A systematic review 1 including 76 studies with more than 100 000 subjects was abstracted in DARE. Most good quality studies, which reported a dietary outcome measure, showed a benefit of intervention (15 studies out of 25). Long-term interventions in the population achieved reductions in dietary fat of 1 to 4% of energy intake. Blood cholesterol was measured in less than half of the studies.
The majority (7 out of 10) of good quality studies in the settings of schools, workplaces and primary care, showed a reduction in blood cholesterol ranging from 2 to 3% among adults in the general population and from 2 to 10% among children and adolescents.
The majority (5 out of 6) of good quality studies of community-based interventions showed no effect on blood cholesterol. The greatest magnitude in change in diet was seen in studies with highly motivated volunteers in intensive programmes. A substantial number of studies showed no effect of the intervention on the main outcomes measured, compared with controls. This was seen particularly in the community setting, where a significant change in the intervention group was often equalled in the long term by a secular change in the control group. The majority of interventions in the supermarket and catering settings showed an effect on food purchases in the short term, i.e. while the intervention was in place. Passive manipulation of food composition decreased the fat content of catered meals. The characteristics of effective and less effective interventions were also reported.
The authors concluded that they found clear evidence from recent controlled studies that, despite difficulties inherent in achieving dietary change in the general population, healthy eating interventions were effective in a variety of settings and populations. They also remarked that the beneficial effect was shown by multiple outcomes: a reduction in blood cholesterol; a reduction in dietary fat intake, as measured by validated methods: and an increase in the purchase of healthy food items, as measured by sales data. The lack of data on cost-effectiveness hinders an objective comparison with other intervention strategies, e.g. high-risk populations or pharmaceutical treatments.
Primary/Secondary Keywords