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Biomedical subjects

D J Jenkins

Publications and source records attributed to D J Jenkins.

At least 19 recordsLinked to original sources
PubMed1979

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.

Anticholesteremic Agents↗
PubMed1979

Combined use of guar and acarbose in reduction of postprandial glycaemia.

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.

Adult↗
PubMed1979

The digestion of pectin in the human gut and its effect on calcium absorption and large bowel function.

1. The effect of dietary fibre digestion in the human gut on its ability to alter bowel habit and impair mineral absorption has been investigated using the technique of metablic balance. 2. Five healthy male students were studied for 9 weeks under controlled dietary conditions and during the last 6 weeks they took 36 g pectin/d. Bowel habit, transit through the gut, faecal fibre excretion, calcium balance and faecal composition were measured. 3. During the control period only 15% of the dietary fibre ingested was excreted in the stools and when pectin was added to the diet there was no increase in fibre excretion. Stool frequency and mean transit time were unchanged by pectin but stool wet weight increased by 33% and faecal excretion increased (%) for fatty acids 80, nitrogen 47, total dry matter 28 and bile acids 35. Ca balance remained unchanged. 4. It may be concluded from these results that dietary fibre is largely metabolized in the human gut and dietary pectin completely so. This could explain its lack of effect on bowel habit and Ca balance. Other changes in the faeces may be related to an increase in bacterial mass.

Adult↗
PubMed1979

Guar gum and reduction of post-prandial glycaemia: effect of incorporation into solid food, liquid food, and both.

1. The influence of the dose and the form in which guar gum was given on the degree of "flattening" of blood glucose curves was studied in five subjects using meals of bread and soup containing 5 or 10 g guar gum. 2. When 5 g guar gum was added to bread the peak increase of blood glucose was reduced by 41% (P less than 0.002), with 5 g guar in soup, the reduction was 54% (P less than 0.001) while a reduction of 68% (P less than 0.001) was seen with 10 g guar gum (5 g in bread and 5 g in soup). The corresponding reduction in insulin peak increases were 37% (P less than 0.002), 50% (P less than 0.001) and 65% (P less than 0.001) respectively. 3. The difference between the two 5 g doses was significant with respect to the reduction of the peak increases in blood glucose and serum insulin; however the difference between the 5 g dose in bread and the 10 g dose was significantly different (P less than 0.02 for glucose, P less than 0.01 for insulin). 4. The results indicate that as little as 5 g guar gum may reduce the glycaemia following a 45 g carbohydrate meal, but perhaps due to earlier and more complete mixing, guar gum is most effective when added to the liquid phase of the meal.

Adult↗
PubMed1979

Dietary fiber and blood lipids: reduction of serum cholesterol in type II hyperlipidemia by guar gum.

Guar gum, a storage polysaccharide galactomannan and a form of dietary fiber, was administered to 10 patients with type II a or b hyperlipidemia for 2 weeks. Five grams of gum was given before each of three meals daily, either in a specially prepared soup or mixed with fruit juice or milk. No other deliberate change of diet was made. Three patients had been taking 12 to 16 g/day of cholestyramine for more than 2 years and one had been taking 1000 mg of clofibrate daily. These drugs were continued throughout the trial. Serum cholesterol levels of all 10 patients had been stable for 6 to 18 months before the trial at the start of which the mean level was 345 +/- 15 mg/dl. After 2 weeks of guar gum the mean was 308 +/- 16 mg/dl, a fall of 10.6% (P less than 0.01). Serum triglyceride was not changed significantly. Guar gum, which can be incorporated into foods, merits further study as a potential hypocholesterolemic agent.

Anticholesteremic Agents↗
PubMed1979

Hypocholesterolemic action of dietary fiber unrelated to fecal bulking effect.

Twenty-two healthy volunteers took approximately 20 g/day of concentrated dietary fiber from either carrot, cabbage, apple, bran, or guar gum or 31 g from pectin, added for 3-week periods to controlled diets. Total serum cholesterol fell by 13% on both guar and pectin (P less than 0.01) with no significant change in high density lipoprotein cholesterol. Over the 3-week supplementation period, the other fibers were without effect with the exception of carrot, where both control and test high density lipoprotein levels fell (P less than 0.05 and less than 0.01, respectively). If, however, the 3rd week of the control was compared with the 3rd test week, the values for total cholesterol were 7% lower after apple (P less than 0.02) while after carrot the high density lipoprotein cholesterol level was 10% lower than the control (P less than 0.01). No significant change was seen in serum triglyceride or body weight either as judged by differences over the 3-week periods or by comparing test and control values at 3 weeks. Comparison of stool weights obtained in this study indicate that the fecal bulking action of dietary fiber is independent of its hypocholesterolaemic effect.

Adult↗
PubMed1978

Dietary fibres, fibre analogues, and glucose tolerance: importance of viscosity.

To define the type of dietary fibre of fibre analogue with the greatest potential use in diabetic treatment, groups of four to six volunteers underwent 50-g glucose tolerance tests (GTT) with and without the addition of either guar, pectin, gum tragacanth, methylcellulose, wheat bran, or cholestyramine equivalent to 12 g fibre. The addition of each substance significantly reduced blood glucose concentration at one or more points during the GTT and generally reduced serum insulin concentrations. The greatest flattening of the glucose response was seen with guar, but this effect was abolished when hydrolysed non-viscous guar was used. The reduction in the mean peak rise in blood glucose concentration for each substance correlated positively with its viscosity (r = 0.926; P less than 0.01), as did delay in mouth-to-caecum transit time (r = 0.885; P less than 0.02). Viscous types of dietary fibre are therefore most likely to be therapeutically useful in modifying postprandial hyperglycaemia.

Adult↗
PubMed1978

An investigation into creatine kinase and other plasma enzymes in thyroid disorders.

The relationship between plasma protein bound iodine (PBI) level and creatine kinase (CK) activity was investigated in 143 males and 528 females suspected of various thyroid disorders; there was significant negative correlation between low PBI level and raised CK activity. CK, aldolase, lactate dehydrogenase (LD), aspartate transaminase (AST), and alanine transaminase (ALT) activities were determined in plasma from patients with reduced PBI levels; apart from CK, LD was the only enzyme increased in an appreciable number of cases. A further series of specimens was collected from 66 patients with low PBI levels and the CK isoenzymes investigated. In all of these MM was the main form present; a trace of MB was found in 6. These findings do not explain the elevation of CK in hypothyroidism which may be a non-specific effect.

Adolescent↗
PubMed1978

Colonic response to dietary fibre from carrot, cabbage, apple, bran.

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.

Adult↗
PubMed1978

Influence of diets high and low in animal fat on bowel habit, gastrointestinal transit time, fecal microflora, bile acid, and fat excretion.

Epidemiological observations and animal experiments suggest that large bowel cancer is related to serveral factors. Among them, high dietary intakes of animal fat, the presence in the colon of relatively high levels of bile acids, specific patterns of intestinal microflora, slow transit through the gut, and low stool weights. Under metabolic conditions we have observed the effect on these variables of dietes containing 62 or 152 g/day of fat mainly of animal origin in six healthy young men over 4-wk periods. No change attributable to the diet was observed in the subjects' bowel habit, fecal weight, mean transit time through the gut, or in the excretion of dry matter. Total fecal bile acid excretion was significantly higher on the high fat diet (320 +/- 120 mg/day) than on the low fat diet (139.7) +/- 63 mg/day) t test = 7.78 P less than 0.001 as also was the total fecal fatty acid excretion, 3.1+/-0.71 and 1.14+/-0.35 g/day, respectively t test = 11.4 P less than 0.001). The fecal microflora including the nuclear dehydrogenating clostridia were unaltered by the dietary changes as was fecal beta-glucuronidase activity. Dietary changes which increase animal fat intake clearly influence fecal bile acid excretion in a way that would favor the development of large bowel cancer if current theories prove to be true. Dietary fat however has no effect on overall colonic function so other components of the diet must be responsible for the observed associations of bowel cancer with slow transit and reduced fecal bulk.

Adult↗