Overgrowth of the indigenous gut microbiome and irritable bowel syndrome.

Culture-independent molecular techniques have demonstrated that the majority of the gut microbiota is uncultivable. Application of these molecular techniques to more accurately identify the indigenous gut microbiome has moved with great pace over recent years, leading to a substantial increase in understanding of gut microbial communities in both health and a number of disorders, including irritable bowel syndrome (IBS). Use of culture-independent molecular techniques already employed to characterise faecal and, to a lesser extent, colonic mucosal microbial populations in IBS, without reliance on insensitive, traditional microbiological culture techniques, has the potential to more accurately determine microbial composition in the small intestine of patients with this disorder, at least that occurring proximally and within reach of sampling. Current data concerning culture-based and culture-independent analyses of the small intestinal microbiome in IBS are considered here.

Does subclinical malabsorption of carbohydrates prevent colorectal cancer? A hypothesis.

The incidence of colorectal cancer (CRC) is high in the western world and low in Asia and Africa. Fibre and starch are thought to be important protective factors, with a strong inverse relationship between starch consumption and CRC incidence. Whether this is true in Asia, particularly, and Africa is debatable. Because rice is the most easily absorbed of carbohydrates, a mechanism whereby there is an increased starch load in the colon in the Asian population needs to be identified. One possible cause is subclinical malabsorption. This is linked to increased mucosal permeability and low gross domestic product (GDP) per capita, which reflects poor sanitation and water supplies with increased risk for small bowel bacterial overgrowth leading to mucosal cell damage. A potential cause of the dramatic rise in CRC incidence in Japan may relate to its equally dramatic increase in GDP per capita of 600% over 50 years. This correlation appears to be stronger than with other dietary factors including fruit, vegetables and meat. Worldwide, a close correlation exists among low GDP per capita, low CRC incidence and presumed subclinical malabsorption. All these factors combine to maintain a low incidence of CRC in poorly developed countries.

Irritable bowel syndrome.

BACKGROUND: Irritable bowel syndrome (IBS) a common worldwide problem, particularly women, and presents from the teenage years onward. OBJECTIVE: This article discusses the causes, diagnosis and management of IBS. DISCUSSION: Disturbed motility and sensory function underlie much of the disturbance in function that, not infrequently, begins following an episode of gastroenteritis. There is an intimate role for the brain-gut axis in modulating symptoms relating to underlying causes of small bowel bacterial overgrowth, food intolerance and sensitivity, and abnormalities of corticotropin releasing factors. Management requires long term involvement with the patient as there is no single therapeutic strategy that is predictably effective. However, diet, bulking agents, antispasmodics and a variety of alternative therapies including herbs, probiotics, and psychological intervention are important in individual patients.