It is well known that food has a considerable environmental impact. Less attention has been given to mapping and analysing the emergence of policy responses. This paper contributes to that process. It summarises emerging policy development on nutrition and sustainability, and explores difficulties in their integration. The paper describes some policy thinking at national, European and international levels of governance. It points to the existence of particular policy hotspots such as meat and dairy, sustainable diets and waste. Understanding the environmental impact of food systems challenges nutrition science to draw upon traditions of thinking which have recently been fragmented. These perspectives (life sciences, social and environmental) are all required if policy engagement and clarification is to occur. Sustainability issues offer opportunities for nutrition science and scientists to play a more central role in the policy analysis of future food systems. The task of revising current nutrition policy advice to become sustainable diet advice needs to begin at national and international levels.

Lipids used in parenteral nutrition provide energy, building blocks and essential fatty acids. Traditionally, these lipids have been based on n-6 PUFA-rich vegetable oils particularly soyabean oil. This may not be optimal because soyabean oil may present an excessive supply of linoleic acid. Alternatives to use of soyabean oil include its partial replacement by medium-chain TAG, olive oil or fish oil, either alone or in combination. Lipid emulsions containing these alternatives are well tolerated without adverse effects in a wide range of hospitalised adult patients. Lipid emulsions that include fish oil have been used in parenteral nutrition in adult patients' post-surgery (mainly gastrointestinal). This has been associated with alterations in patterns of inflammatory mediators and in immune function and, in some studies, a reduction in length of intensive care unit and hospital stay. These benefits are emphasised through recent meta-analyses. Perioperative administration of fish oil may be superior to post-operative administration. Parenteral fish oil has been used in critically ill adults. Here, the influence on inflammatory processes, immune function and clinical endpoints is not clear, since there are too few studies and those that are available report contradictory findings. However, some studies found reduced inflammation, improved gas exchange and shorter length of hospital stay in critically ill patients if they receive fish oil. More and better trials are needed in patient groups in which parenteral nutrition is used and where fish oil may offer benefits.

This paper aims to describe different approaches for studying the overall diet with advantages and limitations. Studies of the overall diet have emerged because the relationship between dietary intake and health is very complex with all kinds of interactions. These cannot be captured well by studying single dietary components. Three main approaches to study the overall diet can be distinguished. The first method is researcher-defined scores or indices of diet quality. These are usually based on guidelines for a healthy diet or on diets known to be healthy. The second approach, using principal component or cluster analysis, is driven by the underlying dietary data. In principal component analysis, scales are derived based on the underlying relationships between food groups, whereas in cluster analysis, subgroups of the population are created with people that cluster together based on their dietary intake. A third approach includes methods that are driven by a combination of biological pathways and the underlying dietary data. Reduced rank regression defines linear combinations of food intakes that maximally explain nutrient intakes or intermediate markers of disease. Decision tree analysis identifies subgroups of a population whose members share dietary characteristics that influence (intermediate markers of) disease. It is concluded that all approaches have advantages and limitations and essentially answer different questions. The third approach is still more in an exploration phase, but seems to have great potential with complementary value. More insight into the utility of conducting studies on the overall diet can be gained if more attention is given to methodological issues.

The human diet has undergone profound changes over recent generations and this trend is likely to accelerate in the 21st century. Innovations in food technology, new ways of producing and processing foods and the increasing use of artificial vitamins and novel ingredients are changing the human diet in ways that our dietary monitoring systems struggle to keep pace with. There is a growing awareness of the importance of diet, but little understanding of how these changes may affect the health of current and future generations. Epigenetic programming, and specifically the persistence of functional epigenetic states following nutritional exposure, is particularly relevant to the issue of dietary change. Epigenetics is emerging as perhaps the most important mechanism through which diet and nutrition can directly influence the genome and there is now considerable evidence for nutritional epigenetic programming of health and the response to diet itself. A number of nutrients and food components that are changing in the human diet have been shown to produce epigenetic states that are stable across different timescales. We need to better understand the nutritional programming of epigenetic states, the persistence of these marks in time and their effect on biological function and the response to diet.

The concept of a healthy and environmentally sustainable diet is not new, but with increasing concern about future global food security and climate change there is a renewed interest in this topic. Dietary intakes in UK accounts for approximately 20–30% of total annual greenhouse gas emissions (GHGE), with the greatest contributions coming from high intakes of meat and dairy products. Dietary proposals to help mitigate climate change (i.e. reduce GHGE) have focused on reducing consumption of meat and dairy products, but this must be considered in the context of the whole diet, alongside any possible nutritional consequences for health. Bringing together health and environmental impact of the diet raises the question of whether a healthy diet can also be an environmentally sustainable diet. While recent research showed that it is possible to achieve a realistic diet that meets dietary requirement for health and has lower GHGE, it cannot be assumed that a healthy diet will always have lower GHGE. With different combinations of food it is possible to consume a diet that meets dietary requirements for health, but has high GHGE. It is important to understand what constitutes a sustainable diet, but this then needs to be communicated effectively to try and change well-established dietary intakes of the population. Studies show that understanding of sustainable diets is poor and there are many misconceptions (e.g. the overestimation of the protein requirements for a healthy diet), which could contribute to the barriers towards changing dietary intakes.

Food synergy is the concept that the non-random mixture of food constituents operates in concert for the life of the organism eaten and presumably for the life of the eater. Isolated nutrients have been extensively studied in well-designed, long-term, large randomised clinical trials, typically with null and sometimes with harmful effects. Therefore, although nutrient deficiency is a known phenomenon, serious for the sufferer, and curable by taking the isolated nutrient, the effect of isolated nutrients or other chemicals derived from food on chronic disease, when that chemical is not deficient, may not have the same beneficial effect. It appears that the focus on nutrients rather than foods is in many ways counterproductive. This observation is the basis for the argument that nutrition research should focus more strongly on foods and on dietary patterns. Unlike many dietary phenomena in nutritional epidemiology, diet pattern appears to be highly correlated over time within person. A consistent and robust conclusion is that certain types of beneficial diet patterns, notably described with words such as ‘Mediterranean’ and ‘prudent’, or adverse patterns, often described by the word ‘Western’, predict chronic disease. Food is much more complex than drugs, but essentially uninvestigated as food or pattern. The concept of food synergy leads to new thinking in nutrition science and can help to forge rational nutrition policy-making and to determine future nutrition research strategies.

Pharmaco-nutrients have beneficial effects on protective and immunological mechanisms in patients undergoing surgery, which are important for recovery after injury and in combating infectious agents. The aim of this review article was to outline the potential of the administration of nutritional substrates to surgical patients and the underlying mechanisms that make them particularly important in peri-operative care. Surgery causes a stress response, which has catabolic effects on the body's substrate stores. The amino acid glutamine is a stimulating agent for immune cells. It activates protective mechanisms through its role as a precursor for antioxidants and it improves the barrier function of the gut. Arginine also enhances the function of the immune system, since it is the substrate for T-lymphocytes. Furthermore, n-3 PUFA stabilise surgery-induced hyper-inflammation. Taurine is another substrate that may counteract the negative effects of surgical injury on acid–base balance and osmotic balance. These pharmaco-nutrients rapidly become deficient under the influence of surgical stress. Supplementation of these nutrients in surgical patients may restore their protective and immune-enhancing actions and improve clinical outcome. Moreover, pre-operative fasting is still common practice in the Western world, although fasting has a negative effect on the patient's condition and the recovery after surgery. This may be counteracted by a simple intervention such as administering a carbohydrate-rich supplement just before surgery. In conclusion, there are various nutritional substrates that may be of great value in improving the condition of the surgical patient, which may be beneficial for post-operative recovery.

The aim of this review is to summarise the evidence linking vitamin D to bone health outcomes in older adults. A plethora of scientific evidence globally suggests that large proportions of people have vitamin D deficiency and are not meeting recommended intakes. Older adults are at particular risk of the consequences of vitamin D deficiency owing to a combination of physiological and behavioural factors. Epidemiological studies show that low vitamin D status is associated with a variety of negative skeletal consequences in older adults including osteomalacia, reduced bone mineral density, impaired Ca absorption and secondary hyperparathyroidism. There seems to be inconsistent evidence for a protective role of vitamin D supplementation alone on bone mass. However, it is generally accepted that vitamin D (17·5 μg/d) in combination with Ca (1200 mg/d) reduces bone loss among older white subjects. Evidence for a benefit of vitamin D supplementation alone on reducing fracture risk is varied. According to a recent Agency for Healthcare Research and Quality review in the USA the evidence base shows mixed results for a beneficial effect of vitamin D on decreasing overall fracture risk. Limitations such as poor compliance with treatment, incomplete assessment of vitamin D status and large drop-out rates however, have been highlighted within some studies. In conclusion, it is generally accepted that vitamin D in combination with Ca reduces the risk of non-vertebral fractures particularly those in institutional care. The lack of data on vitamin D and bone health outcomes in certain population groups such as diverse racial groups warrants attention.

Technologic advances now make it possible to collect large amounts of genetic, epigenetic, metabolomic and gut microbiome data. These data have the potential to transform approaches towards nutrition counselling by allowing us to recognise and embrace the metabolic, physiologic and genetic differences among individuals. The ultimate goal is to be able to integrate these multi-dimensional data so as to characterise the health status and disease risk of an individual and to provide personalised recommendations to maximise health. To this end, accurate and predictive systems-based measures of health are needed that incorporate molecular signatures of genes, transcripts, proteins, metabolites and microbes. Although we are making progress within each of these omics arenas, we have yet to integrate effectively multiple sources of biologic data so as to provide comprehensive phenotypic profiles. Observational studies have provided some insights into associative interactions between genetic or phenotypic variation and diet and their impact on health; however, very few human experimental studies have addressed these relationships. Dietary interventions that test prescribed diets in well-characterised study populations and that monitor system-wide responses (ideally using several omics platforms) are needed to make correlation–causation connections and to characterise phenotypes under controlled conditions. Given the growth in our knowledge, there is the potential to develop personalised dietary recommendations. However, developing these recommendations assumes that an improved understanding of the phenotypic complexities of individuals and their responses to the complexities of their diets will lead to a sustainable, effective approach to promote health and prevent disease – therein lies our challenge.