Globally, diet quality is poor, with populations failing to achieve national dietary guidelines. Such failure has been consistently linked with malnutrition and poorer health outcomes. In addition to the impact of diet on health outcomes, it is now accepted that what we eat, and the resulting food system, has significant environmental or planetary health impacts. Changes are required to our food systems to reduce these impacts and mitigate the impact of climate change on our food supply. Given the complexity of the interactions between climate change, food and health, and the different actors and drivers that influence these, a systems-thinking approach to capture such complexity is essential. Such an approach will help address the challenges set by the UN 2030 Agenda for sustainable development in the form of the sustainable development goals (SDG). Progress against SDG has been challenging, with an ultimate target of 2030. While the scientific uncertainties regarding diet and public and planetary health need to be addressed, equal attention needs to be paid to the structures and systems, as there is a need for multi-level, coherent and sustained structural interventions and policies across the full food system/supply chain to effect behaviour change. Such systems-level change must always keep nutritional status, including impact on micronutrient status, in mind. However, benefits to both population and environmental health could be expected from achieving dietary behaviour change towards more sustainable diets.

Non-communicable diseases (NCD) such as CVD and type 2 diabetes mellitus are major contributors to the burden of disease. NCD are largely driven by modifiable lifestyle factors including poor diet and insufficient physical activity, and consequently, prevention is a public health priority. Although diet and physical activity levels can be improved via lifestyle interventions, long-term adherence to such interventions remains low, which limits their effectiveness. Thus, it is critical to identify the underlying mechanisms that challenge uptake and adherence to such interventions. The current commentary discusses an important, but underexplored, psychological driver of poor adherence to lifestyle interventions, namely, future discounting, which describes the tendency to prefer smaller, short-term rewards over larger, long-term rewards. For example, in the nutrition domain, future discounting refers to valuing the immediate reward of excessive intake of energy-dense, nutrient-poor, discretionary foods high in salt, sugar, and saturated fat, and insufficient intake of low-energy, nutrient-dense, whole foods such as vegetables. Prominent theoretical models propose that excessive future discounting is a major contributor to the development of unhealthy lifestyle behaviours. Furthermore, a vast body of evidence suggests that future discounting plays a key role in risk of NCD. Thus, the evidence to date supports the idea that future discounting is an important multi-behaviour target for supporting lifestyle behaviour change; however, this approach has been largely neglected in preventive health efforts. Furthermore, this commentary discusses promising techniques (e.g. Episodic Future Thinking) for disrupting future discounting to promote improved adherence to lifestyle interventions aimed at reducing NCD risk.

A high intake of fruit and vegetables (FV) has consistently been associated with a reduced risk of a number of non-communicable diseases. This evidence base is largely from prospective cohort studies, with meta-analyses demonstrating an association between increased FV intake and reduced risk of both CHD and stroke, although the evidence is less certain for cancer and diabetes. Controlled intervention trials examining either clinical or intermediate risk factor endpoints are more scarce. Therefore, evidence that FV consumption reduces the risk of disease is so far largely confined to observational epidemiology, which is hampered by some methodological uncertainties. Although increased FV intake is promoted across all dietary guidelines, national surveys confirm that dietary intakes are suboptimal and are not increasing over time. A range of barriers to increasing FV intake exist, including economic, physical and behavioural barriers that must be considered when exploring potential opportunities to change this, considering the feasibility of different approaches to encourage increased FV consumption. Such interventions must include consideration of context, for example, challenges and uncertainties which exist with the whole food system.

Average diet quality is low in the UK and is socioeconomically patterned, contributing to the risk of non-communicable disease and poor health. Achieving meaningful dietary change in the long term is challenging, with intervention required on a number of different levels which reflect the multiple determinants of dietary choice. Dietary patterns have been identified which contribute positively to health outcomes; one of these is the Mediterranean diet (MD) which has been demonstrated to be associated with reduced non-communicable disease risk. Most research exploring the health benefits of the MD has been conducted in Mediterranean regions but, increasingly, research is also being conducted in non-Mediterranean regions. The MD is a dietary pattern that could have positive impacts on both health and environmental outcomes, while being palatable, appetising and acceptable. In this review, we consider the studies that have explored transferability of the MD. To achieve long-term dietary change towards a MD, it is likely that the dietary pattern will have to be culturally adapted, yet preserving the core health-promoting elements and nutritional composition, while considering the food system transition required to support changes at population level. Population-specific barriers need to be identified and ways sought to overcome these barriers, for example, key food availability and cost. This should follow a formal cultural adaptation framework. Such an approach is likely to enhance the extent of adherence in the longer term, thus having an impact on population health.