Acute effects of pistachio consumption on glucose and insulin, satiety hormones and endothelial function in the metabolic syndrome.

BACKGROUND/OBJECTIVE: Nut consumption has been found to decrease risk of coronary heart disease and diabetes and to promote healthy body weights possibly related to their favorable macronutrient profile. We therefore assessed the effect of pistachios on postprandial glucose and insulin levels, gut hormones related to satiety and endothelial function. SUBJECTS/METHODS: In this randomized crossover study, 20 subjects with metabolic syndrome consumed five study meals over 5-10 weeks. The meals differed in fat type and quantity, but were matched according to available carbohydrates (CHOs). Three meals had 50 g available CHO: white bread (WB50g), white bread, butter and cheese (WB+B+Ch) and white bread and pistachios (WB+P). Two meals had 12 g available CHO: white bread (WB12g) and pistachios (P). RESULTS: Within each group of available CHO meals, postprandial glucose levels were the highest following the white bread-only meals, and glucose response was significantly attenuated when butter and cheese or pistachios were consumed (P<0.05). Postprandial insulin levels were highest after the WB+B+Ch meal (P<0.05), but did not differ between the white bread-only and pistachio meals. Both endothelial function (reactive hyperemia index) and arterial stiffness (augmentation index) significantly increased after the white bread-only meals compared with the WB+B+Ch meal (all P<0.05). Insulin secretagogue levels were higher when butter and cheese or pistachios were consumed than when white bread only was consumed (P<0.05). CONCLUSIONS: Compared with white bread, pistachio consumption reduced postprandial glycemia, increased glucagon-like-peptide levels and may have insulin-sparing properties. These effects could be beneficial for individuals with diabetes and metabolic syndrome.

The glycemic effect of nut-enriched meals in healthy and diabetic subjects.

BACKGROUND AND AIMS: The intake of nuts has been linked to a reduced risk of cardiovascular disease (CVD) and diabetes in large cohort studies. One potential contributing mechanism may be the ability of nuts to improve post-meal glycemic response. We, therefore, examined the effect of nuts alone and in combination with white bread on postprandial glycemia. METHODS AND RESULTS: 30, 60 and 90 g (approximately 1, 2 and 3 ounces) of mixed nuts were consumed with and without 50 g available carbohydrate from white bread by 10-14 normoglycemic and 5-10 type 2 diabetic subjects. Glycemic response (GR) was assessed by calculating the incremental area under the 2 h blood glucose curve. All three doses of mixed nuts, when fed alone, significantly reduced the glycemic response in both normoglycemic and diabetic patients. Furthermore, in the normoglycemic subjects, adding nuts to white bread progressively reduced the GR of the meal by 11.2 ± 11.6%, 29.7 ± 12.2% and 53.5 ± 8.5% for the 30, 60, and 90 g doses (P = 0.354, P = 0.031 and P < 0.001, respectively), while in subjects with type 2 diabetes, the effect was half of that seen in the non-diabetic subjects (P = 0.474, P = 0.113 and P = 0.015, respectively). CONCLUSION: Nuts alone have little effect on post-meal blood glucose response. Furthermore, when taken with bread, nuts progressively reduce the glycemic response in a dose-dependent manner. While these findings support a short-term benefit for nuts in postprandial glucose response, more studies are required to determine whether these acute benefits result in long-term improvements in glycemic control.

The relation of low glycaemic index fruit consumption to glycaemic control and risk factors for coronary heart disease in type 2 diabetes.

AIMS/HYPOTHESIS: Sugar has been suggested to promote obesity, diabetes and coronary heart disease (CHD), yet fruit, despite containing sugars, may also have a low glycaemic index (GI) and all fruits are generally recommended for good health. We therefore assessed the effect of fruit with special emphasis on low GI fruit intake in type 2 diabetes. METHODS: This secondary analysis involved 152 type 2 diabetic participants treated with glucose-lowering agents who completed either 6 months of high fibre or low GI dietary advice, including fruit advice, in a parallel design. RESULTS: Change in low GI fruit intake ranged from -3.1 to 2.7 servings/day. The increase in low GI fruit intake significantly predicted reductions in HbA(1c) (r = -0.206, p =0.011), systolic blood pressure (r = -0.183, p = 0.024) and CHD risk (r = -0.213, p = 0.008). Change in total fruit intake ranged from -3.7 to 3.2 servings/day and was not related to study outcomes. In a regression analysis including the eight major carbohydrate foods or classes of foods emphasised in the low GI diet, only low GI fruit and bread contributed independently and significantly to predicting change in HbA(1c). Furthermore, comparing the highest with the lowest quartile of low GI fruit intake, the percentage change in HbA(1c) was reduced by -0.5% HbA(1c) units (95% CI 0.2-0.8 HbA(1c) units, p < 0.001). CONCLUSIONS/INTERPRETATION: Low GI fruit consumption as part of a low GI diet was associated with lower HbA(1c), blood pressure and CHD risk and supports a role for low GI fruit consumption in the management of type 2 diabetes. TRIAL REGISTRATION: ClinicalTrials.gov NCT00438698.

Effect of non-oil-seed pulses on glycaemic control: a systematic review and meta-analysis of randomised controlled experimental trials in people with and without diabetes.

AIMS/HYPOTHESIS: Dietary non-oil-seed pulses (chickpeas, beans, peas, lentils, etc.) are a good source of slowly digestible carbohydrate, fibre and vegetable protein and a valuable means of lowering the glycaemic-index (GI) of the diet. To assess the evidence that dietary pulses may benefit glycaemic control, we conducted a systematic review and meta-analysis of randomised controlled experimental trials investigating the effect of pulses, alone or as part of low-GI or high-fibre diets, on markers of glycaemic control in people with and without diabetes. METHODS: We searched MEDLINE, EMBASE, CINAHL, and the Cochrane Library for relevant controlled trials of >or=7 days. Two independent reviewers (A. Esfahani and J. M. W. Wong) extracted information on study design, participants, treatments and outcomes. Data were pooled using the generic inverse variance method and expressed as standardised mean differences (SMD) with 95% CIs. Heterogeneity was assessed by chi (2) and quantified by I (2). Meta-regression models identified independent predictors of effects. RESULTS: A total of 41 trials (39 reports) were included. Pulses alone (11 trials) lowered fasting blood glucose (FBG) (-0.82, 95% CI -1.36 to -0.27) and insulin (-0.49, 95% CI -0.93 to -0.04). Pulses in low-GI diets (19 trials) lowered glycosylated blood proteins (GP), measured as HbA(1c) or fructosamine (-0.28, 95% CI -0.42 to -0.14). Finally, pulses in high-fibre diets (11 trials) lowered FBG (-0.32, 95% CI -0.49 to -0.15) and GP (-0.27, 95% CI -0.45 to -0.09). Inter-study heterogeneity was high and unexplained for most outcomes, with benefits modified or predicted by diabetes status, pulse type, dose, physical form, duration of follow-up, study quality, macronutrient profile of background diets, feeding control and design. CONCLUSIONS/INTERPRETATION: Pooled analyses demonstrated that pulses, alone or in low-GI or high-fibre diets, improve markers of longer term glycaemic control in humans, with the extent of the improvements subject to significant inter-study heterogeneity. There is a need for further large, well-designed trials.

Long-term effects of a plant-based dietary portfolio of cholesterol-lowering foods on blood pressure.

OBJECTIVE: To determine the effect on blood pressure of dietary advice to consume a combination of plant-based cholesterol-lowering foods (dietary portfolio). METHODS: For 1 year, 66 hyperlipidemic subjects were prescribed diets high in plant sterols (1.0 g/1000 kcal), soy protein (22.5 g/1000 kcal), viscous fibers (10 g/1000 kcal) and almonds (22.5 g/1000 kcal). There was no control group. Seven-day diet record, blood pressure and body weight were monitored initially monthly and later at 2-monthly intervals throughout the study. RESULTS: Fifty subjects completed the 1-year study. When the last observation was carried forward for non-completers (n=9) or those who changed their blood pressure medications (n=7), a small mean reduction was seen in body weight 0.7+/-0.3 kg (P=0.036). The corresponding reductions from baseline in systolic and diastolic blood pressure at 1 year (n=66 subjects) were -4.2+/-1.3 mm Hg (P=0.002) and -2.3+/-0.7 mm Hg (P=0.001), respectively. Blood pressure reductions occurred within the first 2 weeks, with stable blood pressures 6 weeks before and 4 weeks after starting the diet. Diastolic blood pressure reduction was significantly related to weight change (r=0.30, n=50, P=0.036). Only compliance with almond intake advice related to blood pressure reduction (systolic: r=-0.34, n=50, P=0.017; diastolic: r=-0.29, n=50, P=0.041). CONCLUSIONS: A dietary portfolio of plant-based cholesterol-lowering foods reduced blood pressure significantly, related to almond intake. The dietary portfolio approach of combining a range of cholesterol-lowering plant foods may benefit cardiovascular disease risk both by reducing serum lipids and also blood pressure.

Effect of high vegetable protein diets on urinary calcium loss in middle-aged men and women.

OBJECTIVE: To determine the effect of high-protein diets, which have recently been promoted for their health benefits, on urinary calcium losses and bone turnover in older subjects. DESIGN: Randomized controlled cross-over study. SETTING: Teaching hospital and university. SUBJECTS: Twenty hyperlipidemic men and postmenopausal women (age 56+/-2 y) completed the study. INTERVENTION: One-month test and control phases during which subjects consumed equi-energy metabolic diets high in calcium (1578 and 1593 mg/day, respectively). On the test diet 11% of total dietary energy from starch in the control bread was replaced by protein (wheat gluten), resulting in 27% of energy from protein on the test diet vs 16% on the control diet. MAIN OUTCOME MEASURE: Urinary calcium excretion. RESULTS: Compared with the control diet, at week 4, the test diet increased mean (+/-s.e.m.) 24 h urinary output of calcium (139+/-15 vs 227+/-21 mg, P=0.004). The treatment difference in urinary calcium loss correlated with the serum anion gap as a marker of metabolic acid production (r=0.57, P=0.011). Serum calcium levels were marginally lower 2.41+/-0.02 vs 2.38+/-0.02 mmol/l (P=0.075), but there was no significant treatment difference in calcium balance, possibly related to the high background calcium intake on both diets. CONCLUSION: In the presence of high dietary calcium intakes the vegetable protein gluten does not appear to have a negative effect on calcium balance despite increased urinary calcium loss.

High-protein diets in hyperlipidemia: effect of wheat gluten on serum lipids, uric acid, and renal function.

BACKGROUND: The metabolic effects of diets high in vegetable protein have not been assessed despite much recent interest in the effect of soy proteins in reducing serum cholesterol. OBJECTIVE: We assessed the metabolic effects of diets high in vegetable protein (specifically, wheat gluten) on serum lipids, uric acid concentrations, and renal function. DESIGN: Twenty hyperlipidemic men and women consumed isoenergetic test (high-protein) and control metabolic diets for 1 mo in a randomized crossover design. In the high-protein diet, 11% of the total dietary energy from starch in the control bread was replaced by vegetable protein (wheat gluten), resulting in 27% of total energy from protein compared with 16% in the control diet. In other respects, the 2 diets were identical. RESULTS: Compared with the control, the high-protein diet resulted in lower serum concentrations of triacylglycerol (by 19.2 +/- 5.6%; P = 0.003), uric acid (by 12.7 +/- 2.0%; P < 0.001), and creatinine (by 2.5 +/- 1.1%; P = 0.035) and higher serum concentrations of urea (by 42.2 +/- 5.8%; P < 0.001) and a higher 24-h urinary urea output (by 99.2 +/- 17.2%; P < 0.001). No significant differences were detected in total or HDL cholesterol or in the renal clearance of creatinine. LDL oxidation, assessed as the ratio of conjugated dienes to LDL cholesterol in the LDL fraction, was lower with the high-protein diet (by 10.6 +/- 3.6%; P = 0.009). CONCLUSIONS: High intakes of vegetable protein from gluten may have beneficial effects on cardiovascular disease risk by reducing oxidized LDL, serum triacylglycerol, and uric acid. Further studies are required to assess the longer-term effects on renal function.

Effect of a very-high-fiber vegetable, fruit, and nut diet on serum lipids and colonic function.

We tested the effects of feeding a diet very high in fiber from fruit and vegetables. The levels fed were those, which had originally inspired the dietary fiber hypothesis related to colon cancer and heart disease prevention and also may have been eaten early in human evolution. Ten healthy volunteers each took 3 metabolic diets of 2 weeks duration. The diets were: high-vegetable, fruit, and nut (very-high-fiber, 55 g/1,000 kcal); starch-based containing cereals and legumes (early agricultural diet); or low-fat (contemporary therapeutic diet). All diets were intended to be weight-maintaining (mean intake, 2,577 kcal/d). Compared with the starch-based and low-fat diets, the high-fiber vegetable diet resulted in the largest reduction in low-density lipoprotein (LDL) cholesterol (33% +/- 4%, P <.001) and the greatest fecal bile acid output (1.13 +/- 0.30 g/d, P =.002), fecal bulk (906 +/- 130 g/d, P <.001), and fecal short-chain fatty acid outputs (78 +/- 13 mmol/d, P <.001). Nevertheless, due to the increase in fecal bulk, the actual concentrations of fecal bile acids were lowest on the vegetable diet (1.2 mg/g wet weight, P =.002). Maximum lipid reductions occurred within 1 week. Urinary mevalonic acid excretion increased (P =.036) on the high-vegetable diet reflecting large fecal steroid losses. We conclude that very high-vegetable fiber intakes reduce risk factors for cardiovascular disease and possibly colon cancer. Vegetable and fruit fibers therefore warrant further detailed investigation.

Effect of soy-based breakfast cereal on blood lipids and oxidized low-density lipoprotein.

Consumption of soy protein may reduce the risk of cardiovascular disease both through reduction in serum lipids and by the antioxidant properties of protein-associated soy isoflavones. However, the effect that processing required for the manufacture of breakfast cereals may have on the lipid lowering and antioxidant activities of soy has not been studied. We have therefore assessed the health benefits of soy incorporation into breakfast cereals. Twenty-five hyperlipidemic men and women took soy (providing 36 g/d soy protein and 168 mg/d isoflavones) and control breakfast cereals, each for 3 weeks in a randomized crossover study with a 2-week washout period between treatments. Fasting blood samples were obtained pretreatment and at weeks 2 and 3 of each treatment. No significant difference was seen in serum lipids between treatments at week 3 apart from a 3.8% +/- 1.5% higher apolipoprotein A-1 level on control versus soy (P = .021). However, oxidized low-density lipoprotein (LDL) was reduced on the test compared with the control both as total dienes in LDL and as the ratio of conjugated dienes to cholesterol in the LDL fraction by 9.2% +/- 4.3% (P = .042) and 8.7% +/- 4.2% (P = .050), respectively. High isoflavone intakes in soy breakfast cereals may decrease the risk of cardiovascular disease by reducing oxidized LDL, while having no significant effect on the absolute concentration of LDL cholesterol.

Rate of decline of residual renal function in patients on continuous peritoneal dialysis and factors affecting it.

OBJECTIVE: We analyzed residual renal function (RRF) in a large number of new peritoneal dialysis (PD) patients to prospectively define the time course of decline of RRF and to evaluate the risk factors assumed to be associated with faster decline. STUDY DESIGN: Single-center, prospective cohort study. SETTING: Home PD unit of a tertiary care University Hospital. PATIENTS: The study included 242 patients starting continuous PD between January 1994 and December 1997, with a minimum follow-up of 6 months and at least three measurements of RRF. MEASUREMENT: All patients had data on demographic and laboratory variables, episodes of peritonitis and the use of aminoglycoside (AG) antibiotics, temporary hemodialysis, and number of radiocontrast studies. Adequacy of PD was measured from 24-hour urine and dialysate collection and peritoneal equilibration test using standard methodology. Further data on RRF was collected every 3 to 4 months until the patient became anuric (urine volume < 100 mL/day or creatinine clearance < 1.0 mL/min) or until the end of study in December 1998. OUTCOME MEASURE: The slope of the decline of residual glomerular filtration rate (GFR) (an average of renal urea and creatinine clearance) was the main outcome measure. Risk factors associated with faster decline were evaluated by a comparative analysis between patients in the highest and the lowest quartiles of the slopes of GFR, and a multivariate analysis using a stepwise option within linear regression and general linear models. RESULTS: There was a gradual deterioration of residual GFR with time on PD, with 40% of patients developing anuria at a mean of 20 months after the initiation of PD. On multivariate analysis, use of a larger volume of dialysate (p = 0.0001), higher rate of peritonitis (p = 0.0005), higher use of AG (p = 0.0006), presence of diabetes mellitus (p = 0.005), larger body mass index (BMI) (p = 0.01), and no use of antihypertensive medications (p = 0.04) independently predicted the steep slope of residual GFR. Male gender, higher grades of left ventricular dysfunction, and higher 24-hour proteinuria were associated with faster decline on univariate analysis only. CONCLUSION: Faster decline of residual GFR corresponds with male gender, large BMI, presence of diabetes mellitus, higher grades of congestive heart failure, and higher 24-hour proteinuria. Higher rate of peritonitis and use of AG for the treatment of peritonitis is also associated independently with faster decline of residual GFR. Whether the type of PD (CAPD vs CCPD/NIPD) is associated with faster decline of residual GFR remains speculative.

Effect of cocoa bran on low-density lipoprotein oxidation and fecal bulking.

BACKGROUND: Legumes have reported benefits in terms of reduced risk for coronary heart disease and of colonic health. A novel legume fiber, cocoa bran, also may have favorable health effects on serum lipid levels, low-density lipoprotein (LDL) cholesterol oxidation, and fecal bulk. METHODS: Twenty-five healthy normolipidemic subjects (13 men and 12 women) (mean +/- SEM age, 37 +/- 2 years; mean +/- SEM body mass index [calculated as weight in kilograms divided by the square of height in meters], 24.6 +/- 0.7) ate cocoa-bran and chocolate-flavored low-fiber breakfast cereals for 2-week periods, with 2-week washout, in a double-blind crossover study. The cocoa-bran cereal provided 25.0 g/d of total dietary fiber (TDF). The low-fiber cereal (5.6 g/d TDF) was of similar appearance and energy value. Fasting blood samples were obtained at the start and end of each period, and 4-day fecal collections were made from days 11 through 14. RESULTS: High-density lipoprotein (HDL) cholesterol level was higher (7.6% +/- 2.9%; P =.02) and the LDL/HDL cholesterol ratio was lower (6.7% +/- 2.3%; P =.007) for cocoa-bran compared with low-fiber cereal at 2 weeks. No effect was seen on LDL cholesterol oxidation. Mean fecal output was significantly higher for cocoa-bran than for low-fiber cereal (56 +/- 14 g/d; P<.001) and equal to the increase seen in the same subjects with wheat fiber in a previous study. CONCLUSIONS: A chocolate-flavored cocoa-bran cereal increased fecal bulk similarly to wheat bran and was associated with a reduction in the LDL/HDL cholesterol ratio. In view of the low-fat, high-fiber nature of the material, these results suggest a possible role for this novel fiber source in the diets of normal, hyperlipidemic, and constipated subjects.

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.

Effect of soy protein foods on low-density lipoprotein oxidation and ex vivo sex hormone receptor activity--a controlled crossover trial.

Plant-derived estrogen analogs (phytoestrogens) may confer significant health advantages including cholesterol reduction, antioxidant activity, and possibly a reduced cancer risk. However, the concern has also been raised that phytoestrogens may be endocrine disrupters and major health hazards. We therefore assessed the effects of soy foods as a rich source of isoflavonoid phytoestrogens on LDL oxidation and sex hormone receptor activity. Thirty-one hyperlipidemic subjects underwent two 1-month low-fat metabolic diets in a randomized crossover study. The major differences between the test and control diets were an increase in soy protein foods (33 g/d soy protein) providing 86 mg isoflavones/2,000 kcal/d and a doubling of the soluble fiber intake. Fasting blood samples were obtained at the start and at weeks 2 and 4, with 24-hour urine collections at the end of each phase. Soy foods increased urinary isoflavone excretion on the test diet versus the control (3.8+/-0.7 v 0.0+/-0.0 mg/d, P < .001). The test diet decreased both oxidized LDL measured as conjugated dienes in the LDL fraction (56+/-3 v 63+/-3 micromol/L, P < .001) and the ratio of conjugated dienes to LDL cholesterol (15.0+/-1.0 v 15.7+/-0.9, P = .032), even in subjects already using vitamin E supplements (400 to 800 mg/d). No significant difference was detected in ex vivo sex hormone activity between urine samples from the test and control periods. In conclusion, consumption of high-isoflavone foods was associated with reduced levels of circulating oxidized LDL even in subjects taking vitamin E, with no evidence of increased urinary estrogenic activity. Soy consumption may reduce cardiovascular disease risk without increasing the risk for hormone-dependent cancers.

American ginseng (Panax quinquefolius L) reduces postprandial glycemia in nondiabetic subjects and subjects with type 2 diabetes mellitus.

BACKGROUND: Despite a lack of medical evidence to support its therapeutic efficacy, the use of herbal medicine has increased considerably. Ginseng, one of the most widely used herbs, is hypothesized to play a role in carbohydrate metabolism and diabetes mellitus. We therefore undertook a preliminary short-term clinical study to assess whether American ginseng (Panax quinquefolius L) affects postprandial glycemia in humans. DESIGN: On 4 separate occasions, 10 nondiabetic subjects (mean [+/-SD] age, 34+/-7 years; mean [+/-SD] body mass index [BMI], 25.6 +/- 3 kg/m2) and 9 subjects with type 2 diabetes mellitus (mean [+/-SD] age, 62 +/- 7 years; mean [+/-SD] BMI, 29 +/- 5 kg/m2; mean [+/-SD] glycosylated hemoglobin A1c, 0.08+/-0.005) were randomized to receive 3-g ginseng or placebo capsules, either 40 minutes before or together with a 25-g oral glucose challenge. The placebo capsules contained com flour, in which the quantity of carbohydrate and appearance matched the ginseng capsules. A capillary blood sample was taken fasting and then at 15, 30, 45, 60, 90, and 120 (only for subjects with type 2 diabetes mellitus ) minutes after the glucose challenge. RESULTS: In nondiabetic subjects, no differences were found in postprandial glycemia between placebo and ginseng when administered together with the glucose challenge. When ginseng was taken 40 minutes before the glucose challenge, significant reductions were observed (P<.05). In subjects with type 2 diabetes mellitus, the same was true whether capsules were taken before or together with the glucose challenge (P<.05). Reductions in area under the glycemic curve were 18%+/-31% for nondiabetic subjects and 19+/-22% and 22+/-17% for subjects with type 2 diabetes mellitus administered before or together with the glucose challenge, respectively. CONCLUSIONS: American ginseng attenuated postprandial glycemia in both study groups. For nondiabetic subjects, to prevent unintended hypoglycemia it may be important that the American ginseng be taken with the meal.

The effect on serum lipids and oxidized low-density lipoprotein of supplementing self-selected low-fat diets with soluble-fiber, soy, and vegetable protein foods.

An increased intake of soluble fiber and soy protein may improve the blood lipid profile. To assess any additional benefit on serum lipids of providing soy protein and soluble-fiber foods to hyperlipidemic subjects already consuming low-fat, low-cholesterol therapeutic diets, 20 hyperlipidemic men and postmenopausal women completed 8-week test and control dietary treatments in a randomized crossover design as part of an ad libitum National Cholesterol Education Program (NCEP) step 2 therapeutic diet (<7% saturated fat and <200 mg/d cholesterol). During the test phase, foods high in soy, other vegetable proteins, and soluble fiber were provided. During the control phase, low-fat dairy and low-soluble-fiber foods were provided. Fasting blood lipid and apolipoprotein levels were measured at 4 and 8 weeks of each phase. On the test diet, 12 +/- 2 g/d soy protein was selected from the foods chosen. Direct comparison of test and control treatments indicated an elevated high-density lipoprotein (HDL) cholesterol concentration on the test diet (6.4% +/- 2.4%, P = .013) and a significantly reduced total to HDL cholesterol ratio (-5.9% +/- 2.3%, P = .020). The proportion of conjugated dienes in the low-density lipoprotein (LDL) cholesterol fraction was significantly reduced (8.5% +/- 3.3%, P = .020) as a marker of oxidized LDL. A combination of acceptable amounts of soy, vegetable protein, and soluble-fiber foods as part of a conventional low-fat, low-cholesterol therapeutic diet is effective in further reducing serum lipid risk factors for cardiovascular disease.

The Garden of Eden: Implications for cardiovascular disease prevention.

Creationists and evolutionists acknowledge that the human diet has passed through at least four phases. The original plant food-based diet; a second phase of increasing meat consumption; a third phase of agricultural dependence on starchy foods; and, finally, the supermarket high-saturated fat, low-fibre phase with minimal energy expenditure. Our aim is to define the value of the original or 'Garden of Eden' diet and to speculate on which components should be retained in the modern supermarket diet. The original plant-based diet would have been high in vegetable proteins, plant sterols, dietary fibre and antioxidants, and low in saturated fats with no trans fatty acids. This diet would increase fecal cholesterol losses from the body as bile acids and neutral sterols, while providing little stimulus to cholesterol synthesis. To replace the bile acid losses we would have adapted to a relatively high capacity for cholesterol synthesis. Now, in the high-saturated fat, low-fibre supermarket age, this may be a disadvantage and predisposes consumers to high serum cholesterol and increased risk of cardiovascular disease. We believe part of the solution is a return to the plant-based 'Garden of Eden' diet combined with physical activity. A lipid-lowering portfolio containing vegetable proteins, especially soy, plant sterols and high fibre intakes combined with low saturated and trans fatty acids and cholesterol, would go a long way to reducing serum lipids and coronary heart disease risk seen in the modern Western diet.

Effect of soluble and insoluble fiber diets on serum prostate specific antigen in men.

PURPOSE: We assess whether high fiber diets influence serum prostate specific antigen (PSA) related to effects on serum sex hormone levels and fecal steroid excretion. MATERIALS AND METHODS: A randomized crossover controlled trial was performed on 14 healthy men with hyperlipidemia on 2 metabolic diets 4 months in duration with each containing foods high in soluble or insoluble fiber and approximately 25 to 30 gm. dietary fiber per 1,000 kilocalories. Serum PSA, free testosterone and estradiol, and fecal bile acid and neutral sterol excretion were evaluated. RESULTS: Mean serum PSA was lower with the soluble than the insoluble fiber diet (0.07+/-0.03 ng./ml., p = 0.035). No treatment difference was seen in free testosterone or estradiol, although the latter decreased significantly with the insoluble fiber diet (9+/-3 pmol./l., p = 0.004). After 16 weeks total fecal bile acid output was greater with the soluble (341+/-56 mg. daily) compared to the insoluble (203+/-35, p = 0.001) fiber diet but no differences were seen in fecal neutral sterol elimination. The treatment difference in fecal lithocholic acid output related to the difference in serum PSA (r = 0.57, p = 0.035). CONCLUSIONS: A small but statistically significantly lower serum PSA was seen in healthy men consuming soluble fiber, which was not related to changes in serum sex hormones but was related to the increased lithocholic acid output as a possible marker of increased fecal steroid elimination. The effect of soluble fiber on prostatic disease may warrant further investigation.

Combined effect of vegetable protein (soy) and soluble fiber added to a standard cholesterol-lowering diet.

Dietary treatment of hyperlipidemia focuses on reducing saturated fat and dietary cholesterol. Other aspects of diet are not emphasized at present, despite growing evidence that a number of plant components decrease serum cholesterol. We therefore determined whether a combination of two plant components, vegetable protein and soluble fiber, further reduce serum lipids when incorporated into the currently advocated low-saturated-fat diet. Thirty-one hyperlipidemic men and women ate two 1-month low-fat (<7% of total energy from saturated fat), low-cholesterol (<80 mg cholesterol/d) metabolic diets in a randomized crossover study. The major differences between test and control diets were an increased amount of vegetable protein (93% v 23% of total protein), of which 33 g/d was soy, and a doubling of soluble fiber. Fasting blood samples were obtained at the start and end of each phase. On the last 3 days of each phase, fecal collections were obtained. Compared with the low-fat control diet, the test diet decreased total cholesterol (6.2% +/- 1.2%, P < .001), low-density lipoprotein (LDL) cholesterol (6.7% +/- 1.7%, P < .001), apolipoprotein B (8.2% +/- 1.2%, P < .001), and the ratios of LDL to high-density lipoprotein (HDL) cholesterol (6.3% +/- 2.0%, P = .004) and apolipoprotein B to A-I (5.4% +/- 1.5%, P = .001). A combination of vegetable protein and soluble fiber significantly improved the lipid-lowering effect of a low-saturated-fat diet. The results support expanding the current dietary advice to include increased vegetable protein and soluble fiber intake so that the gap in effectiveness between a good diet and drug therapy is reduced.

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.

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.