Socioeconomic status and dietary sodium intake in children from 2008 to 2019 in the UK

Background: Little is known whether children's sodium intake is affected by the national salt reduction programme in the United Kingdom (UK), particularly in relation to socioeconomic groups. We aimed to assess the trend of sodium intake among children from different socioeconomic backgrounds in the UK, from 2008-2009 to 2018-2019.

Methods: Repeated cross-sectional analyses of data from the National Diet and Nutrition Survey in children aged 4-18 years. Sodium intake was estimated from a 4-day dietary record in years 2008-2009 to 2018-2019 and 24-h urine collection (2008-2009 to 2011-2012 only). Socioeconomic status was based on parental occupation and equivalized household income.

Results: We included 6281 children (age 11.0 ± 4.3 years, 51.3% boys). In 2008-2009 to 2011-2012, the mean sodium intake was 2342.4 ± 60.0 mg/day as measured by 24-h urinary sodium excretion, and was 2053.1 ± 18.2 mg/day by dietary records. From 2008-2009 to 2018-2019, the sodium intake as assessed by dietary records decreased by 15, 9 and 12% in children from routine and manual occupation families, intermediate occupation families and higher managerial, administrative and professional occupation families, respectively. On the basis of dietary records, the sodium intake of children from families in routine and manual occupations was 109.6 ± 23.1 mg/day ( P < 0.001) higher than those from higher managerial, administrative and professional occupation families in 2008-2009 to 2011-2012. Sodium intake measured by 24-h urine collection during the same period also showed a difference between occupation groups, but it was not statistically significant. The occupational differences in sodium intake became smaller over time and were no longer significant in 2016-2017 to 2018-2019. Similar findings were found for household income.

Conclusion: Sodium intake as assessed by dietary records decreased over the 10-year period from 2008-2009 to 2018-2019 in children from all socioeconomic groups, particularly in those from lower socioeconomic backgrounds. These findings suggest that the national salt reduction programme could potentially help reduce health inequality related to sodium intake in children.