Abstract P190: Associations of 24-h Urinary Sodium/potassium (Na/K) Ratio with Recommended Intakes of Na and K: The INTERMAP Study

Abstract

Background: High dietary sodium (Na), low dietary potassium (K) and high dietary sodium/potassium (Na/K) ratio are associated with adverse blood pressure levels and excess risks of cardiovascular diseases. 24-h urine collection is the gold standard for measuring dietary Na, K and Na/K ratio. Recommended levels of Na and K intakes are suggested in WHO guidelines; less than 85 mmol/day for Na; at least 90 mmol/day for K; there is no definitive guideline for Na/K ratio. Objective: Our primary aim was to compare the level of urinary Na/K ratio with the current recommended levels of Na and K intakes suggested in WHO guidelines. Methods: INTERMAP is an international study on associations of multiple dietary variables with blood pressure (BP), based on two timed 24-hr urine collections and dietary data from 4 in-depth 24-h dietary recalls in 4,680 men and women ages 40-59 years in China, Japan, United Kingdom and United States (US). Na/K ratio of 24-hr urine stratified in 1 unit intervals was compared with the current recommended levels of Na and K intakes suggested in WHO guidelines. Na intake was evaluated by urinary Na excretion; K intake by dietary K intake. Results: Thirty-one of the 4,680 INTERMAP participants (0.7%) had urinary Na/K ratio less than 1. The proportions of participants with Na excretion less than 2 g/day (85 mmol/day) among all 4,680 individuals were 77% (n=24), 19% (n=117), and 0.2% (n=11) in those with urinary Na/K ratio less than 1, 1 to 2, and more than 4, respectively. In US samples (n=2,195) the proportions were 88% (n=15), 19% (n=70), and 0.3% (n=6), respectively. The proportions of participants with dietary K intake more than 3.51 g/day (90 mmol/day) among all 4,680 individuals were 71% (n=22), 38% (n=233), and 2.4% (n=111) in those with urinary Na/K ratio less than 1, 1 to 2, and more than 4, respectively. In US samples the proportions were 59% (n=10), 38% (n=138), and 2.1% (n=47), respectively. Conclusions: WHO recommends Na intake less than 85 mmol/day, and K intake more than 90 mmol/day. Urinary Na/K ratio less than 1 is needed to ensure reasonable compliance with these recommendations. Currently, very few people satisfy urinary Na/K ratio less than 1, so population-wide efforts are needed to reduce salt (sodium chloride) and increase K intake.