Biomedical subjects

V Vuksan

Publications and source records attributed to V Vuksan.

At least 37 records · Page 2Linked to original sources

PubMed2000

Beneficial effects of viscous dietary fiber from Konjac-mannan in subjects with the insulin resistance syndrome: results of a controlled metabolic trial.

OBJECTIVE: Dietary fiber has recently received recognition for reducing the risk of developing diabetes and heart disease. The implication is that it may have therapeutic benefit in prediabetic metabolic conditions. To test this hypothesis, we investigated the effect of supplementing a high-carbohydrate diet with fiber from Konjac-mannan (KJM) on metabolic control in subjects with the insulin resistance syndrome. RESEARCH DESIGN AND METHODS: We screened 278 free-living subjects between the ages of 45 and 65 years from the Canadian-Maltese Diabetes Study. A total of 11 (age 55+/-4 years, BMI 28+/-1.5 kg/m2) were recruited who satisfied the inclusion criteria: impaired glucose tolerance, reduced HDL cholesterol, elevated serum triglycerides, and moderate hypertension. After an 8-week baseline, they were randomly assigned to take either KJM fiber-enriched test biscuits (0.5 g of glucomannan per 100 kcal of dietary intake or 8-13 g/day) or wheat bran fiber (WB) control biscuits for two 3-week treatment periods separated by a 2-week washout. The diets were isoenergetic, metabolically controlled, and conformed to National Cholesterol Education Program Step 2 guidelines. Serum lipids, glycemic control, and blood pressure were the outcome measures. RESULTS: Decreases in serum cholesterol (total, 12.4+/-3.1%, P<0.004; LDL, 22+/-3.9%, P<0.002; total/HDL ratio, 15.2+/-3.4%, P<0.003; and LDL/HDL ratio, 22.2+/-4.1%, P< 0.002), apolipoprotein (apo) B (15.1+/-4.3%, P<0.0004), apo B/A-1 ratio (13.1+/-3.4%, P< 0.0003), and serum fructosamine (5.2+/-1.4%, P<0.002) were observed during KJM treatment compared with WB-control. Fasting blood glucose, insulin, triglycerides, HDL cholesterol, and body weight remained unchanged. CONCLUSIONS: A diet rich in high-viscosity KJM improves glycemic control and lipid profile, suggesting a therapeutic potential in the treatment of the insulin resistance syndrome.

Aged↗

PubMed2000

Colonic bacterial activity and serum lipid risk factors for cardiovascular disease.

Antibiotics are being proposed for the treatment of cardiovascular disease. In the past, antibiotics were advocated for the control of hypercholesterolemia. We have therefore investigated the relation between colonic bacterial activity and serum lipids. In a four-phase randomized crossover study, we fed a different starch supplement during each 2-week phase to 24 healthy subjects. In two phases, supplements containing resistant starches were fed that reach the colon and are largely fermented by colonic bacteria. Fecal starch recovery therefore reflects the metabolic activity of colonic microflora. The control treatments were conventional starches. Blood lipid levels were obtained at the start and 4-day fecal collections at the end of each phase. Resistant starch supplements increased fecal starch excretion by 3.8 +/- 1.2 g/d more than conventional starches (P = .006). Mean starch excretion was related positively to pretreatment serum high-density lipoprotein (HDL) cholesterol (r = -.57, P = .003) and negatively to low-density lipoprotein (LDL) cholesterol (r = -.57, P = .004), apolipoprotein B:AI (r = -.56, P = .005), and fecal output of fusobacteria (r = -.73, P = .003) and bacteroides (r = -.72, P = .003). The ratio of fusobacteria to total anaerobes was also related to pretreatment LDL cholesterol (r = .56, P = .037). Differences in starch excretion between healthy subjects, as a measure of bacterial activity, accounted for 32% of the variation in pretreatment LDL cholesterol. The activity of colonic microflora therefore appears to influence serum lipid levels. Alterations of bacterial number and activity may provide an additional strategy to control serum lipid risk factors for cardiovascular disease.

Adult↗

PubMed1999

Effect of wheat bran on serum lipids: influence of particle size and wheat protein.

OBJECTIVE: Wheat fiber appears to protect from cardiovascular disease despite its lack of consistent effect on serum lipids. We therefore wished to determine whether reported inconsistencies in the effect of wheat bran resulted from differences in particle size or its high gluten content. METHODS: Two studies were conducted. In one-month metabolic diets, 24 hyperlipidemic subjects consumed breads providing an additional 19 g/d dietary fiber as medium or ultra-fine wheat bran and extra protein (10% of energy as wheat gluten). In two-week ad libitum diets, 24 predominantly normolipidemic subjects consumed breakfast cereals providing an additional 19 g/d of dietary fiber as coarse or a mixture of ultra-fine and coarse wheat bran with no change in gluten intake. Both studies followed a randomized crossover design with control periods when subjects ate low-fiber breads and cereals respectively with no added gluten. Fasting blood lipids were measured on day zero and at the end of each phase. RESULTS: Wheat bran had no effect on total, LDL or HDL cholesterol irrespective of particle size or level of gluten in the diet. However, consumption of increased gluten in the metabolic study was associated with a 13+/-4% reduction in serum triglycerides (p = 0.005) which was not seen in the normal-gluten ad libitum study. CONCLUSIONS: The protective effect of wheat fiber in cardiovascular disease cannot be explained by an effect of wheat bran in reducing serum cholesterol although in hyperlipidemic subjects displacement of carbohydrate by gluten on the high-fiber phases was associated with lower serum triglycerides.

Adult↗

PubMed1999

The effect of wheat bran particle size on laxation and colonic fermentation.

OBJECTIVE: Due to perceived inferior fecal bulking ability, finely ground wheat bran is not recommended for treatment of colonic disorders, despite possible short chain fatty acid generation with potential benefits for colonic mucosal health. We therefore tested the effects of very fine particle size wheat bran on colonic function. METHODS: Two studies, each with three phases, were undertaken in healthy subjects in a randomized crossover design. In one study (metabolic, n=23) subjects took three diets containing either an additional 19 g/d dietary fiber with mean particle size (MPS) 50 microm or 758 microm in bread or a control low fiber bread. In the other study where the supplement was provided as a breakfast cereal (ad libitum, n=24) the respective wheat bran MPS were 692 microm and 1158 microm and the control was low fiber. Fecal collections were obtained during the last week of each diet. In the metabolic study, fecal short chain fatty acids were measured and 12-hour breath gas collections obtained. RESULTS: In both studies, wheat bran supplements significantly increased fecal bulk compared to the control (p<0.004), with no significant differences between brans of different particle size and no differences in fecal water content. However, higher fecal butyrate concentrations (p<0.007), butyrate output and breath CH4 levels (p=0.025) were seen on the low MPS wheat bran compared to the other two treatments, suggesting increased bacterial fermentation. CONCLUSIONS: Fine MPS wheat bran is an effective fecal bulking agent and may have added advantages if increased butyrate concentrations promote colonic mucosal integrity.

Adult↗

PubMed1999

A novel source of wheat fiber and protein: effects on fecal bulk and serum lipids.

BACKGROUND: Wheat fiber is a laxative and wheat protein may affect blood lipids. OBJECTIVE: We therefore tested the effects on laxation and serum lipid metabolism of a novel source of wheat fiber and protein produced by the amylolytic digestion of starch from wheat. DESIGN: Twenty-four healthy men and women consumed 3 different test cereals in random order, each for 2 wk. The test supplement and the positive control, American Association of Cereal Chemists wheat bran supplement, both provided the same amount of fiber (21 g/d) and the negative control supplement provided 1.7 g fiber/d. RESULTS: The test supplement and the positive control supplement increased fecal bulk similarly (239.5+/-19 and 216.7+/-19 g/d, respectively) and significantly more than did the negative control supplement (165.6+/-16 g/d, P < 0.010). Compared with the negative and positive control supplements, the week 2 value of the test supplement for the ratio of total to HDL cholesterol was significantly reduced (P = 0.046). CONCLUSION: We conclude that the product of amylolytic digestion of starch from wheat flakes, which is high in wheat fiber and protein, has a fecal bulking effect similar to that of wheat bran and may have a beneficial effect on serum lipids.

Adult↗

PubMed1999

Inulin, oligofructose and intestinal function.

Inulin and oligofructose have attracted much attention recently as nonabsorbable carbohydrates with prebiotic properties. When inulin and oligofructose were added to a controlled diet, significant increases were noted in colonic bifidobacterial populations, and it has been proposed that these changes promote both colonic and systemic health through modification of the intestinal microflora. Inulin and oligofructose are rapidly and completely fermented by the colonic microflora with the production of acetate and other short-chain fatty acids. As with lactulose, they may also result in the growth of the fecal biomass, and in doing so, entrap ammonia for bacterial protein synthesis or conversion to the ammonium ion. As with dietary fiber and other nonabsorbable carbohydrates, there is also interest in inulin and oligofructose from the standpoint of inhibition of colonic carcinogenesis, blood cholesterol reduction, immune stimulation and enhanced vitamin synthesis. In these areas, the influence of their molecular weight is also an issue, with the longer chain length providing a more sustained fermentation pattern. More human studies are now required, including studies on the long-term effects of inulin and oligofructose consumption on colonic health, in particular on markers of cancer risk such as reduction in colonic polyp recurrence.

Animals↗

PubMed1999

Konjac-mannan (glucomannan) improves glycemia and other associated risk factors for coronary heart disease in type 2 diabetes. A randomized controlled metabolic trial.

OBJECTIVE: To examine whether Konjac-mannan (KJM) fiber improves metabolic control as measured by glycemia, lipidemia, and blood pressure in high-risk type 2 diabetic patients. RESEARCH DESIGN AND METHODS: A total of 11 hyperlipidemic and hypertensive type 2 diabetic patients treated conventionally by a low-fat diet and drug therapy participated. After an 8-week baseline, all were randomly assigned to take either KJM fiber-enriched test biscuits (0.7 g/412 kJ [100 kcal] of glucomannan) or matched placebo wheat bran fiber biscuits during two 3-week treatment phases separated by a 2-week washout period. The diet in either case was metabolically controlled and conformed to National Cholesterol Education Program Step 2 guidelines, while medications were maintained constant. Efficacy measures included serum fructosamine, lipid profiles, apolipoproteins, blood pressure, body weight, and nutritional analysis. RESULTS: Compared with placebo, KJM significantly reduced the metabolic control primary end points: serum fructosamine (5.7%, P = 0.007, adjusted alpha = 0.0167), total:HDL cholesterol ratio (10%, P = 0.03, adjusted alpha = 0.05), and systolic blood pressure (sBP) (6.9%, P = 0.02, adjusted alpha = 0.025). Secondary end points, including body weight, total, LDL, and HDL cholesterol, triglycerides, apolipoproteins A-1, B, and their ratio, glucose, insulin, and diastolic blood pressure, were not significant after adjustment by the Bonferroni-Hochberg procedure. CONCLUSIONS: KJM fiber added to conventional treatment may ameliorate glycemic control, blood lipid profile, and sBP in high-risk diabetic individuals, possibly improving the effectiveness of conventional treatment in type 2 diabetes.

Apolipoproteins↗

PubMed1998

Physiological effects of resistant starches on fecal bulk, short chain fatty acids, blood lipids and glycemic index.

OBJECTIVE: To assess the effects on fecal bulking, fecal short chain fatty acid (SCFA) production, blood lipids and glycemic indices of two different forms of resistant starch (RS2 and RS3) from a high-amylose cornstarch. METHODS: Twenty-four healthy subjects (12 men; 12 women) consumed four supplements taken for 2 weeks in random order separated by 2-week washout periods. The supplements were a low-fiber (control) and supplements providing an additional 30 g dietary fiber as wheat bran (high-fiber control) or the equivalent amount of resistant starch analyzed gravimetrically as dietary fiber from RS2 or RS3. Four-day fecal collections and 12-hour breath gas collections were obtained at the end of each period. Fasting blood was taken at the beginning and end of each period. Glycemic indices of supplements were also assessed. RESULTS: The wheat bran supplement increased fecal bulk 96+/-14 g/day compared with the low-fiber control (p<0.001) with the mean for both resistant starches also being greater (22+/-8 g/day) than the low-fiber control (p=0.013). On the resistant starch phases, the mean fecal butyrate:SCFA ratio, which has been suggested to have positive implications for colonic health, was significantly above the low-fiber control by 31+/-14% (p=0.035). Resistant starches did not alter serum lipids, urea or breath H2 or CH4. No significant differences in glycemic index were seen between the RS and control supplements. CONCLUSION: The potential physiological benefits of the resistant starches studied appear to relate to colonic health in terms of effects on fecal bulk and SCFA metabolism.

Adult↗

PubMed1998

Effect of meal dilution on the postprandial glycemic response. Implications for glycemic testing.

OBJECTIVE: To investigate the effect of varying the volume of sugar meals on the post-prandial glycemic response (PGR). RESEARCH DESIGN AND METHODS: On six separate occasions, after an overnight fast, blood glucose concentrations were measured in eight healthy subjects (34 +/- 4 years of age, BMI 22.9 +/- 0.9 kg/m2) after the consumption of 25 g glucose, sucrose, or fructose dissolved in either 200 or 600 ml of water. Blood was obtained at fasting and then at times 15, 30, 45, 60, and 90 min after the start of the test meal. RESULTS: PGR was found to be influenced by carbohydrate type (P < 0.001). Mean response areas (min.mmol.l-1) to the three sugars were statistically different (P < 0.05). Glucose had the highest response area (90.0 +/- 8.1), followed by sucrose (61.3 +/- 5.0) and then fructose (14.7 +/- 2.8). Independent of this effect, PGR was also found to be influenced by volume dose (P < 0.01). By tripling meal volume from 200 to 600 ml, PGR areas were significantly increased for all three sugars, glucose (79.3 +/- 10.3 vs. 100.8 +/- 12.0, P = 0.035), sucrose (52.6 +/- 5.5 vs. 70 +/- 7.4, P = 0.0094), and fructose (11.0 +/- 3.8 vs. 18.4 +/- 3.9, P = 0.012). Where the effects of time (P < 0.05) and dose (P < 0.05) were determined to be independent (interaction nonsignificant) for all three sugars, this increase in volume also significantly increased glycemic concentrations at 15 min, for glucose (P = 0.033) and sucrose (P = 0.026), suggesting that changes in gastric emptying time may be a mechanism of action. CONCLUSIONS: Varying the volume of liquid sugar meals alters PGR. Understanding this concept may help to reduce variability both in the glycemic testing of foods and oral glucose tolerance testing.

Administration, Oral↗

PubMed1998

The Study of Health Assessment and Risk in Ethnic groups (SHARE): rationale and design. The SHARE Investigators.

The Study of Health Assessment and Risk in Ethnic groups (SHARE) is a study to determine the risk factors for atherosclerosis among three ethnic populations in Canada. Three hundred and thirty South Asian Canadian, 320 Chinese Canadian and 320 European Canadian men and women between 35 and 75 years of age are being randomly sampled from communities in Hamilton and Toronto, Ontario and Edmonton, Alberta for assessment of conventional (i.e., smoking, dyslipidemia, diabetes and hypertension) and emerging (i.e., candidate genes for atherosclerosis, homocysteine, fibrinolytic parameters, neurohormones, glucose intolerance, markers of infection, socioeconomic status, psychosocial status and diet) cardiovascular disease risk factors. Subclinical atherosclerosis is measured by quantitative B-mode ultrasonography of the carotid arteries, and other objective measures of vascular disease are a 12-lead electrocardiogram, a two-dimensional echocardiogram, ankle to arm blood pressure ratio and urine microalbumin concentration. The relationship between the conventional and emerging risk factors, and atherosclerosis, vascular disease and markers of end-organ damage will be evaluated between and within ethnic groups.

Adult↗

PubMed1997

Effect of a diet high in vegetables, fruit, and nuts on serum lipids.

We assessed the effect of a diet high in leafy and green vegetables, fruit, and nuts on serum lipid risk factors for cardiovascular disease. Ten healthy volunteers (seven men and three women aged 33 +/- 4 years [mean +/- SEM]; body mass index, 23 +/- 1 kg/m2) consumed their habitual diet (control diet, 29% +/- 2% fat calories) and a diet consisting largely of leafy and other low-calorie vegetables, fruit, and nuts (vegetable diet, 25% +/- 3% fat calories) for two 2-week periods in a randomized crossover design. After 2 weeks on the vegetable diet, lipid risk factors for cardiovascular disease were significantly reduced by comparison with the control diet (low-density lipoprotein [LDL] cholesterol, 33% +/- 4%, P < .001; ratio of total to high-density lipoprotein [HDL] cholesterol, 21% +/- 4%, P < .001; apolipoprotein [apo] B:A-I, 23% +/- 2%, P < .001; and lipoprotein (a) [Lp(a)], 24% +/- 9%, P = .031). The reduction in apo B was related to increased intakes of soluble fiber (r = .84, P = .003) and vegetable protein (r = -.65, P = .041). On the vegetable compared with the control diet, the reduction in total serum cholesterol was 34% to 49% greater than would be predicted by differences in dietary fat and cholesterol. A diet consisting largely of low-calorie vegetables and fruit and nuts markedly reduced lipid risk factors for cardiovascular disease. Several aspects of such diets, which may have been consumed early in human evolution, have implications for cardiovascular disease prevention.

Adult↗

PubMed1995

Effect of nibbling versus gorging on cardiovascular risk factors: serum uric acid and blood lipids.

Nibbling has been reported to decrease serum cholesterol under fasting conditions, as well as the incidence of cardiovascular disease. It has been suggested that these effects are partly attributable to reduced concentrations of serum insulin, which are also observed. However, data on the effects of nibbling on serum lipids throughout the day are not available, nor is it known how nibbling affects serum uric acid as a further insulin-related risk factor for cardiovascular disease. We have attempted to address these issues. Seven healthy men consumed identical diets in a randomized crossover design either as three meals daily (control) or as 17 meals daily (nibbling) for 2 weeks. On day 13, serum lipid levels were measured over the course of the day (12 hours) together with the 24-hour urinary excretion of mevalonic acid as an indicator of hepatic cholesterol synthesis. Concentrations of uric acid in serum and 24-hour urinary excretion of uric acid were also determined. Mean (+/- SE) percent treatment differences in day-long total, low-density lipoprotein (LDL), and non-high-density lipoprotein (HDL) cholesterol, and apolipoprotein (apo) B were significant, with lower values on the nibbling diet as compared with the control diet (8.1% +/- 1.6%, P = .002; 12.2% +/- 2.6%, P = .005; 10.1% +/- 1.6%, P < .001; and 9.9% +/- 2.6%, P = .008, respectively). No significant difference was seen in the total to HDL cholesterol ratio or in urinary mevalonic acid excretion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Implications of altering the rate of carbohydrate absorption from the gastrointestinal tract.

The rate of absorption of carbohydrate from the small intestine plays a major role in determining the metabolic effects of dietary carbohydrate. Factors which reduce the rate of absorption include the nature of the starch and sugars, and the presence of vegetable proteins, fats, viscous fibre, and antinutrients, including lectins and phytates. The rate of absorption can also be manipulated by the use of specific enzyme inhibitors and by increasing the number and frequency of meals while holding caloric intake constant. All these factors contribute to the creation of what may be termed slow release or "lente carbohydrate". The slowing of small intestinal absorption, as exemplified by increased meal frequency ("nibbling"), results in reduced postprandial insulin secretion and lower low-density lipoprotein (LDL) cholesterol and apolipoprotein B concentrations. A further effect of some manipulations which reduce the rate of absorption is increased delivery of carbohydrate to the colon and its absorption after bacterial fermentation to short-chain fatty acids (SCFA). These SCFA may have beneficial effects on colonic health(butyrate) or further inhibit cholesterol synthesis in the liver (propionate). Thus the absorption of "lente carbohydrate" takes place along the full length of the gastrointestinal tract with a wide variety of physiological consequences.

Carbohydrates↗

PubMed1995

Effect of reduced rate of carbohydrate absorption on carbohydrate and lipid metabolism.

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Bile Acids and Salts↗

PubMed1994

Low glycemic index: lente carbohydrates and physiological effects of altered food frequency.

Many factors influence carbohydrate absorption. Slower rates of absorption may have advantages in reducing postprandial glycemia and insulinemia and, in time, reduce serum low-density-lipoprotein (LDL) cholesterol and apolipoprotein B concentrations. Foods high in viscous fiber or antinutrients, or foods that are resistant to gelatinization, show slower rates of digestion and absorption and may be called low glycemic index or lente carbohydrate foods. Specific enzyme inhibitors may also cause lente effects. Certain small-intestinal effects of lente carbohydrate may be mimicked by altering feeding frequency (eg, nibbling vs gorging). Increased meal frequency reduces post-prandial insulin and glucose responses in people with non-insulin-dependent diabetes and in nondiabetic volunteers and lowers serum concentrations of LDL cholesterol and apolipoprotein B. Reduced hepatic cholesterol synthesis has been reported. Increased meal frequency may also slow small-intestinal absorption in the treatment of conditions such as diabetes, hyperlipidemia, and possibly obesity.

Blood Glucose↗

PubMed1992

Metabolic advantages of spreading the nutrient load: effects of increased meal frequency in non-insulin-dependent diabetes.

The acute effect of increasing meal frequency as a model of slow absorption was studied for 1 d in 11 patients with non-insulin-dependent diabetes. On 1 d they took 13 snacks (the nibbling diet) and on another day the same diet was taken as three meals and one snack (the three-meal diet). The nibbling diet reduced mean blood glucose, serum insulin, and C peptide concentrations over the 9.5 h of observation and 24-h urinary C peptide output by 12.7 +/- 3.7% (mean +/- SE) (P = 0.0062), 20.1 +/- 5.8% (P = 0.0108), 9.2 +/- 2.6% (P = 0.0073), and 20.37 +/- 8.12% (P = 0.039), respectively, compared with the three-meal diet. Serum triglyceride concentrations were lower by 8.5 +/- 3.2% (P = 0.037). Despite lower insulin concentrations on the nibbling diet, the concentrations of free fatty acids, 3-hydroxybutyrate, and the insulin-sensitive branched-chain amino acids responded similarly on both treatments. Metabolic benefits seen with increased meal frequency may explain the success of similar agents that prolong absorption, including fiber and enzyme inhibitors.

Adult↗

PubMed1992

Beneficial effect of a low glycaemic index diet in type 2 diabetes.

Low glycaemic index foods produce low blood glucose and insulin responses in normal subjects, and improve blood glucose control in Type 1 and well-controlled Type 2 diabetic patients. We studied the effects of a low glycaemic index diet in 15 Type 2 diabetic patients with a mean fasting blood glucose of 9.5 mmol l-1 using a randomized, crossover design. Patients were given pre-weighed diets (59% energy as carbohydrate, 21% fat, and 24 g 1000-kcal-1 dietary fibre) for two 2-week periods, with a diet glycaemic index of 60 during one period and 87 during the other. On the low glycaemic index diet, the blood glucose response after a representative breakfast was 29% less than on the high glycaemic index diet (874 +/- 108 (+/- SE) vs 204 +/- 112 mmol min l-1; p less than 0.001), the percentage reduction being almost identical to the 28% difference predicted from the meal glycaemic index values. After the 2-week low glycaemic index diet, fasting serum fructosamine and cholesterol levels were significantly less than after the high glycaemic index diet (3.17 +/- 0.12 vs 3.28 +/- 0.16 mmol l-1, p less than 0.05, and 5.5 +/- 0.4 vs 5.9 +/- 0.5 mmol l-1, p less than 0.02, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗