Objective  To explore the relationship between dietary sodium (Na) and potassium (K) intake and non-alcoholic fatty liver disease (NAFLD) and to provide references for NAFLD prevention.

  Methods   We conducted a hospital-based case-control study among physical examinees aged 18 – 70 years during a period from April 2015 through August 2017. Using a self-designed questionnaire, we interviewed face-to-face a total of 541 cases (68.21% males and 31.79% females) diagnosed with NAFLD by abdominal ultrasonography at a physical examination center of Nanping City First Hospital and 541 gender- and age frequency-matched controls without NAFLD according to abdominal ultrasonography in the same setting.

  Results  The cases had a significantly lower dietary K intake compared to the controls (1 597.10 ± 686.25 vs. 1 638.96 ± 660.89 mg/d, t = – 3.929; P < 0.001) but the dietary Na intake was not significantly different between the cases and the controls (818.39 ± 417.60 vs.742.27 ± 407.08 mg/d, P > 0.05). The results of multivariate conditional logistic regression analysis demonstrated that (1) for the female participants, those with higher dietary Na intake were at a significantly decreased risk of NAFLD (the Na intake of the third Q3 to the highest quintile Q5 vs. the lowest quintile Q1: odds ratio OR = 0.42, 95% confidence interval 95% CI: 0.18 – 0.96; the fourth quintile Q4 to Q5 vs. Q1: OR = 0.28, 95% CI: 0.12 – 0.66) after adjusting for confounding factors such as age, education, occupation, family monthly income per capita, smoking, alcohol drinking, physical exercise time, history of chronic disease, and dietary intakes of energy and protein, cholesterol, fat, carbohydrate, calcium, iron, and potassium; (2) for all the participants, those with higher dietary K intake were at a significantly decreased risk of NAFLD (the K intake of the second quintile Q2 – Q5 vs. Q1: OR = 0.63, 95% CI: 0.43 – 0.94; Q3 – Q5 vs. Q1: OR = 0.45, 95% CI: 0.29 – 0.69; Q4 – Q5 vs. Q1: OR = 0.36, 95% CI: 0.22 – 0.58; Q5 vs. Q1: OR = 0.31, 95% CI: 0.16 – 0.58) after adjusting all confounding factors mentioned above except for adding gender and substituting potassium with sodium; (3) for the male participants, those with higher dietary K intake were at a significantly decreased risk of NAFLD (the dietary K intake of Q3 – Q5 vs. Q1: OR = 0.38, 95% CI: 0.23 – 0.65; Q4 – Q5 vs. Q1: OR = 0.30, 95% CI: 0.16 – 0.57; Q5 vs. Q1: OR = 0.30, 95% CI: 0.13 – 0.67) after adjusting all confounding factors mentioned above except for gender.

  Conclusion   Higher dietary potassium intake may be a protective factor against NAFLD for both Chinese men and women but higher dietary sodium intake may be a protective factor against NAFLD only for Chinese women.