RESUMEN
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.
Asunto(s)
Enfermedad Coronaria/etiología , Diabetes Mellitus Tipo 2/dietoterapia , Índice Glucémico , Anciano , Diabetes Mellitus Tipo 2/complicaciones , Carbohidratos de la Dieta , Fibras de la Dieta , Femenino , Frutas , Humanos , Masculino , Persona de Mediana Edad , Factores de RiesgoRESUMEN
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.
Asunto(s)
Glucemia/análisis , Pan , Diabetes Mellitus Tipo 2/sangre , Dieta , Índice Glucémico , Nueces , Adulto , Anciano , Estudios de Casos y Controles , Carbohidratos de la Dieta/administración & dosificación , Femenino , Humanos , Masculino , Periodo PosprandialRESUMEN
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.
Asunto(s)
Glucemia/metabolismo , Diabetes Mellitus/sangre , Fibras de la Dieta/farmacología , Índice Glucémico/efectos de los fármacos , Glucemia/efectos de los fármacos , Diabetes Mellitus/dietoterapia , Grasas de la Dieta/farmacología , Humanos , Insulina/sangre , Selección de Paciente , Ensayos Clínicos Controlados Aleatorios como Asunto , Valores de Referencia , Proyectos de InvestigaciónRESUMEN
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.
Asunto(s)
Presión Sanguínea/fisiología , Peso Corporal/fisiología , Colesterol/sangre , Hiperlipidemias/dietoterapia , Hipertensión/dietoterapia , Prunus , Colesterol en la Dieta/administración & dosificación , Registros de Dieta , Fibras de la Dieta/administración & dosificación , Fibras de la Dieta/farmacología , Femenino , Humanos , Hiperlipidemias/sangre , Hipertensión/etiología , Masculino , Persona de Mediana Edad , Obesidad/dietoterapia , Obesidad/fisiopatología , Fitosteroles/administración & dosificación , Fitosteroles/farmacología , Proteínas de Soja/administración & dosificación , Proteínas de Soja/farmacología , Pérdida de PesoRESUMEN
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.
Asunto(s)
Glucemia/metabolismo , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Hiperglucemia/prevención & control , Hipoglucemiantes/uso terapéutico , Panax/uso terapéutico , Fitoterapia , Plantas Medicinales , Adulto , Análisis de Varianza , Área Bajo la Curva , Diabetes Mellitus Tipo 2/sangre , Femenino , Humanos , Hiperglucemia/sangre , Masculino , Periodo Posprandial , Valores de Referencia , Resultado del TratamientoRESUMEN
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.
Asunto(s)
Cacao , LDL-Colesterol/sangre , Estreñimiento/dietoterapia , Fibras de la Dieta/administración & dosificación , Grano Comestible , Hipercolesterolemia/dietoterapia , Adulto , HDL-Colesterol/sangre , Estreñimiento/sangre , Estudios Cruzados , Defecación/fisiología , Método Doble Ciego , Femenino , Humanos , Hipercolesterolemia/sangre , Masculino , Persona de Mediana Edad , Oxidación-ReducciónRESUMEN
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.
Asunto(s)
Glucemia/metabolismo , Colesterol/sangre , Enfermedad Coronaria/prevención & control , Diabetes Mellitus Tipo 2/terapia , Dieta para Diabéticos , Fibras de la Dieta/uso terapéutico , Fructosamina/sangre , Mananos/uso terapéutico , Apolipoproteínas/sangre , Presión Sanguínea , Peso Corporal , Enfermedad Coronaria/epidemiología , Diabetes Mellitus/sangre , Diabetes Mellitus/fisiopatología , Diabetes Mellitus/terapia , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/fisiopatología , Femenino , Humanos , Insulina/sangre , Masculino , Persona de Mediana Edad , Obesidad , Factores de Riesgo , Triglicéridos/sangreRESUMEN
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.
Asunto(s)
Fibras de la Dieta/uso terapéutico , Intolerancia a la Glucosa/terapia , Resistencia a la Insulina , Mananos , Anciano , Glucemia/metabolismo , Colesterol/sangre , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Método Doble Ciego , Intolerancia a la Glucosa/sangre , Humanos , Persona de Mediana EdadRESUMEN
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.
Asunto(s)
Catárticos/administración & dosificación , Fibras de la Dieta/administración & dosificación , Proteínas en la Dieta/administración & dosificación , Lípidos/sangre , Triticum , Adulto , Análisis de Varianza , Apolipoproteínas/sangre , Ingestión de Energía/fisiología , Heces , Femenino , Tránsito Gastrointestinal/fisiología , Humanos , Masculino , Persona de Mediana EdadRESUMEN
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.
Asunto(s)
Proteínas en la Dieta/administración & dosificación , Glútenes/farmacología , Hiperlipidemias/dietoterapia , Riñón/fisiología , Lípidos/sangre , Ácido Úrico/sangre , Adulto , Anciano , Creatinina/sangre , Estudios Cruzados , Femenino , Tasa de Filtración Glomerular , Humanos , Hiperlipidemias/sangre , Riñón/efectos de los fármacos , Masculino , Persona de Mediana Edad , Oxidación-Reducción , Triticum , Urea/orinaRESUMEN
BACKGROUND: Currently there is considerable interest in the potential health benefits of oil seeds, such as soy and flaxseed, especially in relation to cardiovascular disease and cancer. OBJECTIVE: We therefore evaluated health aspects of partially defatted flaxseed in relation to serum lipids, indicators of oxidative stress, and ex vivo sex hormone activities. DESIGN: Twenty-nine hyperlipidemic subjects (22 men and 7 postmenopausal women) completed two 3-wk treatment periods in a randomized, crossover trial. Subjects were given muffins that contributed approximately 20 g fiber/d from either flaxseed (approximately 50 g partially defatted flaxseed/d) or wheat bran (control) while they consumed self-selected National Cholesterol Education Program Step II diets. Both muffins had similar macronutrient profiles. Treatment phases were separated by > or = 2 wk. RESULTS: Partially defatted flaxseed reduced total cholesterol (4.6+/-1.2%; P = 0.001), LDL cholesterol (7.6+/-1.8%; P < 0.001), apolipoprotein B (5.4+/-1.4%; P = 0.001), and apolipoprotein A-I (5.8+/-1.9%; P = 0.005), but had no effect on serum lipoprotein ratios at week 3 compared with the control. There were no significant effects on serum HDL cholesterol, serum protein carbonyl content, or ex vivo androgen or progestin activity after either treatment. Unexpectedly, serum protein thiol groups were significantly lower (10.8+/-3.6%; P = 0.007) at week 3 after the flaxseed treatment than after the control, suggesting increased oxidation. CONCLUSIONS: These data indicate that partially defatted flaxseed is effective in lowering LDL cholesterol. No effects on lipoprotein ratios, ex vivo serum androgen or progestin activity, or protein carbonyl content were observed. The significance of increased oxidation of protein thiol groups with flaxseed consumption requires further investigation.
Asunto(s)
Andrógenos/sangre , Colesterol/sangre , Fibras de la Dieta/farmacología , Lino , Hiperlipidemias/dietoterapia , Progestinas/sangre , Semillas , Adulto , Anciano , Estudios Cruzados , Fibras de la Dieta/administración & dosificación , Femenino , Humanos , Hiperlipidemias/sangre , Hiperlipidemias/metabolismo , Masculino , Persona de Mediana Edad , Estrés Oxidativo/efectos de los fármacos , Posmenopausia/metabolismoRESUMEN
We performed two studies to determine whether the lipid-lowering effect of viscous soluble fiber was modified by monounsaturated fatty acid (MUFA). First, psyllium (1.4 g/MJ) was compared with wheat bran (control) in 1-mo metabolic diets by using a randomized crossover design (n = 32 hyperlipidemic subjects). The background diet contained approximately 6% of energy as MUFA (20% of total fat). The second study (n = 27 hyperlipidemic subjects) was similar to the first but the background diet contained approximately 12% MUFA (29% of total fat) because of the addition of canola oil. At both fat intakes, psyllium resulted in significant reductions in total, low-density-lipoprotein (LDL), and high-density-lipoprotein (HDL) cholesterol compared with the wheat bran control. For the psyllium diet at 6% compared with 12% MUFA, the decreases in LDL cholesterol were 12.3 +/- 1.5% (P < 0.001) and 15.3 +/- 2.4% (P < 0.001), respectively. With the higher-MUFA diet triacylglycerol fell significantly over the control phase (16.6 +/- 5.5%, P = 0.006) and the ratio of LDL to HDL cholesterol fell significantly over the psyllium phase (7.3 +/- 2.8%, P = 0.015). Psyllium and MUFA intakes were negatively related to the percentage change in the ratio of LDL to HDL cholesterol (r = -0.34, P = 0.019 and r = -0.44, P = 0.002, respectively). Chenodeoxycholate synthesis rate increased (30 +/- 13%, P = 0.038) with the psyllium diet in the 12 subjects in whom this was assessed. We conclude that psyllium lowered LDL- and HDL-cholesterol concentrations similarly at both MUFA intakes. However, there may be some advantage in combining soluble fiber and MUFA to reduce the ratio of LDL to HDL cholesterol.
Asunto(s)
Grasas Insaturadas en la Dieta/administración & dosificación , Fibras de la Dieta/uso terapéutico , Ácidos Grasos Monoinsaturados/administración & dosificación , Hipercolesterolemia/dietoterapia , Psyllium/uso terapéutico , Apolipoproteínas B/sangre , Ácidos y Sales Biliares/metabolismo , Colesterol/sangre , HDL-Colesterol/sangre , LDL-Colesterol/sangre , Estudios Cruzados , Fibras de la Dieta/administración & dosificación , Heces , Femenino , Humanos , Hipercolesterolemia/sangre , Masculino , Persona de Mediana Edad , Psyllium/administración & dosificaciónRESUMEN
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.
Asunto(s)
Enfermedades Cardiovasculares/sangre , Colon/microbiología , Lípidos/sangre , Adulto , Colesterol/sangre , Estudios Cruzados , Dieta , Heces/química , Femenino , Fermentación , Humanos , Masculino , Persona de Mediana Edad , Factores de Riesgo , Almidón/metabolismoRESUMEN
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.
Asunto(s)
Hormonas Esteroides Gonadales/metabolismo , Lipoproteínas LDL/metabolismo , Receptores de Superficie Celular/metabolismo , Proteínas de Soja/farmacología , Adulto , Anciano , Estudios Cruzados , Femenino , Humanos , Hiperlipidemias/metabolismo , Isoflavonas/orina , Lípidos/sangre , Lipoproteínas LDL/sangre , Masculino , Persona de Mediana Edad , Oxidación-Reducción/efectos de los fármacos , Receptores de Superficie Celular/efectos de los fármacosRESUMEN
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.
Asunto(s)
Dieta , Frutas , Lípidos/sangre , Nueces , Verduras , Adulto , Enfermedades Cardiovasculares , Colesterol/sangre , Estudios Cruzados , Femenino , Humanos , Masculino , Factores de RiesgoRESUMEN
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.
Asunto(s)
Dieta , Grano Comestible , Lípidos/sangre , Lipoproteínas LDL/sangre , Proteínas de Soja/administración & dosificación , Adulto , Anciano , Estudios Cruzados , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
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.
Asunto(s)
Dieta con Restricción de Grasas , Fibras de la Dieta/administración & dosificación , Lípidos/sangre , Lipoproteínas LDL/sangre , Proteínas de Soja/administración & dosificación , Adulto , Anciano , Colesterol/sangre , Estudios Cruzados , Suplementos Dietéticos , Femenino , Humanos , Hiperlipidemias/sangre , Lipoproteínas/sangre , Masculino , Persona de Mediana Edad , Posmenopausia , Triglicéridos/sangreRESUMEN
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.
Asunto(s)
Colesterol/sangre , Fibras de la Dieta/farmacología , Glycine max , Hipercolesterolemia/dietoterapia , Hipercolesterolemia/metabolismo , Proteínas de Plantas/farmacología , Anciano , Apolipoproteínas/sangre , Bilis/metabolismo , Presión Sanguínea , Peso Corporal , Estudios Cruzados , Grasas de la Dieta/administración & dosificación , Ayuno , Heces/química , Femenino , Humanos , Hipercolesterolemia/sangre , Hipercolesterolemia/fisiopatología , Lípidos/sangre , Masculino , Persona de Mediana Edad , Solubilidad , Resultado del TratamientoRESUMEN
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.
Asunto(s)
Colon/fisiología , Fibras de la Dieta/farmacología , Frutas , Lípidos/sangre , Nueces , Verduras , Adulto , Ácidos y Sales Biliares/análisis , Presión Sanguínea/fisiología , Peso Corporal/efectos de los fármacos , Colesterol/análisis , Colesterol/sangre , Estudios Cruzados , Dieta , Ácidos Grasos/análisis , Ácidos Grasos/sangre , Heces/química , Femenino , Análisis de los Alimentos , Humanos , Masculino , Persona de Mediana Edad , Esteroles/análisisRESUMEN
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.