Variations in human DNA, most frequently single-nucleotide polymorphisms (SNPs), can have functional consequences ranging from severe to none. Variations in outcome (phenotype) can be compared, from cystic fibrosis through haemochromatosis to general familial risks in, for example, colo-rectal cancer (CRC). Cystic fibrosis and haemochromatosis have severe phenotypes with high penetrance, with signs and symptoms always or mostly present; thus, they have been easy to identify from family studies. However, the familial risks that are known to contribute markedly to CRC are unknown. The sequencing of the human genome has now made possible the identification of these and other disease variants. Knowing the DNA sequence in an idealised individual adds little unless variants that increase (or decrease) disease risk from the norm can be identified. Such variants can be expected to be very common in the general population, but have low penetrance and only change risk to a limited extent. Many patients will not have the risk variant and many ‘normal’ patients will have the risk variant. Thus, very large case–control cohorts are essential. These case–control cohorts can be analysed at three different levels: (1) individual SNPs; (2) individual genes; (3) genome-wide analysis (GWA). Level 1 looks for case–control differences for specific SNPs. Alternatively, new technology can be applied to examine a range of SNPs within a gene to track differences in its regulation as well as in function. Finally, the whole genome with ≥0·5×106 SNPs could be marked. The first two approaches involve selecting ‘candidate’ SNPs or genes, while GWA looks for any variation in the genome that is enriched in the cases. All three approaches carry the certainty that significant associations will be found by statistical chance, for which correction must be made. This latter issue is helped by large numbers and by independent replication cohorts.

Over the past 20 years major advances have been made in the diagnosis and understanding of pathogenic mechanisms relating to coeliac disease. Recently-identified genetic markers support the immunological–inflammatory nature of the disease. It is hoped that these newly-identified genes will assist further dissection of the inflammatory pathways in coeliac disease and give insight into why certain individuals develop intolerance to dietary gluten.

The exact aetiology of Crohn's disease remains unknown. The consensus is that the disease results from a complex interaction between genes, immunity and environmental factors. Diet is attractive, in theory, as an environmental risk factor in the aetiology of the disease. The epidemiological data, often impeded by methodological issues, have failed to confirm a direct link between pre-diet illness and the development of Crohn's disease. Once diagnosed, however, nutrition has an important role in disease management. Among the nutritional issues are malnutrition, weight loss and suboptimal nutritional status; these outcomes may be present at any stage of the disease but are likely to be overt during acute illness and hospitalisation. Malnutrition has been identified in approximately 40% of hospital admissions with Crohn's disease and is associated with higher mortality, longer hospital stays and higher healthcare costs. Patients in remission may indeed be overweight and appear to be influenced by the general population trends toward overweight and obesity. Irrespective of BMI, patients are at risk of micronutrient deficiencies. Vitamin D deficiency, for example, is common in Crohn's disease and has important implications for bone health. Moreover, newer evidence suggests that vitamin D has potential anti-inflammatory effects. Dietary approaches, in the form of enteral nutrition, have previously been shown to reduce inflammation and treat the active disease. Current guidelines now recommend that corticosteroids are more effective than enteral nutrition for treating adults. Enteral nutrition has important growth and developmental benefits and continues to be a recommended therapy for children with Crohn's disease.

A chronology of food scares combined with a rapid, unchecked, rise in lifestyle-related diseases such as obesity highlights the need for a focus on effective food risk communication. However, food risk communication is highly complex. Many factors will affect its success, including the demeanour and conduct of the source, its transparency, interaction with the public, acknowledgement of risks and timely disclosure. How the message is developed is also important in terms of language, style and pretesting with target audiences, as is the choice of appropriate channels for reaching target audiences. Finally, there are many personal factors that may affect risk perception such as previous experience, knowledge, attitudes and beliefs, personality, psychological factors and socio-demographic factors, many of which remain unexplored. While there is evidence that campaigns that communicate health risk have been associated with behaviour change in relation to major public health and safety issues in the past, it is unknown at this stage whether targeting risk information based on risk-perception segmentation can increase the effectiveness of the messages.

A decline in Zn status with ageing may contribute to the development of frailty, including impaired immune function, and increased incidence of age-related degenerative diseases. This decline may be a result of reduced dietary Zn intake and/or impaired Zn absorption in the gut. The Zn transporter ZnT5 may play a key role in the absorption of dietary Zn. The corresponding gene (SLC30A5) has a CpG island in its promoter region, so could be regulated by epigenetic mechanisms. It is hypothesised that methylation of the SLC30A5 promoter region is increased with age and that a resulting reduction in ZnT5 expression contributes to the decline in Zn status observed with ageing. This hypothesis has been addressed through (1) studies of effects of SLC30A5 promoter methylation on gene expression in vitro and (2) in vivo measurements of the DNA methylation status of this gene domain. It has been established in vitro that methylation of the human SLC30A5 promoter region results in reduced expression of an associated reporter gene. Second, this gene region shows variable levels of methylation in vivo. Correlation between the level of methylation at this locus and age would support the hypothesis that age-related hypermethylation of this region has the potential to modulate dietary Zn absorption. This premise is being investigated by analysis of additional samples from a human adult cohort to test the hypothesis that methylation of the SLC30A5 promoter region contributes to the age-related decline in Zn status.

The average UK adult consumes less than three portions of fruit and vegetables daily, despite evidence to suggest that consuming five portions daily could help prevent chronic diseases. It is recommended that fruit juice should only count as one of these portions, as juicing removes fibre and releases sugars. However, fruit juices contain beneficial compounds such as vitamin C and flavonoids and could be a useful source of dietary phytochemicals. Two randomised controlled cross-over intervention studies investigating the effects of chronic and acute consumption of commercially-available fruit- and vegetable-puree-based drinks (FVPD) on bioavailability, antioxidant status and CVD risk factors are described. Blood and urine samples were collected during both studies and vascular tone was measured using laser Doppler imaging. In the chronic intervention study FVPD consumption was found to significantly increase dietary carotenoids (P=0·001) and vitamin C (P=0·003). Plasma carotenoids were increased (P=0·001), but the increase in plasma vitamin C was not significant. There were no significant effects on oxidative stress, antioxidant status and other CVD risk factors. In the acute intervention study FVPD were found to increase total plasma nitrate and nitrite (P=0·001) and plasma vitamin C (P=0·002). There was no effect on plasma lipids or uric acid, but there was a lower glucose and insulin peak concentration after consumption of the FVPD compared with the sugar-matched control. There was a trend towards increased vasodilation following both chronic and acute FVPD consumption. All volunteers were retrospectively genotyped for the eNOS G298T polymorphism and the effect of genotype on the measurements is discussed. Overall, there was a non-significant trend towards increased endothelium-dependent vasodilation following both acute and chronic FVPD consumption. However, there was a significant time×treatment effect (P<0·05) of acute FVPD consumption in individuals with the GG variant of the eNOS gene.

Nutrigenetics and personalised nutrition are components of the concept that in the future genotyping will be used as a means of defining dietary recommendations to suit the individual. Over the last two decades there has been an explosion of research in this area, with often conflicting findings reported in the literature. Reviews of the literature in the area of apoE genotype and cardiovascular health, apoA5 genotype and postprandial lipaemia and perilipin and adiposity are used to demonstrate the complexities of genotype–phenotype associations and the aetiology of apparent between-study inconsistencies in the significance and size of effects. Furthermore, genetic research currently often takes a very reductionist approach, examining the interactions between individual genotypes and individual disease biomarkers and how they are modified by isolated dietary components or foods. Each individual possesses potentially hundreds of ‘at-risk’ gene variants and consumes a highly-complex diet. In order for nutrigenetics to become a useful public health tool, there is a great need to use mathematical and bioinformatic tools to develop strategies to examine the combined impact of multiple gene variants on a range of health outcomes and establish how these associations can be modified using combined dietary strategies.

The ability to not only replicate but also extend the findings from both historical epidemiological studies and contemporary cohorts of the developmental programming of later disease are critical if the mechanisms by which early diet impacts on later disease are to be fully understood. To date, a plethora of models have been established, with the range including global changes in dietary input, imbalanced diets and diets deficient in single nutrients. Key factors in translating these findings to the human situation are the pronounced differences in the relative growth and development between large and small mammals from the time of conception through pregnancy, lactation and weaning. This disparity is reflected in the very different nutritional requirements between species and the substantial divergence between rodents and large animals in the ontogeny of many of the organ systems that are nutritionally regulated. For example, hypothalamic circuitry is much more developed in species with a long gestation and offspring are born with a mature hypothalamic–pituitary axis in sheep and man compared with mice and rats. Similarly, nephron number is established towards the end of gestation in large mammals compared with the lactational period in rats. These types of differences will impact on the ability of individual and combined nutritional interventions to reset developmental processes, and may be further compounded by the gender of a fetus. The challenge for future work in this exciting and dynamic area of research is to utilise these marked comparative differences to generate imaginative nutritional interventions in order to improve the viability, health and well-being of the offspring.

The hypothesis that early-life growth patterns contribute to non-communicable diseases initially emerged from historical cohort studies, consistently associating low birth weight and infant weight gain with later disease risk. Cohort studies offer crucial life-course data on disease aetiology, but also suffer from important limitations, including the difficulty of adjusting for confounding factors and the challenge of interpreting data on early growth. Prospective randomised trials of infant diet appear to provide evidence in direct contradiction to cohort studies, associating faster early growth with disease risk. The present article attempts to resolve this contradiction on two grounds. First, insufficient attention has been directed to inconsistency of outcomes between cohort studies and prospective trials. Cohort studies can assess actual mortality, whereas prospective trials investigate proxies for disease risk. These proxies are often aspects of phenotype that reflect the ‘normalisation’ of metabolism in response to growth, and not all those displaying normalisation in adolescence and early adulthood may go on to develop disease. Second, a distinction is made between ‘metabolic capacity’, defined as organ development that occurs in early life, and ‘metabolic load’, which is imposed by subsequent growth. Disease risk is predicted to be greatest when there is extreme disparity between metabolic capacity and metabolic load. Whereas cohort studies link disease risk with poor metabolic capacity, prospective trials link it with increased metabolic load. Infancy is a developmental period in which nutrition can affect both metabolic capacity and metabolic load; this factor accounts for reported associations of both slow and fast infant growth with greater disease risk.

The diets of young women are important not just for their own health but also for the long-term health of their offspring. Unbalanced unvaried diets are more common amongst poor and disadvantaged women. If the diets of these women are to be improved, it is first necessary to understand why they make the food choices they do. Influences on women's food choices range from the global to the individual: environmental factors, such as difficulty in acquiring and affording good-quality healthy foods; social support and social relationships, such as those with parents, spouses and children; life transitions, such as leaving home, living with a partner or having children; individual factors, such as having low perceived control or self-efficacy in making food choices and placing a low value on health in general and on their own health in particular. These interrelated factors all influence food choice, suggesting that if the diets of disadvantaged women are to be improved, it will be necessary to do more than simply educate about the link between diet and health.

Observational evidence suggests that improving the diets of women of child-bearing age from disadvantaged backgrounds might be an important component of public health strategies aimed at reducing the burden of chronic disease in their offspring. The development of an intervention to improve the nutrition of young women needs to be informed by a systematic collation of evidence. Such a systematic collation of evidence from systematic reviews of interventions directed at changing health behaviours including diet, breast-feeding, physical activity and smoking has been conducted. Of 1847 potentially-relevant abstracts, fourteen systematic reviews met inclusion criteria. Four aspects of intervention design were identified that were effective at changing one or more of the health behaviours considered in the present review: the use of an educational component; provision of continued support after the initial intervention; family involvement; social support from peers or lay health workers. The findings of the present review suggest that interventions to change the health behaviour of women of child-bearing age from disadvantaged backgrounds will require an educational approach and should provide continued support after the initial intervention. Family involvement and social support from peers may also be important features of interventions that aim to improve diet.

Changing individuals' health behaviour seems to be the key to solving many of the world's health problems. Although there is a multitude of potential influences, many interventions to improve health seek to change intrinsic psychological determinants of health behaviour. To date, most attention has been paid to cognitions, such as attitudes and beliefs, and a number of social cognition models (SCM) are in current use. SCM all describe cognitions as determinants of behaviour, thereby implying that changes in cognitions will lead to changes in behaviour. Although SCM are widely used to predict a range of health behaviours, they are associated with a number of important limitations, including poor levels of predictive power, particularly in relation to eating behaviour, and limited guidance about the operationalisation of theoretical constructs. These limitations may explain why very few interventions to change behaviour are explicitly theory-based, despite the widely-held view that having a clear theoretical underpinning will improve effectiveness. Ultimately, advances in understanding and changing health behaviour will come about only if psychological theory and practice are integrated. The recently-published taxonomy of behaviour-change techniques used in interventions is a good example of integrated research, but more work of this type is essential and will require respectful collaboration between researchers and practitioners working from a range of different disciplines such as health psychology, public health nutrition and health promotion.

Diet-related sources of ill health, including Fe-deficiency anaemia, are prevalent in the local South Asian population. This population also has a high prevalence of low-birth-weight babies. A need for preventative measures that take a holistic view to dietary change was identified in a South Asian community in Southampton, UK. A peer-led approach was used, training and developing a local workforce to become community food assistants. This workforce, drawn from local black and minority ethnic communities, ran practical ‘hands-on’ culturally-appropriate food-related activities within their communities that were successful in achieving long-term change in the diets of local women and their families. This model has the potential for achieving sustained behaviour change and is able to engage key target groups that can often be difficult to reach through more traditional routes.

There are a range of government food policies at national and international level. Overall, their aims are diverse but all will have an impact on women and thus impact on the developmental origins of adult disease through their role as mothers of future generations. The present paper describes the approach of the Food Standards Agency to help consumers choose, cook and eat healthy safe food by influencing individuals, products and the food environment. Examples of activity at the national, local and international level are used to demonstrate this approach.

The present paper considers the need to move from a ‘health education’ approach to dietary health to an approach that focuses on food and nutrition policies at the population level, and especially those policies that avoid widening the inequalities in health between different socio-economic groups and those policies that promote healthy diets among children. Recent moves at the international level include measures to protect children from promotional marketing of fatty and sugary foods and the funding of free fruit for schoolchildren. By improving child health, improvements can be expected in the health of future generations.