Results of the CARDIA study suggest that higher dietary potassium may be kidney protective

The association between dietary sodium and potassium intake with the development of kidney disease remains unclear, particularly among younger individuals. Here, we determined whether dietary sodium and potassium intake are associated with incident chronic kidney disease (CKD) using data from 1,030 adults (age 23-35 in 1990-1991) from the Coronary Artery Risk Development In Young Adults study, based on repeated measurements of estimated glomerular filtration rate (eGFR) and urinary albumin to creatinine ratio (ACR) from 1995 through 2015. Urinary sodium and potassium excretion (mg/day), calculated from three 24-hour urine collections in 1990-1991, were averaged to measure sodium and potassium intake. Serum creatinine was used to calculate eGFR using the CKD EPI equation; spot urine albumin and creatinine were used to calculate ACR, each at five visits from 1995-1996 through 2015-2016. CKD was defined as decreased eGFR (under 60 ml/min/1.73m²) or the development of albuminuria (ACR over 30 mg/g). We used log binomial regression models adjusted for socio-demographic, behavioral, and clinical factors to determine whether sodium and potassium intake were associated with incident CKD (decreased eGFR or developed albuminuria) among those free of CKD in 1995. Dietary sodium intake was not significantly associated with incident CKD. However, every 1,000 mg/day increment of potassium intake in 1990 was significantly associated with a 29% lower risk of incident albuminuria (relative risk 0.71, 95% confidence interval 0.53, 0.95), but not eGFR. Thus, higher dietary potassium intake may protect against the development of kidney damage, particularly albuminuria.