Does a population-based multi-factorial lifestyle intervention increase social inequality in dietary habits? The Inter99 study

Abstract

ObjectiveTo investigate whether the effect of an individualised multi-factorial lifestyle intervention on dietary habits differs across socioeconomic groups. MethodsThe study was an individualised multi-factorial lifestyle intervention study with a control group, Inter99 (1999–2006), Copenhagen, Denmark. Participants in the intervention group (n=6 091) received lifestyle intervention during a five-year period. The control group (n=3 324) was followed by questionnaires. Multilevel regression analyses were used, including interaction term between intervention effect and socioeconomic position (SEP) and analysed separately for men and women. SEP was measured as length of education and employment status and dietary habits were measured by a validated food frequency questionnaire. ResultsMen with a short education improved their dietary habits more (net-change [95% confidence interval]) (0.25 points [−0.01;0.52]) than men with longer education (0.02 points [−0.09;0.14]), (interaction: p=0.02). Furthermore, unemployed women improved their dietary intake more (0.33 points [0.05;0.61]) than employed women (0.01 points [−0.10;0.11]), (interaction: p=0.03). Similar results were found for fruit intake, whereas no significant interactions were found for fish, fat and vegetable intake. ConclusionsIndividualised dietary interventions do not increase and may even decrease or hinder further widening of the social inequalities in health due to unhealthy dietary habits among socially disadvantaged individuals.