PubMed Health⌕ Search

Biomedical subjects

A L Jenkins

Publications and source records attributed to A L Jenkins.

At least 55 records · Page 3Linked to original sources
PubMed1989

Hypocholesterolemic effect of vegetable protein in a hypocaloric diet.

Eleven obese volunteers took part in a 12-week study during 8 weeks of which 2 meals of their control 1000 kcal diets were replaced by a soya based liquid formula (1 month) or a milk based liquid formula (1 month). The mean weight loss per month was 2.5 kg (P less than 0.05). On the soya formula total and LDL cholesterol levels were reduced significantly over the month by 10.0 +/- 2.7% (P less than 0.01) and 17.5 +/- 5.6% (P less than 0.02), respectively. Neither the milk based formula or the control low calorie diet lowered serum cholesterol significantly over the diet period. No change was seen in serum triglycerides on any of the 3 diets. No difference was seen between treatments in 24-h urinary C-peptide excretion. The results indicated that use of a vegetable protein supplement in a weight loss program which induced moderate weight loss was associated with a reduction in blood lipids, whereas moderate weight loss on a control low calorie diet or milk based formula was not.

Adult↗
PubMed1989

Low glycemic index foods and reduced glucose, amino acid, and endocrine responses in cirrhosis.

Carbohydrate intolerance is common in patients with cirrhosis. The aim of the present study was to determine whether the beneficial metabolic effects of low glycemic index diets observed in noncirrhotic diabetics also occurred in patients with cirrhosis. Therefore, for one day, five patients with cirrhosis were fed diets in which low glycemic index foods were substituted, replacing those which produced higher blood glucose rises. Reduction in the estimated glycemic impact of the diet by approximately 30% reduced the mean incremental blood glucose level over the day by 40 +/- 5% (p less than 0.001). Measurement at breakfast of amino acid, insulin, and gastric inhibitory polypeptide profiles confirmed a reduction of similar magnitude. No change was seen in pancreatic glucagon, whereas enteroglucagon levels tended to be higher. In view of these findings and the possible long-term benefits of chronic reduction of hyperinsulinism and alteration in amino acid metabolism, this approach to dietary management of cirrhosis warrants further consideration.

Aged↗
PubMed1989

Effect of rectal infusion of short chain fatty acids in human subjects.

Solutions containing 90 mmol sodium acetate plus 30 mmol sodium propionate (90 mM; isotonic), 180 mmol acetate plus 60 mmol propionate (180 mM; hypertonic) or an equivalent volume of isotonic saline were given over a 30-min period in random order by rectal infusion to six healthy subjects. Peripheral venous blood samples were obtained at 30-min intervals over the next 2 h. After the 90 mM infusion, the serum acetate response reached a peak at 60 min and had fallen to baseline by 120 min. The incremental area under the serum acetate response curve after 180 mM was twice that after 90 mM. Propionate was undetectable in serum at any time. Blood glucose fell after all of the infusions, but there was no significant difference between the saline- and short chain fatty acid (SCFA)-containing infusions. SCFA had no significant effect on serum insulin or c-peptide concentrations. However, compared with the saline control, the 180 mM solution resulted in a significant fall in serum free-fatty acids (FFA) and a significant rise in serum total cholesterol and triglyceride, with no change in beta-hydroxybutyrate levels. The data provide strong evidence that colonic SCFA are absorbed and metabolized in the human subject. The fall in FFA suggests that colonic SCFA have an effect on carbohydrate metabolism. In addition, the data provide indirect evidence for utilization of SCFA for lipid synthesis.

Acetates↗
PubMed1988

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.

Blood Glucose↗
PubMed1988

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.

Aged↗
PubMed1988

Starchy foods and glycemic index.

Different starchy foods produce different glycemic responses when fed individually, and there is some evidence that this also applies in the context of the mixed meal. A major reason appears to relate to the rate at which the foods are digested and the factors influencing this. A similar ranking in terms of glycemic response to specific foods is seen independent of the carbohydrate tolerance status of the groups tested. Potentially clinically useful starchy foods producing relatively flat glycemic responses have been identified. Many of these are considered ethnic or traditional and include legumes; pasta; grains such as barley, parboiled rice, and bulgur (cracked wheat); and whole-grain breads such as pumpernickel. Specific incorporation of these foods into diets has been associated with reductions in low-density lipoprotein cholesterol and triglyceride levels in hyperlipidemia and with improved blood glucose control in insulin-dependent diabetic patients. To facilitate identification of such foods, it has been suggested that the glycemic response should be indexed to a standard (e.g., white bread) to allow comparisons to be made between the glycemic index of foods tested in different groups of subjects. The scope of application of this principle is subject to further investigation. It may be used to expand the range of possibly useful starchy foods for trial in the diets of diabetic patients.

Blood Glucose↗
PubMed1987

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.

Carcinogens↗
PubMed1987

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.

Adult↗
PubMed1987

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.

Animals↗
PubMed1987

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.

Aged↗
PubMed1986

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.

Aged↗
PubMed1986

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.

Colon↗
PubMed1986

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.

Animals↗
PubMed1986

Practical aspects of implementing increased dietary fiber intake.

Two hundred twenty dietitians participated in a workshop conference on Health Implications of Dietary Fiber. They were given lectures to increase their knowledge base, and then in group sessions answered questions and wrote concensus opinions. The results are the content of this paper. The topics covered and responses are reported in four categories, diabetes and obesity, hyperlipidemia, hypertension and coronary heart disease, gut function and gastrointestinal disease, and cancer. Specific recommendation for implementing high fiber diets are made in each category. However, the dietitians expressed caution on accepting all of the conclusions expressed in the literature on the value of fiber and believed much education and instruction is needed in order to increase dietary fiber intake.

Colonic Neoplasms↗
PubMed1985

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.

Blood Glucose↗