A 10-year longitudinal study on the associations between changes in plant-based diet indices, anthropometric parameters and blood lipids in a Flemish adult population

Aim Plant-based diets are recommended in the context of environmental sustainability and health. Since not all plant foods can be considered beneficial, a distinction needs to be made between healthful and unhealthful plant foods. The aim of this study was to investigate longitudinal associations between changes in an overall plant-based diet index, a healthful plant-based diet index and an unhealthful plant-based diet index, with changes in anthropometrics and blood lipids as indicators of morphological and metabolic fitness, respectively. Methods A 3-day dietary record was completed by 650 Flemish adults (420 men, 230 women) in 2002-2004 and 2012-2014. Three plant-based diet indices were calculated based on quintile scores regarding the intake of animal- or plant-based food items. Associations between 10-year changes in diet indices and changes in anthropometrics and blood lipids were tested using multivariate linear regression. Results Plant-based diet indices did not differ over time. Using the unadjusted model, few significant associations were found between changes in diet indices and changes in anthropometrics and blood lipids. However, these relationships disappeared after adjusting for confounding. In women, a positive association was found between changes in overall plant-based diet index and changes in body mass index in the adjusted model. Conclusions Index values did not differ over time and few longitudinal associations were found.