The relationship between nutrition and ageing is complex. The metabolism and synthesis of micronutrients within the gut microbiome can influence human health but is challenging to study. Furthermore, studying ageing in humans is time-consuming and difficult to control for environmental factors. Studies in model organisms can guide research efforts in this area. This review describes how the nematode Caenorhabditis elegans can be used to study how bacteria and diet influence ageing and inform follow-on studies in humans. It is known that certain bacteria accelerate ageing in C. elegans. This age-accelerating effect is prevented by inhibiting folate synthesis within the bacteria, and we propose that in the human microbiome, certain bacteria also accelerate ageing in a way that can be modulated by interfering with bacterial folate synthesis. Bacterial-derived folates do not promote ageing themselves; rather, ageing is accelerated by bacteria in some way, either through secondary metabolites or other bacterial activity, which is dependent on bacterial folate synthesis. In humans, it may be possible to inhibit bacterial folate synthesis in the human gut while maintaining healthy folate status in the body via food and supplementation. The supplement form of folic acid has a common breakdown product that can be used by bacteria to increase folate synthesis. Thus, supplementation with folic acid may not be good for health in certain circumstances such as in older people or those with an excess of proteobacteria in their microbiome. For these groups, alternative supplement strategies may be a safer way to ensure adequate folate levels.

Nutritional requirements of individuals vary across the lifecycle, according to activity, age and gender. To optimize human health, consideration of nutritional priorities at each stage is needed. This conference brought together multidisciplinary experts in maternal and child nutrition and health, cardiometabolic and plant-based nutrition and dietitians involved in the care of vulnerable populations, plus nutritional metabolism, health and ageing. The presentations highlighted the most important nutrition research in these areas, updating knowledge and suggesting how dietary advice and policy could be adapted to incorporate research findings. With the global increase in non-communicable disease (NCD) and nutrition being considered as a key modifiable risk factor for the prevention and management of NCD, this conference was much needed.

It is estimated that more than one-tenth of adults aged ≥60 years are now classified as having sarcopenic obesity (SO), a clinical condition characterised by the concurrent presence of sarcopenia (low muscle mass and weakness) and obesity (excessive fat mass). Independently, sarcopenia and obesity are associated with a high risk of numerous adverse health outcomes including CVD and neurological conditions (e.g. dementia), but SO may confer a greater risk, exceeding either condition alone. This imposes a substantial burden on individuals, healthcare systems and society. In recent years, an increasing number of observational studies have explored the association between SO and the risk of CVD; however, results are mixed. Moreover, the pathophysiology of SO is governed by a complex interplay of multiple mechanisms including insulin resistance, inflammation, oxidative stress, hormonal shifts and alteration of energy balance, which may also play a role in the occurrence of various CVD. Yet, the exact mechanisms underlying the pathological connection between these two complex conditions remain largely unexplored. The aim of this review is to examine the association between SO and CVD. Specifically, we seek to: (1) discuss the definition, epidemiology and diagnosis of SO; (2) reconcile previously inconsistent findings by synthesising evidence from longitudinal studies on the epidemiological link between SO and CVD and (3) discuss critical mechanisms that may elucidate the complex and potentially bidirectional relationships between SO and CVD.

In the UK, populations of Black African and Caribbean (BAC) ethnicity suffer higher rates of cardiometabolic disease than White Europeans (WE). Obesity, leading to increased visceral adipose tissue (VAT) and intrahepatic lipid (IHL), has long been associated with cardiometabolic risk, driving insulin resistance and defective fatty acid/lipoprotein metabolism. These defects are compounded by a state of chronic low-grade inflammation, driven by dysfunctional adipose tissue. Emerging evidence has highlighted associations between central complement system components and adipose tissue, fatty acid metabolism and inflammation; it may therefore sit at the intersection of various cardiometabolic disease risk factors. However, increasing evidence suggests an ethnic divergence in pathophysiology, whereby current theories fail to explain the high rates of cardiometabolic disease in BAC populations. Lower fasting and postprandial TAG has been reported in BAC, alongside lower VAT and IHL deposition, which are paradoxical to the high rates of cardiometabolic disease exhibited by this ethnic group. Furthermore, BAC have been shown to exhibit a more anti-inflammatory profile, with lower TNF-α and greater IL-10. In contrast, recent evidence has revealed greater complement activation in BAC compared to WE, suggesting its dysregulation may play a greater role in the high rates of cardiometabolic disease experienced by this population. This review outlines the current theories of how obesity is proposed to drive cardiometabolic disease, before discussing evidence for ethnic differences in disease pathophysiology between BAC and WE populations.

School food has a major influence on children’s diet quality and has the potential to reduce diet inequalities and non-communicable disease risk. Funded by the UK Prevention Research Partnership, we have established a UK school food system network. The overarching aim was to build a community to work towards a more health-promoting food and nutrition system in UK schools. The network has brought together a team from a range of disciplines, while the inclusion of non-academic users and other stakeholders, such as pupils and parents, has allowed the co-development of research priorities and questions. This network has used a combination of workshops, working groups and pump-priming projects to explore the school food system, as well as creating a systems map of the UK school food system and conducting network analysis of the newly established network. Through understanding the current food system and building network expertise, we hope to advance research and policy around food in schools. Further funding has been achieved based on these findings, working in partnership with policymakers and schools, while a Nutrition Society Special Interest Group has been established to ensure maximum engagement and future sustainability of the network. This review will describe the key findings and progress to date based on the work of the network, as well as a summary of the current literature, identification of knowledge gaps and areas of debate, according to key elements of the school food system.

The aim of this review is to provide an overview of dietary interventions delivered during pregnancy for the prevention of gestational diabetes mellitus (GDM). GDM increases the risk of adverse pregnancy and neonatal outcomes, and also increases future cardiometabolic risks for both the mother and the offspring. Carrying or gaining excessive weight during pregnancy increases the risk of developing GDM, and several clinical trials in women with overweight or obesity have tested whether interventions aimed at limiting gestational weight gain (GWG) could help prevent GDM. Most dietary interventions have provided general healthy eating guidelines, while some had a specific focus, such as low glycaemic index, increased fibre intake, reducing saturated fat or a Mediterranean-style diet. Although trials have generally been successful in attenuating GWG, the majority have been unable to reduce GDM risk, which suggests that limiting GWG may not be sufficient in itself to prevent GDM. The trials which have shown effectiveness in GDM prevention have included intensive face-to-face dietetic support, and/or provision of key foods to participants, but it is unclear whether these strategies could be delivered in routine practice. The mechanism behind the effectiveness of some interventions over others remains unclear. Dietary modifications from early stages of pregnancy seem to be key, but the optimum dietary composition is unknown. Future research should focus on designing acceptable and scalable dietary interventions to be tested early in pregnancy in women at risk of GDM.

Globally, we are currently facing a rapid demographic shift leading to an increase in the proportion of older adults within the population. This raises concerns about the potential increase in age-related diseases and their impact on our ability to provide adequate health and end-of-life care. To apply appropriate interventions, understanding the changes that happen with ageing becomes essential. Ageing is often accompanied by a decrease in appetite and physical activity, which may lead to malnutrition, resulting in decreased muscle mass, physical capabilities and independence. To preserve muscle mass, older adults are advised to increase protein intake and physical activity. However, protein’s high satiating effect may cause reduced energy intake. Physical activity is also advised to maintain or enhance older adult’s appetite. This review paper aims to discuss appetite-related changes that occur with ageing and their consequences. In particular, it will focus on investigating the relationship between protein intake and physical activity and their impact on appetite and energy intake in the ageing population. Recent studies suggest that physical activity might contribute to maintaining or enhancing appetite in older adults. Nevertheless, establishing a definitive consensus on the satiating effect of protein in ageing remains a work in progress, despite some promising results in the existing literature.

This review explores the evolution of dietary protein intake requirements and recommendations, with a focus on skeletal muscle remodelling to support healthy ageing based on presentations at the 2023 Nutrition Society summer conference. In this review, we describe the role of dietary protein for metabolic health and ageing muscle, explain the origins of protein and amino acid (AA) requirements and discuss current recommendations for dietary protein intake, which currently sits at about 0⋅8 g/kg/d. We also critique existing (e.g. nitrogen balance) and contemporary (e.g. indicator AA oxidation) methods to determine protein/AA intake requirements and suggest that existing methods may underestimate requirements, with more contemporary assessments indicating protein recommendations may need to be increased to >1⋅0 g/kg/d. One example of evolution in dietary protein guidance is the transition from protein requirements to recommendations. Hence, we discuss the refinement of protein/AA requirements for skeletal muscle maintenance with advanced age beyond simply the dose (e.g. source, type, quality, timing, pattern, nutrient co-ingestion) and explore the efficacy and sustainability of alternative protein sources beyond animal-based proteins to facilitate skeletal muscle remodelling in older age. We conclude that, whilst a growing body of research has demonstrated that animal-free protein sources can effectively stimulate and support muscle remodelling in a manner that is comparable to animal-based proteins, food systems need to sustainably provide a diversity of both plant and animal source foods, not least for their protein content but other vital nutrients. Finally, we propose some priority research directions for the field of protein nutrition and healthy ageing.

Folate, vitamin B12, vitamin B6 and riboflavin interact by functioning as cofactors within one-carbon metabolism (OCM), a network of interrelated cellular pathways essential for numerous biological processes, including the biosynthesis of DNA, amino acid interconversions and methylation reactions. The pathways of OCM are influenced by endocrine signals and genetic polymorphisms and are particularly responsive to relevant B-vitamin intakes. Physiological changes in healthy pregnancy, leading to a steady decline in B-vitamin status, add another layer of complexity to the regulation of OCM. Although significant advances have been made to improve our understanding of these pregnancy-related changes, no specific reference ranges yet exist for B-vitamin biomarkers in pregnancy to support normal fetal growth without depleting maternal stores. The lack of pregnancy-related criteria for adequacy of B-vitamin status is in turn a major limitation in identifying pregnant women most at risk of B-vitamin deficiency. Another challenge is that the evidence is very limited to provide a basis for establishing pregnancy-specific dietary recommendations for B-vitamins to support successful pregnancy outcomes. In terms of preventing adverse outcomes, periconceptional folic acid supplementation has a proven role, established more than 30 years ago, in protecting against neural tube defect-affected pregnancies and this has been the major focus of public health policy worldwide. This review evaluates the emerging evidence for the less well recognised role of B-vitamins in preventing hypertensive disorders in pregnancy and the intergenerational effects of B-vitamins on offspring neurodevelopment and cognitive performance during childhood. We also consider the underlying biological mechanisms.

This review will provide an overview of the immune system and then describe the effects of frailty, obesity, specific micronutrients and the gut microbiota on immunity and susceptibility to infection including data from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic where relevant. A key role for the immune system is providing host defence against pathogens. Impaired immunity predisposes to infections and to more severe infections and weakens the response to vaccination. A range of nutrients, including many micronutrients, play important roles in supporting the immune system to function. The immune system can decline in later life and this is exaggerated by frailty. The immune system is also weakened with obesity, generalised undernutrition and micronutrient deficiencies, which all result in increased susceptibility to infection. Findings obtained during the SARS-CoV-2 pandemic support what was already known about the effects of ageing, frailty and obesity on immunity and susceptibility to infection. Observational studies conducted during the pandemic also support previous findings that multiple micronutrients including vitamins C, D and E, zinc and selenium and long-chain n-3 fatty acids are important for immune health, but whether these nutrients can be used to treat those already with coronavirus disease discovered in 2019 (COVID-19), particularly if already hospitalised, is uncertain from current inconsistent or scant evidence. There is gut dysbiosis in patients with COVID-19 and studies with probiotics report clinical improvements in such patients. There is an inverse association between adherence to a healthy diet and risk of SARS-CoV-2 infection and hospitalisation with COVID-19 which is consistent with the effects of individual nutrients and other dietary components. Addressing frailty, obesity and micronutrient insufficiency will be important to reduce the burden of future pandemics and nutritional considerations need to be a central part of the approach to preventing infections, optimising vaccine responses and promoting recovery from infection.

Maintaining a healthy weight during pregnancy is critical for both women's and children's health. Excessive gestational weight gain (GWG) can lead to complications such as gestational diabetes, hypertension and caesarean delivery. Insufficient GWG can cause fetal growth restriction and increase infant mortality risk. Additionally, postpartum weight retention raises risk of obesity, type 2 diabetes and other chronic diseases for both mother and child. This review seeks to identify current obstacles in weight management research during and after pregnancy and explore evidence-based strategies to overcome them. Pregnancy offers a window of opportunity for health behaviour changes as women are more receptive to education and have regular contact with health services. Staying within Institute of Medicine's recommended GWG ranges is associated with better maternal and fetal outcomes. Systematic review evidence supports structured diet and physical activity pregnancy interventions, leading to reduced GWG and fewer complications. Health economic evaluation indicates significant returns from implementation, surpassing investment costs due to decreased perinatal morbidity and adverse events. However, the most effective way to implement interventions within routine antenatal care remains unclear. Challenges increase in the postpartum period due to competing demands on women physically, mentally and socially, hindering intervention reach and retention. Flexible, technology-supported interventions are needed, requiring frameworks such as penetration-implementation-participation-effectiveness and template-for-intervention-description-and-replication for successful implementation. Greater research efforts are necessary to inform practice and investigate fidelity aspects through pragmatic implementation trials during the pregnancy and postpartum periods. Understanding the best ways to deliver interventions will empower women to maintain a healthy weight during their reproductive years.

The dual burden of malnutrition is characterised by the coexistence of undernutrition alongside overweight/obesity and diet-related noncommunicable diseases. It is a paradox which disproportionately affects women and is applicable to those who become pregnant after weight loss surgery. Obesity before and during pregnancy is associated with increased risk of adverse perinatal outcomes in both mother and child. Overall lifestyle interventions targeting weight loss in the preconception period have not proven effective, with people, and women in particular, increasingly seeking weight loss surgery. In women with severe obesity, surgery may normalise hormonal abnormalities and improve fertility. In those who become pregnant after surgery, evidence suggests a better overall obstetric outcome compared to those with severe obesity managed conservatively; however, there is heightened risk of maternal nutritional deficiencies and infants born small for gestational age. Specifically, pregnancy soon after surgery, in the catabolic phase when rapid weight loss is occurring, has the potential for poor outcomes. Lifelong micronutrient supplementation is required, and there is considerable risk of malnutrition if nutritional aftercare guidelines are not adhered to. It is therefore recommended that pregnancy is delayed until a stable weight is achieved and is supported by individualised advice from a multidisciplinary team. Further research is required to better understand how weight loss surgery affects the chances of having a healthy pregnancy and to ultimately improve nutritional management and patient care. In this review, we aim to summarise the evidence and guidance around nutrition during pregnancy after weight loss surgery.

Sufficient sleep is necessary for optimal health, daytime performance and wellbeing and the amount required is age-dependent and decreases across the lifespan. Sleep duration is usually affected by age and several different cultural, social, psychological, behavioural, pathophysiological and environmental factors. This review considers how much sleep children and adults need, why this is important, what the consequences are of insufficient sleep and how we can improve sleep. A lack of the recommended amount of sleep for a given age group has been shown to be associated with detrimental effects on health including effects on metabolism, endocrine function, immune function and haemostatic pathways. Obesity has increased worldwide in the last few decades and the WHO has now declared it a global epidemic. A lack of sleep is associated with an increased risk of obesity in children and adults, which may lead to future poor health outcomes. Data from studies in both children and adults suggest that the relationship between sleep and obesity may be mediated by several different mechanisms including alterations in appetite and satiety, sleep timing, circadian rhythm and energy balance. Moreover, there is evidence to suggest that improvements in sleep, in both children and adults, can be beneficial for weight management and diet and certain foods might be important to promote sleep. In conclusion this review demonstrates that there is a wide body of evidence to suggest that sleep and obesity are causally related and recommends that further research is required to inform policy, and societal change.

This review aims to emphasise the impact of poor nutrition on children’s health and psychological well-being, urging those involved in childhood obesity or nutrition services to broaden their intervention approach. Poor nutrition and childhood obesity affect physical and psychological health. The stress of living with obesity further impacts quality of life, well-being and self-esteem. Children living with obesity may experience adverse childhood events and stress, and young people are able to recall the impact of psychosocial issues such as experiencing stigma and discrimination. Food is often a coping mechanism for managing negative emotions, perpetuating cycles of emotional coping and unhealthy eating behaviours. UK guidelines recommend family-based, multi-component weight management interventions for children living with obesity. Interventions mainly target health behaviours and utilise behaviour change techniques attempting to directly improve diet and physical activity as behavioural outcomes. Whilst these interventions may show some improvements in psychological well-being, there is limited consideration or understanding of the underlying mechanisms of action which indirectly influence engagement and the sustainability of the behaviour change. Lack of attention and inclusion of psychosocial variables in intervention implementation may help explain the variable effectiveness reported across childhood obesity interventions. In conclusion, enhancing the effectiveness of childhood obesity interventions requires a broader approach that fully incorporates psychosocial factors. Those responsible for commissioning, designing and implementing these interventions should adopt a holistic approach that addresses psychological and emotional needs while incorporating underlying mechanisms of action. This shift in focus could result in more sustainable and comprehensive treatment for childhood obesity.

The review aims to explore the potential benefit and risk of high-protein diets (HPD) regarding the comorbidity of sarcopoenia and CVD in the setting of cardiac rehabilitation (CR). CR is standard care for individuals who have experienced a cardiac event, but the current practice of predominantly aerobic exercise, a lower-fat diet and weight loss poorly addresses the issue of sarcopoenia. HPD, especially when combined with resistance exercise (RE), may be valuable adjuncts to current CR practice and benefit both muscle and cardiovascular health. Meta-analyses and randomised controlled trials of HPD and CVD risk show beneficial but variable effects regarding weight loss, the lipid profile, insulin resistance and lean body mass in those living with or high risk of CVD. Meta-analyses of prospective cohort studies on hard CVD endpoints favour lower- and plant-protein diets over higher animal protein, but the evidence is inconsistent. HPD augment the strength and muscle gaining benefits of RE in older populations, but there are no published data in those living with CVD providing promising opportunities for CR research. HPD raise concern regarding renal and bone health, the microbiome, branched chain amino acids and environmental sustainability and findings suggest that plant-based HPD may confer ecological and overall health advantages compared to animal-based HPD. However, incorporating RE with HPD might alleviate certain health risks. In conclusion, a largely plant-based HPD is deemed favourable for CR when combined with RE, but further research regarding efficacy and safety in CR populations is needed.

The aim of this review is to provide an overview of the history in support of the role of dietary saturated fatty acids (SFA) in the development of cardiovascular disease (CVD), and the controversy and consensus for the evidence in support of guidelines to remove and replace SFA with unsaturated fatty acids. The review will also examine the existence, origins, and implications for CVD risk of variability in serum LDL-cholesterol in response to these guidelines. While the quality of supporting evidence for the efficacy of restricting SFA on CVD risk has attracted controversy, this has helped to increase understanding of the inter-relationships between SFA, LDL-cholesterol and CVD, and reinforce confidence in this dietary recommendation. Nevertheless, there is significant inter-individual variation in serum LDL-C in response to this dietary change. The origins of this variation are multi-factorial and involve both dietary and metabolic traits. If serum biomarkers of more complex metabolic traits underlying LDL-responsiveness can be identified, this would have major implications for the targeting of these dietary guidelines to LDL-responders, to maximise the benefit to their cardiovascular health.

Plant-based substitutes (PBS) are seen as a convenient way to transition to a more plant-based diet, but their potential health benefits and nutritional concerns remain debated. Based on a review of the literature, it is concluded here that the primary risk of insufficient nutrient intake with PBS concerns iron and calcium, which are critical to the nutritional value of PBS. Other risks were identified but these would depend on the characteristics of the overall diet, as is the case for iodine in a diet containing no seafood or dairy, and vitamin B12 in a vegetarian/vegan diet. Conversely, the use of PBS is also expected to confer some benefits for long-term health because it would result in higher fibre intakes (in the case of meat PBS) and lower SFA intakes (but higher PUFA/MUFA intakes), but attention should be paid to a potential increase in sodium intake with PBS of meat products. In fact, a recurring finding in this review was that PBS is a very heterogeneous food category involving considerable variations in ingredient and nutrient composition, and whose design could be improved in order to foster nutritional and health benefits. The latter also depend on the animal food that is being replaced and are only deemed likely when PBS replace red meat. The fortification of PBS with key nutrients such as iron and calcium may constitute an actionable public health solution to further shift the balance in favour of PBS in the context of the current dietary transition in western countries.