Interactions between diets, nutrients, and the host in promoting health are almost entirely dependent on effective digestive function. Historically somewhat overlooked in nutrition research, recent years have seen the emergence of new research, new funding initiatives, and increased public interest in the role of gut heath and its relationship to diet.

A growing area of interest, challenges remain with translating research into practice

Despite the explosion of public interest in the topic, evidence-based communication around digestive health and the integration of evidence into practice by healthcare professionals is still nascent. A recent online survey of 1,000 Irish adults conducted on behalf of the healthcare company Scope in April 2019 (dubbed ‘the Gut Education Index’), found that the internet is the second most used source of information on gut health after doctors, ahead of both nutritionists (41%) and pharmacists (63%). Moreover, a large cross-sectional study found that while 65% of the UK public believed the effectiveness of probiotics for constipation had been proven in research studies, just 26% of doctors routinely recommended them to patients.

Providing Health Care Practitioners with the skills and resources to communicate evidence-based messages on digestive health to the public remains a challenge, with many health care professionals not considering themselves to have a good working knowledge of the area. A 2016 UK survey found that only 23.4% of dietitians and just 6.3% of GP’s considered themselves to have a good understanding of the area. Part of the challenge is the huge scope and complexity of the rapidly growing evidence base, and the discrepancy of information on (for example) probiotic use across different healthcare resources. A roundtable discussion hosted by the British Nutrition Foundation in February 2019 noted that the nuanced nature of the evidence base, with the health effects of probiotics for example dependant on both disease status and probiotic strain, is an obstacle in encouraging practitioners to translate research into practice.

The roundtable also highlighted the discrepancy between the public interest in gut health, driven for the most part by an interest in pre and probiotic use for optimal health and disease prevention, and the evidence base, which is in fact strongest on probiotic use for specific disease treatment. A further challenge is the current ambiguity around regulation, with the EU regulatory framework currently prohibiting use of the term ‘probiotic’ in commercial communication and with health claims in relation to specific diseases remaining outside the scope of regulation.

Diet and digestive health

Diet plays a role in maintaining general gut health, with both observational and intervention studies showing that exclusionary diets – for example low carbohydrate, low FODMAP or gluten free – can result in changes to gut microbiota such as a reduction in Bifidobacterium and lactobacillus species. Fibre is one particularly notable nutrient for maintaining and promoting both digestive and general health. In addition to preventing constipation by easing the passage of stools, adequate intake of fibrous foods can help to reduce cholesterol levels, and has been associated with a lower risk of heart disease, diabetes type two and colorectal cancer. Production of short chain fatty acids as a product of bacterial fermentation of dietary fibre and resistant starch is also important for maintenance of gastrointestinal mucosal structure and function. As a result, low intakes of fibre at a population level (the latest NDNS survey finding that over 90% of adults fail to meet the recommended intake of fibre) is a cause for concern.

Evidence also suggests that dietary components such as pre and probiotics may help with management of a number of digestive tract disorders. For example, probiotics taken in conjunction with antibiotics can speed up the rate of recovery in acute infectious diarrhoea, and when taken in conjunction with antibiotics, probiotics can reduce antibiotic associated diarrhoea. In fact, NICE recently issued support for the joint use of probiotics with antibiotics to reduce risk of antibiotics associated diarrhoea and primary C.difficile prevention, terming this a ‘safe and effective’ intervention for adults and children.

Interactions between the host, diet, and specific nutrients, in addition to the sensing and signalling functions undertaken by the gut are still being uncovered. Mechanisms remain to be elucidated, for example bacteria-diet-epithelial interactions in the pathogenesis of inflammatory bowel diseases and colorectal cancer. Nutrients beyond fibre also appear to contribute to digestive health, for example polyphenols, and the hypothesised role of vitamin D in patients with Irritable Bowel Syndrome.

The Winter Conference 2019 will focus on diet and digestive health

In order to explore the topic and emerging research areas, the Nutrition Society are looking forward to exploring the topic of diet and digestive health at this year’s Winter Conference, 2-4 December, at the Royal Society of Medicine in London.

This year the conference will be run for the first time in collaboration with the British Society of Gastroenterology (BSG) and the British Association for Parenteral and Enteral Nutrition (BAPEN). This collaboration is intended to provide conference attendees with insight into the practical and clinical aspects of digestive health and disorders as well as emerging research areas. The conference will therefore begin with a half-day BAPEN practitioner’s session covering clinical issues including oral nutrition support, percutaneous endoscopic gastrostomy tube use (PEG), and anorexia nervosa treatment.

The conference will continue to explore the relationships between diet, gut function, gut pathologies and systemic health over the following two days, taking as its focus recent developments in the field and areas of continued debate. Keynote speakers include Professor Jonathan Rhodes, University of Liverpool on “Nutrition and gut health: the impact of specific dietary components – it’s not just five-a-day”, and Professor Christine Edwards, University of Glasgow, with a plenary lecture titled “Feeding the gut, nourishing the body”.

A new journal on the Gut Microbiome

The Nutrition Society are also pleased to announce the launch of a new open access journal in partnership with Cambridge University Press, Gut Microbiome. The journal will look at the factors that influence gut microbiota and how they in turn affect our health and development. Its aim is to support the development of an integrated, interdisciplinary understanding of the gut microbiome, and in doing so it is hoped that it will provide a central resource for those exploring and communicating new scientific insights into digestive health and the gut microbiome.