The present review covers current knowledge about the ageing of oral physiology related to mastication and its effects on eating behaviour. Mastication is the first process undergone by a food during feeding. It has a key role in the maintenance of nutritional status in two respects. First, the perceptions of food's sensory properties elicited during chewing and swallowing are one of the major determinants of the pleasure which drives us to eat; second, the properties of the swallowed bolus are affected by oral conditions and this may modulate the subsequent phases of digestion. Ageing in healthy dentate subjects induces moderate changes in oral physiology. Changes in neuromuscular activity are partly compensated by changes in chewing behaviour. No clear age effect is seen in texture perception, although this does impact on food bolus properties. In contrast, great alterations in both chewing behaviour and food bolus properties are observed when ageing is associated with a compromised dentition, general health alterations and drug intake. Eating behaviour is far more complex than just chewing behaviour and the concerns of the elderly about food cannot be explained solely by oral physiology. Discrepancies are often noticed with older subjects between various objective measurements of oral performance and corresponding measures of self-perception. In addition, although more foods are recognised as hard to chew with increasing age, there is no clear shift in preference towards food that is easy to chew. Food choices and food consumption are also driven by memory, psychology and economic factors. Advances in the understanding of food choice in the elderly need a sustained collaborative research effort between sensory physiologists, nutritionists, and food scientists.

The antioxidant potential (AP) is an important nutritional property of foods, as increased oxidative stress is involved in most diet-related chronic diseases. In dairy products, the protein fraction contains antioxidant activity, especially casein. Other antioxidants include: antioxidant enzymes; lactoferrin; conjugated linoleic acid; coenzyme Q10; vitamins C, E, A and D3; equol; uric acid; carotenoids; and mineral activators of antioxidant enzymes. The AP of dairy products has been extensively studied in vitro, with few studies in animals and human subjects. Available in vivo studies greatly differ in their design and objectives. Overall, on a 100 g fresh weight-basis, AP of dairy products is close to that of grain-based foods and vegetable or fruit juices. Among dairy products, cheeses present the highest AP due to their higher protein content. AP of milk increases during digestion by up to 2·5 times because of released antioxidant peptides. AP of casein is linked to specific amino acids, whereas β-lactoglobulin thiol groups play a major role in the AP of whey. Thermal treatments such as ultra-high temperature processing have no clear effect on the AP of milk. Raw fat-rich milks have higher AP than less fat-rich milk, because of lipophilic antioxidants. Probiotic yoghurts and fermented milks have higher AP than conventional yoghurt and milk because proteolysis by probiotics releases antioxidant peptides. Among the probiotics, Lactobacillus casei/acidophilus leads to the highest AP. The data are insufficient for cheese, but fermentation-based changes appear to make a positive impact on AP. In conclusion, AP might participate in the reported dairy product-protective effects against some chronic diseases.

The Japanese scientific academic community defined ‘functional food’ early in the 1980s. That is, functional foods are those that have three functions. The primary function is nutrition. The secondary function is a sensory function or sensory satisfaction. The third is the tertiary function, which is physiological. The Japanese Ministry of Health, Labour, and Welfare (MHLW) set up ‘Foods for Specified Health Use’ (FOSHU) in 1991 as a regulatory system to approve the statements made on food labels concerning the effect of the food on the human body. Food products applying for approval by FOSHU are scientifically evaluated in terms of their effectiveness and safety by the Council of Pharmaceutical Affairs and Food Hygiene under the MHLW. The regulatory range of FOSHU was broadened in 2001 to accept the forms of capsules and tablets in addition to those of conventional foods. FOSHU increased the total to about 330 items in January 2003. The MHLW enacted a new regulatory system, ‘Foods with Health Claims’, in April 2001, which consists of the existing FOSHU system and the newly established ‘Foods with Nutrient Function Claims’ (FNFC). Under the FNFC, twelve vitamins (vitamins A, B1, B2, B6, B12, C, E, D, biotin, pantothenic acid, folic acid, and niacin) and two minerals (Ca and Fe) are standardized. Examples of claims regarding these substances are as follows: ‘Calcium is a nutrient which is necessary to form bones and teeth’; ‘Vitamin D is a nutrient which promotes calcium absorption in the gut intestine and aids in the formation of bones.’ The upper and lower levels of the daily consumption of these nutrients are also determined. The labelling of functional foods should always be based on scientific evidence and be in harmony with international standards. The nutrient–function claim was adopted in the guidelines for nutrition claims by the Codex Alimentarius in 1997. The claims of the Japanese FNFC are equivalent to the nutrient function claims standardized by the Codex Alimentarius. The enhanced function claim and the disease risk-reduction claims were proposed by both the Codex Alimentarius and an Economic Union project in 1999. The structure function claim, which is similar to the enhanced function claim, was enacted by the Dietary Supplement Health and Education Act in the USA in 1994. Most of the statements of the Japanese FOSHU system are close to the category of structure/function claims in the USA or the enhanced function claims of the Codex Alimentarius.

Dietary lignans are phyto-oestrogens that possibly influence human health. The present review deals with lignan bioavailability, the study of which is crucial to determine to what extent metabolism, absorption and excretion of lignans alter their biological properties. Since intestinal bacteria play a major role in lignan conversion, for instance by producing the enterolignans enterodiol and enterolactone, emphasis is put on data obtained in recent bacteriological studies.

Anaerobic chytridiomycete fungi are found in the gastrointestinal tracts of sheep, cattle and goats, as well as in many other domesticated ruminant and nonruminant herbivores and a wide variety of wild herbivorous mammals. They are principally found associated with the fibrous plant particles of digesta and as free swimming zoospores in the fluid phase. The presence of large fungal populations in animals consuming mature pasture or diets largely composed of hay or straw together with the production of highly active fibre degrading enzymes lead to' the belief that anaerobic fungi may have a significant role to play in the assimilation of fibrous feeds by ruminants. While many early studies focused on anaerobic fungi because of their unusual biology and metabolism, the large part of subsequent research has emphasized the biotechnological potential of their cellulases, xylanases and phenolic esterases. In recent years, the extent of the contribution of anaerobic fungi to the nutrition of ruminants has also been established through studies of fungal populations in the rumen and the dietary factors which influence them, as presented in this review. Further, we discuss the evidence supporting an important contribution of anaerobic fungal populations in the rumen to feed intake and digestion of poor quality feed by domesticated ruminants. In conclusion, the review explores some different methods for manipulating fungi in the rumen for increased feed intake and digestion.

We review recent research on the effect of social context on food intake and food choice and assess the implications for nutritional interventions. We focus on studies of modelling of eating behaviour and the impact of perceived eating norms on the amounts and types of food that individuals eat. We suggest that social context influences eating via multiple mechanisms, including identity signalling and self-presentation concerns. However, building on existing theoretical models, we propose that social factors may be particularly influential on nutrition because following the behaviour of others is adaptive and social norms inform individuals about behaviours that are likely to be optimal (‘if everyone else is doing it, I probably should be’). Guided by understanding of the potential underlying mechanisms, we discuss how social norms might be used to promote healthier nutrition.

The impact of nutritional variation, within populations not overtly malnourished, on cognitive function and arousal is considered. The emphasis is on susceptibility to acute effects of meals and glucose loads, and chronic effects of dieting, on mental performance, and effects of cholesterol and vitamin levels on cognitive impairment. New developments in understanding dietary influences on neurohormonal systems, and their implications for cognition and affect, allow reinterpretation of both earlier and recent findings. Evidence for a detrimental effect of omitting a meal on cognitive performance remains equivocal: from the outset, idiosyncrasy has prevailed. Yet, for young and nutritionally vulnerable children, breakfast is more likely to benefit than hinder performance. For nutrient composition, despite inconsistencies, some cautious predictions can be made. Acutely, carbohydrate-rich–protein-poor meals can be sedating and anxiolytic; by comparison, protein-rich meals may be arousing, improving reaction time but also increasing unfocused vigilance. Fat-rich meals can lead to a decline in alertness, especially where they differ from habitual fat intake. These acute effects may vary with time of day and nutritional status. Chronically, protein-rich diets have been associated with decreased positive and increased negative affect relative to carbohydrate-rich diets. Probable mechanisms include diet-induced changes in monoamine, especially serotoninergic neurotransmitter activity, and functioning of the hypothalamic pituitary adrenal axis. Effects are interpreted in the context of individual traits and susceptibility to challenging, even stressful, tests of performance. Preoccupation with dieting may impair cognition by interfering with working memory capacity, independently of nutritional status. The change in cognitive performance after administration of glucose, and other foods, may depend on the level of sympathetic activation, glucocorticoid secretion, and pancreatic β-cell function, rather than simple fuelling of neural activity. Thus, outcomes can be predicted by vulnerability in coping with stressful challenges, interacting with nutritional history and neuroendocrine status. Functioning of such systems may be susceptible to dietary influences on neural membrane fluidity, and vitamin-dependent cerebrovascular health, with cognitive vulnerability increasing with age.

It is important to be able to characterise foods and feedstuffs according to their available amino acid contents. This involves being able to determine amino acids chemically and the conduct of bioassays to determine amino acid digestibility and availability. The chemical analysis of amino acids is not straightforward and meticulousness is required to achieve consistent results. In particular and for accuracy, the effect of hydrolysis time needs to be accounted for. Some amino acids (for example, lysine) can undergo chemical modification during the processing and storage of foods, which interferes with amino acid analysis. Furthermore, the modified amino acids may also interfere with the determination of digestibility. A new approach to the determination of available lysine using a modified in vivo digestibility assay is discussed. Research is required into other amino acids susceptible to structural damage. There is recent compelling scientific evidence that bacterial activity in the small intestine of animals and man leads to the synthesis and uptake of dietary essential amino acids. This has implications for the accuracy of the ileal-based amino acid digestibility assay and further research is required to determine the extent of this synthesis, the source of nitrogenous material used for the synthesis and the degree of synthesis net of amino acid catabolism. Although there may be potential shortcomings in digestibility assays based on the determination of amino acids remaining undigested at the terminal ileum, there is abundant evidence in simple-stomached animals and growing evidence in human subjects that faecal-based amino acid digestibility coefficients are misleading. Hindgut microbial metabolism significantly alters the undigested dietary amino acid profile. The ileal amino acid digestibility bioassay is expected to be more accurate than its faecal-based counterpart, but correction of the ileal amino acid flow for amino acids of endogenous origin is necessary. Approaches to correcting for the endogenous component are discussed.

Food consumption patterns are influenced by a number of factors, including social and cultural factors. It is difficult to effect dietary change, and one possible barrier to dietary change is optimistic bias. Research indicates that individuals tend to believe that they are less likely to experience negative events, and more likely to experience positive events than their peers; this phenomenon is known as optimistic bias. It has been argued that optimistic bias may have a negative impact both on self-protective behaviour and on efforts to promote risk-reducing behaviours. The present article reviews the literature investigating optimistic bias specifically in the food domain. The review indicated that many food and nutrition issues are associated with optimistic bias. This has important implications for health-promotion activities in the food domain. The paper also describes key aspects of the methodology used to investigate optimistic bias and details the conditions under which optimistic bias has been demonstrated. The importance of identifying the causes of optimistic bias is discussed, and empirical attempts designed to reduce optimistic bias by countering the causes are reviewed. Finally, directions for future research are suggested.

The gastrointestinal tract (GIT) is a metabolically significant site of sulfur amino acid (SAA) metabolism in the body and metabolises about 20 % of the dietary methionine intake which is mainly transmethylated to homocysteine and trans-sulfurated to cysteine. The GIT accounts for about 25 % of the whole-body transmethylation and trans-sulfuration. In addition, in vivo studies in young pigs indicate that the GIT is a site of net homocysteine release and thus may contribute to the homocysteinaemia. The gut also utilises 25 % of the dietary cysteine intake and the cysteine uptake by the gut represents about 65 % of the splanchnic first-pass uptake. Moreover, we recently showed that SAA deficiency significantly suppresses intestinal mucosal growth and reduces intestinal epithelial cell proliferation, and increases intestinal oxidant stress in piglets. These recent findings indicate that intestinal metabolism of dietary methionine and cysteine is nutritionally important for intestinal mucosal growth. Besides their role in protein synthesis, methionine and cysteine are precursors of important molecules. S-adenosylmethionine, a metabolite of methionine, is the principal biological methyl donor in mammalian cells and a precursor for polyamine synthesis. Cysteine is the rate-limiting amino acid for glutathione synthesis, the major cellular antioxidant in mammals. Further studies are warranted to establish how SAA metabolism regulates gut growth and intestinal function, and contributes to the development of gastrointestinal diseases. The present review discusses the evidence of SAA metabolism in the GIT and its functional and nutritional importance in gut function and diseases.

This review provides a rigorous investigation of the question of whether the transtheoretical model (TTM) (or stages of change model) is applicable to eating behaviour change. The TTM is currently the most popular of a number of stage theories being used to examine health behaviour change. Stage theories specify an ordered set of ‘stages of readiness to change’ into which people can be classified and identify the factors that can facilitate movement from one stage to the next. If eating behaviour change follows a stage process, then nutritionists could identify the predominant stage or stages in a population and focus resources on those issues most likely to move people to the next stage (e.g. from no intention of changing, to thinking about changing). In addressing this question, the review draws on the defining characteristics of stage theories as clarified by Weinstein et al. (1998), provides an in-depth coverage of methodological considerations, and a detailed summary table of dietary studies applying the TTM. Specific recommendations are made for improving the accuracy of dietary stage classifications. Among the key conclusions are: (1) dietary studies using the TTM have been hampered by a focus on nutritional outcomes such as dietary fat reduction, rather than clearly understood food behaviours (e.g. five servings of fruit and vegetables per day); (2) accurate stage classification systems are possible for food-based goals, but major misclassification problems occur with nutrient-based goals; (3) observation of an association between stage and dietary intake is not sufficient to demonstrate the validity of the model for dietary behaviour; (4) there is a need for valid questionnaires to measure all aspects of the TTM, and more research on the whole model, particularly the ‘processes of change’, rather than on single constructs such as ‘stage’ (5) cross-sectional studies generally support the predicted patterns of between-stage differences in decisional balance, self-efficacy, and processes of change; (6) studies which test the key hypothesis that different factors are important in distinguishing different stages are rare, as are prospective studies and stage-matched interventions. Only such studies can conclusively determine whether the TTM is applicable to eating behaviour. Since the ultimate test of the TTM will be the effectiveness of stage-matched dietary interventions, the review ends by exploring the requirements for such studies.

As the incidence of obesity is reaching ‘epidemic’ proportions, there is currently widespread interest in the impact of dietary components on body-weight and food intake regulation. The majority of data available from both epidemiological and intervention studies provide evidence of a negative but modest association between milk and dairy product consumption and BMI and other measures of adiposity, with indications that higher intakes result in increased weight loss and lean tissue maintenance during energy restriction. The purported physiological and molecular mechanisms underlying the impact of dairy constituents on adiposity are incompletely understood but may include effects on lipolysis, lipogeneis and fatty acid absorption. Furthermore, accumulating evidence indicates an impact of dairy constituents, in particular whey protein derivatives, on appetite regulation and food intake. The present review summarises available data and provides an insight into the likely contribution of dairy foods to strategies aimed at appetite regulation, weight loss or the prevention of weight gain.

Cereal fibre and whole-grain intakes have been consistently associated in the epidemiological literature with reduced mortality and risk of chronic disease including obesity, CVD and type 2 diabetes. The present review focuses on intervention trials with three primary aims: (1) understanding the mechanisms through which fibre consumption improves health (for example, examination of intermediate endpoints reflecting improved lipid, glucose and energy metabolism); (2) close evaluation of qualitative factors which modify fibre's effectiveness including physiochemical properties (for example, solubility, fermentability and viscosity), fibre extract molecular weight, fibre particle size and botanical structure of the fibre source grain; and (3) identification of areas in which additional research is needed. The first two aims typify the goals of nutrition research, in that improved understanding of the specific factors which determine fibre's health benefits has critical implications for dietary recommendations as well as improving understanding of physiological mechanisms. The third aim acknowledges the substantial gap between recommended and actual fibre intakes in many developed countries including the USA and the UK. In recognition of this deficit in total fibre intake, food manufacturing processes increasingly utilise fibre extracts and concentrates as food additives. However, whether fibre extracts provide similar health benefits to the fibre supplied in the constituents of whole grain is largely unexplored. The relative benefits of fibre extracts compared with whole-grain fibre sources therefore represent a critical area in which additional research is needed.

The transition from liquid to solid feed during weaning results in morphological, histological and microbial changes in the young animal's intestinal tract and often is associated with diarrhoea. The ban of in-feed antibiotics in pig production in the European Union has led to increasing interest in alternatives to overcome weaning-associated problems. Among others, nucleotides may have the potential to alleviate health impairments due to weaning. Nucleotides are natural components of the non-protein fraction of milk and have important effects on the maintenance of health in young animals. Nucleotides and their related metabolic products play key roles in many biological processes and become essential dietary components when endogenous supply is insufficient for normal function. The present review summarises nucleotide composition of milk from different species, the biology of nucleotides and possible effects of dietary nucleotides on intestinal morphology and function, intestinal microbiota, immune function, nutrient metabolism, hepatic morphology and function as well as growth performance. Special attention is given to data available for pigs, and suggestions are made for inclusion of nucleotides in the diet to benefit piglets' health and reduce the consequences accompanying early weaning.

Zn is an essential trace element, involved in many different cellular processes. A relationship between Zn, pancreatic function and diabetes was suggested almost 70 years ago. To emphasise the importance of Zn in biology, the history of Zn research in the field of diabetes along with a general description of Zn transporter families will be reviewed. The paper will then focus on the effects of Zn on pancreatic β-cell function, including insulin synthesis and secretion, Zn signalling in the pancreatic islet, the redox functions of Zn and its target genes. The recent association of two ‘Zn genes’, i.e. metallothionein (MT) and Zn transporter 8 (SLC 30A8), with type 2 diabetes at the genetic level and with insulin secretion in clinical studies offers a potential new way to identify new drug targets to modulate Zn homeostasis directly in β-cells. The action of Zn for insulin action in its target organs, as Zn signalling in other pancreatic islet cells, will be addressed. Therapeutic Zn–insulin preparations and the influence of Zn and Zn transporters in type 1 diabetes will also be discussed. An extensive review of the literature on the clinical studies using Zn supplementation in the prevention and treatment of both types of diabetes, including complications of the disease, will evaluate the overall beneficial effects of Zn supplementation on blood glucose control, suggesting that Zn might be a candidate ion for diabetes prevention and therapy. Clearly, the story of the links between Zn, pancreatic islet cells and diabetes is only now unfolding, and we are presently only at the first chapter.

Traditionally only a small proportion of the workforce was engaged in shift work. Changing economic pressures have resulted in increased engagement in shift work, with approximately 17 % of the workforce in Europe engaged in this work pattern. The present narrative review aimed to summarise the data on the effects of shift work on the diet, lifestyle and health of employees, while addressing the barriers to, and opportunities for, improving health among shift workers. Shift work can result in low-quality diet and irregular eating patterns. Adverse health behaviours are also reported; particularly increased smoking and poor sleep patterns. These altered lifestyle habits, in conjunction with disruption to circadian rhythms, can create an unfavourable metabolic phenotype which facilitates the development and progression of chronic disease. Although the data are inconclusive due to issues such as poor study design and inadequate control for confounding factors; shift workers appear to be at increased mental and physical health risk, particularly with regard to non-communicable diseases. Information is lacking on the obstacles to leading a healthier lifestyle while working shifts, and where opportunities lie for intervention and health promotion among this group. In order to provide an informed evidence base to assist shift workers in overcoming associated occupational hazards, this gap must be addressed. This review highlights the unique nutritional issues faced by shift workers, and the subsequent effect on health. In societies already burdened with increased incidence of non-communicable chronic diseases, there is a clear need for education and behaviour change interventions among this group.