Glycemic response to pasta: effect of surface area, degree of cooking, and protein enrichment.

To see whether food form, the degree of cooking, or protein enrichment affected the glycemic response to pasta, we gave test-meal breakfasts to 13 diabetic patients. Macaroni had a significantly greater glycemic index (GI) (68 +/- 8) than spaghetti (45 +/- 6, P less than .01); the GI of star pastina was intermediate (54 +/- 6). The GI of spaghetti was not significantly affected by cooking for 5 or 15 min (45 +/- 6 and 46 +/- 5, respectively), or by protein enrichment (38 +/- 4). The GI of spaghetti was similar in 11 non-insulin-dependent and 6 insulin-dependent diabetic patients (49 +/- 7 compared with 57 +/- 8). We conclude that different types of pasta may produce different glycemic responses but that these are not necessarily related to differences in cooking or surface area.

Low-glycemic index diet in hyperlipidemia: use of traditional starchy foods.

To define those patients most likely to benefit from the hypolipidemic effect of low-glycemic-index (GI) traditional starchy foods, 30 hyperlipidemic patients were studied for 3 mo. During the middle month, low-GI foods were substituted for those with a higher GI with minimal change in dietary macronutrient and fiber content. Only in the group (24 patients) with raised triglyceride levels (types IIb, III, and IV) were significant lipid reductions seen: total cholesterol 8.8 +/- 1.5% (p less than 0.001), LDL cholesterol 9.1 +/- 2.4% (p less than 0.001), and serum triglyceride 19.3 +/- 3.2% (p less than 0.001) with no change in HDL cholesterol. The percentage reduction in serum triglyceride related to the initial triglyceride levels (r = 0.56, p less than 0.01). The small weight loss (0.4 kg) on the low-GI diet did not relate to the lipid changes. Low-GI diets may be of use in the management of lipid abnormalities associated with hypertriglyceridemia.

Low glycemic response to traditionally processed wheat and rye products: bulgur and pumpernickel bread.

To look at the effect of processing wheat and rye on blood glucose responses with special reference to bulgur and pumpernickel bread, groups of 9-12 Noninsulin-dependent (NIDDM) and 5-6 Insulin-dependent diabetic volunteers (IDDM) were fed test meals containing 50 g carbohydrate portions of four wheat and three rye products. Glycemic indices for IDDM and NIDDM combined, calculated as the incremental area under the blood glucose response curve, where white bread = 100, demonstrated values of 96 +/- 5 for wholemeal wheat bread, 89 +/- 6 for wholemeal rye bread, 78 +/- 3 for pumpernickel bread, 65 +/- 4 for bulgur, 63 +/- 6 for whole wheat kernels and 48 +/- 5 for whole rye kernels. Results for IDDM and NIDDM were similar (r = 0.96, p less than 0.01). It is concluded that traditional processing of cereals, such as parboiling (bulgur) or the use of wholegrains in bread (pumpernickel) may result in the low GI value associated with the unmilled cereal. Cereal foods processed in these ways may form a useful part of the diet where a reduction in postprandial glycemia is required.

Effect of processing on digestibility and the blood glucose response: a study of lentils.

To test the effect of processing on digestibility and the glycemic response to a leguminous seed, a group of eight healthy volunteers took a series of breakfast test meals containing either lentils which had been processed in four different ways or the same amount of carbohydrate as white bread. Lentils, boiled for 20 min, resulted in a flattened blood glucose response by comparison with bread. This was unaltered by blending the lentils to a paste or boiling them for an additional 40 minutes. However the blood glucose response was significantly enhanced by drying the boiled blended lentils for 12 h at 250 degrees F. In vitro digestion with human saliva showed the rate of sugars released from the food related positively to the blood glucose rise. Breath hydrogen studies indicated that carbohydrate malabsorption was too small to account for differences in the blood glucose response. These results emphasize the importance of processing in determining digestibility and hence the glycemic response to a food.

Low glycemic index carbohydrate foods in the management of hyperlipidemia.

Reduction in the mean glycemic index (GI) of diets of 12 hyperlipidemic patients from 82 +/- 1 to 69 +/- 2 units (p less than 0.001) for a 1 mo period resulted in a significant reduction in total and LDL serum cholesterol and serum triglyceride by comparison with the mean lipid values for the preceding and following control months. The change in GI of the diet was achieved largely through manipulation of the cereal products and was not related to large differences in the amount of dietary fiber. In addition, apart from a small mean increase in unsaturated fat and calorie intake during the control periods, no difference was seen between the proportion of macronutrients on either treatment as determined by 1 wk diet histories recorded on alternate weeks throughout the 3 mo study. Selection of low glycemic index foods may therefore be a useful adjunct to the management of hyperlipidemia.

Low-glycemic-index starchy foods in the diabetic diet.

Eight patients with noninsulin-dependent diabetes underwent two 2-wk study periods in random order during which they were provided with carbohydrate foods with either a high or low glycemic index (GI). Over both high-GI and low-GI periods there were significant reductions in body weight, serum fructosamine, and cholesterol. Reductions in fasting blood glucose, HbA1c, and urinary c-peptide-to-creatinine ratio were significant only over the low-GI period despite a smaller mean weight loss. Reductions in triglyceride were significant only over the high-GI diet. Inclusion of low-GI foods into diets of patients with diabetes may be an additional measure that favorably influences carbohydrate metabolism without increasing insulin demand.

Wholemeal versus wholegrain breads: proportion of whole or cracked grain and the glycaemic response.

STUDY OBJECTIVE: To determine the effect on the glycaemic response to bread of the ratio of whole cereal grains to milled flour. DESIGN: Randomised assignment of groups of diabetic volunteers to test and control meals, taken after an overnight fast. Test foods were also analysed for in vitro digestion with human saliva. SETTING: Tertiary care centre. PATIENTS: Groups of six drawn from pool of 16 volunteers with diabetes mellitus (11 men, five women; mean age 64 (SE 3); 10 taking insulin, five taking oral agents, one controlled by diet; other characteristics comparable). INTERVENTIONS: All patients took standard white bread control meals on three occasions spanning the study and on different mornings took test meals containing varying ratios of whole cereal grains (barley or cracked wheat) to milled flour (75:25, 50:50, 0:100). All meals contained 50 g available carbohydrate and were eaten in 15 minutes. Capillary blood samples were taken for determination of glucose concentrations every 30 minutes for three hours. END POINT: Glycaemic index of foods (= increase in area under blood glucose concentration curve for test food divided by increase in area under curve for white bread control X 100). MEASUREMENTS AND MAIN RESULTS: Significant trend to lower glycaemic index with increasing proportion of whole cereal grains in test bread (p less than 0.05) and lower in vitro digestibility (p less than 0.001). Breads containing up to 75% whole grain were considered palatable. CONCLUSIONS: Breads containing a high proportion of whole cereal grains may be useful in reducing the postprandial blood glucose profile in diabetics because they are more slowly digested. These breads should be called "wholegrain" in distinction to "wholemeal" breads made from milled flour.

The glycaemic index of foods tested in diabetic patients: a new basis for carbohydrate exchange favouring the use of legumes.

Recently diabetic patients have been encouraged to increase their carbohydrate intake, but exact details of which foods to use are lacking. To determine whether sufficiently large differences existed to justify more specific dietary advice, we compared the glycaemic responses to 50 g carbohydrate portions of different foods, taken as breakfast test meals by groups of five to seven diabetic patients. Two- to threefold differences were seen amongst the 15 foods tested. The glycaemic responses for spaghetti, 'All-bran', rice and beans were significantly below those for bread, while 'Cornflakes' were above. Factors predicted to influence this were without effect, including: substituting wholemeal for white bread, increasing substantially the simple sugars (using 'All-bran' or bananas instead of wholemeal bread) and doubling meal protein by adding cottage cheese to bread. Paired comparisons of the glycaemic response to the five legumes with those of the seven other starchy foods (breads, spaghetti, rice, Cornflakes, oatmeal porridge and potatoes) showed that the mean peak rise in blood glucose concentration and mean area under the glucose curve after beans were 23 and 28% lower, respectively, than the mean for the other foods (p less than 0.001). Such results suggest a potentially valuable role for dried leguminous seeds in carbohydrate exchanges for individuals with impaired carbohydrate tolerance. These large differences in blood glucose response to different food cannot at present be predicted directly from tables of chemical composition. Nevertheless, physiological testing may both aid in understanding the factors responsible and help selection of the appropriate carbohydrate foods for the diabetic diet.