Effect of chromium-enriched yeast on fasting plasma glucose, glycated haemoglobin and serum lipid levels in patients with type 2 diabetes mellitus treated with insulin

Pharmacokinetics of chromium-enriched yeast in rats following oral administration

Chromium (Cr) is required for carbohydrate, lipid, and protein metabolisms in humans and animals. Cr insufficiency is associated with diabetes and cardiovascular disease. Chromium-enriched yeast (CrY) is a widely used Cr dietary supplement, but its pharmacokinetics remains unavailable. CrY was orally administered to rats at a single dose of 1 mg Cr/kg, and plasma Cr concentration at different time points was measured by inductively coupled plasma mass spectrometry. Pharmacokinetics of CrY in rats was well fitted to a non-compartmental model. Plasma Cr concentration reached the maximum of 8.68 ± 2.87 ng/mL at 0.25 h, and gradually decreased to 4.05 ± 0.47 ng/mL at 24 h. CrY was rapidly absorbed into the blood and was slowly eliminated after the oral administration, which could lead to the accumulation of Cr in vivo.

Anti-diabetic properties of genistein-chromium (III) complex in db/db diabetic mice and its sub-acute toxicity evaluation in normal mice

BACKGROUND

In this study, chromium (III) complex was synthesized from genistein (GEN) which had good hypoglycemic activity and inorganic chromium (III) element, and its hypoglycemic activity and sub-acute toxicity were studied.

METHODS

The genistein-chromium (III) complex was synthesized by chelating chromium with genistein in ethanol and its structure was determined by LC-MS, atomic absorption spectroscopy, UV-vis spectroscopy, infrared spectroscopy, elemental and thermodynamic analysis. The anti-diabetic activity of the complex was assessed in db/db mice and C57 mice by daily oral gavage for 4 weeks. The sub-acute toxicity test was carried out on KM mice with this complex.

RESULTS

The molecular structure of this complex was inferred as a complex [CrGEN₃] formed by three ligands and one chromium element. The complex could significantly improve the body weight of db/db mice, fasting blood glucose, random blood glucose, organ index, glycogen levels and the performance of OGTT (Oral Glucose Tolerance Test) and ITT (Insulin Tolerance Test) in db/db mice (p < 0.05). The morphology of liver, kidney, pancreas and skeletal muscle also had obviously improvement and repairment. Effects on serum indices and antioxidant enzymes activities of db/db mice showed that the serum profiles and antioxidant ability of complex group had significant improvement compared with the diabetic control group (p < 0.05 or p < 0.01), and some indices even returned to normal levels. In addition, this complex did not produce any hazardous symptoms or deaths in sub-acute toxicity test. High dose of [CrGEN₃] had no significant influence on serum indices and antioxidant capacity in normal mice, and the organ tissues maintained organized and integrity in the sub-acute toxicity study.

CONCLUSION

The study of the genistein-chromium (III) complex showed that the complex had good hypoglycemic activity in vivo, and did not have the potential toxicity. These results would provide an important reference for the development of functional hypoglycemic foods or pharmaceuticals.

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

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

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.

Antagonistic effects of nano-selenium on broilers hepatic injury induced by Cr(VI) poisoning in AMPK pathway

Cr (chromium, with common valence states of III and VI) is one of the common broiler feed additives. Liver injury and metabolic disorders could be caused by Cr_(VI) (hexavalent chromium) poisoning in broilers. Oxidative damage and metabolic disorders of organisms caused by heavy metals could be antagonized by nano-Se (nano-selenium). Nano-Se was chosen to study the antagonism of Cr_(VI) poisoning in broilers. AMPK (Adenosine 5^,-monophosphate-activated protein kinase) is known as a "cell energy regulator" and plays a key regulatory role in carbohydrate and lipid metabolism. AMPK pathway and ACACA/CPT1A two genes were selected to study the prevention and treatment of nano-Se on Cr_(VI) poisoning in broilers and its molecular mechanism. For this purpose, 180 1-day-old AA (Arbor Acres) broilers were selected and randomly divided into 6 groups (n = 30) for further testing. After feeding as planned for 35 days, the livers of such broilers were taken for further examination including histopathological examination, differential gene expression analysis, and further validation on both mRNA and protein levels using related techniques like RT-qPCR, western blot, and immunohistochemistry (IHC). The histopathological examination suggested that the liver cells of the Cr_(VI) poisoning group were more severely injured than the nano-Se addition group. RT-qPCR results showed that the relative expression of ACACA gene in the Cr_(VI) poisoning group was significantly increased (P < 0.05), while the CPT1A gene's expression was significantly decreased (P < 0.01). Those results were reversed in the nano-Se addition group. Western blot results were consistent with RT-qPCR and both suggested antagonism of nano-Se on Cr_(VI). Through morphological and histopathological observation, as well as the measurement of the mRNA and protein expression levels of ACACA and CPT1A genes in AMPK pathway, it was confirmed that nano-Se has certain preventive and protective effects on Cr_(VI) poisoning in broiler chickens. Furthermore, the adverse effects of Cr_(VI) on carbohydrate and lipid metabolism in broilers can be antagonized by nano-Se through AMPK pathway. A new method and experimental basis were provided to the future study of Cr_(VI) poisoning in broilers.

The Influences of Chromium Supplementation on Metabolic Status in Patients with Type 2 Diabetes Mellitus and Coronary Heart Disease

This investigation was conducted to determine the effects of chromium supplementation on metabolic status in diabetic patients with coronary heart disease (CHD). This randomized, double-blind, placebo-controlled trial was performed in 64 diabetic patients with CHD between October 2017 and January 2018. Patients were randomly divided into two groups to obtain either 200 μg chromium (n = 32) or placebo (n = 32) for 12 weeks. Chromium supplementation significantly reduced body weight (- 0.9 ± 1.6 vs. + 0.1 ± 0.8 kg, P = 0.001), BMI (- 0.4 ± 0.7 vs. + 0.1 ± 0.3 kg/m², P = 0.002), fasting glucose (β - 11.03 mg/dL; 95% CI, - 18.97, - 3.09; P = 0.007), insulin (β - 1.33 μIU/mL; 95% CI, - 1.90, - 0.76; P < 0.001), and insulin resistance (β - 0.44; 95% CI, - 0.62, - 0.25; P < 0.001) and significantly increased insulin sensitivity (β 0.007; 95% CI, 0.003, 0.01; P < 0.001) compared with the placebo. In addition, taking chromium led to a significant reduction in serum high-sensitivity C-reactive protein (hs-CRP) (β - 0.49 mg/L; 95% CI, - 0.91, - 0.06; P = 0.02) and plasma malondialdehyde (MDA) levels (β - 0.22 μmol/L; 95% CI, - 0.35, - 0.10; P = 0.001); also, a significant rise in total antioxidant capacity (TAC) (β 84.54 mmol/L; 95% CI, 31.05, 138.02; P = 0.002) was observed in comparison with placebo. Additionally, chromium administration significantly reduced diastolic blood pressure (DBP) (β - 5.01 mmHg; 95% CI, - 9.04, - 0.97; P = 0.01) compared with the placebo. Overall, the 12-week supplementation of chromium to diabetic patients with CHD had beneficial impacts on weight, BMI, glycemic control, hs-CRP, TAC, MDA, and DBP.Trial Registration www.irct.ir: http://www.irct.ir: IRCT20170513033941N30.

Chromium(III) Glycinate Complex Supplementation Improves the Blood Glucose Level and Attenuates the Tissular Copper to Zinc Ratio in Rats with Mild Hyperglycaemia

The aim of the study was to evaluate the hypoglycaemic potential of supplementary Cr in the form of chromium(III) glycinate (CrGly) in the diabetic model of rats. The experiment was conducted on 40 male Wistar rats, of which 30 were made diabetic by injection of a single dose of streptozotocin (55 mg/kg b.m.), while the remaining 10 rats served as the healthy control. After inducing hyperglycaemia, 2 groups of diabetic rats (10 rats each) were supplemented with Cr either as CrGly or chromium(III) picolinate (CrPic) given orally at a dose of 10 mg/kg diet (about 0.75 mg Cr/kg b.m.) with adequate AIN-93M diet for 7 weeks. At the termination of experiment, all animals were sacrificed to collect blood and internal organs for biochemical assays. Blood biochemical indices and tissular trace element contents (Fe, Zn, Cu, Cr) were measured and compared with the values of the untreated groups. It was found that CrGly significantly decreased blood glucose, total cholesterol, HDL cholesterol and triacylglycerol levels more efficiently than CrPic. Furthermore, both Cr compounds normalized disturbed the serum, renal and cardiac molar Cu/Zn ratio, as well as restored the kidney Zn and Cu levels in rats with hyperglycaemia. Supplementary Cr did not increase the tissular Cr levels in diabetic rats. The study confirmed the hypoglycaemic potential of CrGly in the diabetic model of rats.

The Possibilities of Using Chromium Salts as an Agent Supporting Treatment of Polycystic Ovary Syndrome

The polycystic ovary syndrome (PCOS) is the most frequent endocrinopathy in women in reproductive age with the so far undetermined causes of development. In the etiopathogenesis of PCOS, the role of insulin resistance is emphasised, which was an indication for the attempts at using chromium III salts (Cr) in augmenting pharmacotherapy applied in patients. The analysis of the usefulness and efficacy of this approach was the direct goal of this thesis. Animal tests confirmed the efficacy of chromium in maintaining the appropriate level of glycaemia and insulinaemia, normalisation of plasma concentrations of microelements and also a correlation between the Cr level, insulin and dehydroepiandrosterone (DHEA) was found. A decrease in the expression of 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase was identified in adipose tissue. Clinical studies, although sparse, show that the supplementation with chromium can improve BMI and the parameters evaluating the control of glycaemia and increase the chances for ovulation and regular menstruation. However, the small number and a variability in study protocols makes comparing them very difficult. A completely new subject that has not been yet studied is the possibility of using chromium in levelling mood disorders in patients with PCOS. Currently, there are still no sufficient proofs for introducing chromium as a standard in treating and preventing insulin resistance in patients with PCOS. However, this direction remains open, and treating insulin resistance is an important challenge in clinical practice.

The Combined Effects of Cr(III) Supplementation and Iron Deficiency on the Copper and Zinc Status in Wistar Rats

The aim of the study was to assess the combined effects of chromium(III) supplementation and iron deficiency on the copper (Cu) and zinc (Zn) status in female rats. The Cr, Fe, Cu and Zn dietary and tissular levels were measured by Atomic Absorption Spectrometry (AAS) method. The data show that chromium(III) supplementation compensated for the negative effects of Fe deficiency on the Cu content but it deepened the effect on Zn levels in the female rats. Detailed data on the status of trace elements and their interactions in healthy subjects and patients with metabolic disorders (e.g. anaemia, diabetes mellitus) are strongly required for effective nutritional and therapeutic strategies.

Chromium Supplementation Reduces Resting Heart Rate in Patients with Metabolic Syndrome and Impaired Glucose Tolerance

Chromium (Cr) is considered as an important mineral, involved in biochemical reactions in human metabolic pathways. Organically bound Cr supplementation has been suggested to improve glycemia especially in patients with type 2 diabetes mellitus, but there are conflicting reports on efficacy. Effect of Cr is not clear in prediabetes status. Seventy patients with metabolic syndrome and impaired glucose tolerance (IGT), who are observed and treated in the Center of Preventive Cardiology of the University Hospital in Pilsen, were included in the prospective, randomized, double-blind, and placebo-controlled clinical study. Effect of Cr-enriched yeast (200 μg of elementary Cr in the morning and 100 μg in the evening) on glucose, lipid metabolism, fat tissue hormones, oxidative stress, and DNA damage markers was analyzed. There were no significant changes in glucose and lipid parameters, oxidative stress, or other laboratory markers. Only resting heart rate was significantly reduced in patients treated by Cr yeast, reflecting reduced sympathetic activity. This could represent an important cardiovascular risk reduction in patients with high cardiometabolic risk.

Maternal chromium restriction induces insulin resistance in adult mice offspring through miRNA

Increasing evidence suggests that undernutrition during the fetal period may lead to glucose intolerance, impair the insulin response and induce insulin resistance (IR). Considering the importance of chromium (Cr) in maintaining carbohydrate metabolism, the present study aimed to determine the effects of maternal low Cr (LC) on glucose metabolism in C57BL mice offspring, and the involved mechanisms. Weaned C57BL mice were born from mothers fed a control diet or LC diet, and were then fed a control or LC diet for 13 weeks. Subsequently, the liver microRNA (miRNA/miR) expression profile was analyzed by miRNA array analysis. A maternal LC diet increased fasting serum glucose (P<0.05) and insulin levels (P<0.05), homeostasis model assessment of IR index (P<0.01), and the area under curve for glucose concentration during oral glucose tolerance test (P<0.01). In addition, 8 upregulated and 6 downregulated miRNAs were identified in the maternal LC group (fold change ≥2, P<0.05). miRNA‑gene networks, Kyoto Encyclopedia of Genes and Genomes pathway analysis of differentially expressed miRNAs, and miRNA overexpression in HepG2 cells revealed the critical role of insulin signaling, via miR‑327, miR‑466f‑3p and miR‑223‑3p, in the effects of early life Cr restriction on glucose metabolism. In conclusion, maternal Cr restriction may irreversibly increase IR, which may involve a specific miRNA affecting the insulin signaling pathway.

Maternal Chromium Restriction Leads to Glucose Metabolism Imbalance in Mice Offspring through Insulin Signaling and Wnt Signaling Pathways

An adverse intrauterine environment, induced by a chromium-restricted diet, is a potential cause of metabolic disease in adult life. Up to now, the relative mechanism has not been clear. C57BL female mice were time-mated and fed either a control diet (CD), or a chromium-restricted diet (CR) throughout pregnancy and the lactation period. After weaning, some offspring continued the diet diagram (CD-CD or CR-CR), while other offspring were transferred to another diet diagram (CD-CR or CR-CD). At 32 weeks of age, glucose metabolism parameters were measured, and the liver from CR-CD group and CD-CD group was analyzed using a gene array. Quantitative real-time polymerase chain reaction (qPCR) and Western blot were used to verify the result of the gene array. A maternal chromium-restricted diet resulted in obesity, hyperglycemia, hyperinsulinemia, increased area under the curve (AUC) of glucose in oral glucose tolerance testing and homeostasis model assessment of insulin resistance (HOMA-IR). There were 463 genes that differed significantly (>1.5-fold change, p < 0.05) between CR-CD offspring (264 up-regulated genes, 199 down-regulated genes) and control offspring. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and STRING (Search Tool for the Retrieval of Interacting Genes/Proteins) analysis revealed that the insulin signaling pathway and Wnt signaling pathway were in the center of the gene network. Our study provides the first evidence that maternal chromium deficiency influences glucose metabolism in pups through the regulation of insulin signaling and Wnt signaling pathways.

Chromium Supplements in the Feed for Lactating Murrah Buffaloes (Bubalus bubalis): Influence on Nutrient Utilization, Lactation Performance, and Metabolic Responses

This study was conducted to evaluate the effect of different levels of inorganic chromium (Cr) on nutrient intake, nutrient utilization, milk mineral contents, and blood biochemical in lactating Murrah buffaloes. Twenty-four multifarious Murrah buffaloes were blocked into four groups having six animals in each group and fed for 150 days post-partum. Feeding regimen was same in all the groups except that treatment groups were supplemented with 0.0, 0.5, 1.0, and 1.5 mg inorganic Cr/kg dry matter (DM) in the four respective groups. Group fed on basal diet supplemented with 0.0 mg Cr/kg DM served as a control. Adding inorganic Cr to the diet of lactating buffaloes increased feed intake, milk yield, and nutrient digestibility. Nitrogen (N) and Cr balance were significantly increased (P<0.05) by adding Cr. Milk and plasma Cr concentration could be increased by adding Cr (P<0.001), while no significant differences were found between the four treatments in milk and plasma concentration of calcium (Ca), copper (Cu), and zinc (Zn). Feeding of diet supplemented with inorganic Cr decreased plasma insulin concentration (P=0.016). Concentration of blood glucose and the ratio of blood glucose to insulin were increased by adding Cr (P=0.037 and P=0.011, respectively). Adding Cr to the diet of lactating buffaloes did not show any effect on blood hemoglobin (Hb), while plasma concentration of progesterone and antioxidant status was increased (P<0.05). It could be concluded that adding Cr to the diet of lactating buffaloes improved nutrient intake, nutrient utilization, and lactation performance.

Evaluation of the Reproductive Toxicity, Glycometabolism, Glycometabolism-Related Enzyme Levels and Lipid Metabolism of Chromium Malate Supplementation in Sprague-Dawley Rats

Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the reproductive toxicity of chromium malate in Sprague-Dawley rats and then inspected the effect of chromium malate on glycometabolism, glycometabolism-related enzymes, and lipid metabolism. The results showed that no pathological, toxic feces and urine changes were observed in clinical signs of parental and fetal rats in chromium malate groups. The fasting blood glucose, serum insulin, insulin resistance index, C-peptide, hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride levels of chromium malate groups have no significant change compared with control group and chromium picolinate group. The serum and organ contents of Cr in chromium malate groups have no significant change when compared with control group. No measurable damage on liver, brain, kidney, and testis/uterus of chromium malate groups was found. No significant change in body mass, absolute and relative organ weights, and hematological and biochemical changes of rats were observed compared with the control and chromium picolinate groups. The results indicated that supplements with chromium malate does not cause obvious damage and has no obvious effect on glycometabolism, glycometabolism-related enzyme, and lipid metabolism on female and male rats. The results of this study suggested that chromium malate is safe for human consumption and has the potential for application as a functional food ingredient and dietary supplement.

Beneficial effects of oral chromium picolinate supplementation on glycemic control in patients with type 2 diabetes: A randomized clinical study

BACKGROUND

Chromium is an essential mineral that contributes to normal glucose function and lipid metabolism. This study evaluated the effect of chromium picolinate (CrPic) supplementation in patients with type 2 diabetes mellitus (T2DM).

METHODS

A four month controlled, single blind, randomized trial was performed with 71 patients with poorly controlled (hemoglobin A1c [HbA1c]>7%) T2DM divided into 2 groups: Control (n=39, using placebo), and supplemented (n=32, using 600μg/day CrPic). All patients received nutritional guidance according to the American Diabetes Association (ADA), and kept using prescribed medications. Fasting and postprandial glucose, HbA1c, total cholesterol, high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, triglycerides and serum ferritin were evaluated.

RESULTS

CrPic supplementation significantly reduced the fasting glucose concentration (-31.0mg/dL supplemented group; -14.0mg/dL control group; p<0.05, post- vs. pre-treatment, in each group) and postprandial glucose concentration (-37.0mg/dL in the supplemented group; -11.5 mg/dL in the control group; p<0.05). HbA1c values were also significantly reduced in both groups (p<0.001, comparing post- vs. pre-treatment groups). Post-treatment HbA1c values in supplemented patients were significantly lower than those of control patients. HbA1c lowering in the supplemented group (-1.90), and in the control group (-1.00), was also significant, comparing pre- and post-treatment values, for each group (p<0.001 and p<0.05, respectively). CrPic increased serum chromium concentrations (p<0.001), when comparing the supplemented group before and after supplementation. No significant difference in lipid profile was observed in the supplemented group; however, total cholesterol, HDL-c and LDL-c were significantly lowered, comparing pre- and post-treatment period, in the control group (p<0.05).

CONCLUSIONS

CrPic supplementation had a beneficial effect on glycemic control in patients with poorly controlled T2DM, without affecting the lipid profile. Additional studies are necessary to investigate the effect of long-term CrPic supplementation.

Effect of glucose tolerance factor (GTF) from high chromium yeast on glucose metabolism in insulin-resistant 3T3-L1 adipocytes

Relative expression of IR, IRS-1, IRS-2 and GLUT4 mRNA was determined in insulin-resistant 3T3-L1 adipocytes with different treatments.

Chromium does not belong in the diabetes treatment arsenal: Current evidence and future perspectives

Chromium is considered to have positive effects on insulin sensitivity and is marketed as an adjunctive therapy for inducing glucose tolerance in cases of insulin resistance (“the glucose tolerance factor”). Case reports on patients who received prolonged parenteral nutrition indeed showed that the absence of trivalent chromium caused insulin resistance and diabetes. However, whether patients with type 2 diabetes can develop a clinically relevant chromium deficiency is unclear. This review summarizes the available evidence regarding the potential effectiveness of chromium supplementation on glycemic control (Hemoglobin A1c levels) in patients with type 2 diabetes. No studies investigating the long-term safety of chromium in humans were found. All clinical trials that have been performed had a relative short follow-up period. None of the trials investigated whether the patients had risk factors for chromium deficiency. The evidence from randomized trials in patients with type 2 diabetes demonstrated that chromium supplementation does not effectively improve glycemic control. The meta-analyses showed that chromium supplementation did not improve fasting plasma glucose levels. Moreover, there were no clinically relevant chromium effects on body weight in individuals with or without diabetes. Future studies should focus on reliable methods to estimate chromium status to identify patients at risk for pathological alterations in their metabolism associated with chromium deficiency. Given the present data, there is no evidence that supports advising patients with type 2 diabetes to take chromium supplements.

Effects of chromium propionate on egg production, egg quality, plasma biochemical parameters, and egg chromium deposition in late-phase laying hens

This study was conducted to investigate the effects of chromium propionate on egg production, egg quality, plasma biochemical parameters and egg chromium deposition in late-phase laying hens. Four hundred thirty-two 60-weeks old laying hens were divided into four groups of 108 birds per group according to egg production. The dietary treatments consisted of the basal diet adding with 0, 200, 400, and 600 μg/kg chromium as chromium propionate. All laying hens were given feed and water ad libitum for 8 weeks. The addition of 400 μg/kg Cr as chromium propionate increased egg production (P < 0.01) during the later 4 weeks, but decreased albumen height, yolk color score, and Haugh unit of eggs. Six hundred micrograms per kilogram Cr as chromium propionate supplementation improved shell thickness (P < 0.05). 200 μg/kg Cr as chromium propionate supplementation decreased the uric acid concentration by 31 % (P < 0.05). However, supplemental Cr did not affect the egg chromium deposition of hens (P > 0.05). These data indicated that feeding of late-phase laying hens with chromium propionate could improve egg production, increase eggshell thickness, but do not result in abnormal levels of chromium deposition in eggs.