Sodium Intake and Hypertension Risk in Children

Abstract

Yang Y, Zhang Z, et al. Sodium intake and blood pressure among US children and adolescents. Pediatrics. 2012; 130(4): 611-619; doi: 10.1542/peds.2011-3870Investigators from the Centers for Disease Control and Prevention utilized 2003 to 2008 data from the National Health and Nutrition Examination Survey (NHANES) to determine the association between dietary sodium intake and blood pressure in children aged 8 to 18 years. In addition, the investigators evaluated the joint effect of dietary sodium intake and weight on the risk for pre-hypertension (P-HTN) and hypertension (HTN). Dietary sodium intake was estimated from 24-hour dietary recalls that were adjusted to minimize measurement error. Patients were classified as having normal blood pressure, P-HTN or HTN based on the average of three blood pressure measurements. Overweight was defined as 85th to 95th BMI percentile and obese as >95th percentile. Other covariates accounted for were race and gender.A total of 6,235 children were included in the study, 49% of whom were female. The prevalence of overweight and obesity combined was 37% and the prevalence of P-HTN and HTN combined was 15%. Children consumed an average of 3,387 mg of sodium per day. Among all participants, the systolic blood pressure increased by approximately 1 mm Hg for every 1,000 mg per day of sodium intake (P = .037). Diastolic blood pressure was not associated with sodium intake. There was a nonsignificant trend for children in the highest quartile of sodium intake to be more likely to have P-HTN or HTN than children who were in the lowest quartile of sodium intake (adjusted odds ratio [aOR]=2.0; 95% CI, 0.95-4.10). Children in the highest quartile of sodium intake who were also overweight or obese were at higher risk (aOR=3.5; 95% CI, 1.34-9.20). The risk for P-HTN or HTN increased by 74% for every 1,000 mg/day increase in sodium among overweight or obese children but increased by only 6% among normal weight children.The authors conclude that sodium intake is associated with systolic blood pressure and risk of P-HTN or HTN in a nationally representative sample of US children. Furthermore, overweight and obese children with high sodium intake may have a higher risk for P-HTN/HTN compared to normal weight children.Elevated blood pressure in childhood is a risk factor for the development of HTN and cardiovascular disease in adulthood. The prevalence of HTN in children has increased in recent years due partly to obesity and other lifestyle factors such as physical inactivity and consumption of high-calorie and -sodium foods.1 In the current study, investigators were able to demonstrate that sodium intake was associated with systolic blood pressure and risk of P-HTN or HTN in children, which is consistent with previous studies in children and adults. A novel finding of the study is the joint synergy between sodium intake and weight, suggesting that high sodium intake in overweight/obese children may have a greater effect on risk for P-HTN or HTN than in normal weight children. The authors suggest that sodium sensitivity in obesity may be related to hyperinsulinemia, hyperaldosteronism, and activity of the sympathetic nervous system.The authors of this study also found that children in the United States consume roughly the same amount of sodium as the average adult, around 3400 mg/day. The 2010 Dietary Guidelines for Americans advise reducing daily sodium intake to less than 2,300 milligrams for most individuals aged 2 years and older, and cutting back to 1,500 milligrams for people aged ≥51 years and those of any age who are African American or have hypertension, diabetes, or chronic kidney disease.2 In 2008, Congress asked the Institute of Medicine to suggest strategies to reduce sodium consumption to the recommended allowance. The Institute of Medicine released a brief report in 2010 that recommended a coordinated effort by government agencies, health industry, consumer agencies, and the food industry to support FDA-set mandatory national standards for sodium content in foods by gradually reducing excess sodium in processed foods and menu items.3 Further interventions to prevent HTN should be aimed at reducing sodium intake, increasing physical activity, and maintaining a healthy weight for all children and adolescents.As noted over 2 years ago in these pages, current levels of dietary salt intake impose a costly public health burden (see AAP Grand Rounds, June 2010;23[6]:664). Isn't it time for pediatricians to inform their patients that salt – as well as calories – counts?