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Background: Reducing the glycemic load (GL) is considered beneficial for managing insulin resistance. The GL can be reduced either by reducing carbohydrate intake or by reducing the glycemic index (GI). Objective: We studied whether these 2 dietary maneuvers have the same long-term effects on postprandial plasma glucose, insulin, triacylglycerol, and free fatty acid (FFA) concentrations in subjects with impaired glucose tolerance (IGT). Design: Thirty-four subjects with IGT were randomly assigned to high-carbohydrate, high-GI (high-GI); high-carbohydrate, low-GI (low-GI); and low-carbohydrate, high-monounsaturated fatty acid (MUFA) diets for 4 mo. Plasma glucose, insulin, and FFAs were measured from 0800 to 1600 at baseline in response to high-GI meals (60% carbohydrate, GI = 61, GL = 63) and after 4 mo in response to meals representative of the study diet. Results: Carbohydrate intake (% of energy), GI, and GL in the high-GI, low-GI, and MUFA groups (breakfast and lunch meals combined), respectively, were 60%, 61, and 63; 60%, 53, and 55; and 49%, 61, and 52. Compared with the change after 4 mo of the high-GI diet, both the low-GI and MUFA diets reduced 0-8-h mean plasma glucose concentrations by 0.35 mmol/L (P < 0.05). Mean plasma insulin was [approximately equal to] 20% higher (P < 0.05) and FFAs [approximately equal to] 12% lower (P < 0.05) after the low-GI diet than after the high-GI diet, with no significant effect of MUFA. Changes in 0-8-h mean plasma triacylglycerols in the 3 treatment groups differed significantly: -0.14, 0.04, and 0.18 mmol/L, respectively, with the high-GI, MUFA, and low-GI diets. Conclusions: In subjects with IGT, reducing the GI of the diet for 4 mo reduced postprandial plasma glucose by the same amount as did reducing carbohydrate intake. The 2 dietary maneuvers had different effects on postprandial plasma insulin, triacylglycerols, and FFAs. KEY WORDS Glycemic index, glycemic load, randomized clinical trial, postprandial plasma glucose, postprandial plasma insulin, postprandial plasma fatty acids

Background: The US Food and Drug Administration (FDA) approved health claims for 2 dietary fibers, [beta]-glucan (0.75 g/serving) and psyllium (1.78 g/serving), on the assumption that 4 servings/d would reduce cardiovascular disease risk. Objective: We assessed the efficacy of this dose of fibers in reducing serum lipid risk factors for cardiovascular disease. Design: Sixty-eight hyperlipidemic adults consumed a test (high-fiber) and a control low-fat (25% of energy), low-cholesterol (< 150 mg/d) diet for 1 mo each in a randomized crossover study. The high-fiber diet included 4 servings/d of foods containing [beta]-glucan or psyllium that delivered 8 g/d more soluble fiber than did similar, unsupplemented foods in the control diet. Fasting blood samples and blood pressure readings were obtained at baseline and weeks 2 and 4, and the subjects' weight was monitored weekly. Results: Compared with the control diet, the high-fiber diet reduced total cholesterol (2.1 [+ or -] 0.7%; P = 0.003), total:HDL cholesterol (2.9 [+ or -] 0.8%; P = 0.001), LDL:HDL cholesterol (2.4 [+ or -] 1.0%; P = 0.015), and apolipoprotein B:A-I (1.4 [+ or -] 0.8%; P = 0.076). Applying the Framingham cardiovascular disease risk equation to the data confirmed a reduction in risk of 4.2 [+ or -] 1.4% (P = 0.003). Small reductions in blood pressure were found after both diets. The subjects reported no significant differences in palatability or gastrointestinal symptoms between the diets. Conclusions: The reduction in serum lipid risk factors for cardiovascular disease supports the FDA's approval of a health claim for a dietary fiber intake of 4 servings/d. Although relatively small in terms of patient treatment, the reduction in cardiovascular disease risk is likely to be significant on a population basis. KEY WORDS Soluble fiber, psyllium, oats, [beta]-glucan, LDL cholesterol, HDL cholesterol, coronary artery disease, National Cholesterol Education Program, Food and Drug Administration, health claim, functional foods

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 equals] 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 equals] 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 [+ or -] 1.5% (P [is less than] 0.001) and 15.3 [+ or -] 2.4% (P [is less than] 0.001), respectively. With the higher- MUFA diet triacylglycerol fell significantly over the control phase (16.6 [+ or -] 5.5%, P = 0.006) and the ratio of LDL to HDL cholesterol fell significantly over the psyllium phase (7.3 [+ or -] 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 [+ or -] 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. Am J Clin Nutr 1997;65:1524-33.

We hypothesized that a high carbohydrate (CHO), low GI diet would be beneficial in the treatment of IGT by improving insulin sensitivity and insulin secretion. Thus, we compared the effects [...]