Phytic acid and calcium affect the in vitro rate of navy bean starch digestion and blood glucose response in humans

Carbohydrate foods that are slowly digested appear beneficial in the management of diabetes and hyperlipidemia. This study determined the effect of endogenous and added phytic acid as well as Ca on the in vitro rate of starch digestion and in vivo blood glucose response to navy bean flour, prepared as unleavened bread. Removal of phytic acid from and addition of Ca to navy bean flour increased the starch digestion in vitro and raised the glycemic response in vivo while readdition of phytic acid to dephytinized flour produced the opposite effect. Carbohydrate malabsorption assessed by breath H2 measurement related negatively to glycemic response but the changes observed were much lower than the changes in glycemic response. This study confirmed the role of both added and endogenous phytic acid in slowing the in vitro rate of starch digestibility and in vivo glycemic response to legumes and the ability of Ca to modify this effect.

Digestibility of carbohydrate foods in an ileostomate: relationship to dietary fiber, in vitro digestibility, and glycemic response

The aim of this study was to assess differences between starchy foods in the amount of carbohydrate which escapes small intestinal absorption. One ileostomate volunteer tested in metabolic feeding trials a total of 20 starchy foods (nine of which were repeated on two to seven occasions, mean 3.5 +/- 1.7). This ileostomate volunteer exhibited macronutrient and fiber losses that were within 97.3 +/- 6.6% of the mean, for a range of foods eaten by three other ileostomates and was therefore believed to be representative. Measurement of available carbohydrate in ileal effluent demonstrated a wide range of recoveries from 2.7 to 18% from different starchy foods. The available carbohydrate losses related to the fiber content (r = 0.885, p less than 0.001), in vitro digestibility of the food (r = -0.867, p less than 0.01), and their glycemic responses (r = -0.611, p less than 0.05). Our data support the concept that available carbohydrate losses to the colon may be greater in many foods than the carbohydrate entering the colon as dietary fiber. The food factors responsible are diverse and the possible metabolic consequences of carbohydrate malabsorption may be broad.

The glycemic index: similarity of values derived in insulin-dependent and non-insulin-dependent diabetic patients

To see whether relative differences in the glycemic responses to different foods were similar in insulin-dependent (IDDM) and non-insulin-dependent diabetic patients (NIDDM) we determined the glycemic index (GI) of a total of 20 foods and mixed test meals in groups of IDDM and NIDDM volunteers. The mean GI values ranged from 32 in NIDDM and 41 in IDDM (pearled barley) to 105 in NIDDM and 111 in IDDM (bread with cheese and tomato). The correlation between the mean GI values in IDDM and NIDDM was highly significant (r = 0.927, p less than 0.001). The mean GI values for 15 of the 20 test meals was greater in IDDM than in NIDDM (mean of GI for all 20 foods, 76 in IDDM compared with 68 in NIDDM, p less than 0.005). However, the difference in GI between IDDM and NIDDM was t statistically significant for 19 of the 20 individual test meals. Greater within-individual variability of glycemic responses in IDDM probably accounts for the slightly greater mean GI value seen in IDDM compared with NIDDM. The addition of 32 g cheddar cheese to four foods which were also fed without cheese had no significant effect on the GI in NIDDM (mean GI of 68 without cheese compared with 72 for the meals with cheese), but had a small effect in IDDM where the mean GI was increased from 72 to 87 (p less than 0.05). However, despite small increases in glycemic response to foods with added cheese, the relative differences between foods were unaffected by the addition of cheese in both IDDM and NIDDM. It is concluded that mean GI values for foods are very similar in IDDM and NIDDM patients.

Starchy foods, type of fiber, and cancer risk

Fibers have been classified broadly as predominantly "soluble" or "insoluble," The soluble fibers have little effect on fecal bulk because they are largely fermented to short-chain fatty acids, so lowering colonic pH, and their influence on cancer risk is in relation to these variables. They are associated with increased fecal bile acid losses. Insoluble fibers are much less fermented and enhance fecal bulk without greatly increasing bile acid losses. Their effect in diluting carcinogens or bile acid promoters relates to their protective role in colon cancer. However, high-fiber foods not only contain combinations of different fiber types but also usually contain starch. Under various conditions, and possibly influenced by fiber, substantial amounts of starch (3-20% of dietary intake) may also enter the colon depending on the nature of the foods eaten. These carbohydrates will contribute to the effective fiber load. In considering the action of fiber in the human gut, fiber type, starch, and other components as well as the nature of foods making up the diet must be assessed. These factors are of importance both in interpreting epidemiological leads and in devising logical trials of fiber in terms of intervention.

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.

Concurrent ingestion of fat and reduction in starch content impairs carbohydrate tolerance to subsequent meals

We examined the effect of breakfasts of different macronutrient compositions on blood glucose and insulin levels after a standard lunch fed 4 h later. Fat-containing breakfasts were compared with a breakfast of equal carbohydrate and protein content and another with higher carbohydrate but equal calorie content. Concurrent ingestion of fat resulted in a large impairment of glucose tolerance following the standard lunch 4 h later. There was no significant difference in glucose and insulin if the fat eaten was butter or peanut butter. When the fat breakfast was compared with the isocaloric larger carbohydrate meal, the effect of fat on carbohydrate tolerance at lunch was even greater. Part of the reason for this additional difference is an improved glucose tolerance at lunch due to the higher carbohydrate content of the breakfast. Concurrent ingestion of fat and reduction of starch content have a persistent effect on carbohydrate tolerance to subsequent meals.

The effect of starch-protein interaction in wheat on the glycemic response and rate of in vitro digestion

To determine the effect on blood glucose of removal of protein from wheat products, healthy volunteers took test meals of white bread made from either regular or gluten-free flour. After bread made from gluten-free flour, the blood-glucose rise was significantly greater. This corresponded with a significantly more rapid rate of digestion in vitro and reduced starch malabsorption in vivo as judged by breath-H2 measurements. Addition of gluten to the gluten-free bread mix did not reverse these effects. Factors associated with unprocessed wheat flour, such as the natural starch-protein interaction, may therefore be important in wheat products in reducing both their rate of absorption and glycemic response. They may have implications in the dietary management both of diabetes and of diseases where small intestinal absorptive capacity is impaired.

Effect of canning on the blood glucose response to beans in patients with type 2 diabetes

Cooked dried legumes have been shown to stimulate low blood glucose responses, and their consumption by individuals with diabetes has been encouraged. However, canned beans are more convenient to use than dried beans. Since the glycaemic effects of canned beans have not been determined, we fed 50 g carbohydrate portions of five varieties of beans, both cooked dried and canned, to groups of diabetic patients and calculated their glycaemic indices (GI). All canned and dried beans tested had significantly lower GIs than that of white bread, which was ascribed a GI of 100. The mean GI of the five types of canned beans, 71 +/- 4, was less than that of bread, 100 (P less than 0.001), and greater than that of the same five varieties of cooked dried beans, 47 +/- 5 (P less than 0.001). It is concluded that the glycaemic effect of dried legumes is increased by the canning process. Nevertheless, canned beans give lower blood glucose responses than bread and may be of use in low glycaemic index diets.

Effect of modifying the rate of digestion of a food on the blood glucose, amino acid, and endocrine responses in patients with cirrhosis

To see whether foods with slower rates of digestion may benefit the metabolic abnormalities seen in cirrhosis, the same food, processed in two different ways, was fed to seven patients with cirrhosis. The breakfast of lentils processed by prolonged heating, to produce more rapid in vitro digestion, resulted in a significantly higher incremental rise in large neutral amino acid levels at 60 min (p less than 0.02) and a tendency for a more rapid rise in total amino acid concentrations by comparison with conventionally cooked lentils with slower in vitro digestion rates. After more rapidly digested lentils, incremental levels of branched-chain amino acids were also higher at 60 min (67 +/- 9, p less than 0.001) despite a greater overall insulin response. Comparable incremental amino acid areas after both meals suggested that the total amount of amino acids absorbed was not influenced by processing. Greater blood glucose, insulin, and gastric inhibitory polypeptide responses were seen after the more processed meal with no significant differences in pancreatic glucagon, entroglucagon, or neurotensin levels. Processing a food to alter the rate of digestion may therefore be used to manipulate amino acid, glucose, and endocrine responses in cirrhosis.

Starchy foods and fiber: reduced rate of digestion and improved carbohydrate metabolism

The rate of the small intestine amylolytic digestion appears to be a major determinant of the glycemic response. Foods such as legumes appear to be digested less rapidly than many cereal foods although even amongst these large differences in rates of in vitro digestion exist. Studies of diabetes using high fibre, high legume diets have almost uniformly noted improvements in glycemic control and blood lipid profile. However, diets where changes in fibre content have been relatively small, but where the foods were selected on the basis of their slow rates of digestion and flatter glycemic response, have also produced similar beneficial effects. The reasons for the altered rates of digestion include fibre, food form, the nature of the starch, antinutrients etc. Through reducing the rate of digestion of starchy foods post prandially "slow release" starchy foods blunt many gut hormone responses, and prolong FFA and ketone body suppression. In addition increased starch losses to the colon may enhance production of SCFA. All these events may modify carbohydrate and lipid metabolism. Many foods which produce these effects are traditional starchy foods and so strengthen current recommendations of the diabetes association, heart foundations and cancer institutes to increase the use of starchy foods through reducing fat intake. Recognition of the nutritional value of these foods is however not new, but was well accepted in the ancient world and is still preserved in traditional cultures where freedom from many of the major non-infective Western diseases is a notable phenomenon.

Cancer risk: possible protective role of high carbohydrate high fiber diets

Epidemiological data from different populations have suggested positive relationships between the incidence of colon cancer and meat and fat intake and a negative relationship with dietary fiber consumption. Within population comparisons have been less clearcut. Current theories on colonic carcinogenesis in man involve increased concentrations of bile acids and their metabolites, alterations in colonic pH, low Ca++, raised NH3 and long chain fatty acid levels, and alterations in bacterial numbers, type, and metabolic capabilities. The many laboratory studies in rats have been difficult to interpret since powerful initiators of carcinogenesis are always required and this rather than the promotion of spontaneous neoplastic change is the sine qua non for tumor growth in this situation. The current dilemma highlights the lack of knowledge of most aspects of human colonic physiology. Until these issues are more clearly resolved the epidemiological leads would point to low fat diets rich in less processed starchy foods with increased fiber as possible protection. Such advice is in common with the pronouncements of heart foundations, diabetes associations, and recommendations of official bodies to the general public.

Fiber and starchy foods: gut function and implications in disease

Increased intake of fiber and starchy foods has been recommended in the treatment or prevention of a range of diseases including dumping syndrome, hyperlipidemia, gallstones, diabetes, Crohn's disease, constipation, irritable bowel, diverticular disease, and colonic cancer. The nature and physiological effects of fiber are diverse. However in general, insoluble fibers increase fecal bulk and decrease transit time. On the other hand, soluble fibers have metabolic effects secondary to reducing the rate of small intestinal absorption. In the colon, along with undigested starch, they are largely fermented yielding short-chain fatty acids which may have further metabolic effects. At present although much further work is required, the clinical management of hyperlipidemia, diabetes, constipation, and diverticular disease have already been significantly influenced as a result of the ideas and experimental evidence generated by the fiber hypothesis.

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 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.

Specific antibody responses in dogs experimentally infected with Echinococcus granulosus

Six dogs reared helminth-free were divided into 2 groups. Four dogs were infected per os with 200,000 protoscoleces each of Echinococcus granulosus and 2 were kept as uninfected controls. All the dogs were kept together until 32 days after infection, when 1 infected dog was killed, its intestine removed and the contents examined to confirm that the infection with E. granulosus had been successful. The remaining 3 infected dogs were transferred to high security housing and their feces inspected daily to establish the time infections became patent. The infected and control dogs were bled every 5 days for 75 days from the time of infection and the sera were stored at -70 degrees C. Sera were tested by the enzyme-linked immunosorbent assay (ELISA) for antibodies to E. granulosus scolex excretory/secretory (ES) antigen, protoscolex antigen and oncosphere antigen. Antibodies to scolex ES antigen and protoscolex antigen were detected in the sera of infected dogs within 2 weeks of infection. Antibody titers rose rapidly and remained at a high level until the dogs were killed 75 days after infection. Antibodies in these sera did not cross react with antigens prepared from Taenia ovis, T. hydatigena, T. pisiformis, Ancylostoma caninum, Trichuris vulpis and Toxocara canis.

Specificity of scolex and oncosphere antigens for the serological diagnosis of taeniid cestode infections in dogs

Groups of dogs raised free of helminths were monospecifically infected with the common nematodes Toxocara canis, Ancylostoma caninum and Trichuris vulpis. Serums from these dogs, and a group of dogs of unknown history but infected with Dirofilaria immitis and Dipylidium caninum, had levels of antibody to their homologous nematode antigens readily detectable by ELISA. No cross-reactions were apparent when these serums were tested by ELISA using oncosphere antigens of Taenia hydatigena, T. pisiformis and T. ovis, scolex excretory/secretory antigens of T. hydatigena, T. pisiformis and Echinococcus granulosus or protoscolex antigen of E. granulosus.

Ileal loss of available carbohydrate in man: comparison of a breath hydrogen method with direct measurement using a human ileostomy model

The breath hydrogen technique has suggested that a considerable amount of available plus unavailable carbohydrate enters the large intestine after the consumption of starchy foods (white bread 11%, wholemeal bread 8%, and red lentils 18%). Direct measurement of the available carbohydrate in ileal effluent after the consumption of test meals by three individuals with ileostomies gave values similar to those determined by the breath hydrogen technique (white bread 10%, wholemeal bread 8%, and red lentils 22%). These studies confirm that considerable amounts of "available carbohydrate" may be lost to the small intestine and physiologically must be considered as dietary fiber. The implications of this with respect to metabolism and colonic disease remain to be investigated.

The use of the glycemic index in predicting the blood glucose response to mixed meals

There has been much interest in the use of the glycemic index (GI). A recent study reporting plasma glucose responses to mixed meals containing fat and protein concluded that the results were totally disparate from what would have been expected from published GI values of the foods fed. However, this conclusion was based upon an inappropriate assessment of the data using absolute rather than incremental blood glucose response areas. The present report demonstrates how data may be analyzed to make use of the GI values of individual foods to predict the GI of mixed meals (r = 0.987; p less than 0.02). It is concluded that the GI concept applies well to mixed meals containing fat and protein.

Dietary fiber and the glycemic response

Addition of purified fiber to carbohydrate test meals has been shown to flatten the glycemic response in both normal and diabetic volunteers, reduce the insulin requirement in patients on the artificial pancreas and in the longer term reduce urinary glucose loss and improve diabetes control. In the context of high fiber-high carbohydrate diets these findings have had a major impact in influencing recommendations for the dietary management of diabetes internationally. The mechanism of action appears in part to be due to the effect of fiber in slowing absorption rather than by increasing colonic losses of carbohydrate. Consequently postprandial GIP and insulin levels are reduced and the more viscous purified fibers (e.g., guar and pectin) appear most effective. In addition it has been suggested that colonic fermentation products of fiber may enhance glucose utilization. More recently it has become clear that many aspects of carbohydrate foods (food form, antinutrients, etc.) in addition to fiber may influence the rate of digestion and has led to a classification especially of starchy foods in terms of glycemic index to define the degree to which equicarbohydrate portions of different foods raise the blood glucose. Use of such data may maximize the effectiveness of high carbohydrate and high fiber diets in the management of diabetes and related disorders.

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.

Prediction of the relative blood glucose response of mixed meals using the white bread glycemic index

Unexpected plasma glucose responses to different mixed meals fed to normal and diabetic volunteers have recently been reported. We have therefore examined in normal volunteers the effect of mixing carbohydrate foods of different glycemic indices (GIs) without the addition of fat and protein. The observed GI of the mixed meal was within 2% of the expected value. In studies in the literature where fat and protein were added to mixed meals, the observed blood glucose responses also related significantly to the meal GIs calculated from the individual foods. Addition of fat and protein in the quantities used did not obscure this relationship. Studies to determine sources of error in comparing glycemic responses showed that type II diabetic patients displayed the least within-individual variation, and type I diabetic patients the most. Expression of results as the GI rather than as absolute glycemic response areas reduced by 50% the between-subject variation. The mean GI values of rice tested in type I and type II patients were similar (82 +/- 22 compared with 74 +/- 19) and the reproducibility 22 mo later in the same group of subjects was excellent (81 +/- 15 compared with 83 +/- 15). However, the lack of precise GI values for all foods fed in the test meals indicates a need for GI values to be derived for a wider range of individual foodstuffs. The GI approach to classifying foods according to physiologic effect may play a useful role in planning meals and diets in which specific blood glucose profiles are required.

Specific antibody responses to Taenia hydatigena, Taenia pisiformis and Echinococcus granulosus infection in dogs

Groups of dogs reared free of both nematodes and cestodes were infected with Taenia hydatigena, Taenia pisiformis or Echinococcus granulosus. After infections with the Taenia spp became patent, dogs were purged to remove the worms. They were later reinfected and the second infections again removed by purging after patency. A group of 3 uninfected worm free dogs was kept as age-matched controls. The dogs were bled at intervals of 5 days and their serums tested for antibodies using the enzyme-linked immunosorbent assay (ELISA) with excretory/secretory (ES) antigens collected during in vitro incubation of evaginated scoleces (scolex ES antigen) and oncosphere antigens. Antibodies to scolex ES antigen were detected by 3 weeks after infection with each cestode species whereas antibodies to oncosphere antigen were not detected until about one week after eggs were found in the faeces of the infected dogs. Antibody responses to both oncosphere and scolex ES antigens decreased rapidly following removal of the worms by purging. Uninfected control dogs were invariably negative to both oncospheral and scolex ES antigens. There were cross-reactions between the serums from dogs infected with T. pisiformis and T. hydatigena when tested with scolex ES antigens, but oncospheral antigens showed a high degree of species specificity. Scolex ES antigens from E. granulosus were compared with those prepared from T. hydatigena and T. pisiformis for their ability to discriminate between antibodies in serums collected from dogs 31 and 32 days after infection with 100,000 protoscoleces of E. granulosus or dogs infected with Taenia spp.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between glycemic response, digestibility, and factors influencing the dietary habits of diabetics

A significant relationship was found between the rate of release of the sugars; glucose, maltose, and maltotriose from amylitic digestion of 10 foods tested in vitro (expressed as the digestibility index) and the blood glucose response to 50-g carbohydrate portions of the same foods eaten by diabetics (expressed as the glycemic index), (r = 0.815, n = 10, p greater than 0.01). The glycemic index related to both the palatability of the foods (r = 0.731, p less than 0.05) and their frequency of use (r = 0.698, p less than 0.05). However, in this group of motivated diabetics food use was not related directly to palatability, but rather to health belief (r = 0.689, p less than 0.05). The results suggest that carbohydrate foods of potential use to the diabetic may be identified by their in vitro digestion characteristics but to a large extent their acceptance will depend on health belief and possibly ease of preparation.

Glycemic responses to foods: possible differences between insulin-dependent and noninsulin-dependent diabetics

The effect on the blood glucose response of varying the amount (25 or 50 g) and type (bread or beans) of carbohydrate (CH2O) in test meals and of adding fat and protein was examined in a group of insulin dependent and noninsulin dependent diabetic volunteers. With noninsulin-dependent diabetics, the blood glucose area after a half bread portion was 48% that of the full bread meal (p less than 0.001). White pea beans (50 g CH2O) gave a blood glucose response of 41 +/- 5% (p less than 0.001) that of bread (50 g CH2O). A combined meal of bread (25 g CH2O) and beans (25 g CH2O) gave a blood glucose response of 60 +/- 8% of the full bread meal (p less than 0.005) and similar to that expected. Addition to bread of butter and skim milk cheese either singly or in combination had little effect on the glycemic response although a reduced rise was seen after addition of fat and protein as peanut butter. Insulin-dependent diabetics tended to respond similarly to noninsulin-dependent diabetics but their greater variability indicates that other factors in addition to the nature of the food may also be major determinants of their glycemic responses to foods.

Haematological and serological data from dogs raised worm-free and monospecifically infected with helminths

Pups free from helminth infection were obtained by treating the bitch prior to parturition, and the bitch and her pups after whelping, with oxfendazole and praziquantel. They were then housed in an area free from contamination with helminth eggs. Freedom from infection was confirmed by necropsy examinations and by serological tests using the Enzyme Linked Immunosorbent Assay (ELISA). Groups of pups were infected with Toxocara canis, Echinococcus granulosus, Taenia ovis, T. pisiformis and T. hydatigena and bled at 5-day intervals. Haematological examinations and measurement of serum proteins were performed on blood samples obtained throughout 30 days of infection. Levels of serum proteins were not significantly altered in any infection. Pups infected with T. canis showed a marked increase in numbers of circulating eosinophils during the phase of larval migration through the liver and lungs; they also showed marked antibody responses to T. canis larval ES antigen. Haematological values were not significantly altered in any other pups.

Slowly digested carbohydrate food improves impaired carbohydrate tolerance in patients with cirrhosis

To test whether impaired carbohydrate tolerance in cirrhosis could be modified by dietary means ten cirrhotic patients, five of them taking insulin, took as breakfast either lentils or wholemeal bread and cottage cheese containing the same amount of carbohydrate and protein. Lentils resulted in significantly diminished blood glucose, insulin (in those not on insulin) and gastric inhibitory peptide responses. Enteroglucagon and neutrotensin levels were high with lentils, suggesting that absorption of lentil carbohydrate continued into the ileum with perhaps some malabsorption, so confirming the results of earlier studies in vitro. However, breath hydrogen studies on a separate group of eight healthy volunteers indicated that the difference in carbohydrate malabsorption between lentil, and wholemeal bread was insignificant. It is suggested that slowly digested carbohydrate foods, such as leguminous seeds, may minimize carbohydrate intolerance in patients with cirrhosis.

Relationship between polyphenol intake and blood glucose response of normal and diabetic individuals

Five leguminous and eight nonleguminous foods were analyzed for polyphenol concentration by the Prussian Blue and the Folin Denis methods and correlated with blood glucose response (glycemic index) in normal or diabetic volunteers. Polyphenol concentrations and intakes per 50 g available carbohydrate portions were higher in the leguminous foods than those in the nonleguminous foods. In both normal and diabetic individuals, a negative correlation was observed between glycemic index and the concentration or total intake of polyphenols. Polyphenols, especially the large polymeric type or condensed tannins, appear to be responsible in part for the reduced glycemic response to carbohydrate foods and in part to lower blood glucose response to legumes compared with cereal products.

The effect of phytic acid on in vitro rate of starch digestibility and blood glucose response

The effect of phytic acid on starch digestibility was studied in vitro and related to the blood glucose response (glycemic index) in healthy volunteers. The glycemic index was found to correlate negatively with the phytic acid content of the food tested. In vitro digestion studies involving human saliva at physiological pH and temperature showed that in the presence of sodium phytate (equivalent to 2% phytic acid based on the starch portion), the rate of digestion of raw wheat starch was reduced significantly by 50%. This was reversed by the addition of calcium which is known to complex phytic acid. Similarly, when sodium phytate was added to unleavened bread, its digestibility was also decreased and in feeding trials high phytate bread produced a flattened blood glucose response.

Leguminous seeds in the dietary management of hyperlipidemia

Seven male hyperlipidemic patients substituted approximately 140g dried beans daily for other sources of starch in their diet over a 4-month period. After this, mean fasting serum triglyceride levels were reduced by 25 +/- 5% (p less than 0.01) while total serum cholesterol levels were 7 +/- 2% (p less than 0.5) lower than the values measured during the previous five clinic attendances (12 +/- 2.5 months). However, low- and high-density lipoprotein cholesterol levels remained unaltered. While taking beans a nonsignificant fall (0.7 kg) was seen in body weight. Nevertheless no change was seen in macronutrient intake determined by 1-wk diet histories recorded both before and four times during the study, although cholesterol intake decreased by 80 mg (p less than 0.02). Reintroduction of dried leguminous seeds into a Western diet may be a useful adjunct to the management of hyperlipidemia.

Factors affecting starch digestibility and the glycemic response with special reference to legumes

Large differences exist in the degree to which different starch containing foods affect the blood glucose levels of both normal volunteers and diabetics. These differences appear to relate to the digestibility of the starch and the factors determining this, including: the interaction of starch with fiber, antinutrients (eg, phytate) and protein in the food, together with the nature of the starch itself and its physical form (eg, raw or cooked, ground or whole). In this respect legumes exemplify a class of foods, high in fiber, protein and antinutrients, with a starch which is digested slowly in vitro. They also produce relatively small blood glucose rises after consumption by both normals and diabetics and in the longterm result in improved diabetic control. Identification of more such foods and further understanding of factors determining starch digestibility will allow greater therapeutic use of diet in the management of diabetics and disorders of carbohydrate metabolism.

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.

Glycemic response to wheat products: reduced response to pasta but no effect of fiber

The blood glucose response to feeding 50-g carbohydrate portions of white and wholemeal bread and white spaghetti was studied in a group of nine diabetic subjects. Blood glucose rises after white and wholemeal bread were identical, but the response after spaghetti was markedly reduced. These results emphasize that food form rather than fiber may be important in determining the glycemic response and that pasta may be a useful source of carbohydrate in the diabetic diet.

The effect of fermented and unfermented milks on serum cholesterol

Groups of 10 to 13 healthy volunteers were provided with 11 supplements of 2% butterfat milk (2% milk), whole milk, skim milk, yogurt, buttermilk, and sweet acidophilus milk daily for a 3-wk period. Despite increases in caloric intakes on all supplements, no significant increases were found in total, low-density, and high-density lipoprotein cholesterol. A significant weight gain was seen in subjects taking yogurt and acidophilus groups; these were the only two groups showing significant rises in triglyceride levels. These results in normal volunteers focus attention on the current practice of recommending only skim or 2% milk for hyperlipidemic individuals.

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.

Lente carbohydrate: a newer approach to the dietary management of diabetes

The dietary fiber hypothesis has stimulated interest in the possibility that the glycemic response to carbohydrate foods may be reduced by modifying gastrointestinal events to produce sustained-release or "lente" carbohydrate. Associated with this interest, a new branch of pharmacology has been developed involving the use of purified fiber preparations and enzyme inhibitors. These measures, together with the selection of diets containing foods that naturally release their carbohydrate products of digestion slowly, may contribute a useful facet to diabetic management in the future.

Slow release dietary carbohydrate improves second meal tolerance

Breakfasts of lentils or wholemeal bread of identical carbohydrate content were taken by seven healthy volunteers. The lentils produced a significant 71% (p less than 0.001) reduction in the blood glucose area and flattened the plasma insulin and gastric inhibitory polypeptide responses by comparison with the bread. In addition, the lentil breakfast was followed by a significantly flatter blood glucose response to the standard bread lunch which followed 4 h later (by 38%, p less than 0.01). The blood glucose pattern was mimicked by feeding the bread breakfast slowly over the 4 h before lunch. Giving a bread breakfast containing a quarter of the carbohydrate reduced the breakfast glucose profile but resulted in a significantly impaired blood glucose response to lunch (168% of control, p less than 0.01). These results, together with breath hydrogen studies, performed on a separate group of four volunteers, indicate that the flattened response to lentils is not due to carbohydrate malabsorption. Slow release or "lente" carbohydrate foods such as lentils may form a useful part of the diets of those with impaired carbohydrate tolerance.

Relationship between rate of digestion of foods and post-prandial glycaemia

The amount of carbohydrate released at 1 and 5 h by digestion in vitro of 2 g carbohydrate portions of 14 foods by human digestive juices was compared with the area under the 2-h blood glucose response curve when 50 g carbohydrate portions were fed to groups of five to ten healthy volunteers. A significant relationship was found between the amounts of sugars and oligosaccharides liberated at 1 and 5 h and the food blood glucose area expressed as a percentage of the blood glucose area for 50 g glucose (r = 0.8627 and 0.8618, p less than 0.001). A significant relationship was also found between the glycaemic index and the food fibre content (p less than 0.02) and between the glycaemic index and the glucose trapping capacity of the foods (p less than 0.05). Legumes as a group liberated 56% less sugars and oligosaccharides (p less than 0.01) than the eight cereal foods over 5 h. It is suggested that such studies in vitro may help to identify food of use for diabetic patients, and at the same time throw further light on factors which affect post-prandial glycaemia.

Effect of acarbose on the 24-hour blood glucose profile and pattern of carbohydrate absorption

Acarbose (Bay g 5421) is a powerful alpha-glucoside hydrolase inhibitor of potential value in the treatment of diabetes and hypoglycemic dumping syndrome after gastric surgery. The extent of its use may be limited by symptoms produced by carbohydrate malabsorption. To minimize these, the action of low doses of acarbose on 24-h blood glucose profiles and hydrogen evolution have been studied on four ambulant volunteers on control diets, after exclusion of sucrose and also after addition of guar in an attempt to enhance the therapeutic effect. Replacement of dietary sucrose by starch abolished significant hydrogen evolution in the morning after low doses of acarbose but did not reduce its effectiveness in decreasing the mean three-meal blood glucose area by 41% (P less than 0.002). Addition of hydrated guar to this diet reduced the mean three-meal glucose area after acarbose further by 72% (P less than 0.001) but increased hydrogen evolution. The results suggest that acarbose will be both effective and acceptable given at low dose when the dietary carbohydrate is starch.