Elevated blood pressure at a young age is a predictor of blood pressure elevation later in life and has been associated with being overweight. However, it seems that there are other factors related to hypertension in childhood.

To determine the anthropometric, physical activity, and dietary factors associated with both systolic and diastolic hypertension in a group of Mexican school-aged children.

In this cross-sectional descriptive study, blood pressure, anthropometrics, physical activity, and dietary intake (assessed with a multiple-pass 24-hour dietary recall) evaluations were performed on school-aged children from September 2005 to July 2006.

Children aged 8 to 10 years (626 boys and 613 girls) from a convenience sample of 23 public schools of low socioeconomic status in Mexico City were included. Systolic and diastolic hypertension were defined as blood pressure ≥95th percentile for age, sex, and height, without diastolic or systolic prehypertension or hypertension, respectively. Mixed hypertension was defined as the presence of both systolic and diastolic hypertension.

Descriptive statistics, χ² tests, analysis of variance, post hoc analysis with Bonferroni method, and logistic regression analysis were performed. Continuous variables are presented as mean±standard deviation, categorical variables as percentages, and the association measures as adjusted odds ratios (ORs). A P value <0.05 was considered statistically significant, and 95% confidence intervals were calculated for adjusted ORs.

The dietary intake analysis showed that both boys and girls had low fiber intake (<25 g/day) as well as an excessive mean consumption of total and saturated fat (>35% and >10% of daily energy, respectively). From the total group of children, 3.6% had systolic hypertension, 14.2% diastolic hypertension, and 22.8% mixed hypertension. The higher values of weight, body mass index, waist circumference, and prevalence of overweight and obesity were more commonly seen among children with mixed hypertension, followed by children in the systolic group. Subjects with diastolic and mixed hypertension had an elevated intake of dietary total fat (37.7% and 38.2% of daily energy intake, respectively). Moreover, an adjusted OR of 1.06 (95% confidence interval 1.01 to 1.11) for systolic hypertension per increase of 1 cm in waist diameter was found and total fat intake >35% of the daily energy showed an adjusted OR of 2.61 (95% confidence interval 1.27 to 5.36) for diastolic hypertension.

In a sample of Mexican children of low socioeconomic status, the prevalence of hypertension was high. Waist circumference was the main factor associated with systolic hypertension, and higher intake of total fat was related to diastolic hypertension.