DavidJ.A. Jenkins

UNABSORBABLE CARBOHYDRATES AND DIABETES: DECREASED POST-PRANDIAL HYPERGLYCÆMIA

Two test meals were taken in random order on separate days by 8 non-insulin-requiring diabetic volunteers after 14-hour overnight fasts. Addition of 16 g guar and 10 g pectin to the control meal containing 106 g carbohydrate decreased markedly and significantly the rise in blood-glucose between 30 and 90 minutes and also resulted in significantly lower insulin levels between 30 and 120 minutes. When these meals were fed to 3 insulin-dependent diabetic subjects, a similar flattening of the post-prandial glucose rise ensued. This addition of certain forms of dietary fibre to the diet of diabetics significantly decreases post-prandial hyperglycaemia and would be expected to improve the control of blood-glucose concentration.

COLONIC RESPONSE TO DIETARY FIBRE FROM CARROT, CABBAGE, APPLE, BRAN, AND GUAR GUM

Approximately 20 g/day of concentrated dietary fibre from carrot, cabbage, apple, bran, and guar gum was added to the controlled basal diet of nineteen healthy volunteers. Faecal weight increased by 12% on bran, 69% on cabbage, 59% on carrot, 40% on apple, and 20% on guar gum. These changes in faecal weight were correlated with an increased intake of pentose-containing polysaccharides from the fibre. On the basal diet there were pronounced individual differences in faecal weight, and from these the response of subjects to the fibre preparations could be predicted. Addition of fibre shortened mean transit-time through the gut and significantly diluted an inert marker in the faeces. Diet-induced changes in colonic function may explain international differences in the prevalence of colonic disease, whilst personal variation in the response to dietary fibre may determine individual susceptibility to large-bowel disease within a community.

Effect of pectin, guar gum, and wheat fibre on serum-cholesterol.

36 G of wheat fibre, pectin, or guar gum was given over 2-week periods to healthy volunteers taking normal diet. Mean serum-cholesterol levels fell significantly while the volunteers were taking guar and pectin by 36-3 and 29-2 mg, per 100. respectively, but rose slightly after wheat fibre by 6-7, mg per 100., Attention should be focused on fruit and vegetable gels rather than wheat fibre in the search of natural hypocholesterolaemic agents.

BREATH HYDROGEN AS A DIAGNOSTIC METHOD FOR HYPOLACTASIA

Breath hydrogen (H2), collected by end-expiratory sampling, was measured in twenty-five patients with abdominal symptoms or diarrhoea after ingesting 50 g. of lactose. This was compared with established tests of hypolactasia. Fifteen patients with a blood-glucose rise of more than 20 mg. per 100 ml. had less than 4 parts per million (p.p.m.) rise in breath H2 at 2 hours. In contrast, ten patients with blood-glucose rises of less than 20 mg. per 100 ml. had more than a 20 p.p.m. H2 rise (mean 85.8 p.p.m. plus or minus s.d. 44.3) at 2 hours. Similarly, two patients with normal jejunal lactase activity had no significant H2 production, whereas six patients with hypolactasia had more than a 20 p.p.m. rise in H2. Symptoms related to milk or lactose ingestion were found to be unreliable. End-expiratory sampling of breath H2 would seem to be a simple, non-invasive, and accurate method of diagnosing hypolactasia, which is also very acceptable to patients. This should make it a valuable tool both in diagnostic gastroenterology and in epidemiological surveys.

Breath-hydrogen test for small-intestinal bacterial colonisation.

Breath-hydrogen production after oral glucose administration was examined in patients suspected of having small-intestinal colonisation and compared with the 14C-glycine-cholate breath test (14C-G.C.) and with bacteriological examination of the small intestine. Of 17 patients, 12 had bacteriological evidence of small-intestinal colonisation. Each breath test showed 8 of the 12 patients to be colonised, but only 5 patients gave positive results with both tests. Nevertheless, using both tests only 1 patients out of 12 with small-intestinal colonisation would have been missed. There were no false-positive results in the 5 bacteriologically normal patients when the breath-hydrogen test was used. It is concluded that simultaneous use of these two relatively simple breath tests may improve the indirect diagnosis of small-intestinal colonisation.

TREATMENT OF DIABETES WITH GUAR GUM: Reduction of Urinary Glucose Loss in Diabetics

When nine diabetic patients supplemented either their normal home diets (four patients) or metabolic ward diets (five patients) with 25 g guar gum daily for 5 or 7 days their mean urinary glucose excretion fell by 46% (P less than 0-05) and 54% (P less than 0-01), respectively. Gel-forming,, unabsorbable carbohydrate may therefore be a useful adjunct to anti-diabetic therapy, irrespective of the type of treatment or insulin dosage used.

Improved glucose tolerance four hours after taking guar with glucose

SummaryTo gain some insights about the possible cumulative metabolic effect after a high-fibre meal, 6 subjects took two 80 g oral glucose loads, 4 h apart. Addition of 22.3 g guar to the first load decreased the rise in blood glucose and insulin after the second (guar-free) load by 50% (p<0.002) and 31% (p< 0.02) respectively. This corresponded with decreased 3-hydroxybutyrate levels at the start of the glucose tolerance test after guar (by 20%, p<0.02). When no guar was added to the first glucose load, both 3-hydroxybutyrate and non-esterified fatty acids tended to rise before the second test. No significant effect was seen in the responses of the gut hormones, gastric inhibitory peptide and enteroglucagon. Spreading the intake of the first 80 g of glucose over the initial 4 h (2 subjects) similarly flattened the glycaemic but increased the insulin response. The effect of guar on carbohydrate and fat metabolism, therefore, lasts at least 4 h and may result in improved carbohydrate tolerance to subsequent guar-free meals.

INHIBITION OF NOCTURNAL ACID SECRETION IN DUODENAL ULCER BY ONE ORAL DOSE OF METIAMIDE

Abstract The effect on nocturnal acid secretion of a single oral dose of metiamide 400 mg. taken on retiring was studied in eleven males with duodenal ulcer. Ten of them responded to the drug with striking and highly significant reduction of acid output and rise in pH of gastric contents. Eight patients were rendered anacidic for varying periods of time after the drug. There were no unwanted effects.

COMBINED USE OF GUAR AND ACARBOSE IN REDUCTION OF POSTPRANDIAL GLYCÆMIA

Symptoms associated with carbohydrate malabsorption limit the usefulness to diabetics of a powerful glycoside-hydrolase inhibitor (acarbose) which reduces postprandial glycaemia. Addition of a low dose (50 mg) of a acarbose together with 14.5 g guar gum to a breakfast test meal taken by 8 healthy volunteers reduced the mean peak rise in blood-glucose at 30 min by 70%. Areas under the insulin and gastrointestinal-polypeptide response curves were also greatly reduced. No evidence of carbohydrate malabsorption, as assessed by measurement of breath hydrogen, was found during any of the test periods. When acarbose was taken alone, 3 of the 8 subjects had troublesome symptoms and the 30 min rise in blood-glucose was reduced by only 28%. Thus, combination of these two agents effectively reduces the rate of carbohydrate absorption without increasing side-effects and may make combined acarbose and guar acceptable in the management of some diabetics.

Dietary fibre, diabetes, and hyperlipidaemia. Progress and prospects.

When diabetes and cardiovascular disease were first classed as possible fibre-deficiency diseases, laboratory and clinical evidence was lacking. Subsequent studies indicated that the gums and viscous types of fibre (e.g., guar and pectin) are more effective than other fibres in slowing carbohydrate absorption and hence in reducing the postprandial rise in blood glucose and serum insulin. This effect has longer term metabolic consequences. In addition, gums and viscous fibres reduce serum cholesterol, possibly by mechanisms other than simply increasing bile-salt loss. If these potential therapeutic effects of fibre are to be exploited, palatable formulations must be developed. The effect of fibre in whole foods should also be determined.