The Eatwell Guide: Modelling the Health Implications of Incorporating New Sugar and Fibre Guidelines
Cobiac LJ, Scarborough P, Kaur A, Rayner M (2016) The Eatwell Guide: Modelling the Health Implications of Incorporating New Sugar and Fibre Guidelines. PLOS ONE 11(12): e0167859. http://journals.plos.org/plosone/article/citation?id=10.1371/journal.pone.0167859
This study sought to look at the implication of the updates to dietary recommendations (as illustrated in the Eatwell Guide) for the long-term health of the UK population.
The Eatwell Guide (Public Health England, 2016), is the UK policy tool used to define government recommendations on eating healthily and achieving a balanced diet. The previous model, the Eatwell Plate, was revised to incorporate the updated recommendations around increasing fibre and decreasing free sugars intake published in SACN’s 2015 Carbohydrates and Health report.
In an interesting related paper by the same research group (Scarborough et al. 2016), it was calculated that an optimal diet to meet new dietary recommendations compared to our current average diet (using baseline consumption data from National Diet and Nutrition Survey (NDNS) Years 1–4, 2008/09-2011/12), would require substantial changes in consumption patterns including:
Overall consumption of “potatoes, bread, rice, pasta and other starchy carbohydrates” and “fruit and vegetables” would need to increase by 69 % and 71 % respectively.
Consumption of “beans, pulses, fish, eggs, meat and other proteins”, “dairy and alternatives” and “foods high in fat and sugar” groups would need to decrease by 24 %, 29 % and 53 % respectively.
When looking at individual foods, the average amount of fruit juice consumed would need to halve, whereas average amounts of oily fish and pulses consumed would need to substantially increase.
The paper by Cobiac et al, the subject of this month’s research spotlight looks at the implications of such an optimal diet on the burden of type 2 diabetes, cardiovascular disease, cancer and mortality in the UK.
The aim of this study was to model the health impacts of dietary changes associated with the redevelopment of the UK food-based dietary guidelines (the ‘Eatwell Guide’) at the population level.
The authors used a new model, (PRIMEtime), to assess the impact on disease burden if all adults changed from consuming the current average UK diet, as described in the NDNS, to consuming a diet in line with the Eatwell Guide. The effects of previous dietary guidelines (those in place before the 2015 SACN Carbohydrates and Health report) on the same parameters were also modelled.
The model was based on various assumptions including that the population would change their diet immediately and that these changes would be sustained. The composition of the modelled diet was one which was minimally changed from the current UK diet but met all food and nutrient-based recommendations, with no increase in energy intake. Data relating to the impact of dietary changes on diet-related diseases such as cardiovascular disease, type 2 diabetes and cancers were derived from meta-analyses of epidemiological studies. Both the direct impact of diet on disease (e.g. fibre intake and colorectal cancer) and the impact via intermediate variables (blood pressure, cholesterol and body mass index) were considered. From this model, the authors determined change in life expectancy and disability-adjusted life years (DALYs- years lived by the population, adjusted for time spent in ill-health) that could be averted.
There are substantial health benefits to be gained if UK adults can change to a diet that meets recommended levels of foods and nutrients without increasing total energy intake. The model predicts that changing the average diet to that recommended in the new Eatwell Guide would:
Increase average life expectancy by 5.4 months for men and 4.0 months for women.
Avert 10.4 million and 7.4 million DALYS for men and women respectively.
In terms of DALYS averted, the Eatwell Guide diet was predicted to be more than twice as effective as the old dietary guidelines due to the stronger fibre and free sugars recommendations. Health improvements were greater for men than women as on average in the UK, women have better quality diets.
More specifically the authors reported their analysis suggested that Eatwell Guide recommendations would have the following effects over the next ten years:
440,000 fewer new cases of type 2 diabetes in men and 340,000 fewer cases in women.
170,000 fewer new cases of coronary heart disease in men and 94,000 fewer cases in women.
110,000 fewer new cases of colorectal cancer in men and 60,000 fewer cases in women.
80,000 fewer new cases of stroke in men and 84,000 fewer cases in women.
Smaller reductions in cases of lung, stomach, breast, pancreas, kidney and liver cancers and cirrhosis.
If dietary energy intake is constrained within the model to the average reported in the NDNS, the majority of the predicted health gains were attributable to reducing the consumption of red and processed meat and increasing intake of fibre and fruit and vegetables, with other dietary changes (free sugars, total cholesterol and sodium) having comparatively minor impact. When total energy of the diet was allowed to increase within the model, the changes in red and processed meats, fibre and fruits and vegetables were still responsible for the majority of health gains, but there was also a substantial health loss associated with the increase in energy intake.
Limitations of the analysis
Data on the current average UK diet from the NDNS, giving an average daily energy intake of 1711 kcal, was used to calculate the segment sizes of the Eatwell Guide and carry out the modelling in the current paper. While the NDNS is the most robust national dietary survey data available, this average energy intake is low compared to the estimated requirements of 2000 kcal for women and 2500 kcal for men. This is likely due to underreporting. As such, the outcomes predicted by the model may have been over or under estimated. However the authors felt that modelling to SACN energy recommendations (SACN, 2011), which would result in an increase in energy intake, is incompatible with UK Government aims to reduce obesity. Furthermore, some of the links between diet and disease remain equivocal and disease trends may change in the future, creating further uncertainty in the outcomes of the model.
Dietary changes required to meet recommendations in the Eatwell Guide are large but the potential population health benefits are substantial, particularly in preventing type 2 diabetes which is responsible for approximately 10 % of the NHS budget (Diabetes UK, 2014).
Wider research context
There is increasing recognition that healthy dietary patterns play an important role in disease prevention. Examination of the Global Burden of Disease study (Newton et al. 2015) enables us to assess the impact of specific risks on the overall disease burden in UK. The data shows us that, in general, behavioural risk factors make the greatest contribution to years lost to death and disability. In the UK it is estimated that unhealthy diet and tobacco are the two largest contributors with diet accounting for 10.8 % of total disease burden and tobacco 10.7 %. In the Global Burden of Disease study, dietary risk was an aggregate of dietary factors that included low consumption of fruit, vegetables, wholegrains, nuts, seeds, milk and seafood and high consumption of red and processed meat and sugars-sweetened beverages. In terms of nutrients there was a pattern of low intake of fibre, calcium, omega-3 fatty acids and polyunsaturated fatty acids and high intake of trans fatty acids and sodium.
At present the vast majority of the UK population is not meeting dietary recommendations. In the latest NDNS data for example, mean intake of fibre was around 19 g, less than two thirds of the recommended 30 g per day and only 27 % were eating 5 or more portions of fruit and vegetable a day.
This paper highlights the substantial impact of diet on human health and disease and the benefit of adjusting the diet to achieve dietary recommendations, particularly the higher fibre recommendations. However, this would require a significant change in consumer behaviour and a need for considerable support from all stakeholders.
The health gains that are likely to result from consuming a diet similar to the Eatwell Guide are undoubtedly significant but, further research is needed to identify interventions that will help people change their dietary choices.
Diabetes UK (2014) The cost of diabetes report. https://www.diabetes.org.uk/Documents/Diabetes%20UK%20Cost%20of%20Diabetes%20Report.pdf
Newton, John N., et al. "Changes in health in England, with analysis by English regions and areas of deprivation, 1990–2013: a systematic analysis for the Global Burden of Disease Study 2013." The Lancet 386.10010 (2015): 2257-2274.
Public Health England (2016) The Eatwell Guide booklet http://www.nhs.uk/Livewell/Goodfood/Documents/FINAL-Eatwell-Guide-booklet-with-image-pullout-2016.pdf
Scarborough, Peter, et al. "Eatwell Guide: modelling the dietary and cost implications of incorporating new sugar and fibre guidelines." BMJ open 6.12 (2016): e013182.
Scientific Advisory Committee on Nutrition (2011). “Dietary reference values for energy.” https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/339317/SACN_Dietary_Reference_Values_for_Energy.pdf
Scientific Advisory Committee on Nutrition (2015). "Carbohydrates and Health." https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/445503/SACN_Carbohydrates_and_Health.pdf