Background 

The goal of this systematic review was to determine whether sodium intake is associated with blood pressure in children from two to 18 years. In order to answer this question, the 2015 Dietary Guidelines Advisory Committee (DGAC) updated a systematic review done on this topic by the 2010 DGAC.

Conclusion statement

The 2015 DGAC concurs with the 2010 DGAC that “a moderate body of evidence has documented that as sodium intake decreases, so does blood pressure in children, birth to age 18 years.”

2015 DGAC Grade: Moderate

Methods 

To update the 2010 DGAC systematic review on this topic, literature searches were conducted using PubMed, Embase, Navigator (BIOSIS, CAB Abstracts and Food Science and Technology Abstracts) and Cochrane databases to identify studies that evaluated the association between sodium and blood pressure. Studies that met the following criteria were included in the review: randomized controlled trials (RCTs), non-randomized controlled trials, or prospective cohort studies; human subjects aged two years to 18 years who were healthy or at elevated chronic disease risk; subjects from countries with high or very high human development (2012 Human Development Index); and published in English in peer-reviewed journals. The date range was from January 2009 to January 2014, as the 2010 DGAC review include studies published between January 1970 and May 2009. The intervention or exposure was sodium intake, and the outcome was blood pressure.

Data from each included article were extracted, and risk of bias was assessed. The evidence was qualitatively synthesized, a conclusion statement was developed and the strength of the evidence (grade) was assessed using pre-established criteria including evaluation of the quality and risk of bias, quantity, consistency, magnitude of effect and generalizability of available evidence. The 2015 DGAC then considered the studies published since 2010 on sodium and blood pressure in children, and determined whether the 2010 DGAC Conclusion Statement or Grade needed to be modified.

Findings

• The 2010 DGAC conducted a systematic review to examine the relationship between sodium intake and blood pressure in children from birth to age 18 years, examining studies published from January 1970 to May 2009. That systematic review included 19 articles from 15 intervention studies and four prospective cohort studies
• The 2015 DGAC updated this systematic review and identified two additional articles published since May 2009, including one RCT and one prospective cohort study
• The 2015 DGAC considered the evidence reviewed by the 2010 DGAC related to dietary sodium intake and blood pressure in children, and determined that, based on the two new studies identified in the updated search, changes were not warranted to the conclusion statement or grade. In aggregate, the data reviewed by the 2010 DGAC indicated that sodium reduction modestly lowers BP in infants and children. Neither of the two studies identified in the update found a relationship between dietary sodium intake and blood pressure in healthy, normotensive children.

Limitations

The ability to draw strong conclusions was limited by the following issues: 

• A lack of rigorous intervention studies in children and adolescents, particularly controlled feeding studies that measure blood pressure multiple times over several days to account for variability in blood pressure and obtain measures of 24-hour urinary sodium excretion to determine levels of sodium before, during and after the intervention, rather than relying on estimates drawn from dietary intake assessment
• Studies are generally conducted in health children and adolescents with normal blood pressure, who are not likely to experience a benefit from sodium reduction.