Recent advances in dietary fiber and colorectal diseases

The effect of the fiber components cellulose and lignin on experimental colon neoplasia

Sixty Sprague-Dawley rats were pair-fed one of three nutritionally identical diets. One diet contained "low-fiber" (3.8% crude fiber); the others contained "high fiber" (28.7% crude fiber) composed of either cellulose or lignin. Although both "high fiber" diets had similar stool bulking effects, only the cellulose diet was associated with a reduction in 1,2-dimethylhydrazine (DMH)-induced colon neoplasms. The cellulose diet was also associated with distinct changes in the gut bacterial profile and with a lowered serum cholesterol.

Diverticular disease

Although most often clinically silent, colonic diverticula are responsible for a large number of gastrointestinal illnesses in our society. Complications of diverticular disease, including perforation and hemorrhage, may occur in 15% to 20% of patients with diverticula during their lifetime, and although often mild and self-limiting diseases, they too frequently cause life-threatening problems that require prompt surgical intervention. Despite a cadre of sophisticated laboratory and radiologic tests that have been developed to aid in the diagnosis of complicated diverticular disease, the diagnosis and treatment of diverticulitis still relies heavily on patient history, physical examination, physician judgment, and the patient's clinical response to treatment. Thus it is important for the managing physician to fully understand the pathogenesis of diverticula, the clinical consequences and modes of presentation of complicated diverticular disease, and the array of interventions available for treatment of these problems. This monograph summarizes our knowledge of diverticular disease to date and tries to give specific guidelines for the treatment of patients with complicated diverticulitis. However, it must be understood that the presentation and severity of these complications vary widely from patient to patient. Thus one cannot take a single approach toward a patient who has diverticulitis or diverticular bleeding. Rather, successful outcomes depend on an individual approach to each patient while maintaining certain generally accepted principles of treatment.

Major influences on median energy and nutrient intakes among teenagers: a Tasmanian survey

This report explores the characteristics that influenced median intakes of energy and ten nutrients in a representative sample of 1055 adolescents (11-16 years) in Tasmania, Australia. Among girls, the characteristic with greatest influence on intakes was different for different nutrients. Thus, median intakes of fat, iron, thiamin and niacin-equivalent were lower in heavier, fatter girls. Girls from larger families consumed more riboflavin, while girls with poorly educated mothers consumed less vitamin A. Girls who regularly took vitamin supplements had higher median intakes of (food-derived) calcium. Among boys the increase of intakes of energy and nutrients with age overshadowed the influence of other characteristics. Among younger boys the characteristic with greatest influence varied. Those with highly educated fathers had lower median intakes of energy and carbohydrate; those who exercised vigorously consumed more fat; those who smoked 'heavily' (greater than 10 cigarettes in the previous week) consumed more thiamin and niacin-equivalent. Among older boys the characteristic with greatest influence varied. Those who drank 'heavily' (greater than five glasses in the previous week) had higher intakes of energy and fat. Those from professional-managerial households consumed more thiamin. For vitamin C, there was no sex difference in intakes. Social status had the greatest influence, with children from professional-managerial households eating more. Food choices underlying these differences in energy and nutrient intakes were explored.

Differing effects of pectin, cellulose and lignin on stool pH, transit time and weight

Randomized cross-over studies were undertaken to determine the effects of daily dietary supplements of pectin (12 g/d), cellulose (15 g/d) and lignin (12 g/d) on stool characteristics of healthy volunteers. Detailed dietary records were kept throughout the study. Stool collections over 48 h were used to determine mean stool pH and weight. The single stool transit time was measured using radio-opaque markers. Pectin did not significantly alter the mean stool pH, transit time or 24 h wet weight. Cellulose lowered the mean stool pH from 6.38 to 6.12, decreased mean stool transit time by 27% and increased mean wet stool weight by 57%. Lignin lowered the mean pH from 6.34 to 6.25, decreased the stool transit time by 20% and increased stool weight by 27% but these changes were not statistically significant. These findings have shown that individual fibre components have different colonic metabolic effects and support the view that associations between dietary fibre intakes and diseases such as colorectal cancer should be evaluated with regard to the type of fibre components consumed.