Kw Heaton

DEPLETION AND DISRUPTION OF DIETARY FIBRE: EFFECTS ON SATIETY, PLASMA-GLUCOSE, AND SERUM-INSULIN

Ten normal subjects ingested test meals based on apples, each containing 60 g available carbohydrate. Fibre-free juice could be consumed eleven times faster than intact apples and four times faster than fibre-disrupted purée. Satiety was assessed numerically. With the rate of ingestion equalised, juice was significantly less satisfying than purée, and purée than apples. Plasma-glucose rose to similar levels after all three meals. However, there was a striking rebound fall after juice, and to a lesser extent after purée, which was not seen after apples. Serum-insulin rose to higher levels after juice and purée than after apples. The removal of fibre from food, and also its physical disruption, can result in faster and easier ingestion, decreased satiety, and disturbed glucose homoeostasis which is probably due to inappropriate insulin release. These effects favour overnutrition and, if often repeated, might lead to diabetes mellitus.

Defecation frequency and timing, and stool form in the general population: a prospective study.

Because the range of bowel habits and stool types in the community is unknown we questioned 838 men and 1059 women, comprising 72.2% of a random stratified sample of the East Bristol population. Most of them kept records of three consecutive defecations, including stool form on a validated six point scale ranging from hard, round lumps to mushy. Questionnaire responses agreed moderately well with recorded data. Although the most common bowel habit was once daily this was a minority practice in both sexes; a regular 24 hour cycle was apparent in only 40% of men and 33% of women. Another 7% of men and 4% of women seemed to have a regular twice or thrice daily bowel habit. Thus most people had irregular bowels. A third of women defecated less often than daily and 1% once a week or less. Stools at the constipated end of the scale were passed more often by women than men. In women of child bearing age bowel habit and the spectrum of stool types were shifted towards constipation and irregularity compared with older women and three cases of severe slow transit constipation were discovered in young women. Otherwise age had little effect on bowel habit or stool type. Normal stool types, defined as those least likely to evoke symptoms, accounted for only 56% of all stools in women and 61% in men. Most defecations occurred in the early morning and earlier in men than in women. We conclude that conventionally normal bowel function is enjoyed by less than half the population and that, in this aspect of human physiology, younger women are especially disadvantaged.

Symptomatic and silent gall stones in the community.

The prevalence of gall stone disease in a stratified random sample of 1896 British adults (72.2% of those approached) was established using real time ultrasound. The prevalence rose with age, except in women of 40-49 years, so that at 60-69 years, 22.4% of women and 11.5% of men had gall stones or had undergone cholecystectomy. The cholecystectomy rate of people with gall stone disease was higher in women than in men (43.5% v 24%, p less than 0.05). Very few subjects with gall stones had convincing biliary symptoms. In women, 10.4% had symptoms according to a questionnaire definition of biliary pain and 6.3% according to conventional history taking, while no men at all admitted to biliary pain. Nevertheless, cholecystectomy in men had nearly always been preceded by convincing biliary symptoms. The age at cholecystectomy was, on average, nine years less than the age at detection of silent gall stones in both sexes. It is concluded that either gall stones are especially prone to cause symptoms in younger people or that there are two kinds of cholelithiasis - symptomatic and silent. The lack of symptomatic gall stones in cross sectional surveys is probably due to their rapid diagnosis and treatment.

MODERATE ALCOHOL INTAKE REDUCES BILE CHOLESTEROL SATURATION AND RAISES HDL CHOLESTEROL

The effect of alcohol on plasma high-density lipoprotein (HDL) cholesterol and on bile cholesterol saturation was measured in 12 healthy volunteers with a very low initial alcohol intake who drank 39 g alcohol daily for six weeks, and then abstained from alcohol for 6 weeks. HDL cholesterol (mean +/- SEM) rose significantly from 1.07 +/- 0.05 to 1.25 +/- 0.08 mmol/l (41.4 +/- 1.9 to 48.3 +/- 3.1 mg/dl) when alcohol was being consumed and fell to 1.04 +/- 0.06 mmol/l (40.2 +/- 2.3 mg/dl) during abstention. Bile cholesterol saturation index fell from 1.31 +/- 0.06 to 1.08 +/- 0.06 during the period of alcohol consumption and rose to 1.27 +/- 0.09 during abstention. There was a significant inverse correlation between bile saturation index and HDL cholesterol (r = -0.56). These data provide further evidence of a biochemical link between cardiovascular disease and cholesterol gallstones and suggest that moderate alcohol intake has some protective effect against both diseases.

FOOD FIBRE AS AN OBSTACLE TO ENERGY INTAKE

Abstract Food fibre (or unavailable carbohydrate) provides three physiological obstacles to energy intake. (1) It displaces available nutrients from the diet. (2) It requires chewing, which slows down intake, especially of sugars, which, when freed of fibre, are soluble and can be drunk. Chewing also limits intake by promoting the secretion of saliva and gastric juice, which distend the stomach and promote satiety. (3) Fibre reduces the absorptive efficiency of the small intestine. The stripping of fibre, which occurs partially in the milling of white flour and completely in the refining of sugar, removes these obstacles. The refined products have an artificially increased energy/satiety ratio, increased ease of ingestion, and more complete absorption. Thus they are inherently liable to cause excess energy intake. The extreme commonness of obesity in Western countries may be related to the fact that most dietary carbohydrate is refined and fibre-depleted.

EFFECTS OF INCREASED DIETARY FIBRE ON INTESTINAL TRANSIT

Abstract Intestinal-transit time was measured once in twenty subjects eating their usual diet (in each case a refined diet with a relatively low content of plant fibre), and again after at least 4 weeks on either a high-fibre diet or their usual diet supplemented with unprocessed bran (about 30 g. per day). Subjects whose transit was initially slow demonstrated a significant decrease in transit-time on this regimen (mean decrease from 3·8 to 2·4 days, P

Diet and Crohn's disease: characteristics of the pre-illness diet.

Thirty newly diagnosed patients with Crohns disease were interviewed about their habitual, pre-illness diet and compared with 30 healthy controls, matched for age, sex, social class, and marital status. The patients ate substantially more refined sugar, slightly less dietary fibre, and considerably less raw fruit and vegetables than the controls. A diet high in refined sugar and low in raw fruit and vegetables precedes and may favour the development of Crohns disease.

Sugar, fat, and the risk of colorectal cancer.

The habitual diet of 50 patients with large bowel cancer, as assessed by a dietary history method, was compared with that of 50 closely matched controls. Patients were included only if their symptoms were unlikely to have changed previous eating habits. The mean daily intakes of all major nutrient classes and of dietary fibre were estimated. Patients with large bowel cancer consumed 16% more energy than controls (mean (SEM) daily intake 9.92 (0.41) v 8.56 (0.32) MJ (2370 (98) v 2046 (76) kcal), respectively; p less than 0.0001), mainly in the form of carbohydrate (21% more; 282.6 (13.7) v 233.4 (10.5) g; p less than 0.0001) and fat (14% more; 100.8 (4.3) v 88.4 (3.2) g; p less than 0.001). The extra carbohydrate was largely in the form of sugars depleted in fibre and the extra fat as combinations of fat and such sugars. As the selection criteria used make it unlikely that this eating pattern was caused by the disease the data suggest that a high intake of sugars depleted in fibre and fat predisposes to the development of large bowel cancer.

Treatment of Crohn's disease with an unrefined-carbohydrate, fibre-rich diet.

Thirty-two patients with Crohns disease were treated with a fibre-rich, unrefined-carbohydrate diet in addition to conventional management and followed for a mean of four years and four months. Their clinical course was compared retrospectively with that of 32 matched patients who had received no dietary instruction. Hospital admissions were significantly fewer and shorter in the diet-treated patients, who spent a total of 111 days in hospital compared with 533 days in the non-diet-treated control group. Whereas five of the controls required intestinal operation, only one diet-treated patient needed surgery. This is in strong contrast to general experience with this disease. Treatment with a fibre-rich, unrefined-carbohydrate diet appears to have a favourable effect on the course of Crohns disease and does not lead to intestinal obstruction.

EFFECT OF BRAN ON BLOOD LIPIDS AND CALCIUM

Abstract There was a significant lowering of serum-triglycerides and plasma-calcium in fourteen subjects fed unprocessed wheat bran (median dose 38 g. per day) for 4-9 weeks (median 5 weeks).