Irritable bowel syndrome (IBS) is a disorder of chronic abdominal pain, altered bowel habit and abdominal distension. It is the commonest cause of referral to gastroenterologists in the developed world and yet current therapeutic strategies are often unsatisfactory. There is now increasing evidence linking alterations in the gastrointestinal (GI) microbiota and IBS. Changes in faecal and mucosa-associated microbiota, post-infectious IBS, a link with small intestinal bacterial overgrowth and an up-regulation of the GI mucosal immune system all suggest a role for the GI microbiota in the pathogenesis of IBS. Given this evidence, therapeutic alteration of the GI microbiota by probiotic bacteria could be beneficial. The present paper establishes an aetiological framework for the use of probiotics in IBS and comprehensively reviews randomised placebo-controlled trials of probiotics in IBS using multiple electronic databases. It highlights safety concerns over the use of probiotics and attempts to establish guidelines for their use in IBS in both primary and secondary care.

More than 3 million individuals are estimated to be at risk of malnutrition in the UK, of whom about 93% live in the community. BAPEN's Nutrition Screening Week surveys using criteria based on the ‘Malnutrition Universal Screening Tool’ (‘MUST’) revealed that 28% of individuals on admission to hospital and 30–40% of those admitted to care homes in the previous 6 months were malnourished (medium+high risk using ‘MUST’). About three quarters of hospital admissions and about a third of care home admissions came from their own homes with a malnutrition prevalence of 24% in each case. Outpatient studies using ‘MUST’ showed that 16–20% patients were malnourished and these were associated with more hospital admissions and longer length of stay. In sheltered housing, 10–14% of the tenants were found to be malnourished, with an overall estimated absolute prevalence of malnutrition which exceeded that in hospitals. In all cases, the majority of subjects were at high risk of malnutrition. These studies have helped establish the magnitude of the malnutrition problem in the UK and identified the need for integrated strategies between and within care settings. While hospitals provide a good opportunity to identify malnourished patients among more than 10 million patients admitted there annually and the five- to six-fold greater number attending outpatient departments, commissioners and providers of healthcare services should be aware that much of the malnutrition present in the UK originates in the community before admission to hospitals or care homes or attendance at outpatient clinics.

Asthma is characterised by chronic lung airway inflammation, increased airway responsiveness and variable airflow obstruction. In Westernised countries asthma is a public health concern because of its prevalence, associated ill health and high societal and healthcare costs. In recent decades there has been a marked increase in asthma prevalence, particularly in Westernised countries. It has been proposed that changing diet has contributed to the increase in asthma. Several dietary hypotheses exist; the first relates the increase in asthma to declining dietary antioxidant intake, the second to decreased intake of long-chain n-3 PUFA and increasing intake of n-6 PUFA. Vitamin D supplementation and deficiency have also been hypothesised to have contributed to the increase in asthma. Observational studies have reported associations between asthma and dietary antioxidants (vitamin E, vitamin C, carotenoids, Se, flavonoids, fruit), lipids (PUFA, butter, margarine, fish) and vitamin D. However, supplementing the diets of adults with asthma with antioxidants and lipids has minimal, if any, clinical benefit. There is growing interest in the possibility that childhood asthma is influenced by maternal diet during pregnancy, with studies highlighting associations between childhood asthma and maternal intake of some nutrients (vitamin E, vitamin D, Se, PUFA) during pregnancy. It has been suggested that maternal diet during pregnancy influences fetal airway and/or immune development. Further intervention studies are needed to establish whether modification of maternal nutrient intake during pregnancy can be used as a healthy low-cost public health measure to reduce the prevalence of childhood asthma.

Epidemiological evidence suggests that a high intake of plant foods is associated with lower risk of chronic diseases. However, the mechanism of action and the components involved in this effect have not been identified clearly. In recent years, the scientific community has agreed to focus its attention on a class of secondary metabolites extensively present in a wide range of plant foods: the flavonoids, suggested as having different biological roles. The anti-inflammatory actions of flavonoids in vitro or in cellular models involve the inhibition of the synthesis and activities of different pro-inflammatory mediators such as eicosanoids, cytokines, adhesion molecules and C-reactive protein. Molecular activities of flavonoids include inhibition of transcription factors such as NF-κB and activating protein-1 (AP-1), as well as activation of nuclear factor-erythroid 2-related factor 2 (Nrf2). However, the in vitro evidence might be somehow of limited impact due to the non-physiological concentrations utilized and to the fact that in vivo flavonoids are extensively metabolized to molecules with different chemical structures and activities compared with the ones originally present in the food. Human studies investigating the effect of flavonoids on markers of inflammation are insufficient, and are mainly focused on flavonoid-rich foods but not on pure molecules. Most of the studies lack assessment of flavonoid absorption or fail to associate an effect on inflammation with a change in circulating levels of flavonoids. Human trials with appropriate placebo and pure flavonoid molecules are needed to clarify if flavonoids represent ancillary ingredients or key molecules involved in the anti-inflammatory properties of plant foods.

Food hypersensitivity (FHS) is the umbrella term used for food allergies that involve the immune system and food intolerances that do not involve the immune system. FHS has a huge impact on quality of life and any dietary advice given should aim to minimise this effect. Despite many advances made in diagnosing and managing patients with FHS, the cornerstone of management still remains avoidance of the relevant food. However, a commonly-presenting dilemma in clinical practice is deciding to what extent the food(s) should be avoided. The level of avoidance required is currently based on the type of FHS the patient has, characteristics of the particular food protein and the natural history of the particular FHS. In addition to management of other FHS, management of cow's milk allergy requires the healthcare professional to choose the appropriate formula. Information required by the patient also includes understanding food labels and issues surrounding cross-contamination. In order to ensure that the diet is nutritionally sound, advice should be given about suitable food choices and following a healthy balanced diet, whilst taking into account the dietary restrictions. Practical issues that need to be addressed include going on holiday, travelling and eating away from home. The dietitian plays a crucial role in this process. At present, there are no standardised documents or protocols for the management of FHS and practices differ within and between countries. If adrenaline auto-injectors are prescribed, correct administration should be demonstrated and reviewed on an ongoing basis.