MEDICAL ASPECTS OF DIETARY FIBER TOPICS IN GASTROENTEROLOGY Series Editor: Howard M. Spiro, M.D. Yale University School of Medicine PANCREATITIS Peter A. Banks, M.D. MEDICAL ASPECTS OF DIETARY FIBER Edited by Gene A. Spiller, Ph.D., and Ruth McPherson Kay, Ph.D. NUTRITION AND DIET THERAPY IN GASTROINTESTINAL DISEASE Martin H. Floch, M.S., M.D., F.A.C.P. A Continuation Order Plan is available for this series. A continuation order will bring delivery of each new volume immediately upon publication. Volumes are billed only upon actual shipment. For further information please contact the publisher. MEDICAL ASPECTS OF DIETARY FIBER Edited by Gene A. Spiller Syntex Research Palo Alto, California and Ruth McPherson Kay University of Toronto Toronto, Ontario, Canada PLENUM MEDICAL BOOK COMPANY NEW YORK AND LONDON Library of Congress Cataloging in Publication Data Main entry under title: Medical aspects of dietary fiber. (Topics in gastroenterology) Includes bibliographical references and index 1. Fiber deficiency diseases. 2. High-fiber diet. I. Spiller, Gene A. II. Kay, Ruth McPherson. III. Series. [DNLM: 1. Cellulose, 2. Cellulose - Therapeutic use. WB427 M489] RC627.F5M43 616.3'96 80-16519 ISBN-13: 978-1-4615-9178-8 e-ISBN-13: 978-1-4615-9176-4 DOl: 10.1007/978-1-4615-9176-4 © 1980 Plenum Publishing Corporation Softcover reprint of the hardcover 1s t edition 1980 227 West 17th Street, New York, N.Y. 10011 Plenum Medical Book Company is an imprint of Plenum Publishing Corporation All righ ts reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher In order to appreciate the requirements of the science, the student must make himself familiar with a considerable body of most intricate mathematics, the mere retention of which in the memory materially interferes with further pro- gress. The first process in the effectual study of the science must be one of simplification and reduction of the results of previous investigations to a form in which the mind can grasp them. The results of this simplification may take the form of a purely mathematical formula or of a physical hypothesis. The dis- advantage of a physical hypothesis is that we see the phenomenon only through a medium. So we are liable to a blindness to facts and rashness in assumptions which a partial explanation encourages. James Clerk Maxwell, 1855 On Faraday's lines of force Selected by contributors Martin A. Eastwood Gordon Brydon Kebede Tadesse Contributors James W. Anderson, M.D., F.A.C.P., Medical Service, Veterans Administra- tion Medical Center; University of Kentucky College of Medicine, Lex- ington, Kentucky Sheila Bingham, B.S., Dunn Clinical Nutrition Centre, Addenbrookes Hospi- tal, Cambridge, England A. John M. Brodribb, B.S., M.B.B.S., F.R.C.s., M.S., Plymouth General Hos- pital, Plymouth, England William Gordon Brydon, B.S., M.C.B., Wolfson Gastrointestinal Laboratories, Gastrointestinal Unit, Department of Medicine, University of Edinburgh, Western General Hospital, Edinburgh, Scotland Denis P. Burkitt, M.D., F.R.C.S., Unit of Geographical Pathology, St. Thomas' Hospital Medical School, London, England John H. Cummings, M.B., M.S., M.R.C.P., Dunn Clinical Nutrition Centre, Addenbrookes Hospital, Cambridge, England Martin A. Eastwood, M.B., Ch.B., M.S., F.R.C.P., Wolfson Gastrointestinal Laboratories, Gastrointestinal Unit, Department of Medicine, University of Edinburgh, Western General Hospital, Edinburgh, Scotland Hugh James Freeman, B.S., M.D., C.M., F.R.C.P. (Canada), Vancouver Gen- eral Hospital; Gastrointestinal Cancer and Nutrition Laboratory, Envi- ronmental Carcinogenesis Unit, University of British Columbia Cancer Research Center, Vancouver, British Columbia, Canada Kenneth W. Heaton, M.A., M.D., F.R.C.P., University Department of Medi- cine, Bristol Royal Infirmary, Bristol, England W. P. T. James, M.A., M.D., F.R.C.P., Dunn Clinical Nutrition Centre, Addenbrookes Hospital, Cambridge, England David J. A. Jenkins. D.M., D. Phil., Department of Nutrition and Food Science, Faculty of Medicine, University of Toronto, Toronto, Canada Ruth McPherson Kay, Ph.D., Department of Surgery, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Flora Lubin, B.A., Department of Clinical Epidemiology, Tel Aviv University Medical School, Tel Hashomer, Israel vii viii CONTRIBUTORS Baruch Modan, M.D., Department of Clinical Epidemiology, Tel Aviv Uni- versity Medical School, Tel Hashomer, Israel Adam N. Smith, F.R.C.S.E., Clinical Surgery, University of Edinburgh and Western General Hospital, Edinburgh, Scotland David A. T. Southgate, B.S., Ph.D., Nutrition and Food Quality Division, Agricultural Research Council, Food Research Institute, Norwich, England Jon A. Story, Ph.D., Department of Foods and Nutrition, Purdue University, Lafayette, Indiana Kebede Tadesse, M.D., Wolfson Gastrointestinal Laboratories, Gastrointes- tinal Unit, Department of Medicine, University of Edinburgh, Western General Hospital, Edinburgh, Scotland Clifford Tasman-Jones, M.D., Gastroenterology Department, Auckland Hos- pital; Department of Medicine, University of Auckland, Auckland, New Zealand A. Stewart Truswell, M.D., F.R.C.P., University of Sydney, Sydney, New South Wales, Australia Margaret A. White, B.S., Agricultural Research Council, Food Research Insti- tute, Norwich, England Foreword Dietary therapy has always been important to medical practice even if it has more often been sacramental than physiological in effect. "You are what you eat" meant a lot to primitive tribes whose new leader had to eat part of his predecessor, and giving diets brought out the priest in the physician even if he or she had heard that "nothing that enters into a man defiles a man." What people eat began to take on new meaning, however, a generation ago when Schoenheimer and others made clear that body fat and muscle protein were not the sluggish unchanging masses they had appeared but instead were store- houses of energy and material influenced by food, activity, and metabolic pro- cesses. Fiber, or residue as it was then still called, however, seemed unimpor- tant; even the gastroenterologist concerned with keeping the bowels open by three cooked fruits, three cooked vegetables, and twelve glasses of water each day sometimes felt like a shaman if his cure for constipation worked. Nobody any longer read Arbuthnot Lane's charming Victorian book, The Way Out, which placed the blame for most human ailments on constipation; Lane even removed the bowel to cure the costive ills. Burkitt revived a scientific interest in fiber and the possible connection between diet. constipation, and many physical disorders by observing the vol- ume and frequency of stools on an African diet and on an English diet. His first observation stirred up a whole cauldron of scientific experimentation, and others have taught the evils of the low-fiber diet. Today, high-fiber diets are as popular among the laity as among physicians, who prescribe the amount of fiber in the diet as punctiliously as the degree of blandness a few years ago. Now is certainly the moment for fiber, as interest in high-fiber diets greets the increasing vegetarianism of the children. Spinach today has a finer image than 40 years ago, when it stood for the authority of parents and divided the generations! The father on a high-fiber diet to prevent diverticular disease and colon cancer, and incidentally to scrub his coronary arteries, can meet his vegetarian children in one great if sometimes gassy festival of love. Yet proof of the virtues of fiber is needed, and that is what Spiller and Kay's fine book is all about. ix x FOREWORD It is hard for the physician to keep abreast of the patient who reads hand- outs from the local nature food stores, but physician and nutritionist alike should realize what is being learned about the superficially so rigid material. In their fine up-to-date compendium Spiller and Kay and their contributors tell the reader what fiber is, what it does, and how it apparently works. This book has all the latest information, reviewing even the benefits that fiber may have for the patient with high plasma or biliary lipids, and is an example of how workers at the very frontiers of the field can quickly bring what they know to the practitioner. In this book, I learned that fiber is more than a simple sub- stance, that fiber from carrots differs from fiber from bran, and that the role of fiber in human disease depends upon its behavior within the gut, which in turn depends upon the type of fiber and how it affects lipids, carbohydrates, and sterol absorption. High-fiber diets may be turning eating habits back 50 or 100 years, and that seems to be all for the good. Still, it is important for physicians to separate the wheat from the chaff-even if this book may make them believe that the chaff is better for them. Spiller and his colleagues have given so much useful information that I am delighted to include this book in our series on gastroin- testinal problems. I believe the book is important reading for dieticians, nurses, general internists, gastroenterologists, surgeons, and the concerned layman. Howard M. Spiro, M.D. Preface In the late 1970s, our books Fiber in Human Nutrition and Topics in Dietary Fiber Research were published. The contents of these volumes reflected a sys- tematic effort to clarify nomenclature, chemistry, analytical procedures, and physical properties of fiber. Epidemiological data were reviewed, as were phys- iological studies in man and animals. In the brief span of four years, consid- erable progress has been made, particularly in the prophylactic and therapeutic status of fiber in clinical medicine. This volume presents a complete and cur- rent analysis of the medical aspects of dietary fiber and is intended for use by physicians, clinical nutritionists, and the growing body of investigators active in fiber research. The role of fiber in human disease depends on its behavior within the gas- trointestinal tract. The fiber content and the composition of the ingesta influ- ence the time required for passage through the gut as well as the rate and site of nutrient absorption. Moreover, disparate effects are observed, dependent on the type of fiber, anatomical location within the gut, and characteristics of the material available for mucosal uptake. Changes in glucose, lipid, and sterol absorption occur that are relevant to disorders of carbohydrate and cholesterol metabolism. Recent clinical studies suggest that fiber may have important therapeutic potential in the treatment of diabetes mellitus (Chapters 10 and 11) and may also influence plasma and biliary lipids (Chapters 8 and 9). The clinical effects of dietary fiber in the lower bowel are well docu- mented, but responsible mechanisms remain uncertain. Early hypotheses sug- gesting that the beneficial effect of fiber on colonic function was related to the hygroscopic properties of the ingested material are probably oversimplistic. A series of complex events in the large bowel result in significant degradation of fiber and attendant and important alterations in the bacterial metabolism of other compounds. In the realm of colonic disease, the role of fiber in the treat- ment of simple constipation and diverticular disease is well established (Chap- ters 1-3). The link between fiber intake and colonic carcinoma is attractive, but as yet unproven (Chapters 5-7). The effects of the metabolites, such as volatile fatty acids, produced by microbial fermentation of dietary fiber in the xi