N° 89 | May 2014

Modelling the impact of specifi c food policy options on coronary heart disease and stroke deaths in Ireland

In Europe, cardiovascular disease (CVD) remains the main cause of premature deaths and disability. It is estimated that 80% of premature coronary heart disease (CHD) and stroke deaths can be prevented1. Ireland has seen significant declines in CHD death rates between 1985 and 2000 and more recently until 20062,3. Half of these reduced CHD deaths could be linked to improvements in population risk factors, mainly reductions in smoking, blood pressure and cholesterol levels. Two recent studies in the United Kingdom estimated that approximately 30,000–33,000 premature deaths every year could be averted if UK dietary recommendations were met4,5. Poor diet has been consistently linked with increased cardiovascular disease and cancer1,6. The evidence on salt and blood pressure, for instance, now overwhelmingly supports action to reduce population exposure to this dietary additive7.

It is estimated in the Irish population potential reductions in CHD and stroke mortality are achievable by specific and feasible decreases in consumption of:

  1. saturated fat,
  2. trans fat,
  3. salt; and
  4. increases in consumption of fruits and vegetables.

This study employed a previously validated CHD epidemiological model, the IMPACT model. Two scenarios were modelled: a conservative scenario and a substantial but politically feasible scenario.

The IMPACT model

This is a cell-based population model described in detail elsewhere2,3. Few assumptions were made in the modelling study. A sensitivity analyses was also conducted to estimate robust estimates with confi dence. The conceptual framework is based on a theoretical model relating the consumption of foods and nutrients to adverse health outcomes through biological risk factors for ill health – details of which are available elsewhere8.

The main outcomes of interest were CHD and stroke deaths in Ireland for the latest calendar year 2010 for which data were available. Age-specific and sex-specific aggregate data for both CHD and stroke deaths were obtained from the Central Statistics Offi ce of Ireland.

In the current model, available estimates were used of the direct association between the four food components and CHD and stroke deaths, similar to the recent UK studies4,5. For example, reducing daily salt intake by 5g would translate into approximately 17% and 23% fewer CHD and stroke deaths in a year, respectively9. Details of the two scenarios (modest versus feasible) and corresponding effect estimates based on meta-analyses from large cohort studies for each of the food components are available elsewhere8.

We estimated that there would be about 1,000 fewer premature deaths from coronary heart disease or stroke in Ireland if better food policy was followed

A total of 4,080 cardiovascular deaths (2,966 CHD deaths; 1,114 Strokes) were reported in the age group of 25–85 years in 2010 in Ireland.

It was estimated that modest changes in food policy could result in approximately 395 (minimum 315; maximum 475) fewer cardiovascular deaths per year, a 10% overall reduction in CVD mortality in Ireland. Approximately 28% of the 395 fewer CVD deaths could be attributable to 0.5% decreased trans fat energy consumption levels; 22–1.0% decreased saturated fat energy consumption levels; 23% to decreased aily salt intake by 1g; and 26% to one portion increased consumption of fruits and vegetables from the current consumption levels.

When this study modelled with more ambitious but feasible food policy options, it was found approximately 1,070 fewer CVD deaths could be prevented per year, representing an overall 26% reduction in annual CVD mortality in Ireland. As regards consumption of fatty acids, a 3% decrease in saturated fat energy consumption has the greatest potential impact on stroke deaths in both sexes, while a 1% decrease in trans fat energy consumption level has a relatively higher benefit on CHD deaths in both sexes. Reducing the average salt intake by 3 g/day would reduce CVD mortality by approximately 270 (minimum 220; maximum 325) deaths per year. Increasing fruits and vegetable portions to 3/day would result in the maximum health benefi ts—approximately 310 (minimum 250; maximum 370) fewer CVD deaths per year.

Conclusions

• Coronary heart disease (CHD) mortality in Ireland fell by more than 50% between 1985 and 2006.
• A further 26% overall decline in both CHD and stroke deaths per year could be achieved if more substantial but politically feasible food policy options were adopted in Ireland.
• A total of 1,070 fewer CHD and stroke deaths per year could occur in Ireland by achieving reductions in current dietary salt by 3g/day, trans fat by 1% of current energy intake and saturated fat by 3% of current energy intake and increasing fruit and vegetable intake by three portions/day.

Based on: O’Keeffe C, Kabir Z, O’Flaherty M, Walton J, Capewell S, Perry IJ. Modelling the impact of specifi c food policy options on coronary heart disease and stroke deaths in Ireland. BMJ Open
2013 Jul 3; 3 (7)

  1. WHO. World Health Organization diet, nutrition and the prevention of chronic diseases.Report of a Joint WHO/FAO Expert Consultation. WHO Technical Report Series no. 916.Geneva: WHO, 2003.
  2. Bennett K, Kabir Z, Unal B, et al. Explaining the decline in CHD mortality in Ireland 1985–2000. J Epidemiol Community Health 2006; 60: 322–7.
  3. Kabir Z, Perry IJ, Critchley J, et al. Modelling coronary heart disease mortality declines in the Republic of Ireland, 1985–2006. Int J Cardiol 2013
  4. ÓFlahery M, Flores-Mateo G, Ninoaham K, et al. Potential cardiovascular mortality reductions with stricter food policies in the United Kingdom of Great Britain and Northern Ireland. WHO Bull World Health Org 2012;90:522–31
  5. Scarborough P, Nnoaham KE, Clarke D, et al. Modelling the impact of a healthy diet on cardiovascular disease and cancer mortality. J Epidemiol Community Health2012;66:420–6
  6. American Institute for Cancer Research (AICR), World Cancer Research Fund. Food, nutrition, physical activity and the prevention of cancer: a global perspective. Washington, DC: AICR, 2007
  7. He FJ, MacGregor GA. A comprehensive review on salt and health and current experience of worldwide salt reduction programmes. J Hum Hypertens 2009;23:363–84
  8. O’Keeffe C, Kabir Z, O’Flaherty M, Walton J, Capewell S, Perry IJ. Modelling the impact of specific food policy options on coronary heart disease and stroke deaths in Ireland. BMJ Open 2013 Jul 3; 3 (7)
  9. Strazzullo P, D’Elia L, Kandala NB, et al. Salt intake, stroke, and cardiovascular disease: meta-analysis of prospective studies. BMJ 2009;339:b4567
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