Hypocholesterolemic effects of nicotinic acid and chromium supplementation

During the course of a study of the hypoglycemic effects of nicotinic acid and chromium on humans, two hypercholesterolemic subjects were found to experience clinically significant decreases in serum cholesterol levels. These subjects have now been followed for one year. The first subject had a cholesterol level of 10.33 mmol/L (399 mg/dL). Daily supplementation for four weeks with 100 mg of nicotinic acid (niacin) and 200 micrograms of chromium chloride led to a decrease in serum cholesterol to 8.86 mmol/L (342 mg/dL). Further supplementation for four months led to a further decrease in serum cholesterol to 7.25 mmol/L (280 mg/dL). The second subject had a cholesterol level of 8.73 mmol/L (337 mg/dL). Four weeks of supplementation lowered the level to 6.73 mmol/L (260 mg/dL). When supplementation was discontinued, the cholesterol level rose slightly. When supplementation was reinstituted, the cholesterol level decreased to 6.68 mmol/L (258 mg/dL).     

The effects of inorganic chromium and brewer's yeast on glucose tolerance, plasma lipids, and plasma chromium in elderly subjects

Twenty-three healthy, well-nourished, free-living elderly volunteers were given daily, for 10 wk, 5 g brewer's yeast, 200 micrograms Cr3+ as chromic chloride (CrCl3), or placebo. There were no significant changes in glucose tolerance, insulin, cholesterol or triglycerides after supplementation in any of the three groups. Plasma Cr3+ rose significantly after supplementation with CrCl3 but did not change after yeast or placebo supplementation. Plasma Cr3+ did not increase after an oral glucose load and did not correlate with glucose, insulin or lipid values in any of the groups. Calculated intakes of eight indicator nutrients were well above 100% of the RDA except for calcium. These healthy elderly persons, eating nutritious diets, are not at risk for Cr3+ deficiency as measured by the absence of a clinical response to CrCl3 or brewer's yeast supplementation. This study suggests that age per se is not a factor leading to Cr deficiency.     

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.     

Supplemental-chromium effects on glucose, insulin, glucagon, and urinary chromium losses in subjects consuming controlled low-chromium diets

The effects of low-chromium diets containing chromium in the lowest quartile of normal intake on glucose tolerance and related variables in 11 females and 6 male subjects were evaluated. Subjects with glucose concentration greater than 5.56 mmol/L but less than 11.1 mmol/L 90 min after an oral-glucose challenge were designated as the hyperglycemic group and the remainder, the control group. Glucose tolerance and circulating insulin and glucagon of the hyperglycemic group all improved during chromium supplementation (200 micrograms/d) whereas those of the control group were unchanged. Glucose and insulin concentrations 60 min after the oral-glucose challenge and the sum of the 0-90 min and 0-240 min glucose values were all significantly lower after chromium supplementation in the hyperglycemic group. These data demonstrate that consumption of diets in the lowest 25% of normal chromium intake lead to detrimental effects on glucose tolerance, insulin, and glucagon in subjects with mildly impaired glucose tolerance.     

Serum lipids and glucose concentrations in subjects using antihypertensive drugs: Finnmark 1977.

As a side project to a study of coronary risk factors 4878 men and women aged 20-53 were interviewed about present and previous use of antihypertensive drugs. Serum lipid and glucose concentrations were compared in 124 present users, 73 previous users, and 124 controls matched for age, sex, and systolic and diastolic blood pressure. Users of betablockers, thiazides, and other antihypertensive drugs had higher total cholesterol, triglycerides, and glucose and lower HDL-cholesterol than the other groups, but only the difference in HDL-cholesterol was statistically significant. Smokers had statistically significant lower HDL-cholesterol than non-smokers in drug users, whereas there were only minor differences between them in previous and never users. This indicates an interaction between smoking and current antihypertensive medication. The unfavourable serum lipid pattern may, if caused by drug use, explain the lack of influence that antihypertensive treatment has had on the incidence of coronary heart disease in intervention studies.     

Resistant starch supplementation influences blood lipid concentrations and glucose control in overweight subjects

Resistant starch (RS) includes the sum of starch and degradation products of starch that resist small intestinal digestion and enter the colon. This study was planned to examine the effect of resistant starch on hypolipidemic actions, blood glucose, insulin levels and humoral immune responses in healthy overweight subjects. Healthy overweight subjects (over 120% of their ideal body weights) were fed either 24 g/d of resistant corn starch (RS) or regular corn starch (CS) for 21 d with their regular meals. Although this double-blind feeding regiment resulted in no significant changes in their weights or other physical parameters for the relatively acute period of intakes, there were significant lowering effects of serum total cholesterol (p < 0.05) and serum LDL-cholesterol (p < 0.05) in subjects supplemented RS. Compared with the control starch group, the RS supplementation also reduced the mean fasting serum glucose concentrations (p < 0.05). Resistant starch supplement resulted in the increase in serum immunoglobulin G (IgG) concentrations. Serum insulin and complement 3 (C3) were unaffected. Tested resistant starch supplementation was reported to be palatable with minimal bowel discomfort. These results suggest that RS supplementation improves the blood lipid profile and controls the blood glucose levels in healthy overweight subjects without bowel discomfort. Therefore, RS has a potential to be used as one of the promising food ingredients for reducing risk factors involved in the development of atherosclerosis and type 2 diabetes in overweight individuals. However, in order to prove RS as a novel therapeutic agent of cardiovascular diseases and diabetes, controlled trials with larger sample sizes and longer duration are warranted.     

The effects of chromium on human health

This is a review of studies dealing with the physiological role of chromium in the body and its harmful effects to human health. Trivalent chromium is discussed as a trace element essential to normal metabolism of hydrocarbons and to functioning of some enzymes. Toxic and carcinogenic effects of chromium due to occupational exposure, environmental pollution, food contamination and accidental poisoning are described.     

Effect of chromium supplementation on hair chromium concentration and diabetic status

Thirty-nine diabetic and 39 non-diabetic subjects matched for age and sex were given torula yeast (placebo) or brewer's yeast (68 μg chromium/day) in a double blind experiment. Hair chromium concentration was determined on all subjects before and after the 90 day yeast supplementation period. An overnight fasting blood sample was drawn from all diabetic subjects before and after yeast supplementation. The blood was analyzed for glycosylated hemoglobin and for serum glucose, insulin, total cholesterol, HDL cholesterol, and triglycerides. Mean initial hair chromium concentration of the non-diabetic subjects was 383±75 ppb, which was greater than that of the diabetic subjects (317±74 ppb) (p<0.001). Hair chromium concentration increased 111±78 ppb in subjects who received high chromium yeast compared with 17±80 ppb in those who received the placebo (p<0.001). The amount of increase in hair chromium concentration was similar between non-diabetic and diabetic subjects who received the high chromium yeast (p<0.05). No significant effect of chromium supplementation occurred in diabetic subjects as measured by any of the blood parameters (p>0.05).     

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.     

Effect of chromium supplementation on blood glucose and lipid levels in type 2 diabetes mellitus elderly patients

Intervention trials have shown the beneficial effects of chromium supplementation in type 2 diabetes (non-insulin-dependent diabetes mellitus). This study investigated the effects of chromium picolinate on elderly diabetic patients within a rehabilitation program. Thirty-nine diabetic subjects, average age 73 years (18 males and 21 females), undergoing rehabilitation following stroke or hip fracture, were recruited to participate in this study. An additional 39 diabetic patients constituted the control group. Along with standard treatment for diabetes, the study group received 200 microg of chromium twice a day for a three-week period. Blood samples, dietary intake, and anthropometric data were collected prior to and post-intervention. Throughout the study period, participants received a diet of approximately 1500 kcal/day. Significant differences in the fasting blood level of glucose compared to the baseline (190 mg/dL vs 150 mg/dL, p < 0.001) were found at the end of the study. HbA1c also improved from 8.2% to 7.6% (p < 0.01). Total cholesterol was also reduced from 235 mg/dL to 213 mg/dL (p < 0.02). A trend towards lowered triglyceride levels was also observed (152 mg/dL vs 136 mg/dL). We conclude that, in this population of elderly, diabetic patients undergoing rehabilitation, dietary supplementation with chromium is beneficial in moderating glucose intolerance. In addition, chromium intake appears to lower plasma lipid levels.     

The effects of sugar-beet fibre supplementation for five weeks on zinc, iron and copper status in human subjects.

The present study was conducted to evaluate the effects of fibre supplementation on zinc, iron and copper status in human subjects. Ten males (53 +/- 8 years of age) participated in this study which consisted of three phases: baseline-1 period (2 weeks) in which subjects were on their normal, habitual dietary intake, followed by a period of fibre supplementation (5 weeks) in which subjects were supplemented with 26 g dietary fibre/d, and baseline-2 period (4 weeks) in which fibre supplement was withdrawn. Parametric measurements of zinc, iron and copper status were conducted on weeks 1,2 (zero-time), 7 and 11. Results showed that fibre supplementation for 5 weeks did not cause any significant change in the status of zinc (measured by concentration of zinc in plasma and urine and alkaline phosphatase activity), iron (measured by packed cell volume (PCV%), HB, transferrin saturation % and ferritin), or copper (measured by plasma copper concentration and erythrocyte superoxide dismutase activity). We conclude that consumption of sugar-beet fibre added to the daily diet does not constitute any risk with respect to zinc, iron and copper nutriture.     

Serum chromium and gestational diabetes.

OBJECTIVE: To prospectively assess if chromium levels are different in gestational diabetics than in nondiabetic pregnant women. Therapeutic options could exist if levels are different. METHODS: We conducted a 2-year prospective, gestational cohort study. The cohort included newly diagnosed pregnant patients. Two blood samples were taken, the first at consent, the second at the time of diabetes screening. RESULTS: Five hundred eighty patients entered the cohort. One hundred fifty-five were lost to follow up and 425 patients completed the study (396 nondiabetics and 29 diabetics). The patients with gestational diabetes were significantly older, with a family history of gestational diabetes, and were significantly more likely to have been a gestational diabetic in a previous pregnancy (P < 05). There was no significant difference between the 2 groups for chromium levels both at enrollment (0.15 +/- 0.06 ng/mL vs 0.14 +/- 0.03 ng/mL; P = .28) and during the second trimester (0.14 +/- 0.06 ng/mL vs 0.14 +/- 0.04 ng/mL; P = .82). CONCLUSION: Serum chromium levels do not exhibit any significant variation between gestational diabetic women and nondiabetic women when assessed prospectively.     

Blood glucose lowering effects of brown rice in normal and diabetic subjects

Carbohydrate foods, which produce low glycemic responses, have been shown to be beneficial in the dietary management of chronic diseases such as diabetes and hyperlipidemia. This study determined the starch digestion rate in vitro and, in a randomised crossover design, the postprandial blood glucose response of 10 healthy and nine type 2 diabetic volunteers to brown rice compared to milled rice from the same batch and variety. The total sugar released in vitro was 23.7% lower in brown rice than in milled rice. In healthy volunteers, the glycemic area and glycemic index were, respectively, 19.8% and 12.1% lower (p < 0.05) in brown rice than milled rice, while in diabetics, the respective values were 35.2% and 35.6% lower. The effect was partly due to the higher amounts of phytic acid, polyphenols, dietary fiber and oil in brown compared to milled rice and the difference in some physicochemical properties of the rice samples such as minimum cooking time and degree of gelatinisation. In conclusion, brown rice is a more health beneficial food for diabetics and hyperglycemic individuals than milled rice.     

Vinegar supplementation lowers glucose and insulin responses and increases satiety after a bread meal in healthy subjects

OBJECTIVE: To investigate the potential of acetic acid supplementation as a means of lowering the glycaemic index (GI) of a bread meal, and to evaluate the possible dose-response effect on postprandial glycaemia, insulinaemia and satiety. SUBJECTS AND SETTING: In all, 12 healthy volunteers participated and the tests were performed at Applied Nutrition and Food Chemistry, Lund University, Sweden. INTERVENTION: Three levels of vinegar (18, 23 and 28 mmol acetic acid) were served with a portion of white wheat bread containing 50 g available carbohydrates as breakfast in randomized order after an overnight fast. Bread served without vinegar was used as a reference meal. Blood samples were taken during 120 min for analysis of glucose and insulin. Satiety was measured with a subjective rating scale. RESULTS: A significant dose-response relation was seen at 30 min for blood glucose and serum insulin responses; the higher the acetic acid level, the lower the metabolic responses. Furthermore, the rating of satiety was directly related to the acetic acid level. Compared with the reference meal, the highest level of vinegar significantly lowered the blood glucose response at 30 and 45 min, the insulin response at 15 and 30 min as well as increased the satiety score at 30, 90 and 120 min postprandially. The low and intermediate levels of vinegar also lowered the 30 min glucose and the 15 min insulin responses significantly compared with the reference meal. When GI and II (insulinaemic indices) were calculated using the 90 min incremental area, a significant lowering was found for the highest amount of acetic acid, although the corresponding values calculated at 120 min did not differ from the reference meal. CONCLUSION: Supplementation of a meal based on white wheat bread with vinegar reduced postprandial responses of blood glucose and insulin, and increased the subjective rating of satiety. There was an inverse dose-response relation between the level of acetic acid and glucose and insulin responses and a linear dose-response relation between acetic acid and satiety rating. The results indicate an interesting potential of fermented and pickled products containing acetic acid.     

Blood glucose lowering effects of brown rice in normal and diabetic subjects

Carbohydrate foods, which produce low glycemic responses, have been shown to be beneficial in the dietary management of chronic diseases such as diabetes and hyperlipidemia. This study determined the starch digestion rate in vitro and, in a randomised crossover design, the postprandial blood glucose response of 10 healthy and nine type 2 diabetic volunteers to brown rice compared to milled rice from the same batch and variety. The total sugar released in vitro was 23.7% lower in brown rice than in milled rice. In healthy volunteers, the glycemic area and glycemic index were, respectively, 19.8% and 12.1% lower (p?<?0.05) in brown rice than milled rice, while in diabetics, the respective values were 35.2% and 35.6% lower. The effect was partly due to the higher amounts of phytic acid, polyphenols, dietary fiber and oil in brown compared to milled rice and the difference in some physicochemical properties of the rice samples such as minimum cooking time and degree of gelatinisation. In conclusion, brown rice is a more health beneficial food for diabetics and hyperglycemic individuals than milled rice.     

Potential antioxidant effects of zinc and chromium supplementation in people with type 2 diabetes mellitus.

OBJECTIVE: To determine the effects of combined zinc (Zn) and chromium (Cr) supplementation on oxidative stress and glucose homeostasis of people with type 2 diabetes. DESIGN: Tunisian adult subjects with HbA1C > 7.5% were supplemented for 6 months with 30 mg/d of Zn as Zn gluconate or 400 microg/d of Cr as Cr pidolate or combined Zn/Cr supplementation or placebo. The effects of supplementation on plasma zinc (Zn), copper (Cu), selenium (Se), urinary Zn, Cr, plasma thiobarbituric acid reactive substances (TBARS), Cu-Zn superoxide dismutase (SOD) and Se glutathione peroxidase (GPx) in red blood cells, blood lipids and lipoproteins, HbA1C and fasting glucose were measured at the beginning of the study and after six months. RESULTS: At the beginning of the study, more than 30% of the subjects may have been Zn deficient with plasma Zn values less than 10.7 mircomol/L, whereas levels of plasma Cu, Se and antioxidant RBC enzyme activities were in the normal ranges. Following supplementation, there were significant decreases of plasma TBARS in the Cr (13.6%), Zn (13.6%) and Zn/Cr (18.2%) groups with no significant changes in the placebo group. The value for the TBARS of the control healthy Tunisian subjects was 2.08 +/- 0.04 micromol/L and that of the Tunisian subjects with diabetes was 3.32 +/- 0.05 micromol/L. This difference of 1.24 micromol/L between the control group and the subjects with diabetes was reduced from 36% to 50% in the three supplemented groups. Supplementation did not modify significantly HbAIC nor glucose homeostasis. No adverse effects of Zn supplementation were observed on Cu status. HDL cholesterol nor interactions in Zn or Cr. CONCLUSIONS: These data suggest the potential beneficial antioxidant effects of the individual and combined supplementation of Zn and Cr in people with type 2 DM. These results are particularly important in light of the deleterious consequences of oxidative stress in people with diabetes.     

Chromium supplementation in impaired glucose tolerance of elderly: effects on blood glucose, plasma insulin, C-peptide and lipid levels.

Altogether twenty-six elderly subjects (aged 65-74 years) with persistent impaired glucose tolerance (World Health Organization (1985) criteria) identified in a population-based study, were randomly treated either with chromium-rich yeast (160 micrograms Cr/d) or with placebo for 6 months. The 24 h urinary Cr increased from 0.13 (SE 0.03) to 0.40 (SE 0.06) micrograms/d in the Cr group (n 13) but no change was found in the placebo group (n 11) (0.13 (SE 0.02) v. 0.11 (SE 0.02) micrograms/d). No significant change was observed in the oral glucose tolerance test (glucose dose 75 g; 0, 1 and 2 h blood glucose respectively): 5.3 (SE 0.1), 9.3 (SE 0.3), 8.2 (SE 0.3) mmol/l v. 5.0 (SE 0.1), 8.5 (SE 0.4), 7.3(SE 0.5) mmol/l in the Cr group; 4.9 (SE 0.2), 9.2 (SE 0.6), 8.1 (SE 0.3) mmol/l v. 4.8 (SE 0.2), 8.5 (SE 0.5), 7.0 (SE 0.6) mmol/l in the placebo group (baseline v. 6 months). Glycosylated haemoglobin, plasma insulin, C-peptide and apolipoprotein A1 and B levels remained unchanged, and no improvement was seen in serum total cholesterol (6.2 (SE 0.3) v. 6.4 (SE 0.3) mmol/l for the Cr group, 6.2 (SE 0.4) v. 6.5 (SE 0.3) mmol/l for the placebo group), high-density-lipoprotein-cholesterol (1.1 (SE 0.1) v. 1.2 (SE 0.1) mmol/l for the Cr group, 1.0 (SE 0.1) v. 1.1 (SE 0.1) mmol/l for the placebo group) or triacylglycerols (2.5 (SE 0.4) v. 2.0 (SE 0.4) mmol/l for the Cr group, 2.4 (SE 0.2) v. 2.5 (SE 0.2) mmol/l for the placebo group). The present results indicate that Cr supplementation does not improve glucose tolerance or serum lipid levels in elderly subjects with stable impaired glucose tolerance.