Table 1.
Baseline characteristics of participants according to the quintiles of dietary sodium-to-potassium ratio among participants of NIPPON DATA80 (National Integrated Project for Prospective Observation of Non-communicable Disease And its Trends in the Aged) aged 30–79 years without antihypertensive treatment
| Q1 | Q2 | Q3 | Q4 | Q5 | p Value* | p Trend† | |
|---|---|---|---|---|---|---|---|
| Men | |||||||
| Sodium-to-potassium ratio (mol/mol) | 1.30 (0.18) | 1.64 (0.07) | 1.90 (0.08) | 2.19 (0.10) | 2.81 (0.49) | – | – |
| (Range) | (0.55) (1.51) | (1.51) (1.77) | (1.77) (2.03) | (2.04) (2.37) | (2.37) (6.13) | ||
| Number | 696 | 736 | 749 | 752 | 749 | ||
| Age (years) | 49.6 (12.5) | 48.4 (12.2) | 48.4 (12.1) | 48.4 (12.0) | 49.3 (12.7) | 0.178 | 0.724 |
| Sodium intake (mmol/day) | 179.4 (56.0) | 221.9 (52.7) | 252.2 (68.1) | 285.2 (70.3) | 356.8 (109.8) | <0.001 | <0.001 |
| (mg/day) | 4127 (1289) | 5103 (1211) | 5801 (1567) | 6559 (1617) | 8206 (2526) | – | – |
| Potassium intake (mmol/day) | 81.4 (22.6) | 79.7 (18.6) | 78.3 (20.7) | 76.8 (18.7) | 75.1 (20.1) | <0.001 | <0.001 |
| (mg/day) | 3174 (882) | 3109 (727) | 3054 (809) | 2996 (731) | 2928 (784) | – | – |
| Protein intake (energy per cent) | 14.9 (2.3) | 15.0 (2.0) | 15.0 (2.1) | 15.1 (1.9) | 15.2 (2.2) | <0.001 | <0.001 |
| Total fat intake (energy per cent) | 21.1 (5.1) | 20.6 (5.0) | 20.2 (5.2) | 20.2 (5.0) | 19.1 (5.5) | <0.001 | <0.001 |
| Systolic blood pressure (mm Hg) | 134.4 (18.6) | 135.0 (19.4) | 134.9 (19.3) | 136.5 (18.8) | 139.0 (20.8) | <0.001 | <0.001 |
| Diastolic blood pressure (mm Hg) | 82.2 (11.7) | 82.1 (12.4) | 82.5 (11.7) | 82.9 (12.0) | 83.4 (11.7) | 0.160 | 0.015 |
| Body mass index (kg/m2) | 22.5 (2.9) | 22.4 (2.8) | 22.6 (2.8) | 22.5 (2.8) | 25.1 (50.6) | 0.100 | 0.049 |
| Serum cholesterol (mg/dL) | 190.3 (32.8) | 184.7 (31.6) | 188.0 (33.0) | 184.9 (32.9) | 181.5 (32.7) | <0.001 | <0.001 |
| Serum creatinine (mg/dL) | 1.066 (0.389) | 1.050 (0.151) | 1.060 (0.290) | 1.038 (0.136) | 1.027 (0.182) | 0.021 | 0.003 |
| Regular drinking (%) | 43.1 | 47.5 | 48.8 | 51.3 | 50.5 | 0.041 | 0.010 |
| Current smoking (%) | 60.8 | 61.5 | 63.1 | 66.5 | 70.8 | <0.001 | <0.001 |
| Diabetes‡ (%) | 8.3 | 5.4 | 4.7 | 6.5 | 6.8 | 0.049 | 0.049 |
| Hypertension§ (%) | 43.2 | 40.2 | 45.3 | 45.7 | 48.6 | 0.020 | 0.004 |
| Women | |||||||
| Sodium-to-potassium ratio (mol/mol) | 1.22 (0.16) | 1.55 (0.07) | 1.80 (0.07) | 2.08 (0.09) | 2.65 (0.44) | – | – |
| (Range) | (0.59) (1.42) | (1.42) (1.67) | (1.67) (1.93) | (1.93) (2.25) | (2.25) (5.83) | ||
| Number | 885 | 916 | 936 | 932 | 932 | ||
| Age (years) | 50.2 (12.0) | 48.7 (11.8) | 48.2 (12.1) | 47.9 (12.3) | 49.0 (12.9) | 0.001 | 0.015 |
| Sodium intake (mmol/day) | 155.5 (44.7) | 190.9 (48.9) | 215.9 (59.6) | 247.2 (63.1) | 300.0 (91.7) | <0.001 | <0.001 |
| (mg/day) | 3575 (1027) | 4392 (1124) | 4966 (1372) | 5685 (1452) | 6900 (2110) | – | – |
| Potassium intake (mmol/day) | 75.2 (20.1) | 72.6 (18.2) | 70.9 (19.4) | 70.2 (17.9) | 67.1 (18.3) | <0.001 | <0.001 |
| (mg/day) | 2933 (784) | 2833 (710) | 2764 (757) | 2739 (699) | 2617 (712) | – | – |
| Protein intake (energy per cent) | 15.4 2.2 | 15.3 2.0 | 15.3 1.9 | 15.5 2.0 | 15.5 2.2 | <0.001 | <0.001 |
| Total fat intake (energy per cent) | 22.9 5.5 | 22.6 5.8 | 22.1 5.7 | 21.9 5.5 | 20.9 6.0 | <0.001 | <0.001 |
| Systolic blood pressure (mm Hg) | 131.7 (20.2) | 130.9 (19.5) | 129.5 (19.1) | 129.7 (18.0) | 131.3 (19.0) | 0.044 | 0.342 |
| Diastolic blood pressure (mm Hg) | 78.7 (11.4) | 78.6 (11.4) | 77.7 (11.0) | 78.1 (10.6) | 78.5 (11.2) | 0.196 | 0.453 |
| Body mass index (kg/m2) | 22.6 (3.4) | 22.7 (3.3) | 22.6 (3.2) | 22.7 (3.3) | 22.7 (3.2) | 0.932 | 0.572 |
| Serum cholesterol (mg/dL) | 195.5 (33.1) | 189.6 (34.1) | 188.8 (34.1) | 185.7 (32.0) | 184.9 (33.6) | <0.001 | <0.001 |
| Serum creatinine (mg/dL) | 0.847 (0.241) | 0.833 (0.123) | 0.832 (0.121) | 0.825 (0.115) | 0.829 (0.122) | 0.031 | 0.008 |
| Regular drinking (%) | 3.5 | 2.1 | 3.6 | 2.4 | 2.9 | 0.063 | 0.152 |
| Current smoking (%) | 9.0 | 8.1 | 8.7 | 8.4 | 10.2 | 0.535 | 0.545 |
| Diabetes‡ (%) | 4.3 | 3.8 | 3.5 | 2.9 | 4.5 | 0.388 | 0.376 |
| Hypertension§ (%) | 35.6 | 33.1 | 31.3 | 32.3 | 34.7 | 0.290 | 0.290 |
| Men and women combined | |||||||
| Sodium-to-potassium ratio (mol/mol) | 1.25 (0.17) | 1.59 (0.09) | 1.84 (0.09) | 2.13 (0.11) | 2.72 (0.47) | – | – |
| (Range) | (0.55) (1.51) | (1.42) (1.77) | (1.67) (2.03) | (1.93) (2.37) | (2.25) (6.13) | ||
| Number | 1581 | 1652 | 1685 | 1684 | 1681 | ||
| Age (years) | 49.9 (12.2) | 48.6 (12.0) | 48.3 (12.1) | 48.1 (12.2) | 49.1 (12.8) | <0.001 | 0.042 |
| Sodium intake (mmol/day) | 166.0 (51.3) | 204.7 (52.9) | 232.1 (66.1) | 264.2 (69.0) | 325.3 (104.1) | <0.001 | <0.001 |
| (mg/day) | 3818 (1181) | 4709 (1216) | 5337 (1519) | 6076 (1588) | 7482 (2394) | – | – |
| Potassium intake (mmol/day) | 77.9 (21.5) | 75.8 (18.7) | 74.2 (20.3) | 73.2 (18.6) | 70.7 (19.5) | <0.001 | <0.001 |
| (mg/day) | 3039 (837) | 2956 (730) | 2893 (793) | 2854 (725) | 2755 (761) | – | – |
| Protein intake (energy per cent) | 15.2 2.2 | 15.2 2.0 | 15.2 2.0 | 15.4 2.0 | 15.4 2.2 | <0.001 | <0.001 |
| Total fat intake (energy per cent) | 22.1 5.4 | 21.7 5.6 | 21.3 5.6 | 21.1 5.4 | 20.1 5.8 | <0.001 | <0.001 |
| Systolic blood pressure (mm Hg) | 132.9 (19.5) | 132.7 (19.5) | 131.9 (19.4) | 132.7 (18.7) | 134.8 (20.2) | 0.001 | 0.012 |
| Diastolic blood pressure (mm Hg) | 80.2 (11.6) | 80.2 (12.0) | 79.8 (11.5) | 80.2 (11.5) | 80.7 (11.7) | 0.248 | 0.241 |
| Body mass index (kg/m2) | 22.6 (3.2) | 22.6 (3.1) | 22.6 (3.0) | 22.6 (3.0) | 23.8 (33.8) | 0.100 | 0.042 |
| Serum cholesterol (mg/dL) | 193.3 (33.1) | 187.4 (33.1) | 188.4 (33.6) | 185.3 (32.4) | 183.4 (33.3) | <0.001 | <0.001 |
| Serum creatinine (mg/dL) | 0.944 (0.333) | 0.930 (0.174) | 0.933 (0.241) | 0.920 (0.163) | 0.917 (0.181) | 0.006 | 0.008 |
| Regular drinking (%) | 20.9 | 22.3 | 23.7 | 24.2 | 24.1 | 0.111 | 0.011 |
| Current smoking (%) | 30.0 | 30.2 | 31.0 | 32.9 | 35.0 | 0.008 | <0.001 |
| Diabetes‡ (%) | 11.3 | 10.7 | 9.4 | 9.3 | 11.8 | 0.057 | 0.852 |
| Hypertension§ (%) | 40.4 | 37.9 | 39.2 | 40.0 | 43.0 | 0.046 | 0.057 |
Values are means (SD), numbers or percentages.
*p Values obtained by analysis of variance for continuous values and by χ2 test for categorical values.
†p Trend was obtained by trend analysis for continuous variables, and χ2 test for trend for categorical variables.
‡History of diabetes and/or non-fasting blood glucose of 11.1 mmol/L or higher.
§Systolic blood pressure ≥140 mm Hg and/or diastolic blood pressure ≥90 mm Hg.