were not affected by Cr(pic)3 treatment. Urinary excretion of 8-hydroxydeoxyguanosine (8-OHdG), an index of oxidative DNA damage, was greater in the OZR than LZR; dietary Cr(pic)3 treatment attenuated 8-OHdG excretion. However, immunostaining of kidney for 8-OHdG revealed similar staining pattern and intensity, despite significant renal accumulation of chromium in Cr(pic)3-treated groups. Finally, increased renal nitrotyrosine and cyclooxygenase-2 levels and urinary excretion of monocyte chemoattractant protein-1 of OZR were partially reversed by Cr(pic)3 treatment.

Conclusion

Dietary Cr(pic)3 treatment of OZR does not beneficially influence glycemic status or increase the risk for oxidative DNA damage; rather, the treatment attenuates indices of oxidative stress and inflammation.