For decades, the UK government has provided science-based recommendations and guidelines for healthy eating, but British diets still fall short of these recommendations. Understanding the population-level factors behind this shortfall is necessary so we can devise how the guidance can better serve public health.

A major influence on which foods people buy and their overall eating habits is the cost of food. Evidence has been mounting from research in the UK and other high-income countries that healthier foods and healthier diet patterns tend to cost more than less-healthy alternatives. For example, researchers have compared the retail costs of less and more healthy food groups. Or they have compared diets that differ in their nutritional quality, for example their vitamin and mineral content, or how well they align with certain healthy diet patterns. Despite this growing evidence base, there has been little empirical evidence to date to evaluate specifically whether diets that meet UK government dietary recommendations cost more than less-healthy diets.

Moreover, research on the cost of diets is not straightforward, because dietary data from national surveillance or epidemiological studies don’t usually include information on food prices or expenditures, and economic data on food spending are generally at the household-level, lacking information on food and drink actually consumed by individuals. So appropriate data have to be developed, linking information on prices or expenditures on food to dietary intake data coming from epidemiological studies or national surveillance.

A new study from CEDAR and the MRC Epidemiology Unit, published in the journal Public Health Nutrition, tested whether diets achieving recommendations from the UK’s Scientific Advisory Committee on Nutrition (SACN) was associated with higher food costs in a nationally-representative sample of UK adults. This was a cross-sectional study linking four-day diet diaries in the National Diet and Nutrition Survey Rolling Programme (2008-2012) to a commercial food price database from a market research firm. The cost that the consumer would likely have to pay for their diet was assessed in relation to whether or not the diets met eight food and nutrient based recommendations from SACN: fruit and vegetables, oily fish, red and processed meat, fibre, fat, saturated fat, sugars and salt. The analysis adjusted for potential confounding factors.

This study found that diets meeting the recommendations for fruit and vegetables, oily fish, sugars, fat, saturated fat and salt were estimated to be between 3% and 17% more expensive. Diets meeting the recommendation for red and processed meats were 4% less expensive, whilst meeting the recommendation for fibre was cost-neutral. Meeting multiple recommendations was also associated with higher costs: on average, diets meeting six or more SACN recommendations were estimated to be 29% more costly than diets that met none of these recommendations.

This evidence means that the extra cost of meeting dietary recommendations may pose a population-level structural barrier to the adoption of healthy diets. Interventions at different levels and different stages of the entire food system will be needed to reduce the cost of healthier diets and provide strategies that enable people, especially those with limited resources, to eat healthfully.

• Paper: Meeting UK dietary recommendations is associated with higher estimated consumer food costs: an analysis using the National Diet and Nutrition Survey and consumer expenditure data, 2008–2012. Public Health Nutrition. Jones NRV, Tong TY, Monsivais P. December 2017 doi: 10.1017/S1368980017003275