Lysine is an important indispensable amino acid, and describing the lysine content of a food or feedstuff provides useful information about nutritional value. However, when a food or feedstuff is subjected to heating the lysine present can be altered to nutritionally unavailable derivatives. These derivatives can revert back to lysine during the acid hydrolysis step used in amino acid analysis causing an overestimate of the lysine content. There have been many chemical methods developed to determine the reactive (unmodified) lysine content of foods and feedstuffs, but these do not take into account the incomplete absorption of lysine from the small intestine. There are also a number of animal-based assays for determining available lysine (the lysine that can be absorbed in a form that can be used for protein synthesis). The true ileal amino acid digestibility assay is commonly used to determine amino acid availability and is accurate for application to unprocessed foods and feedstuffs but is not accurate for lysine and possibly other amino acids when applied to heat-processed foods or feedstuffs. For such protein sources, assays such as the slope-ratio assay, indicator amino acid oxidation assay and the BIOLYSINE™ assay (true ileal digestible reactive lysine assay) have been developed to determine available lysine. The present paper discusses the efficacy of the BIOLYSINE™ assay as well as other assays for determining available lysine in processed foods and feedstuffs.

Guidelines for sugars intake range from a population mean of less than 10 % energy from free sugars, to a maximum for individuals of 25 % energy from added sugars. The aim of the present review was to examine the evidence for micronutrient dilution by sugars and evaluate its nutritional significance. From a web-based search of MEDLINE and hand search of linked papers, forty-eight relevant publications were identified on sugars (total sugars, non-milk extrinsic sugars, or added sugars) or sugar-containing drinks. These included five reports from expert committees, six reviews, thirty-three observational studies and four small-scale interventions. There was inconsistency between studies as to the relationship between sugars intake (however expressed) and micronutrients. The statistical patterns varied between nutrients and population groups. Curvilinear associations were found in some analyses, with lower nutrient intakes at both extremes of sugar intake; however, factors such as dieting and under-reporting may confound the associations observed. Some studies found statistically significant inverse associations but these were weak, with sugars explaining less than 5 % of the variance. Mean intakes of most micronutrients were above the RDA or reference nutrient intake except among very high consumers of sugars. The available evidence does not allow for firm conclusions on an optimal level of added sugars intake for micronutrient adequacy and the trends that exist may have little biological significance except for a few nutrients (for example, Fe). It is established that energy intake is the prime predictor of micronutrient adequacy. A better understanding of valid approaches to energy adjustment, misreporting and the assessment of micronutrient adequacy is crucial to further progress in this area.

Voluntary food intake and the selection between foods are important subjects especially in ruminants in view of the economic importance of this class of animal and the complex digestive system with its attendant metabolic peculiarities. There is evidence that intake is limited by the capacity of the rumen as well as by metabolic factors; some theories assume that intake is controlled by the first limiting factor but this is not satisfying on physiological grounds and there is evidence that signals from feedback factors are integrated in an additive manner. It is now well established from research in which animals are given the chance to learn the metabolic consequences of eating food with a particular sensory profile, including a choice of foods, that animals including ruminants can adjust their diet, both quantitatively and qualitatively, to their nutrient requirements. It is proposed that they do this in order to minimise the total of the discomfort generated by the several signals from various body systems. The learning process is aided by the considerable day-to-day variation often seen in the intake of individual animals. An optimisation model is proposed and presented in a simple form, involving the addition of discomforts (calculated as the square of the deviation of the supply of metabolisable energy, crude protein and neutral-detergent fibre) and iterative elucidation of the intake at which total discomfort is minimal. With parameters appropriate for growing lambs the model provides reasonable agreement with observations, both in terms of daily intake and selection between foods of different protein contents. Manipulation of food composition and of nutrient requirements produces predictions broadly in agreement with reality except that protein deficiency has less severe consequences for the model than for real animals; it is proposed that protein deficiency be given more weighting than protein excess, and this may be true for other resources as well. This model is proposed as a philosophy and a starting point for further development and is not purveyed as a complete, working model. It nevertheless provides support for the concept of total minimal discomfort as a suitable base from which to view the control of intake and selection in all animals.

Sheep and cattle are frequently subjected to feed and water deprivation (FWD) for about 12 h before, and then during, transport to reduce digesta load in the gastrointestinal tract. This FWD is marked by weight loss as urine and faeces mainly in the first 24 h but continuing at a reduced rate subsequently. The weight of rumen contents falls although water loss is to some extent masked by saliva inflow. FWD is associated with some stress, particularly when transportation is added. This is indicated by increased levels of plasma cortisol that may be partly responsible for an observed increase in the output of water and N in urine and faeces. Loss of body water induces dehydration that may induce feelings of thirst by effects on the hypothalamus structures through the renin–angiotensin–aldosterone system. There are suggestions that elevated cortisol levels depress angiotensin activity and prevent sensations of thirst in dehydrated animals, but further research in this area is needed. Dehydration coupled with the discharge of Na in urine challenges the maintenance of homeostasis. In FWD, Na excretion in urine is reduced and, with the reduction in digesta load, Na is gradually returned from the digestive tract to the extracellular fluid space. Control of enteropathogenic bacteria by normal rumen microbes is weakened by FWD and resulting infections may threaten animal health and meat safety. Recovery time is required after transport to restore full feed intake and to ensure that adequate glycogen is present in muscle pre-slaughter to maintain meat quality.

Whilst the prevention of childhood obesity is the only viable, enduring, cost-effective solution to the obesity epidemic, effective methods for it remain elusive. Furthermore, strategies to influence obesogenic environments remain relatively unexplored. In order to be able to develop powerful population-level interventions and public health policies to prevent childhood obesity, it is important to understand its aetiology and those environments that are most amenable to measurable change. First, the present paper considers why we should be concerned about obesity in children, from both the perspective of the increased health risk to the individual and the high economic cost of treatment of obesity and related diseases, highlighting why the prevention of childhood obesity is important. Next, the determinants of health behaviour and the obesogenic environment are explored, which helps us to understand why the aetiology is so complex and that potential causal factors should not be considered in isolation, as the interaction between these factors is also important. The paper then considers the multi-factorial aetiology of childhood obesity and the rationale for the increasing trends in obesity that are evident, in order to understand what is changing in society and our children's behaviour that is triggering the positive energy balance leading to obesity. The review emphasises the need for multi-level approaches if we truly want to prevent childhood obesity. It also serves to highlight that there is a need to extend the current research base in order to build a well-founded framework to form the basis of a strategy for the prevention of childhood obesity.

The food consumption of oats has increased in recent years due to a perceived association with a range of health benefits. Oats are unusual in that the bran is not as physically distinct as in other cereals. This provides a possible benefit in providing a high β-glucan content of the grains. However, oats contain many other phytochemicals including a range of antioxidants that may be associated with health benefits, although the evidence for such benefits is largely indirect and often confusing and contradictory. Nevertheless, the consumption of oats as part of a balanced diet does seem a reasonable approach.

The retina is unique in the human body in containing three xanthophyll carotenoids; 3R,3′R-zeaxanthin, meso-zeaxanthin (MZ) and lutein. Humans consume 1 to 3 mg lutein per d and the lutein:zeaxanthin ratio in the diet is about 5:1.Xanthophyll pigments occur widely in vegetables and fruits but MZ is found in only a few foods such as the shrimp carapace and fish skin. In spite of the amounts of the different xanthophylls in the diet, zeaxanthin and MZ occur in approximately equal amounts in the eye, and their combined concentration can exceed that of lutein. In the present review the bioavailablity of zeaxanthin and lutein is assessed using the plasma xanthophyll response to dietary intervention. A number of studies have used single and mixed sources of the pure xanthophylls to achieve steady-state plasma responses. Mostly these have been with lutein and zeaxanthin but two using MZ are also described. Responses following the intervention with the pure xanthophylls are compared with those following food intervention. Vegetables are the richest source of dietary lutein and several vegetable-feeding studies are discussed. Intervention studies with eggs, which are a good source of zeaxanthin, suggest that the xanthophyll carotenoids in egg yolk may be more bioavailable than those in other foods and are described separately. MZ has been a component of a xanthophyll supplement added to chicken feed in Mexico in the last 10 years. Egg consumption in Mexico is approximately one egg/person per d and the potential contribution of this food source of MZ to Mexican dietary intakes is described. Very limited information from human feeding studies of MZ-containing supplements suggests that MZ is less well absorbed than zeaxanthin. However, MZ is unusual in the diet and not reported in the plasma. Thus plasma responses may not reflect true absorption if it takes MZ longer to equilibrate with body tissues than the other xanthophylls and competition with zeaxanthin may lower the relative concentrations of MZ in plasma. Lastly, the effects of long-term feeding with both pure and food sources of the xanthophyll pigments on macular pigment optical density is compared and the importance of previous dietary intake on the effects of intervention is discussed.

The transtheoretical model (TTM) is a behavioural theory that describes behaviour change as occurring in five stages, ranging from precontemplation to maintenance. The purpose of the present paper is to review and synthesise the literature published since 1999 on applications of the TTM to dietary behaviour so that the evidence for the use of assessment tools and interventions based on this model might be evaluated. Six databases were identified and searched using combinations of key words. Sixty-five original, peer-reviewed studies were identified and summarised in one of three tables using the following categories: population (n 21), intervention (n 25) and validation (n 19). Internal validity ratings were given to each intervention, and the body of intervention studies as a whole was rated. The evidence for using stage-based interventions is rated as suggestive in the areas of fruit and vegetable consumption and dietary fat reduction. Valid and reliable staging algorithms are available for fruit and vegetable consumption and dietary fat intake, and are being developed for other dietary behaviours. Few assessment tools have been developed for other TTM constructs. Given the popularity of TTM-based assessments and interventions, more research is warranted to identify valid and reliable assessment tools and effective interventions. While the evidence supports the validity of the TTM to describe populations and to form interventions, evidence of the effectiveness of TTM-based interventions is not conclusive.

Diet is an important factor in the causation of cancer. Previous systematic reviews of one-to-one interventions to encourage dietary change have found that such interventions can achieve modest improvements in diet. However, such interventions are resource intensive and unlikely to be good value for money at a population level. Interventions that address groups, communities or whole populations may be less resource intensive and effect change in a wider population. We report a systematic review of such interventions. We set wide inclusion criteria, including before-and-after studies and studies with a non-randomized comparison group as well as randomized trials. We found eighteen studies based in the community, seventeen based on worksites, five based in churches and one based in a supermarket. Interventions which targeted fruit and vegetable intake were most likely to be successful, particularly in worksites and churches. There was also evidence of small positive effects on reducing fat intake in worksites and churches. Overall the community-based interventions showed little effect. The studies included in the present review were generally poorly reported. Dietary changes are reported in the relatively short-term studies reviewed here but may not be sustained in the long term. The effects that we have identified are small but the reach is potentially very wide, in some cases as wide as a whole country. The cost effectiveness of such strategies remains to be evaluated.

Each year, millions of dogs worldwide are abandoned by their owners, relinquished to animal shelters, and euthanised because of behaviour problems. Nutrition is rarely considered as one of the possible contributing factors of problem behaviour. This contribution presents an overview of current knowledge on the influence of nutrition on canine behaviour and explores the underlying mechanisms by which diet may affect behaviour in animals. Behaviour is regulated by neurotransmitters and hormones, and changes in the availability of their precursors may influence behaviour. Tryptophan, the precursor of serotonin, may affect the incidence of aggression, self-mutilation and stress resistance. The latter may also be influenced by dietary tyrosine, a precursor to catecholamines. As diet composition, nutrient availability and nutrient interactions affect the availability of these precursors in the brain, behaviour or stress resistance may be affected. PUFA, especially DHA, have an important role as structural constituents in brain development, and dietary supply of n-3 and n-6 PUFA could modify aspects of the dopaminergic and serotonergic system and, consequently, cognitive performance and behaviour. Finally, persistent feeding motivation between meals can increase stereotyped behaviour and aggression and decrease resting time. This feeding motivation may be altered by dietary fibre content and source. At present, few studies have been conducted to evaluate the role of nutrition in canine (problem) behaviour through the above mentioned mechanisms. Studies that explore this relationship may help to improve the welfare of dogs and their owners.

Several studies have shown beneficial associations between tea consumption and bone mineral density (BMD) and fracture risk. Current investigations into potential mechanisms of benefit are focused upon the F and polyphenol components of tea. However, previous studies have pointed towards caffeine consumption as a potential risk factor for low BMD and high fracture risk. Tea, therefore, represents an interesting paradox as a mildly caffeinated beverage that may enhance bone health. Fruit and vegetable intake has also been associated with BMD, and it is now apparent that several fruit and vegetable components, including polyphenols, may contribute positively to bone health. Evidence surrounding the function(s) of polyphenol-rich foods in bone health is examined, along with more recent studies challenging the relevance of caffeine consumption to in vivo Ca balance. Plant foods rich in polyphenols such as tea, fruit and vegetables, as significant factors in a healthy diet and lifestyle, may have positive roles in bone health, and the negative role of caffeine may have been overestimated. The present review covers evidence of dietary mediation in positive and negative aspects of bone health, in particular the roles of tea, fruit and vegetables, and of caffeine, flavonoids and polyphenols as components of these foods. Since the deleterious effects of caffeine appear to have been overstated, especially in respect of the positive effects of flavonoids, it is concluded that a reassessment of the role of caffeinated beverages may be necessary.

The present review investigates the role of sleep and its alteration in triggering metabolic disorders. The reduction of the amount of time sleeping has become an endemic condition in modern society and the current literature has found important associations between sleep loss and alterations in nutritional and metabolic aspects. Studies suggest that individuals who sleep less have a higher probability of becoming obese. It can be related to the increase of ghrelin and decrease of leptin levels, generating an increase of appetite and hunger. Sleep loss has been closely associated with problems in glucose metabolism and a higher risk for the development of insulin resistance and diabetes, and this disturbance may reflect decreased efficacy of the negative-feedback regulation of the hypothalamic–pituitary–adrenal axis. The period of sleep is also associated with an increase of blood lipid concentrations, which can be intensified under conditions of reduced sleep time, leading to disorders in fat metabolism. Based on a review of the literature, we conclude that sleep loss represents an important risk factor for weight gain, insulin resistance, type 2 diabetes and dyslipidaemia. Therefore, an adequate sleep pattern is fundamental for the nutritional balance of the body and should be encouraged by professionals in the area.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3), the active form of vitamin D3, is a central player in Ca and bone metabolism. More recently, important immunomodulatory effects have been attributed to this hormone. By binding to its receptor, the vitamin D receptor, 1,25(OH)2D3 regulates the expression of various genes and consequently affects the behaviour of different cell types within the immune system. 1,25(OH)2D3 can potently inhibit pathogenic T cells and gives rise to elevated numbers of regulatory T cells via the induction of tolerogenic dendritic cells. These immunomodulatory activities of 1,25(OH)2D3 have also been proven useful in vivo: administration of 1,25(OH)2D3 in several animal models can prevent or cure different autoimmune diseases and graft rejection. To overcome the dose-limiting side effects of 1,25(OH)2D3 on Ca and bone, less calcaemic structural analogues (alone or in combination with synergistically acting drugs or bone-resorption inhibitors) have been successfully used in animal models. Furthermore, as 1,25(OH)2D3 also contributes to host defence against infectious agents by the induction of antimicrobial responses, this molecule might provide a new strategy to deal with drug-resistant infections. According to the pleiotropic effects of 1,25(OH)2D3 in the immune system, increasing epidemiological data underline the importance of adequate vitamin D intakes in reducing the risk of several autoimmune diseases and infections such as tuberculosis.