Effects of chromium supplementation on fasting insulin levels and lipid parameters in healthy, non-obese young subjects

Parametric optimization of hexavalent chromium removal by electrocoagulation technology with vertical rotating cylindrical aluminum electrodes using Taguchi and ANN model

This study aims to evaluate the performance of rotating aluminum electrodes in the electrocoagulation reactor for removing hexavalent chromium (Cr6+) from synthetic tannery wastewater. Taguchi and Artificial Neural Network (ANN) based models were developed to obtain the optimum condition for maximum Cr6+ removal. The optimum working condition obtained by Taguchi approach for the maximum Cr6+ removal (94%) was: Initial Cr6+ concentration (Cr6+ i) = 15 mg/L; Current Density (CD) = 14.25 mA/cm2; Intial pH = 5; Rotational Speed of Electrode (RSE) = 70 rpm. In contrast, the optimal condition for maximum Cr6+ ions removal (98.83%) obtained from the BR-ANN model was: Cr6+ i = 15 mg/L; CD = 14.36 mA/cm2; pHi = 5.2; RSE = 73 rpm. Compared to the Taguchi model, the BR-ANN model outperformed in terms of providing higher Cr6+ removal (+ 4.83%); reduced energy demand (-0.035 KWh/gm Cr6+ remove); lower error function value (χ2 = -7.9674 and RMSE = -3.5414); and highest R2 value (0.9991). The data for the conditions 91,007 < Re < 227,517 and Sc = 102.834 were found to fit the equation for the initial Cr6+ concentration of 15 mg/l; Sh = 3.143Re0.125 Sc0.33. The Cr6+ removal kinetics was best described by Pseudo 2nd Order model, as validated by high R2 and lower error functions value. The SEM and XRF analysis confirmed that Cr6+ was adsorbed and precipitated along with metal hydroxide sludge. The rotating electrode led to lower SEEC (10.25 kWh/m3), as well as maximum Cr6+ removal (98.83%), compared to EC process with stationary electrodes.

The effects of chromium supplementation on lipidprofile in humans: A systematic review and meta-analysis ofrandomized controlled trials

BACKGROUND AND AIM

This systematic review and meta-analysis aimed to evaluate the effects of chromium supplementation on lipid profile consisting of total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), high-density lipoprotein (HDL) and very low-density lipoprotein (VLDL) in humans.

METHODS

The PubMed/Medline, Scopus, Web of sciences, Google Scholar and Cochrane library were systematically searched for randomised control trails (RCTs) available which published before August 2020. The meta-analysis was conducted using Random or fixed-effects models, and between-study heterogeneity was assessed by I².

RESULTS

Thirty-eight studies comprising 41 treatment arms and 7605 participants included to the present meta-analysis. Our results of overall analysis show only a significant reduction in serum TC level in response to chromium supplementation (WMD: -0.17 mmol/l, 95 % CI: -0.27, -0.07, P = 0.001). In accordance with the results of the subgroup analyses, the lowering-effect of chromium supplementation may be synergist during short-term (less than 12 weeks), low dose (less than 200), diabetics patient, younger adults (less than 54 years) and picolinate and elemental form for TC, older and non-obese subjects (>54 years and ≤ 29 kg/m2, respectively), women, Asian and Australian and picolinate form for TG, short-term, low dose, non-obese subjects, women, and Asian for VLDL, and nicotinate form for HDL-C, but had no effect on LDL-C.

CONCLUSION

Our meta-analysis reveals that there was only an overall significant association between chromium supplementation with decreases in the concentration of TC. Additionally, we found considerable evidence of subgroup analysis that support a significant lowering effect of chromium supplementation on TC, TG and VLDL. Further RCTs with short-term and low dose chromium supplementation in subjects with diabetes are necessitated for a firm conclusion of the lipid-modulating properties.

The effect of chromium supplementation on apolipoproteins: A systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Apos play a role in lipoprotein metabolism. Several studies have been carried out on the effect of chromium supplement in improving CVD risk factors.

OBJECTIVE

This study is a systematic review and meta-analysis that aimed to investigate the effect of chromium supplementation on Apos levels of human studies.

MATERIALS AND METHODS

We searched PubMed, Scopus up to May 2020 up to September 2019. We retrieved studies from identified articles. The studies' quality was evaluated using Cochrane Risk of Bias Tool. We estimated the effect of chromium supplementation on Apo A, Apo A1, and Apo B by pooling mean and standard deviation (SD) values.

RESULTS

We obtained six trials involving 231 participants. Chromium consumption resulted significantly decreased Apo B while the subjects were ingesting chromium picolinate. Chromium supplementation did not significantly decrease Apo A (WMD: -3.89 mg/dl; 95% CI, -11.96 to 4.18) with no significant heterogeneity (I² = 0.00%, p = 0.37). The serum level of Apo A1 did not statistically change following chromium intervention (WMD: 6.11 mg/dl; 95% CI, -7.01 to 19.23) with no significant heterogeneity (I² = 0.00%, p = 0.68). Chromium supplementation did not significantly decrease Apo B (WMD: 3.81 mg/dl; 95% CI, -5.32 to 12.94). With no significant heterogeneity (I² = 42.3%, p = 0.12).

CONCLUSIONS

The chromium supplement did not have a significant effect on the Apolipoproteins (Apo A, ApoA1 and Apo B).

Association of twenty-three plasma elements with fasting serum glucose among Chinese population from four areas with different pollution level

BACKGROUND

Association between fasting serum glucose (FSG) and certain mineral elements has been extensively reported. Investigation regarding multi-element exposure among subjects with different exposure level is warranted to confirm the association and further explore dose-dependent relationship.

METHODS

A total of 3488 participants were recruited from four counties of Hunan province, South China. Basic characteristics were collected by face to face interview and 23 elements in plasma were determined by inductively coupled plasma mass spectrometry. We applied fully adjusted generalized linear regression model and multivariable restricted cubic spline function to test the association and dose-response relationship of FSG with 23 elements.

RESULTS

The results indicated that FSG was positively associated with plasma78selenium level [regression coefficient (β), 0.001; 95 % confidence interval (CI), 0.001, 0.001] in a dose-dependent manner, robust to the adjustment for suspected covariates and stratification by age, gender, BMI and smoking status. A negative association was found between FSG and plasma 208lead (β, -0.004; 95 % CI, -0.016, -0.002), 52chromium (β, -0.002; 95 % CI, -0.004, -0.001) and 47titanium (β, -0.001; 95 % CI, -0.002, -0.001).

CONCLUSION

78selenium was positively while 208lead, 52chromium and 47titanium were negatively associated with FSG in the present study. However, prospective studies are needed to confirm the results.

Chromium Supplementation; Negotiation with Diabetes Mellitus, Hyperlipidemia and Depression

Chromium (Cr) is an essential trace element which found naturally in a daily diet and available in the form of supplementary tablets to boost disorders like diabetes mellitus (DM) and functions like lipid metabolism and beneficial on depression too. Diabetes is one of the most prevalent endocrine diseases or in other words, the most severe metabolic syndrome (MS), which associated with high production of free-radicals which is out of bodies detoxifying machine capacity or high oxidative stress (HOS), vasculitis and elevated lipid profile. many research papers and clinical trials published about the significance of chromium on biological activities, pre and post clinical. For this review research articles, clinical trials, from 1^st Jan'10 to 31^st Dec'18 and refer literature for the biochemical, pharmacological and biological activity of Chromium. Primarily articles gathered from the above search engines. Then precisely according to our aim and goal and regarding designed objectives dismisses similar articles and finally came to 84 articles for the above said period. This review trying to cover the entire picture from what chromium is to the recent updates on their greater role in increasing insulin sensitivity of cells and enhancing lipid metabolism and even recent findings suggest its positive effects including prevention and ameliorating properties on depression. The biological activities, pharmacological features, clinical implications including efficacy and role of chromium compounds on the glycaemic index will be discussed. The outcome of this review is to bring the pros and cons of chromium supplementation along with is safety and toxicity concern beside molecular pathways, biochemistry and clinical trials, all in one comprehensive review.

Nanofiltration and microfiltration for the removal of chromium, total dissolved solids, and sulfate from water

This study was designed to evaluate the hybrid system performance of nanofiltration (NF) and microfiltration (MF) processes in removing the hexavalent chromium (Cr(VI)) and sulfate from water. To do so, we made a hybrid pilot, including 1 μm and 5 μm filters, sand filter, activated carbon filters, and a nanofilter. We studied the effects of various parameters on the removal of Cr(VI) from polluted water and drinking water such as pH, pressure, concentrations of chromium, concentrations of sulfate, and total dissolved solids (TDS). The selected parameters were as follows: pressure: 0.1-0.4 MPa, pH: 2–10, Cr(VI) concentration: 0.1–0.4 mg/l, and sulfate concentration: 40–500 mg/l. According to the results, the efficiency of chromium removal increased with increasing the pH, while increasing the pressure from 0.1 to 0.4 MPa decreased the removal rate of chromium. In addition, increasing the concentrations of sulfate led to a decreasing trend in the removal efficiency. According to the findings of the study, the hybrid pilot made is able to reduce the chromium and sulfate to the levels under the WHO standard (Cr(VI) = 0.05 mg/l and sulfate = 500 mg/l).

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The optimal conditions for removal of Cr(VI) included the initial chromium concentration of 0.1 mg/l, pressure of 0.1 Mpa, pH of 10, and the sulfate concentration of 40 mg/l.

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In general, the experimental results revealed that the fabricated hybrid system including MF, NF, sand filter, and carbon filter has the ability to remove chromium and sulfate from drinking water (tap water) at a rate of 99%.

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At sulfate concentration of 40 mg/l, the TDS elimination efficiency was 97.75% and increased by 99.87% as the concentration increased to 500 mg/l. The presence of sulfate ions increases the TDS in water.

2,3-Pyridine dicarboxylic acid functionalized gold nanoparticles: Insight into experimental conditions for Cr3+ sensing

Selectivity of gold nanoparticles (AuNPs) depends upon surface functionality; small changes in structure or concentration bring significant changes in the behavior of AuNPs. In this study, citrate-capped AuNPs were functionalized with ortho-dicarboxylate substituted pyridine (2,3-PDCA) and detailed studies on experimental conditions were carried out to check the stability of AuNPs and response for Cr³⁺. Stability of PDCA-AuNPs was found sensitive to the pH, ionic strength of buffer and its type. Capping behavior of PDCA on C-AuNPs was examined by FTIR spectroscopy. Surface morphology and size of synthesized AuNPs were confirmed by AFM, XRD, and DLS techniques where particles were found 11nm in size, monodisperse and spherical in shape. Interaction of stabilized AuNPs was tested with various metal ions; where Cr³⁺ induced the changes in localized surface plasmon band (LSPR) of PDCA-AuNPs which leads to a color change from wine red to violet blue. The phenomenon is explained as cooperative effect of citrate and pyridine nitrogen on surface of AuNPs in contrary to meta-dicarboxylate substituted pyridine derivatives. Further, under optimized and controlled conditions Cr³⁺ shows linear response with decrease in absorbance at LSPR intensity of AuNPs (518nm). Moreover, to demonstrate the applicability of method, Cr³⁺ was determined in the presence of Cr (VI) which shows 96% recovery.

Survey of Alternative Medicine Use among Organ Transplant Patients

Herbal medicine and health food supplements have become increasingly popular. However, many of these pharmacologically active compounds remain poorly understood. Patients with chronic and life-threatening conditions often use alternative therapies while receiving conventional medical care, and this population is at increased risk for complications and adverse drug interactions due to poor health and complex drug regimens. Patients awaiting or who had received solid organ transplants were surveyed about their use of herbal medicines and health food supplements. Twenty percent of respondents acknowledged experience with these products, which they used to prolong the function of a failing organ or to obtain relief from fatigue and insomnia. Transplant staff often were unaware of their patients' use of these treatments, despite patients' claims to the contrary. The potential for unexpected drug interactions, toxicity, and other adverse reactions resulting from the use of herbal medicines or supplements must be recognized and identified by transplant teams.

The adipogenic potential of Cr(III). A molecular approach exemplifying metal-induced enhancement of insulin mimesis in diabetes mellitus II

Insulin resistance is identified through numerous pathophysiological conditions, such as Diabetes mellitus II, obesity, hypertension and other metabolic syndromes. Enhancement of insulin action and\or its complete replacement by insulin-enhancing or insulin-mimetic agents seems to improve treatment of metabolic diseases. Over the last decades, intensive research has targeted the investigation of such agents, with chromium emerging as an important inorganic cofactor involved in the requisite metabolic chemistry. Chromium in its trivalent state has been shown to play a central role in carbohydrate metabolism by enhancing insulin signaling, action, and thus the sensitivity of insulin-sensitive tissues. A very likely link between diabetes and obesity is the adipose tissue, which stores energy in the form of triglycerides and releases free fatty acids. To date, there is paucity of information on the exact mechanism of the chromium effect concerning insulin-activated molecular paths, such as adipogenesis. The aim of the present study is to delve into such an effect by employing a well-defined form of chromium (Cr(III)-citrate) on the a) survival of pre- and mature adipocytes (3T3-L1), b) endogenous cell motility, and c) insulin-enhancing adipogenic capacity. The emerging results suggest that Cr(III)-citrate a) is (a)toxic in a concentration- and time-dependent manner, b) has no influence on cell motility, c) can induce 3T3-L1 pre-adipocyte differentiation into mature adipocytes through elevation of tissue specific biomarker levels (PPAR-γ, GLUT 4 and GCK), and d) exemplifies structurally-based metal-induced adipogenesis as a key process contributing to the development of future antidiabetic metallodrugs.

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.

Chromium chloride increases insulin-stimulated glucose uptake in the perfused rat hindlimb

AIM

To determine the effect of chromium chloride (CrCl3 ) on healthy skeletal muscle glucose uptake in the absence and presence of submaximal insulin using the rat hindlimb perfusion technique.

METHODS

Sprague-Dawley rats were randomly assigned to an experimental group: basal (Bas), chromium chloride (Cr), submaximal insulin (sIns) or chromium chloride plus submaximal insulin (Cr-sIns).

RESULTS

Insulin significantly increased [H(3)]-2 deoxyglucose (2-DG) uptake in the gastrocnemius muscles. Additionally, Cr-sIns displayed greater rates of 2-DG uptake than sIns (Cr-sIns 6.86 ± 0.74 μmol g h(-1) vs. sIns 4.83 ± 0.42 μmol g h(-1)). There was no difference between Cr and Bas treatment groups. It has been speculated that chromium works to increase glucose uptake by increasing insulin signalling. We found that Akt and AS160 phosphorylation was increased in the sINS treatment group, while chromium treatment had no additional effect on Akt or AS160 phosphorylation in the absence or presence of insulin. Cr-sIns significantly increased plasma membrane GLUT4 concentration above that of sIns (Cr-sIns 72.22 ± 12.7%, sIns 53.4 ± 6.1%), but in the absence of insulin, chromium had no effect.

CONCLUSION

Exposure of healthy skeletal muscle to chromium may increase skeletal muscle insulin-stimulated GLUT4 translocation and glucose uptake. However, these effects do not appear to result from enhanced insulin signalling proximal to AS160.

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.

Chromium picolinate supplementation for overweight or obese adults

BACKGROUND

Obesity is a global public health threat. Chromium picolinate (CrP) is advocated in the medical literature for the reduction of bodyweight, and preparations are sold as slimming aids in the USA and Europe, and on the Internet.

OBJECTIVES

To assess the effects of CrP supplementation in overweight or obese people.

SEARCH METHODS

We searched The Cochrane Library, MEDLINE, EMBASE, ISI Web of Knowledge, the Chinese Biomedical Literature Database, the China Journal Full text Database and the Chinese Scientific Journals Full text Database (all databases to December 2012), as well as other sources (including databases of ongoing trials, clinical trials registers and reference lists).

SELECTION CRITERIA

We included trials if they were randomised controlled trials (RCT) of CrP supplementation in people who were overweight or obese.We excluded studies including children, pregnant women or individuals with serious medical conditions.

DATA COLLECTION AND ANALYSIS

Two authors independently screened titles and abstracts for relevance. Screening for inclusion, data extraction and 'Risk of bias'assessment were carried out by one author and checked by a second. We assessed the risk of bias by evaluating the domains selection,performance, attrition, detection and reporting bias. We performed a meta-analysis of included trials using Review Manager 5.

MAIN RESULTS

We evaluated nine RCTs involving a total of 622 participants. The RCTs were conducted in the community setting, with interventions mainly delivered by health professionals, and had a short- to medium-term follow up (up to 24 weeks). Three RCTs compared CrPplus resistance or weight training with placebo plus resistance or weight training, the other RCTs compared CrP alone versus placebo.We focused this review on investigating which dose of CrP would prove most effective versus placebo and therefore assessed the results according to CrP dose. However, in order to find out if CrP works in general, we also analysed the effect of all pooled CrP doses versus placebo on body weight only.Across all CrP doses investigated (200 μg, 400 μg, 500 μg, 1000 μg) we noted an effect on body weight in favour of CrP of debatable clinical relevance after 12 to 16 weeks of treatment: mean difference (MD) -1.1 kg (95% CI -1.7 to -0.4); P = 0.001; 392 participants;6 trials; low-quality evidence (GRADE)). No firm evidence and no dose gradient could be established when comparing different doses of CrP with placebo for various weight loss measures (body weight, body mass index, percentage body fat composition, change in waist circumference).Only three studies provided information on adverse events (low-quality evidence (GRADE)). There were two serious adverse events and study dropouts in participants taking 1000 μg CrP, and one serious adverse event in an individual taking 400 μg CrP. Two participants receiving placebo discontinued due to adverse events; one event was reported as serious. No study reported on all-cause mortality,morbidity, health-related quality of life or socioeconomic effects.

AUTHORS' CONCLUSIONS

We found no current, reliable evidence to inform firm decisions about the efficacy and safety of CrP supplements in overweight or obese adults.

Chromium Therapy for Insulin Resistance Associated with HIV-Disease

OBJECTIVE

With the advent of highly active anti-retroviral therapy, HIV disease has become a chronic condition, but with a number of metabolic complications including insulin resistance and diabetes mellitus, dyslipidemia and hypertension and an increased incidence of atherosclerosis. The aim of the current study was to test the safety and efficacy of chromium picolinate for HIV- associated insulin resistance.

MATERIALS/METHODS

The study was a randomized, double-blind, placebo-controlled trial with subjects receiving 500μg of chromium picolinate or placebo twice daily for two months. HIV- infected subjects were selected based on a fasting concentration of plasma glucose greater than 5.5mmol/L or a plasma glucose concentration of greater than 7.7mmol/L (but less than 11mmol/L) 2h after oral ingestion of 75g of glucose. Insulin sensitivity was assessed with a hyper-insulinemic-euglycemic clamp and glucose tolerance was assessed with the oral glucose tolerance test. Subjects were monitored closely for alterations in viral load, CD4+ cells, hemoglobin and hematocrit, kidney and liver function, and fasting lipid profiles.

RESULTS

Forty-three subjects were enrolled and 39 completed the protocol (20 in the chromium-supplemented and 19 in the placebo arm). Following chromium-supplementation, there were no significant changes in either insulin sensitivity or glucose tolerance. There was a significant improvement in serum HDL cholesterol concentration in the group supplemented with chromium.

CONCLUSIONS

Chromium picolinate supplementation at this level was well-tolerated, but overall was not an effective therapy for insulin resistance in these HIV-infected subjects.

Chromium supplementation in non-obese non-diabetic subjects is associated with a decline in insulin sensitivity

BACKGROUND

The use of chromium supplements is widespread for the prevention and treatment of diabetes mellitus but there are conflicting reports on efficacy, possibly reflecting discrepant effects across different populations. In the present studies, we test the hypothesis that chromium supplementation raises serum chromium levels and correspondingly improves insulin sensitivity.

METHODS

A double blind placebo-controlled randomized trial was conducted on 31 non-obese, normoglycemic subjects. After baseline studies, the subjects were randomized to placebo or chromium picolinate 500 μg twice a day. The primary endpoint was change in insulin sensitivity as measured by euglycemic hyperinsulinemic clamp. Pre-specified secondary endpoints included fasting lipids, blood pressure, weight, body composition measured by DXA scan.

RESULTS

After 16 weeks of chromium picolinate therapy there was no significant change in insulin sensitivity between groups (p=0.83). There was, however, a strong association between serum chromium and change in insulin resistance (β = -0.83, p=0.01), where subjects with the highest serum chromium had a worsening of insulin sensitivity. This effect could not be explained by changes in physiological parameters such as body weight, truncal fat and serum lipids with chromium therapy.

CONCLUSIONS

Chromium therapy did not improve insulin sensitivity in non-obese normoglycemic individuals. Further, subjects who have high serum chromium levels paradoxically had a decline in insulin sensitivity. Caution therefore should be exercised in recommending the use of this supplement.

TRIAL REGISTRATION

The study was registered on the NIH registry (clinicaltrials.gov) and the identifier is NCT00846248.

Effects of short-term chromium supplementation on insulin sensitivity and body composition in overweight children: randomized, double-blind, placebo-controlled study

Excessive body weight is inversely associated with insulin sensitivity in children and adults. Chromium supplementation produces modest improvement in insulin sensitivity in adults. The aim of this study was to examine the beneficial effects of chromium supplementation on insulin sensitivity and body composition in overweight children simultaneously modifying lifestyle. Twenty-five overweight children aged 9-12 years were randomized to receive either 400 μg of chromium chloride or placebo in double-blind fashion, during a 6-week lifestyle modification regimen that included nutritional education and 3×90 min of aerobic physical activity weekly. Insulin sensitivity was demonstrated using homeostasis model assessment-insulin resistance and quantitative insulin sensitivity check index (QUICKI). Changes in body mass index (BMI; kg/m(2)), BMI Z-score, waist circumference, body composition and fasting plasma glucose were measured. Although no significant benefit of chromium supplementation over placebo was evident for BMI, BMI Z-score and fasting insulin level, children who received chromium chloride demonstrated more positive changes versus the placebo group in HOMA (-1.84±1.07 vs. 0.05±0.42, P=.05), QUICKI (0.02±0.01 vs. -0.002±0.01, P=.05), lean body mass (2.43±0.68 kg vs. 1.36±1.61 kg, P=.02) and percentage body fat (-3.32±1.29% vs. 0.65±1.05%, P=.04). The desirable effects of chromium supplementation on insulin sensitivity and body composition were more apparent in pre-pubertal children. These results suggest that short-term chromium supplementation can improve insulin sensitivity and body composition in overweight children.

Chromium picolinate does not improve key features of metabolic syndrome in obese nondiabetic adults

BACKGROUND

The use of chromium-containing dietary supplements is widespread among patients with type 2 diabetes. Chromium's effects in patients at high risk for developing diabetes, especially those with metabolic syndrome, is unknown. The objective of this study was to determine the effects of chromium picolinate (CrPic) on glucose metabolism in patients with metabolic syndrome.

METHOD

A double-blind, placebo-controlled, randomized trial was conducted at a U.S. academic medical center. Sixty three patients with National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III)-defined metabolic syndrome were included. The primary end point was a change in the insulin sensitivity index derived from a frequently sampled intravenous glucose tolerance test. Prespecified secondary end points included changes in other measurements of glucose metabolism, oxidative stress, fasting serum lipids, and high sensitivity C-reactive protein.

RESULTS

After 16 weeks of CrPic treatment, there was no significant change in insulin sensitivity index between groups (P = 0.14). However, CrPic increased acute insulin response to glucose (P 0.02). CrPic had no significant effect on other measures of glucose metabolism, body weight, serum lipids, or measures of inflammation and oxidative stress.

CONCLUSION

CrPic at 1000 microg/day does not improve key features of the metabolic syndrome in obese nondiabetic patients.

Chromium picolinate for insulin resistance in subjects with HIV disease: a pilot study

AIM

Multidrug regimens in HIV disease are associated with an increased incidence of insulin resistance, by as much as 50%. Not only does insulin resistance predisposes subjects to diabetes but also it is associated with the metabolic syndrome and increased risk of cardiovascular disease. Previous studies suggest that chromium picolinate can improve insulin resistance in patients with type 2 diabetes. The objective was to study the efficacy and safety of chromium picolinate as a treatment of insulin resistance in subjects infected with HIV.

METHODS

The ability of chromium picolinate (1000 mug/day) to improve insulin sensitivity, determined with a hyperinsulinaemic-euglycaemic insulin clamp, was determined in eight HIV-positive subjects on highly active antiretroviral therapy.

RESULTS

The mean rate of glucose disposal during the clamp was 4.41 mg glucose/kg lean body mass (LBM)/min (range 2.67-5.50), which increased to 6.51 mg/kg LBM/min (range 3.19-12.78, p = .03), an increase of 25% after 8 weeks of treatment with chromium picolinate. There were no significant changes in blood parameters, HIV viral burden or CD4+ lymphocytes with chromium picolinate treatment. Two subjects experienced abnormalities of liver function during the study. Another subject experienced an elevation in blood urea nitrogen.

CONCLUSIONS

The study shows that chromium picolinate therapy improves insulin resistance in some HIV-positive subjects, but with some concerns about safety in this population.

Phenotype of subjects with type 2 diabetes mellitus may determine clinical response to chromium supplementation

Considerable controversy exists regarding the use of chromium (Cr) supplementation to modulate carbohydrate metabolism in subjects with diabetes. Recently, we reported that Cr supplementation, provided as 1000 microg/d as Cr picolinate, enhanced insulin sensitivity in subjects with type 2 diabetes mellitus. Our data agreed with some, but not all, studies that evaluated a similar dose and formulation in type 2 diabetes mellitus and suggested that subject selection and characteristics may be important considerations when assessing the clinical response. Thus, the goal of this study was to assess which metabolic or clinical characteristics, when obtained at baseline, best determine a clinical response to Cr when assessing changes in insulin sensitivity. Seventy-three subjects with type 2 diabetes mellitus were assessed in a double-blinded, randomized, placebo-controlled study. Subjects were assessed at baseline for glycemic control with glycated hemoglobin measures, oral glucose tolerance tests, and body weight and body fat measures (dual-energy x-ray absorptiometry). After baseline, insulin sensitivity in vivo was assessed with the use of hyperinsulinemic-euglycemic clamps. After the baseline clamp, subjects were randomized to receive Cr supplementation (1000 microg Cr/d provided as Cr picolinate) or placebo daily for 6 months. All study parameters were repeated after 6 months. The relationship of the baseline characteristics of the study subjects to the change in insulin sensitivity was determined. Sixty-three percent of the subjects with type 2 diabetes mellitus responded to the Cr treatment as compared with 30% with placebo. The only subject variable significantly associated with the clinical response to Cr was the baseline insulin sensitivity, as assessed with the hyperinsulinemic-euglycemic clamp (partial R(2) = .4038) (P = .0004). Subject phenotype appears to be very important when assessing the clinical response to Cr because baseline insulin sensitivity was found to account for nearly 40% of the variance in the clinical response to Cr.

Effect of chromium supplementation on glucose metabolism and lipids: a systematic review of randomized controlled trials

OBJECTIVE

A systematic review of the effect of chromium supplementation on glucose metabolism and lipid levels.

RESEARCH DESIGN AND METHODS

A literature search was conducted in MEDLINE and the Commonwealth Agricultural Bureau. Eligible studies were English language randomized controlled trials of chromium supplement intake > or = 3 weeks, with > or = 10 participants receiving chromium. All trials with glucose metabolism outcomes and trials of individuals with diabetes or glucose intolerance for lipid outcomes were included. Meta-analyses were performed as appropriate.

RESULTS

Forty-one studies met criteria, almost half of which were of poor quality. Among participants with type 2 diabetes, chromium supplementation improved glycosylated hemoglobin levels by -0.6% (95% CI -0.9 to -0.2) and fasting glucose by -1.0 mmol/l (-1.4 to -0.5) but not lipids. There was no benefit in individuals without diabetes. There were some indications of dose effect and differences among chromium formulations. Larger effects were more commonly observed in poor-quality studies. The evidence was limited by poor study quality, heterogeneity in methodology and results, and a lack of consensus on assessment of chromium status.

CONCLUSIONS

No significant effect of chromium on lipid or glucose metabolism was found in people without diabetes. Chromium supplementation significantly improved glycemia among patients with diabetes. However, future studies that address the limitations in the current evidence are needed before definitive claims can be made about the effect of chromium supplementation.

Effects of chromium supplementation on selected metabolic responses in resting and exercising horses

Chromium (Cr) is required for insulin function in the control of cellular glucose uptake. Other functions of Cr relate to its effects on growth, lipid metabolism, immune responses and interactions with nucleic acids. This study was conducted to obtain information on the effect of Cr supplementation on the metabolic responses of five exercising Standardbred horses. During the experiment, horses were fed every day for a 21-day period in a randomized order either a yeast product without Cr (control) or with 4.15 or 8.3 mg Cr day−1. Horses were exercised on a treadmill, alternating a work day of low-speed exercise at 5 m s−1 on a 3% incline for 45 min with a rest day. Each horse was adapted over a 21-day period to his or her respective supplementation before undergoing a standardized exercise test (SET). The SET comprised five incremental steps, each of 4 min duration, on a treadmill with a 3% incline; the first step was at 5 m s−1 and was followed with increments of 1 m s−1. Blood samples were taken for lactate, plasma glucose, serum insulin and cortisol estimation before, during and after each SET (30, 120 min and 24 h post-exercise). Blood Cr was estimated 2 h after feeding the control or Cr-enriched yeast (intake 8.3 mg Cr) in two horses. Heart rate was monitored throughout each SET. Blood lactate and plasma glucose peaks were highest at 8 and 9 m s−1 during the SET when 8.3 mg Cr was supplied. Serum insulin levels declined during the SET and there were no treatment-related changes. Twenty-four hours after exercise, plasma glucose and serum cortisol concentrations returned to basal levels or lower. Serum insulin rebounded 30 min after exercise but 24 h later, serum insulin concentrations were below resting levels. During the recovery period, Cr supplementation did not clearly affect metabolic responses. These results suggest that Cr supplementation had no beneficial effect in healthy, exercising horses.

Conjugated linoleic acid and chromium lower body weight and visceral fat mass in high-fat-diet-fed mice

More than half of the U.S. population has a body mass index of 25 kg/m2 or more, which classifies them as overweight or obese. Obesity is often associated with comorbidities such as diabetes, cardiovascular diseases, and cancer. CLA and chromium have emerged as major dietary supplements that reduce body weight and fat mass, and increase basal metabolic rate in animal models. However, studies show that CLA induces insulin resistance in mice and in humans, whereas Cr improves insulin sensitivity. Hence, we designed the present study to examine the combined effect of CLA and Cr on body composition and insulin sensitivity in a Balb/c mice (n = 10/group) model of high-fat-diet-induced obesity. CLA alone lowered body weight, total body fat mass, and visceral fat mass, the last of which decreased further with the combination of CLA and Cr. This effect was accompanied by decreased serum leptin levels in CLA-fed and CLA + Cr-fed mice, and by higher energy expenditure (EE) and oxygen consumption (OC) in CLA + Cr-fed mice. Serum levels of glucose, insulin, the pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-alpha), and interleukin-6 (IL-6), as well as insulin resistance index (IRI), decreased with CLA, whereas CLA and Cr in combination had significant effects on insulin and IL-6 concentrations and IRI. In summary, CLA + Cr decreased body weight and fat mass in high-fat-diet-fed mice, which may be associated with decreased leptin levels and higher EE and OC.

Chromium picolinate intake and risk of type 2 diabetes: an evidence-based review by the United States Food and Drug Administration

The labeling of both health claims that meet significant scientific agreement (SSA) and qualified health claims on conventional foods and dietary supplements requires pre-market approval by the US Food and Drug Administration (FDA). Approval by the FDA involves, in part, a thorough review of the scientific evidence to support an SSA or a qualified health claim. This article discusses FDA's evidence-based review of the scientific evidence on the role of chromium picolinate supplements in reducing the risk of type 2 diabetes. Based on this evidence-based review, FDA issued a letter of enforcement discretion for one qualified health claim on chromium picolinate and risk of insulin resistance, a surrogate endpoint for type 2 diabetes. The agency concluded that the relationship between chromium picolinate intake and insulin resistance is highly uncertain.

Chromium picolinate enhances skeletal muscle cellular insulin signaling in vivo in obese, insulin-resistant JCR:LA-cp rats

Chromium is one of the few trace minerals for which a specific cellular mechanism of action has not been identified. Recent in vitro studies suggest that chromium supplementation may improve insulin sensitivity by enhancing insulin receptor signaling, but this has not been demonstrated in vivo. We investigated the effect of chromium supplementation on insulin receptor signaling in an insulin-resistant rat model, the JCR:LA-corpulent rat. Male JCR:LA-cp rats (4 mo of age) were randomly assigned to receive chromium picolinate (CrPic) (obese n=6, lean n=5) or vehicle (obese n=5, lean n=5) for 3 mo. The CrPic was provided in the water, and based on calculated water intake, rats randomized to CrPic received 80 microg/(kg.d). At the end of the study, skeletal muscle (vastus lateralis) biopsies were obtained at baseline and at 5, 15, and 30 min postinsulin stimulation to assess insulin signaling. Obese rats treated with CrPic had significantly improved glucose disposal rates and demonstrated a significant increase in insulin-stimulated phosphorylation of insulin receptor substrate (IRS)-1 and phosphatidylinositol (PI)-3 kinase activity in skeletal muscle compared with obese controls. The increase in cellular signaling was not associated with increased protein levels of the IRS proteins, PI-3 kinase or Akt. However, protein tyrosine phosphatase 1B (PTP1B) levels were significantly lower in obese rats administered CrPic than obese controls. When corrected for protein content, PTP1B activity was also significantly lower in obese rats administered CrPic than obese controls. Our data suggest that chromium supplementation of obese, insulin-resistant rats may improve insulin action by enhancing intracellular signaling.

Complementary therapies for diabetes: the case for chromium, magnesium, and antioxidants

A growing body of interest on the possible beneficial role of chromium, magnesium, and antioxidant supplements in the treatment of diabetes has contributed to debate about their value for reaching metabolic control and to prevent chronic complications in diabetic subjects. In this article we use a systematic approach focused on clinically based evidence from clinical trials regarding the benefits of chromium, magnesium, and antioxidant supplements as complementary therapies in type 2 diabetes. Chromium, magnesium, and antioxidants are essential elements involved in the action of insulin and energetic metabolism, without serious adverse effects. However, at present there is insufficient clinically based evidence and its routine use in the treatment of type 2 diabetes is still controversial. Because the most frequent origin of deficiencies in micronutrients is an inadequate diet, health care providers should invest more effort on nutrition counseling rather than focusing on micronutrient supplementation in order to reach metabolic control of their patients. Results from long-term trials are needed in order to assess the safety and beneficial role of chromium, magnesium, and antioxidant supplements as complementary therapies in the management of type 2 diabetes.

Insulin sensitising action of chromium picolinate in various experimental models of diabetes mellitus

Although chromium is an essential element for carbohydrate and lipid metabolism, its effects in diabetic patients are still debated. We have studied the effect of 6 week treatment with chromium picolinate (8 microg/ml in drinking water) in streptozotocin (STZ)-induced type 1 and type 2 diabetic rat models. The mechanism of anti-diabetic action of chromium picolinate was studied using C2C12 myoblasts and 3T3-L1 adipocytes. Chromium picolinate significantly decreased the area under the curve over 120 min for glucose of both STZ-induced type 1 (40mg/kg, i.v. in adult rats) and type 2 (90 mg/kg, i.p. in 2 day old rat neonates) diabetic rats without any significant change in area under the curve over 120 min for insulin as compared to controls. The composite insulin sensitivity index and insulin sensitivity index (KITT) values of both type 1 and type 2 diabetic rats were increased significantly by chromium picolinate. Treatment with chromium picolinate produced a significant decrease in elevated cholesterol and triglyceride levels in both types of diabetic rats. In 3T3-L1 adipocytes, chromium picolinate (0-10 micromol) per se did not produce any effect, however, when co-incubated with insulin it significantly increased the intracellular triglyceride synthesis (EC50 = 363.7nmol/1). Similarly in C2C12 myoblasts, chromium picolinate alone did not produce any effect, however, it significantly increased insulin-induced transport of 14C-glucose. In conclusion, chromium picolinate significantly improves deranged carbohydrate and lipid metabolism of experimental chemically induced diabetes in rats. The mechanism of in vivo anti-diabetic action appears to be peripheral (skeletal muscle and adipose tissue) insulin enhancing action of chromium.

Chromium as adjunctive treatment for type 2 diabetes

OBJECTIVE

To review the chemistry, pharmacology, efficacy, and safety of trivalent chromium in the treatment of type 2 diabetes and hyperlipidemia.

DATA SOURCES

The English literature was searched from 1966 through May 2002 using MEDLINE, International Pharmaceutical Abstracts, and EMBASE. The key words included chromium, glucose, lipids, and diabetes. Pertinent references from review articles and studies were used as additional sources.

DATA SYNTHESIS

Trivalent chromium is an essential nutrient and has a key role in lipid and glucose metabolism. Supplementation with chromium does not appear to reduce glucose levels in euglycemia. It may, however, have some efficacy in reducing glucose levels in hyperglycemia. The effects of chromium on lipid levels are variable. Chromium in doses <1000 microg/d appears to be safe for short-term administration. Kidney function and dermatologic changes need to be monitored.

CONCLUSIONS

Chromium appears to be a safe supplement and may have a role as adjunctive therapy for treatment of type 2 diabetes. Additional large-scale, long-term, randomized, double-blind studies examining the effect of various doses and forms of chromium are needed.

Chromium picolinate for reducing body weight: meta-analysis of randomized trials

The aim of this meta-analysis was to assess the evidence of chromium picolinate for reducing body weight. Literature searches were conducted on Medline, Embase, The Cochrane Library, Amed and Ciscom. Nine experts and four manufacturers of commercial preparations containing chromium picolinate were asked to contribute published and unpublished studies. There were no restrictions regarding the language of publication. The screening of studies, selection, data extraction, validation and the assessment of methodological quality were performed independently by two reviewers. To be included, studies were required to state that they were randomized, double-blind and placebo-controlled, and report on body weight. Ten trials met all inclusion criteria and provided data, which were suitable for statistical pooling. For body weight a significant differential effect was found in favour of chromium picolinate (weighted mean difference: -1.1 kg; 95% confidence interval (CI): -1.8 to -0.4 kg, n=489). Sensitivity analysis suggests that this effect is largely dependent on the results of a single trial (weighted mean difference: -0.9 kg; 95% CI: -2.0 to 0.2 kg, n=335). Three of the reviewed trials reported on adverse events, indicating their absence in the treatment groups. In conclusion, our meta-analysis suggests a relatively small effect of chromium picolinate compared with placebo for reducing body weight. The clinical relevance of the effect is debatable and the lack of robustness means that the result has to be interpreted with caution.

Study of heavy metal pollution and speciation in Buyak Menderes and Gediz river sediments

In this study, two economically important rivers of Turkey, Gediz and Buyuk Menderes (BM) are studied to determine their environmental pollution levels. An old analytical procedure involving sequential chemical extraction is improved and used for the partitioning of particulate trace metals (Cu, Co, Cr, Mn, Fe, Zn, Pb and Ni). Cationic and anionic Mn and Cr species with different phases are also determined by using leaching, extraction and ion exchange speciation processes. The sediment samples are analysed using graphic-furnace atomic absorption spectroscopy and differential pulse anodic stripping voltameter. Experimental results obtained on five replicate samples of fluvial bottom surface sediments at the sampling points demonstrate that the relative standard deviation of the sequential extraction procedure is generally better than +/-10%. The accuracy, determined by comparing total metal concentrations with the sum of the five sequential chemical extractions, is proved to be satisfactory. The detection limits established for three standard deviations of blank for different metals are identical and found to be 0.1mg/kg for sediment samples and 1 ppb for water samples. The results show that the pollution levels are significant especially for Pb, Cr, Mn and Zn in the Gediz river and Co, Mn, and Zn in the BM river. Comparison between our results and the measurements outlined before industrialization and the beginning of the intensive pesticide applications in agricultural fields (In: Broekaert et al., editors, Metal speciation in the environment, vol. 23. 1989. p. 601-11; A research on the environmental pollution in the agricultural fields and watering in the Aegean region, Ege University Research Project, No. 127 1988 (in Turkish); DSI Water Analyses Report, Ankara, 1985 (in Turkish)) show that the pollution in these rivers is probably originated from industrial, agricultural and domestic waste discharges.

Glucose and insulin responses to dietary chromium supplements: a meta-analysis

BACKGROUND

Several authors, mostly on the basis of nonrandomized studies, have suggested dietary trivalent chromium supplementation as an attractive option for the management of type 2 diabetes and for glycemic control in persons at high risk of type 2 diabetes.

OBJECTIVE

The study aimed to determine the effect of chromium on glucose and insulin responses in healthy subjects and in individuals with glucose intolerance or type 2 diabetes.

DESIGN

The study design was a systematic review and meta-analysis of randomized clinical trials (RCTs).

RESULTS

The authors identified 20 reports of RCTs assessing the effect of chromium on glucose, insulin, or glycated hemoglobin (Hb A(1c)). This review summarizes data on 618 participants from the 15 trials that reported adequate data: 193 participants had type 2 diabetes and 425 were in good health or had impaired glucose tolerance. The meta-analysis showed no association between chromium and glucose or insulin concentrations among nondiabetic subjects. A study of 155 diabetic subjects in China showed that chromium reduced glucose and insulin concentrations; the combined data from the 38 diabetic subjects in the other studies did not. Three trials reported data on Hb A(1c): one study each of persons with type 2 diabetes, persons with impaired glucose tolerance, and healthy subjects. The study of diabetic subjects in China was the only one to report that chromium significantly reduced Hb A(1c).

CONCLUSIONS

Data from RCTs show no effect of chromium on glucose or insulin concentrations in nondiabetic subjects. The data for persons with diabetes are inconclusive. RCTs in well-characterized, at-risk populations are necessary to determine the effects of chromium on glucose, insulin, and Hb A(1c).

Oral chromium picolinate improves carbohydrate and lipid metabolism and enhances skeletal muscle Glut-4 translocation in obese, hyperinsulinemic (JCR-LA corpulent) rats

Human studies suggest that chromium picolinate (CrPic) decreases insulin levels and improves glucose disposal in obese and type 2 diabetic populations. To evaluate whether CrPic may aid in treatment of the insulin resistance syndrome, we assessed its effects in JCR:LA-corpulent rats, a model of this syndrome. Male lean and obese hyperinsulinemic rats were randomly assigned to receive oral CrPic [80 microg/(kg. d); n = 5 or 6, respectively) in water or to control conditions (water, n = 5). After 3 mo, a 120-min intraperitoneal glucose tolerance test (IPGTT) and a 30-min insulin tolerance test were performed. Obese rats administered CrPic had significantly lower fasting insulin levels (1848 +/- 102 vs. 2688 +/- 234 pmol/L; P < 0.001; mean +/- SEM) and significantly improved glucose disappearance (P < 0.001) compared with obese controls. Glucose and insulin areas under the curve for IPGTT were significantly less for obese CrPic-treated rats than in obese controls (P < 0.001). Obese CrPic-treated rats had lower plasma total cholesterol (3.57 +/- 0.28 vs. 4.11 +/- 0.47 mmol/L, P < 0.05) and higher HDL cholesterol levels (1.92 +/- 0.09 vs. 1.37 +/- 0.36 mmol/L, P < 0.01) than obese controls. CrPic did not alter plasma glucose or cholesterol levels in lean rats. Total skeletal muscle glucose transporter (Glut)-4 did not differ among groups; however, CrPic significantly enhanced membrane-associated Glut-4 in obese rats after insulin stimulation. Thus, CrPic supplementation enhances insulin sensitivity and glucose disappearance, and improves lipids in male obese hyperinsulinemic JCR:LA-corpulent rats.

Serum chromium does not predict glucose tolerance in late pregnancy

BACKGROUND

Chromium is an essential element in human nutrition. Serum concentrations of chromium are not well characterized during pregnancy or in gestational diabetes mellitus.

OBJECTIVE

The objective of this study was to determine whether low plasma chromium concentrations (< or =3 nmol/L) are associated with altered glucose, insulin, or lipid concentrations during pregnancy.

DESIGN

The study was conducted prospectively and took place at the medical obstetric clinic of a tertiary referral hospital. Seventy-nine women with abnormal results of a 50-g glucose challenge test in the third trimester of pregnancy were studied. All women had a formal 75-g oral-glucose-tolerance test, and fasting insulin, lipid, and chromium concentrations were determined. Chromium was measured by graphite furnace atomic absorption spectrometry.

RESULTS

The median chromium concentration was 2 nmol/L (95% CI: 0, 12). There were no significant differences in age, plasma glucose, insulin, lipids, calculated insulin resistance, or calculated ss cell function between women with normal and those with abnormal (< or =3 nmol/L) chromium concentrations.

CONCLUSIONS

Plasma chromium during pregnancy does not correlate with glucose intolerance, insulin resistance, or serum lipids. Plasma chromium concentrations may not accurately reflect tissue stores of chromium. Several trials showed a beneficial effect of chromium supplementation on glucose tolerance, insulin, and lipids. A method for assessing body chromium stores is required to allow further study.

Effects of chromium picolinate supplementation on insulin sensitivity, serum lipids, and body composition in healthy, nonobese, older men and women

BACKGROUND

Chromium is an essential nutrient required for carbohydrate and lipid metabolism. Chromium supplementation in humans has been reported to improve glucose metabolism and improve serum lipid parameters and to reduce body fat; parameters that worsen with aging. As a result, chromium picolinate has been widely promoted as a health aid for the general population. The purpose of the study was to examine the effects of chromium supplementation on insulin sensitivity, serum lipids, and body composition in nonobese, healthy men and women of advanced age.

METHODS

A randomized, double-blind, placebo-controlled study with 19 subjects (9 men and 10 women), aged 63-77, were given either chromium picolinate, 1,000 microg/d, or a placebo for 8 weeks. Serum lipids were measured at baseline and 8 weeks. Insulin sensitivity and body composition were measured with the minimal-model intravenous glucose tolerance test and dual-energy x-ray absorptiometry scan, respectively, at baseline and after 8 weeks of chromium or placebo supplementation.

RESULTS

No significant change in serum lipids, insulin sensitivity, or body composition was observed in the chromium group compared with the placebo group.

CONCLUSIONS

Chromium picolinate supplementation alone does not appear to improve insulin sensitivity, serum lipids, or change body composition in nonobese, healthy men and women of advanced age.

High chromium yeast supplementation improves glucose tolerance in pigs by decreasing hepatic extraction of insulin

Twenty Landrace x Yorkshire cross pigs (body wt, 47.9+/-2.9 kg) were used to evaluate effects of dietary high chromium (Cr) yeast supplementation on plasma kinetics of glucose, insulin and C-peptide. Pigs were provided free access to either a control diet (C) containing 204 microg Cr/kg or a diet supplemented with an additional 200 microg Cr/kg as high Cr yeast (CR) for between 23 and 30 d. After overnight food deprivation, dextrose (500 g/L) was infused through a jugular vein catheter at a dose of 0.5 g glucose/kg body weight with an infusion rate of 10 g glucose/min within 6 min. High Cr yeast supplementation did not affect body weight gain or food intake. There were no differences in fasting plasma concentrations of either glucose or C-peptide, although basal plasma concentration of insulin tended to be higher in pigs fed CR (P<0.10). Plasma glucose concentrations were lower (P<0.01) at postinfusion times 5, 10, 15 and 20 min in pigs fed CR. Plasma insulin concentrations in pigs fed CR were higher (P<0.05) at 2 and 0 min before the completion of dextrose infusion. However, the increase in plasma insulin concentrations was not accompanied by a comparable elevation in plasma C-peptide concentrations. The 30-min (postinfusion) area of plasma glucose concentrations tended to be lower (P<0.10) in pigs fed CR, but there were no differences in 30-min areas of either plasma insulin or plasma C-peptide concentrations between treatments. Plasma clearance rates of glucose, insulin and C-peptide were higher and their half-lives shorter (P<0.05) in pigs fed CR. In conclusion, dietary high Cr yeast supplementation improved glucose tolerance, possibly through a decrease in hepatic extraction of insulin.

The role of chromium in nutrition and therapeutics and as a potential toxin

Since the 1950s it has been known that chromium is important for the expression of glucose tolerance and that in chromium deficiency the use of glucose is impaired. Chromium has been recognized as an essential nutrient since the finding of low-molecular-weight chromium as a biological modifier of insulin action and the clinical demonstration of deficiency associated with glucose intolerance that responded to the administration of chromium. The major impediment to the use of orally administered chromium is poor absorption of trivalent chromium in its inorganic form. Trivalent chromium is more available in yeast and, more recently, as chromium picolinate for oral absorption. The widespread use of these supplements has resulted in controversy regarding chromium's role as a nutrient, its use for treatment of insulin resistance, and its potential toxicity. This report reviews the evidence for the potential toxicity of chromium supplements in contrast with its usefulness as a nutrient or therapeutic agent in the treatment or prevention of insulin resistance.

Chromium, glucose intolerance and diabetes

Within the last 5 years chromium (Cr) has been shown to play a role in glucose intolerance, Type 2 diabetes mellitus (Type 2 DM), and gestational diabetes. In addition, diabetes and the neuropathy of a patient on home parenteral nutrition were alleviated when supplemental Cr was added to total parenteral nutrition (TPN) solutions. In a study conducted in China that has been supported by studies in the United States, supplemental Cr as Cr picolinate improved the blood glucose, insulin, cholesterol, and hemoglobin A1C in people with Type 2 DM in a dose dependent manner. Follow-up studies of > 1 year have confirmed these studies. The requirement for Cr is related to the degree of glucose intolerance: 200 microg/day of supplemental Cr is adequate to improve glucose variables of those who are mildly glucose intolerant. However, people with more overt impairments in glucose tolerance and diabetes usually require more than 200 microg/day. Daily intake of 8 microg of Cr per kg body weight was also more effective than 4 microg/kg in women with gestational diabetes. The mechanism of action of Cr involves increased insulin binding, increased insulin receptor number, and increased insulin receptor phosphorylation. In summary, supplemental Cr has been shown to have beneficial effects without any documented side effects on people with varying degrees of glucose intolerance ranging from mild glucose intolerance to overt Type 2 DM.

Survey of alternative medicine use among organ transplant patients

Herbal medicine and health food supplements have become increasingly popular. However, many of these pharmacologically active compounds remain poorly understood. Patients with chronic and life-threatening conditions often use alternative therapies while receiving conventional medical care, and his population is at increased risk for complications and adverse drug interactions due to poor health and complex drug regimens. Patients awaiting or who had received solid organ transplants were surveyed about their use of herbal medicines and health food supplements. Twenty percent of respondents acknowledged experience with these products, which they used to prolong the function of a failing organ or to obtain relief from fatigue and insomnia. Transplant staff often were unaware of their patients' use of these treatments, despite patients' claims to the contrary. The potential for unexpected drug interactions, toxicity, and other adverse reactions resulting from the use of herbal medicines or supplements must be recognized and identified by transplant teams.

Chromium and exercise training: effect on obese women

Chromium supplementation may affect various risk factors for coronary artery disease (CAD) and non-insulin-dependent diabetes mellitus (NIDDM), including body weight and composition, basal plasma hormone and substrate levels, and response to an oral glucose load. This study examined the effects of chromium supplementation (400 micrograms.d-1), with or without exercise training, on these risk factors in young, obese women. Chromium picolinate supplementation resulted in significant weight gain in this population, while exercise training combined with chromium nicotinate supplementation resulted in significant weight loss and lowered the insulin response to an oral glucose load. We conclude that high levels of chromium picolinate supplementation are contraindicated for weight loss in young, obese women. Moreover, our results suggest that exercise training combined with chromium nicotinate supplementation may be more beneficial than exercise training alone for modification of certain CAD and NIDDM risk factors.