From the foregoing, we may conclude that much of the current health loss in the Netherlands is due to unfavourable dietary composition and overweight. In theory, this loss is also the gain that can be achieved through interventions addressing the five dietary factors and overweight (the ‘maximum’ scenario). However, experience shows that it would be unrealistic to expect that everyone would comply with the recommendations within the foreseeable future, even if substantial investments are made. Accordingly, a realistic ‘middle’ scenario has been produced, representing the health gain to be made by the interventions which are thought feasible, and which have proven themselves to be so during small-scale trials.
Table 2.7 presents selected key figures and figure 2.7 shows the results in terms of new cases of disease under the middle scenario, in a direct comparison with the maximum scenario. As may be seen from figure 2.7, the outcomes for the dietary factors in the middle scenario are some 1.5 to 2.5 times smaller than in the maximum scenario. In the case of overweight, the reduction is more than four times. In terms of deaths, the reductions are comparable (see tables in appendix 12). The reduction in cardiovascular diseases which could be achieved by addressing all dietary factors in combination is 13-14% in the middle scenario (compared to approximately 25% in the maximum sce- nario), with 5% to 6% only by increasing the consumption of fish. Interventions target- ing BMI would yield a 50% reduction in diabetes under the maximum scenario; in the middle scenario this figure falls to approximately 11%. Accordingly, the reduction in the total death rate which could be achieved through dietary interventions falls from
Figure 2.7: Calculated health gain for five dietary factors and overweight, by new cases of dis- ease (incidence), directly attributable on a one-year basis: the maximum scenario (in which everyone complies with the recommendations) compared to the middle scenario (interventions considered feasible). 0 5 10 15 20 25 30 35 40 45 incidence x 1,000
max= maximum scenario; mid = middle scenario
max mid max mid max mid max mid max mid max mid max mid
Diabetes Cardiovascular diseases Cancer saturated fatty acids trans fatty acids five dietary factors combined overweight fish fruit vegetables
10% in the maximum scenario to approximately 5% in the middle scenario, while that of interventions addressing overweight falls from 5% to 1%. It would seem that the health loss due to the current prevalence of overweight will be more difficult to ‘reclaim’ than that caused by dietary factors.
Overweight must be regarded as a special case, since in practice its prevalence is expected to increase while policy strives for a stabilization. However, it is reasonable to expect that the health gain to be achieved through the realistic scenario presented here (weight reduction of one BMI unit, being approximately three kilograms, rather than a stabilization), will be broadly equivalent to the health gain achieved by stabiliz- ing weight rather than allowing a further increase of one BMI unit.
In general, the same reductions in the effects (compared to the maximum scenario) are to be seen in the cumulative calculations over a 20-year period. While in the maximum scenario deaths attributable to the five dietary factors in combination fall by 5% and those attributable to BMI by 3%, the figures fall to approximately 2% and less than 1% in the middle scenario. Nevertheless, the 20-years model shows a 14% reduction in the inci- dence of diabetes and a 3% reduction in that of cardiovascular diseases (almost 140,000 cases each). For these and other figures, please refer to the tables in appendix 12. The effect in terms of life expectancy is also halved in the middle scenario, to 0.6 years in the case of dietary composition (all five factors in combination) and 0.3 years for BMI. Half of the additional life term will be spent in good health.
The current trends have not been taken into account in these middle scenarios. As previously stated, improvements can now be seen in the consumption of saturated and trans fatty acids and fish consumption, while the situation is worsening in terms of the consumption of fruit and vegetables and with respect to overweight. If these trends continue, it is reasonable to assume that the health gain calculated for the pos- itive trends (0.3 years additional life expectancy; see table 2.7) will indeed be achieved, but will be offset by negative developments (loss of 0.3 years due to inadequate con- sumption of fruit and vegetables and 0.3 years due to overweight, with some overlap rendering it inappropriate to add these figures together). If all other factors remain constant, life expectancy would then fall.
A recent study examining policy objectives with regard to overweight chose to adopt different scenarios to those used in this report (Bemelmans et al., 2004). However, insofar as the results are directly comparable, they present a consistent picture.
Conclusion: realistic health gain through dietary and body weight interventions
Taking all factors into account, we conclude that substantial health gains can be made through dietary interventions which are considered feasible. For example, there would be over 20,000 fewer cases of cardiovascular diseases each year. Similarly, inter- ventions addressing body weight would result in almost 5,000 fewer new cases of dia- betes each year and 4,000 fewer cases of cardiovascular disease. Seen over a longer
period, this would result in a limited gain in terms of mortality and life expectancy, due to the substitution effect of other causes of death. Of the possible dietary inter- ventions, those targeting consumption of fish and fruit will have the greatest effect. By means of the feasible interventions in these areas, approximately half of the health loss due to unfavourable dietary composition can be reversed (See section 4.2.1). The formulated BMI intervention will offset only a quarter of the health loss that would otherwise be experienced. Given the principles adopted, overweight is therefore likely to prove a more stubborn problem than a sub-optimal choice of food.