Multimorbidity, the existence of two or more concurrent chronic conditions in a single individual, represents a major global health challenge. The Nutrition Society’s 2023 Winter Conference at the Royal Society, London focused on the topic of ‘Diet and lifestyle strategies for prevention and management of multimorbidity’, with symposia designed to explore pathways for prevention of multimorbidity across the lifecourse, the role of ageing, the gut-brain-heart connection and lifestyle strategies for prevention and management of multimorbidity. It also considered machine learning and precision nutrition approaches for addressing research challenges in multimorbidity. The opening plenary lecture discussed advancing diet and lifestyle research to address the increasing burden and complexity of multimorbidity. The two-day programme concluded with a plenary which addressed the key dietary risk factors and policies in multimorbidity prevention.

Oral health is a critical component of overall health and well-being, not just the absence of disease. The objective of this review paper is to describe relationships among diet, nutrition and oral and systemic diseases that contribute to multimorbidity. Diet- and nutrient-related risk factors for oral diseases include high intakes of free sugars, low intakes of fruits and vegetables and nutrient-poor diets which are similar to diet- and nutrient-related risk factors for systemic diseases. Oral diseases are chronic diseases. Once the disease process is initiated, it persists throughout the lifespan. Pain and tissue loss from oral disease leads to oral dysfunction which contributes to impaired biting, chewing, oral motility and swallowing. Oral dysfunction makes it difficult to eat nutrient-dense whole grains, fruits and vegetables associated with a healthy diet. Early childhood caries (ECC) associated with frequent intake of free sugars is one of the first manifestations of oral disease. The presence of ECC is our ‘canary in the coal mine’ for diet-related chronic diseases. The dietary sugars causing ECC are not complementary to an Eatwell Guide compliant diet, but rather consistent with a diet high in energy-dense, nutrient-poor foods – typically ultra-processed in nature. This diet generally deteriorates throughout childhood, adolescence and adulthood increasing the risk of diet-related chronic diseases. Recognition of ECC is an opportunity to intervene and disrupt the pathway to multimorbidities. Disruption of this pathway will reduce the risk of multimorbidities and enable individuals to fully engage in society throughout the lifespan.

In 2023, the UK government announced a Major Conditions Strategy, publishing ‘The case for change and our strategic framework’, which set out the focus on cancers, diabetes, dementia, mental ill health, musculoskeletal disorders, CVD and chronic respiratory diseases. Together, these conditions account for 60% of total disability-adjusted life years lost to early death or ill health in England, and one in four adults has at least two (multimorbidity). This review considers some of the key dietary risks for these major conditions and population policies that may improve diets and reduce risks. UK Government dietary recommendations, based on independent risk assessment and advice from the Scientific Advisory Committee on Nutrition, are encapsulated in the national food model, the Eatwell Guide. Based on key sources of dietary data – chiefly consumption data from the National Diet and Nutrition Survey and consumer purchase data from Kantar – most people do not meet dietary recommendations. This review considers how science and evidence inform health improvement policy. This includes policies that encourage healthier food choices, such as labelling and public procurement standards to those that minimise the impact of the less healthy choice such as sugar and salt reduction and reformulation. The review also considers nutritional approaches to managing some non-communicable diseases. Given the role nutrition and excess weight play in the onset, prognosis and quality of life for those living with one or more of the major conditions, there are huge potential gains from even small dietary improvements across population groups.

Musculoskeletal disorders and age-related musculoskeletal decline are major contributors to the burden of ill health seen in older subjects. Despite this increased burden, these chronic disorders of old age receive a relatively small proportion of national research funds. Much has been learned about fundamental processes involved in ageing from basic science research and this is leading to identification of key pathways that mediate ageing which may help the search for interventions to reduce age-related musculoskeletal decline. This short review will focus on the role of reactive oxygen species in age-related skeletal muscle decline and on the implications of this work for potential nutritional interventions in sarcopenia. The key physiological role of reactive oxygen species is now known to be in mediating redox signalling in muscle and other tissues and ageing leads to disruption of such pathways. In muscle, this is reflected in an age-related attenuation of specific adaptations and responses to contractile activity that impacts the ability of skeletal muscle from ageing individuals to respond to exercise. These pathways provides potential targets for identification of logical interventions that may help maintain muscle mass and function during ageing.

There are many health and nutrition implications of suffering from multimorbidity, which is a huge challenge facing health and social services. This review focuses on malnutrition, one of the nutritional consequences of multimorbidity. Malnutrition can result from the impact of chronic conditions and their management (polypharmacy) on appetite and nutritional intake, leading to an inability to meet nutritional requirements from food. Malnutrition (undernutrition) is prevalent in primary care and costly, the main cause being disease, accentuated by multiple morbidities. Most of the costs arise from the deleterious effects of malnutrition on individual’s function, clinical outcome and recovery leading to a substantially greater burden on treatment and health care resources, costing at least £19·6 billion in England. Routine identification of malnutrition with screening should be part of the management of multimorbidity together with practical, effective ways of treating malnutrition that overcome anorexia where relevant. Nutritional interventions that improve nutritional intake have been shown to significantly reduce mortality in individuals with multimorbidities. In addition to food-based interventions, a more ‘medicalised’ dietary approach using liquid oral nutritional supplements (ONS) can be effective. ONS typically have little impact on appetite, effectively improve energy, protein and micronutrient intakes and may significantly improve functional measures. Reduced treatment burden can result from effective nutritional intervention with improved clinical outcomes (fewer infections, wounds), reducing health care use and costs. With the right investment in nutrition and dietetic resources, appropriate nutritional management plans can be put in place to optimally support the multimorbid patient benefitting the individual and the wider society.

Loss of skeletal muscle strength and mass (sarcopenia) is common in older adults and associated with an increased risk of disability, frailty and premature death. Finding cost-effective prevention and treatment strategies for sarcopenia for the growing ageing population is therefore of great public health interest. Although nutrition is considered an important factor in the aetiology of sarcopenia, its potential for sarcopenia prevention and/or treatment is still being evaluated. Nutrition research for sarcopenia utilises three main approaches to understand muscle-nutrition relationships, evaluating: single nutrients, whole foods and whole diet effects – both alone or combined with exercise. Applying these approaches, we summarise recent evidence from qualitative and quantitative syntheses of findings from observational and intervention studies of healthy older adults, and those with sarcopenia. We consider protein supplements, whole foods (fruits and vegetables) and the Mediterranean diet as exemplars. There is some evidence of beneficial effects of protein supplementation ≥ 0·8 g/kg body weight/d on muscle mass when combined with exercise training in intervention studies of healthy and sarcopenic older adults. In contrast, evidence for effects on muscle function (strength and physical performance) is inconclusive. There is reasonably consistent epidemiological evidence suggesting benefits of higher fruits and vegetables consumption for better physical performance. Similarly, higher adherence to the Mediterranean diet is associated with beneficial effects on muscle function in observational studies. However, intervention studies are lacking. This review discusses how current evidence may inform the development of preventive and intervention strategies for optimal muscle ageing and nutritional public policy aimed at combatting sarcopenia.