Salt, fruit and vegetable consumption and blood pressure development: a longitudinal investigation in healthy children

Abstract

Low salt intake and high fruit and vegetable intake (FVI) have been shown to reduce blood pressure (BP) in adults. Longitudinal data on the independent effect of both FVI and salt intake on BP in healthy normotensive children are not available yet. In the present study, we aimed to characterise the concomitant influence of salt intake and FVI on BP development throughout childhood and adolescence. We examined 435 healthy subjects, for whom at least three repeated measurements of BP had been taken and who had provided 24 h urine samples and 3 d weighed dietary records between 4 and 18 years of age. BP was measured using a mercury sphygmomanometer (Mercuro 300, WelchAllyn) and salt intake was determined based on 24 h Na excretion. The intra-individual change in salt intake was almost significantly associated with the change in systolic BP (SBP, P= 0·06) and marginally (P= 0·09) with that in diastolic BP (DBP) in puberty, but not in pre-puberty. A 1 g/d increase in salt intake was associated with a 0·2 mmHg increase in SBP. In pre-puberty, but not in puberty, differences in FVI between children predicted between-person variations in SBP and DBP (P= 0·03). Corresponding findings were obtained for 24 h K excretion (a urinary indicator for FVI). A 100 g/d lower FVI was related to a 0·4 mmHg higher BP value. In conclusion, in healthy children and adolescents with BP in the low-normal range, both salt intake and FVI may already start to influence BP, although at a small magnitude. The potential importance of establishing healthy eating habits in childhood for later BP development emphasises the role of higher FVI and lower salt intake in the prevention of hypertension in the long run.