Effect of chromium nicotinic acid supplementation on selected cardiovascular disease risk factors

Nutritional Composition and Bioactive Compounds of Native Brazilian Fruits of the Arecaceae Family and Its Potential Applications for Health Promotion

The fruits from the Arecaceae family, although being rich in bioactive compounds with potential benefits to health, have been underexplored. Studies on their composition, bioactive compounds, and effects of their consumption on health are also scarce. This review presents the composition of macro- and micronutrients, and bioactive compounds of fruits of the Arecaceae family such as bacaba, patawa, juçara, açaí, buriti, buritirana, and butiá. The potential use and reported effects of its consumption on health are also presented. The knowledge of these underutilized fruits is important to encourage production, commercialization, processing, and consumption. It can also stimulate their full use and improve the economy and social condition of the population where these fruits are found. Furthermore, it may help in future research on the composition, health effects, and new product development. Arecaceae fruits presented in this review are currently used as raw materials for producing beverages, candies, jams, popsicles, ice creams, energy drinks, and edible oils. The reported studies show that they are rich in phenolic compounds, carotenoids, anthocyanins, tocopherols, minerals, vitamins, amino acids, and fatty acids. Moreover, the consumption of these compounds has been associated with anti-inflammatory, antiproliferative, antiobesity, and cardioprotective effects. These fruits have potential to be used in food, pharmaceutical, and cosmetic industries. Despite their potential, some of them, such as buritirana and butiá, have been little explored and limited research has been conducted on their composition, biological effects, and applications. Therefore, more detailed investigations on the composition and mechanism of action based on in vitro and/or in vivo studies are needed for fruits from the Arecaceae family.

Effects of chromium supplementation on oxidative Stress biomarkers

Aim: This systematic review and meta-analysis aimed to evaluate the effects of chromium supplementation on oxidative stress biomarkers such as superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPX), malondialdehyde (MDA), total antioxidant status (TAS), thiobarbituric acid reactive substances (TBARS), catalase (CAT), nitric oxide (NO), total antioxidant capacity (TAC) and protein carbonyl. Methods: Relevant studies, published from inception until July 2019, were searched through PubMed/Medline, Scopus, ISI Web of Science, Embase, and Google Scholar. All randomized clinical trials investigating the effect of chromium supplementation on oxidative stress were included. Results: Out of 252 citations, 10 trials that enrolled 595 subjects were included. Chromium supplementation resulted in a significant increase in GSH (WMD: 64.79 mg/dl, 95% CI: 22.43 to 107.15; P=0.003) but no significant change in MDA, TAS, TBARS levels, SOD, CAT levels and GPX. Chromium picolinate supplementation resulted in a significant increase in TAC while failing to have a significant effect on NO. Moreover, both chromium picolinate and chromium dinicocysteinate supplementation reduced protein carbonyl levels. Conclusion: Overall, this meta-analysis demonstrated that chromium supplementation increased GSH without any significant changes in the mean of GPX, MDA, TAS, TBARS, CAT and SOD.

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.

Trace Elements, PPARs, and Metabolic Syndrome

Metabolic syndrome (MetS) is a constellation of metabolic derangements, including central obesity, insulin resistance, hypertension, glucose intolerance, and dyslipidemia. The pathogenesis of MetS has been intensively studied, and now many factors are recognized to contribute to the development of MetS. Among these, trace elements influence the structure of proteins, enzymes, and complex carbohydrates, and thus an imbalance in trace elements is an independent risk factor for MetS. The molecular link between trace elements and metabolic homeostasis has been established, and peroxisome proliferator-activated receptors (PPARs) have appeared as key regulators bridging these two elements. This is because on one hand, PPARs are actively involved in various metabolic processes, such as abdominal adiposity and insulin sensitivity, and on the other hand, PPARs sensitively respond to changes in trace elements. For example, an iron overload attenuates hepatic mRNA expression of Ppar-α; zinc supplementation is considered to recover the DNA-binding activity of PPAR-α, which is impaired in steatotic mouse liver; selenium administration downregulates mRNA expression of Ppar-γ, thereby improving lipid metabolism and oxidative status in the liver of high-fat diet (HFD)-fed mice. More importantly, PPARs' expression and activity are under the control of the circadian clock and show a robust 24 h rhythmicity, which might be the reasons for the side effects and the clinical limitations of trace elements targeting PPARs. Taken together, understanding the casual relationships among trace elements, PPARs' actions, and the pathogenesis of MetS is of great importance. Further studies are required to explore the chronopharmacological effects of trace elements on the diurnal oscillation of PPARs and the consequent development of MetS.

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

SCOPE

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

METHODS AND RESULTS

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

CONCLUSION

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

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.

Micronutrient status in type 2 diabetes: a review

Type 2 diabetes is characterized by significant losses of important micronutrients due to metabolic basis of the disease and its complications. Evidence of changes in trace mineral and vitamin metabolism as a consequence of type 2 diabetes is reviewed in this chapter. This review is not a meta-analysis but an overview of the micronutrient status, metabolic needs, and potential micronutrient requirements in type 2 diabetics. This chapter will not concentrate on vitamin D and type 2 diabetes as this is a topic that has been extensively reviewed before. The less well-known micronutrients notably zinc, magnesium, chromium, copper, manganese, iron, selenium, vanadium, B-group vitamins, and certain antioxidants are assessed. While some evidence is available to demonstrate the positive influence of micronutrient supplementation on glycemic control, much remains to be investigated. Additional research is necessary to characterize better biomarkers of micronutrient status and requirements in type 2 diabetics. The optimal level of micronutrient supplementation to achieve glucose homeostasis in type 2 diabetics remains a challenge.

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

WHAT IS KNOWN AND OBJECTIVE

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

METHODS

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

RESULTS AND DISCUSSION

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

WHAT IS NEW AND CONCLUSIONS

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

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.

Role of trace elements in parenteral nutrition support of the surgical neonate

BACKGROUND

Parenteral nutrition (PN) has transformed the outcome for neonates with surgical problems in the intensive care unit. Trace element supplementation in PN is a standard practice in many neonatal intensive care units. However, many of these elements are contaminants in PN solutions, and contamination levels may, in themselves, be sufficient for normal metabolic needs. Additional supplementation may actually lead to toxicity in neonates whose requirements are small.

METHODS

An electronic search of the MEDLINE, Cochrane Collaboration, and SCOPUS English language medical databases was performed for the key words "trace elements," "micro-nutrients," and "parenteral nutrition additives." Studies were categorized based on levels of evidence offered, with randomized controlled trials and meta-analyses accorded the greatest importance at the apex of the data pool and case reports and animal experiments the least importance. Articles were reviewed with the primary goal of developing uniform recommendations for trace element supplementation in the surgical neonate. The secondary goals were to review the physiologic role, metabolic demands, requirements, losses, deficiency syndromes, and toxicity symptoms associated with zinc, copper, chromium, selenium, manganese, and molybdenum supplementation in PN.

RESULTS

Zinc supplementation must begin at initiation of PN. All other trace elements can be added to PN 2 to 4 weeks after initiation. Copper and manganese need to be withheld if the neonate develops PN-associated liver disease. The status of chromium supplementation is currently being actively debated, with contaminant levels in PN being sufficient in most cases to meet neonatal requirements. Selenium is an important component of antioxidant enzymes with a role in the pathogenesis of neonatal surgical conditions such as necrotizing enterocolitis and bronchopulmonary dysplasia. Premature infants are often selenium deficient, and early supplementation has shown a reduction in sepsis events in this age group.

CONCLUSION

Appropriate supplementation of trace elements in surgical infants is important, and levels should be monitored. In certain settings, it may be more appropriate to individualize trace element supplementation based on the predetermined physiologic need rather than using bundled packages of trace elements as is the current norm. Balance studies of trace element requirements should be performed to better establish clinical recommendations for optimal trace element dosing in the neonatal surgical population.

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 effects of chromium histidinate on mineral status of serum and tissue in fat-fed and streptozotocin-treated type II diabetic rats

The present study was conducted to investigate the effects of chromium histidinate (CrHis) against experimentally induced type II diabetes and on chromium (Cr), zinc (Zn), selenium (Se), manganese (Mn), iron (Fe), and copper (Cu) in serum, liver, and kidney of diabetic rats. The male Wistar rats (n = 60, 8 weeks old) were divided into four groups. Group I received a standard diet (12% of calories as fat); group II were fed standard diet and received CrHis (110 mcg CrHis/kg body weight per day); group III received a high-fat diet (HFD; 40% of calories as fat) for 2 weeks and then were injected with streptozotocin (STZ) on day 14 (STZ, 40 mg/kg i.p.; HFD/STZ); group IV were treated as group III (HFD/STZ) but supplemented with 110 mcg CrHis/kg body weight per day. The mineral concentrations in the serum and tissue were determined by atomic absorption spectrometry. Compared to the HFD/STZ group, CrHis significantly increased body weight and reduced blood glucose in diabetic rats (p < 0.001). Concentrations of Cr, Zn, Se, and Mn in serum, liver, and kidney of the diabetic rats were significantly lower than in the control rats (p < 0.0001). In contrast, higher Fe and Cu levels were found in serum and tissues from diabetic versus the non-diabetic rats (p < 0.001). Chromium histidinate supplementation increased serum, liver, and kidney concentrations of Cr and Zn both in diabetic and non-diabetic rats (p < 0.001). Chromium supplementation increased Mn and Se levels in diabetic rats (p < 0.001); however, it decreased Cu levels in STZ-treated group (p < 0.001). Chromium histidinate supplementation did not affect Fe levels in both groups (p > 0.05). The results of the present study conclude that supplementing Cr to the diet of diabetic rats influences serum and tissue Cr, Zn, Se, Mn, and Cu concentrations.

Chromium infusion reverses extreme insulin resistance in a cardiothoracic ICU patient

Insulin resistance is common and often multifactorial in acutely critically ill patients. At our institution, glycemic control is achieved in these patients using an intravenous insulin protocol. The authors present a case in which a patient developed severe insulin resistance following surgical repair of a thoracic aorta aneurysm. Postoperatively, the patient required 2110 units of insulin over 40 hours while receiving pressors and glucocorticoids. After the administration of intravenous chromium at 3 microg/h, the blood sugar normalized and insulin therapy was discontinued. This case represents a unique approach using intravenous chromium to achieve glycemic control in a patient with extreme insulin resistance and acute critical illness. Prospective clinical trials using intravenous chromium may provide the means to optimize intensive insulin therapy for critically ill patients.

Effects of niacin and chromium on the expression of ATP-binding cassette transporter A1 and apolipoprotein A-1 genes in HepG2 cells

The ATP-binding cassette transporter A1 (ABCA1) and apolipoprotein A1 (ApoA-1) are both involved in the regulation of cholesterol efflux from cells. The overexpression of ABCA1 and ApoA-1 genes are associated with increased high-density lipoprotein (HDL) levels. Previous studies have shown that niacin and chromium reduce plasma cholesterol while increasing HDL levels. The aim of the present study was to determine the effects of niacin and chromium on HDL formation by investigating the changes in ABCA1 and ApoA-1 transcription in the human hepatoblastoma cell line (HepG2 cells). Cells were treated with either niacin or chromium, or the combination of both. The expression of ABCA1 and ApoA-1 mRNA was measured by a relative quantitative real-time reverse transcriptase-polymerase chain reaction method. Results showed that niacin at concentrations of 1 and 5 mM significantly increased ABCA1 (1.3-1.7-fold), without affecting ApoA-1 (0.8-1.2-fold), whereas chromium at 3 mM significantly increased both ABCA1 (1.7+/-0.01-fold) and ApoA-1 (1.5+/-0.1-fold) transcription when compared to untreated cells. Niacin and chromium cotreatment significantly induced the expression of peroxisome proliferator-activated receptor-alpha (PPARalpha) mRNA by approximately 1.3-1.8-fold. It was likely that the increases observed for the ABCA1 transcript may be regulated by the increases in PPARalpha transcription. A combination of niacin and chromium chloride did not significantly increase (3+1 mM) but instead reduced (1+3 mM) ABCA1 gene expression. In the case of ApoA gene, the combination of niacin and chromium chloride at concentrations of 1+3 mM significantly elevated expression; however, this effect was not observed at concentrations of 3+1 mM. When cells were treated with the combination at both concentrations, only slight increases in PPARalpha mRNA was observed. Niacin, but not chromium, significantly reduced intracellular cholesterol. We hypothesize that the stimulation of ABCA1 gene expression causes an enhanced cholesterol efflux, perhaps mediated by PPARalpha pathway(s).

Algorithm for Complementary and Alternative Medicine Practice and Research in Type 2 Diabetes

OBJECTIVE

To develop a model to direct the prescription of nutritional and botanical medicines in the treatment of type 2 diabetes for both clinical and research purposes.

METHODS

Available literature on nutritional and botanical medicines was reviewed and categorized as follows: antioxidant/anti-inflammatory; insulin sensitizer; and beta-cell protectant/insulin secretagogue. Literature describing laboratory assessment for glycemic control, insulin resistance, and beta-cell reserve was also reviewed and a clinical decision tree was developed.

RESULTS

Clinical algorithms were created to guide the use of nutritional and botanic medicines using validated laboratory measures of glycemic control, insulin sensitivity, and beta-cell reserve. Nutrient and botanic medicines with clinical trial research support include coenzyme Q10, carnitine, alpha-lipoic acid, N-acetylcysteine, vitamin D, vitamin C, vitamin E, chromium, vanadium, omega-3 fatty acids, cinnamon (Cinnamomum cassia), fenugreek (Trigonella foenum-graecum), and gymnema (Gymnema sylvestre).

CONCLUSIONS

Clinical algorithms can direct supplementation in clinical practice and provide research models for clinical investigation. Algorithms also provide a framework for integration of future evidence as it becomes available. Research funding to investigate potentially beneficial practices in complementary medicine is critically important for optimal patient care and safety.

Clinical studies on chromium picolinate supplementation in diabetes mellitus--a review

Chromium (Cr) picolinate (CrPic) is a widely used nutritional supplement for optimal insulin function. A relationship among Cr status, diabetes, and associated pathologies has been established. Virtually all trials using CrPic supplementation for subjects with diabetes have demonstrated beneficial effects. Thirteen of 15 clinical studies (including 11 randomized, controlled studies) involving a total of 1,690 subjects (1,505 in CrPic group) reported significant improvement in at least one outcome of glycemic control. All 15 studies showed salutary effects in at least one parameter of diabetes management, including dyslipidemia. Positive outcomes from CrPic supplementation included reduced blood glucose, insulin, cholesterol, and triglyceride levels and reduced requirements for hypoglycemic medication. The greater bioavailability of CrPic compared with other forms of Cr (e.g., niacin-bound Cr or CrCl(3)) may explain its comparatively superior efficacy in glycemic and lipidemic control. The pooled data from studies using CrPic supplementation for type 2 diabetes mellitus subjects show substantial reductions in hyperglycemia and hyperinsulinemia, which equate to a reduced risk for disease complications. Collectively, the data support the safety and therapeutic value of CrPic for the management of cholesterolemia and hyperglycemia in subjects with diabetes.

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.

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.

Role of chromium supplementation in Indians with type 2 diabetes mellitus

Type 2 diabetes mellitus is a complex metabolic disorder with adverse cardiovascular risk. The role of micronutrients has not yet been well clarified in this condition, especially in India.THE OBJECTIVES OF THIS STUDY WERE TO: (1) evaluate chromium status in Indian subjects with type 2 diabetes mellitus, (2) assess the effect of chromium picolinate (200 &mgr;g trivalent chromium twice daily) administration on glycaemic control and lipid profile in these subjects and (3) comment on the possible mechanism of any beneficial effect noted above.Fifty subjects were studied in a double blind, placebo-controlled, crossover fashion, with each treatment arm (chromium/placebo) lasting 12 weeks and 4 weeks' wash-off period in between. 50 healthy age- and sex-matched volunteers served as controls. Serum chromium level appeared to be higher in the general population in our country compared to western countries (36.5-59.5 nmol/L as compared to 2.3-40.3 nmol/L) However, the local diabetics were found to have a lower serum chromium level than the healthy controls (32.3 nmol/L against 44.7 nmol/L; p < 0.0001) and a mean increase of 3.5 nmol/L was noted after 12 weeks of chromium supplementation that was, expectedly, not seen in the placebo phase (p < 0.0001).Significant improvement in glycaemic control was noted in the chromium-treated group (DeltaFasting serum glucose = 0.44 mmol/L, p < 0.001; DeltaPost-prandial serum glucose = 1.97 mmol/L, p < 0.001; Deltaglycated hemoglobin = 0.01; p = 0.04, in comparison to placebo) This was accompanied by a significant greater fall in fasting serum insulin in the chromium-treated group, p < 0.05.The change in lipid parameters (total serum cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol and triglycerides) did not show significant difference between the chromium and placebo groups.Clinically significant hematological, renal or hepatic toxicity were excluded by routine hemogram, serum urea, creatinine, alanine amino transferase (ALT) and alkaline phosphatase estimations.In conclusion, chromium supplementation seems to improve glycaemic control in type 2 diabetic patients, which appears to be due to an increase in insulin action rather than stimulation of insulin secretion.

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.

Oral nutritional supplements and heart disease: a review

The use of nutritional supplements in the treatment of cardiovascular disease is rapidly growing in the United States. Many substances are marketed with anecdotal claims of efficacy. Most have not been scientifically studied. Excitement exists in the lay press about the homocysteine hypothesis of coronary artery disease and vitamin cures. A MEDLINE search and review of papers covering the study of popular nutritional supplements were undertaken. The papers were limited to peer-review journals using patient series reports, double-blinded prospective studies, and population studies. A compendium of the available data was obtained and an analysis of each paper's methodology was done. A review of the most popular and most studied oral nutritional supplements for the treatment of heart disease demonstrated relatively few well-founded indications for the widespread application of substances with the exception of the bioflavonoids. Some modest effects for endothelial dysfunction were noted for vitamins C and E. Red wines and beers were also noted to be beneficial. The majority of substances either had no effect or were deleterious.

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.

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.