Highlighting the ratio of sodium to potassium in population-level dietary assessments: cross-sectional data from New York City, USA

Objective: To contrast mean values of Na:K with Na and K mean intakes by demographic factors, and to calculate the prevalence of New York City (NYC) adults meeting the WHO guideline for optimal Na:K (<1 mmol/mmol, i.e. <0.59 mg/mg) using 24 h urinary values. Design: Data were from the 2010 Community Health Survey Heart Follow-Up Study, a population-based, representative study including data from 24 h urine collections. Setting: Participants were interviewed using a dual-frame sample design consisting of random-digit dial telephone exchanges that cover NYC. Data were weighted to be representative of NYC adults as a whole. Subjects: The final sample of 1656 adults provided 24 h urine collections and self-reported health data. Results: Mean Na:K in NYC adults was 1.7 mg/mg. Elevated Na:K was observed in young, minority, low-education and high-poverty adults. Only 5.2 % of NYC adults had Na:K in the optimal range. Conclusions: Na intake is high and K intake is low in NYC adults, leading to high Na:K. Na:K is a useful marker and its inclusion for nutrition surveillance in populations, in addition to Na and K intakes, is indicated.