Plant-based diets contain a plethora of secondary metabolites that may impact on health and disease prevention. Much attention has been focused on the potential bioactivity and nutritional relevance of several classes of phytochemicals such as flavonoids, carotenoids, phyto-oestrogens and glucosinolates. Less attention has been paid to simple phenolic acids that are widely found in fruit, vegetables, herbs, spices and beverages. Daily intakes may exceed 100 mg. In addition, bacteria in the gut can perform reactions that transform more complex plant phenolics such as anthocyanins, procyanidins, flavanones, flavonols, tannins and isoflavones into simple phenolic metabolites. The colon is thus a rich source of potentially active phenolic acids that may impact both locally and systemically on gut health. Both the small and large intestine (colon) contain absorption sites for phenolic acids but low post-prandial concentrations in plasma indicate minimal absorption early in the gastrointestinal tract and/or rapid hepatic metabolism and excretion. Therefore, any bioactivity that contributes to gut health may predominantly occur in the colon. Several phenolic acids affect the expression and activity of enzymes involved in the production of inflammatory mediators of pathways thought to be important in the development of gut disorders including colon cancer. However, at present, we remain largely ignorant as to which of these compounds are beneficial to gut health. Until we can elucidate which pro-inflammatory and potentially carcinogenetic changes in gene expression can be moderated by simple phenolic acids, it is not possible to recommend specific plant-based foods rich in particular phenolics to optimise gut health.

The recently discovered SCFA-activated G-coupled protein receptors FFA receptor 2 and FFA receptor 3 are co-localised in l-cells with the anorexigenic ‘ileal brake’ gut hormone peptide YY, and also in adipocytes, with activation stimulating leptin release. Thus, SCFA such as acetate and propionate show promise as a candidate to increase satiety-enhancing properties of food. We therefore postulate SCFA may have a role in appetite regulation and energy homeostasis. SCFA can be delivered either directly within food, or indirectly via the colon by the provision of fermentable non-digestible carbohydrates. A review of studies investigating the effects of oral SCFA ingestion on appetite suggests that while oral SCFA ingestion is associated with enhanced satiety, this may be explained by product palatability rather than a physiological effect of SCFA. Colon-derived SCFA generated during microfloral fermentation have also been suggested to explain satiety-enhancing properties of non-digestible carbohydrates. However, findings are mixed from investigations into the effects of the prebiotic inulin-type fructans on appetite. Overall, data presented in this review do not support a role for SCFA in appetite regulation.

The British Bangladeshi community is one of the youngest and fastest growing ethnic minority groups in the UK. Many report poor socio-economic and health profiles with the existence of substantial health inequalities, particularly in relation to type 2 diabetes. Although there is compelling evidence for the effectiveness of lifestyle interventions in the prevention of type 2 diabetes, there is little understanding of how best to tailor treatments to the needs of minority ethnic groups. Little is known about nutrition related lifestyle choices in the Bangladeshi community or the factors influencing such decisions. Only by exploring these factors will it be possible to design and tailor interventions appropriately. The Bangladeshi Initiative for the Prevention of Diabetes study explored lay beliefs and attitudes, religious teachings and professional perspectives in relation to diabetes prevention in the Bangladeshi community in Tower Hamlets, London. Contrary to the views of health professionals and previous research, poor knowledge was not the main barrier to healthy lifestyle choices. Rather the desire to comply with cultural norms, particularly those relating to hospitality, conflicted with efforts to implement healthy behaviours. Considerable support from Islamic teachings for diabetes prevention messages was provided by religious leaders, and faith may have an important role in supporting health promotion in this community. Some health professionals expressed outdated views on community attitudes and were concerned about their own limited cultural understanding. The potential for collaborative working between health educators and religious leaders should be explored further, and the cultural competence of health professionals addressed.