TABLE 1.
Summary of experimental studies exploring the association between sodium to potassium ratio and blood pressure in adults, using 24-h urine collections1
| Reference, year, country, study type | Subjects (n, age, sex, BMI2, BP3) | Intervention | Urinary Na4 and K4 | Na:K ratio5 | Change SBP and DBP (mmHg) | Conclusions, quality rating6, and level of evidence (NHMRC)7 |
|---|---|---|---|---|---|---|
| Wing et al. (24) 1984USAQuasi-experiment | Total n = 41, HTWeight intervention: n = 19Age: 56.53 ± 6.08ySBP: 155.74 ± 14.40 mmHgDBP: 93.47 ± 6.28 mmHgNa:K intervention:n = 22Age: 52.77 ± 9.84ySBP: 147.00 ± 20.24 mmHgDBP: 93.59 ± 8.86 mmHg | Weight control:5% reduction in body weightNo change in Na, K, or Na:K ratioNa:K interventionDecrease Na intake <70 mEq/dayIncrease K intake >100 mEq/day | Urinary Na:Weight intervention:Pre: 147.75 ± 69.27 mEq/dayPost: 139.87 ± 107.62 mEq/dayChange: −7.88 mEq/day Na:K intervention:Pre: 168.87 ± 96.01 mEq/dayPost: 107.72 ± 48.09 mEq/dayChange: −61.15 mEq/dayUrinary K: | Weight intervention:- Pre: 2.61- Post: 2.69- Change: +0.08Na:K intervention:- Pre: 2.50- Post: 1.52- Change: −0.98 | SBP:Weight intervention: -13.94 mmHg***Na:K intervention:-6.20 mmHg** DBP:Weight intervention:-7.71 mmHg**Na:K intervention: -4.1 mmHg** | Weight reduction reduced BP more than dietary modification aimed to lower |
| Na/K ratioØ, II | ||||||
| Weight intervention: | ||||||
| Pre: 59.09 ± 17.61 mEq/day | ||||||
| Post: 52.49 ± 22.33 mEq/day | ||||||
| Change: -6.60 mEq/day | ||||||
| Na:K intervention: | ||||||
| Pre: 76.11 ± 32.69 mEq/day | ||||||
| Post: 82.34 ± 35.22 mEq/day | ||||||
| Change: +6.23 mEq/day | ||||||
| Lin et al. (25) 2012 | Total n = 20, HT | Intervention: | Urinary Na: | Control: | SBP: | Lower Na/K ratio associated with lowered BPP, II |
| USA | Age: 44.3 ± 7.8y | DASH diet | Control: | Baseline: 2.76 ± 1.13 | Control: -0.9 ± 16.4 mmHg | |
| RCT | BMI: 33.9 ± 6.6 kg/m2 | Control: | Baseline: 122.6 ± 40.82 mmol/day | Change: 0.61 ± 1.20 | DASH: -9.6 ± 11.2* mmHg | |
| SBP: 144.2 ± 9.38 mmHg | American control diet | Change: 17.85 ± 65.93 mmol/day | DASH: | DBP | ||
| DBP: 88.5 ± 6.03 mmHg | DASH: | Baseline: 3.20 ± 0.69 | Control: 1.6 ± 11.6 mmHg | |||
| Baseline: 131.4 ± 42.83 mmol/day | Change: −.06 ± 2.91 | DASH: -8.6 ± 9.1 * mmHg | ||||
| Change: -1.5 ± 64.40 mmol/day | ||||||
| Urinary K: | ||||||
| Control: | ||||||
| Baseline: 46.6 ± 13.3 mmol/day | ||||||
| Change: -7.9 ± 16.4 mmol/day | ||||||
| DASH: | ||||||
| Baseline: 42.2 ± 14.7 mmol/day | ||||||
| Change: 25.3 ± 28.6 mmol/day | ||||||
| Dodson (20) 1983UKRCT | Total n = 53, HTModified diet:Age: 53.6 ± 8.5y | Modified diet:High dietary fibre (35-40 g/day)High unrefined carbohydrate (65% E) | Urinary Na:Modified diet:- Pre: 195 ± 78.1 mmol/day | Modified diet:- Pre: 2.68 ± 1.08- Post: 1.82 ± 1.09 | SBPModified diet: -5.3 mmHgControl: +4.4 mmHg | Lower Na/K ratio associated with lowered BPØ, II |
| SBP: 173.8 ± 23.8 mmHg | Low fat (15% E) | - Post: 136.7 ± 70.2 mmol/day | Control: | DBP | ||
| DBP: 98.4 ± 9.2 mmHg | Low Na (40-450 mmol/day) | Control: | - Pre: 2.96 ± 1.39 | Modified diet: -6.7 mmHg*** | ||
| Control: | Normal K (70-80 mmol/day) | - Pre: 180.2 ± 58.2 mmol/day | - Post: 2.84 ± 1.33 | Control: +2.3 mmHg | ||
| Age: 55.3 ± 6.7y | Control: | - Post: 162.6 ± 48.1 mmol/day | ||||
| SBP: 169.7 ± 18.2 mmHg | Normal Western diet | Urinary K: | ||||
| DBP: 94.4 ± 7.3 mmHg | Modified diet: | |||||
| - Pre: 83.5 ± 61.5 mmol/day | ||||||
| - Post: 80.1 ± 25.5 mmol/day | ||||||
| Control: | ||||||
| - Pre: 66.9±20 mmol/day | ||||||
| - Post: 68.2 ± 21.7 mmol/day | ||||||
| Sacks FM et al. (21) 2001USARCT | Total n = 412,NT and HTDASH diet: | Intervention:DASH dietControl: | Urinary Na:High sodium level:- DASH: 144±58 mmol/day | High sodium level:- DASH: 1.92- Control: 3.53 | SBP net change (95% CI)High: -5.9 (−8.0 to -3.7) mmHgIntermediate: -5.0 (-7.6 to -2.5) mmHg | Lower Na/K ratio associated with lowered BPP, II |
| Age: 47 ± 10y | Usual American diet | - Control: 141 ± 55 mmol/day | Intermediate sodium: | Low: -2.2 (-4.4 to -0.1) mmHg | ||
| BMI: 29±5 kg/m2 | Intermediate sodium: | - DASH: 1.32 | DBP: (net change) | |||
| SBP: 134 ± 10 mmHg | - DASH: 107±52 mmol/day | - Control: 2.59 | High: -2.9 (-4.3 to -1.5) mmHg | |||
| DBP: 86 ± 5 mmHg | - Control: 106±44 mmol/day | Low sodium level: | Intermediate: -2.5 (-4.1 to -0.8) mmHg | |||
| Control diet: | Low sodium level: | - DASH: 0.83 | Low: -1.0 (-2.5 to -0.4) mmHg | |||
| Age: 49 ± 10y | - DASH: 67±46 mmol/day | - Control: 1.52 | ||||
| BMI: 30±5 kg/m2 | - Control: 64±37 mmol/day | |||||
| SBP: 135 ± 10 mmHg | Urinary K: | |||||
| DBP: 86 ± 4 mmHg | High sodium level: | |||||
| - DASH: 75±27 mmol/day | ||||||
| - Control: 40 ± 14 mmol/day | ||||||
| Intermediate sodium: | ||||||
| - DASH: 81±31 mmol/day | ||||||
| - Control: 41±14 mmol/day | ||||||
| Low sodium level: | ||||||
| - DASH: 81±29 mmol/day | ||||||
| - Control: 42±14 mmol/day | ||||||
| Nowson et al. (22) | Total n = 212, | A: Normal diet | Urinary Na: | A: | SBP: | Lower Na/K ratio associated with lowered BPP, II |
| 1988 | HT | B: High potassium diet | A: | Pre: 1.4 | A: -3.8 ± 1.0 mmHg | |
| Australia | Age: NR | C: Low sodium diet | Pre: 107 mmol/day | Post: 1.5 | B: -7.7 ± 1.1 mmHg | |
| RCT | BMI: NR | D: Low sodium, | Post: 107 mmol/day | B: | C: -8.9 ± 1.0 mmHg | |
| SBP: NR | high potassium diet | B: | Pre: 1.2 | D: -7.9 ± 0.9 mmHg | ||
| DBP: Mean of 4 readings | Pre: 92 mmol/day | Post: 0.9 | DBP: | |||
| between 90 and 100 mmHg | Post: 99 mmol/day | C: | A: -1.6 ± 0.6 mmHg | |||
| C: | Pre: 1.3 | B: -4.7 ± 0.7 mmHg | ||||
| Pre: 97 mmol/day | Post: 0.7 | C: -5.8 ± 0.6 mmHg | ||||
| Post: 50 mmol/day | D: | D: -4.2 ± 0.7 mmHg | ||||
| D: | Pre: 1.2 | |||||
| Pre: 93 mmol/day | Post: 0.5 | |||||
| Post: 49 mmol/day | ||||||
| Urinary K: | ||||||
| A: | ||||||
| Pre: 84 mmol/day | ||||||
| Post: 75 mmol/day | ||||||
| B: | ||||||
| Pre: 82 mmol/day | ||||||
| Post: 114 mmol/day | ||||||
| C: | ||||||
| Pre: 79 mmol/day | ||||||
| Post: 72 mmol/day | ||||||
| D: | ||||||
| Pre: 81 mmol/day | ||||||
| Post: 104 mmol/day | ||||||
| Jenkins et al. (23) | Total n = 241 | Two diets: | Urinary Na: | Portfolio diet: | SBP: | Lower Na/K ratio associated with lowered BPP, II |
| 2015 | Age: >20–85 y | Portfolio diet | NR | Baseline: | Portfolio diet: | |
| Canada | Portfolio diet: Mean (95% CI) | per 1000 kcal diet | Urinary K: | 2.1 (95% CI: 1.9, 2.3) | -0.11 mmHg | |
| RCT | BMI: 27 (95% CI: 26-27) | 9.8g viscous fibres | NR | Change: | DASH: | |
| SBP: 120 (95% CI: 118-122) mmHg | 22.5g soy protein | 0 (95% CI: −0.2, 0.2) | -0.08 mmHg | |||
| DBP: 73 (95% CI: 72-75) mmHg | 0.94g plant sterols | Control DASH: | DBP: | |||
| Control DASH diet: | Control (DASH diet) | Baseline: | Portfolio diet: | |||
| Mean (95% CI) | 2.1 (95% CI: 1.8, 2.3) | -0.18*** mmHg | ||||
| BMI: 27 (95% CI: 26-28) | Change: | DASH: | ||||
| SBP: 118 (95% CI: 115–121) mmHg | 0 (95% CI: −0.3, 0.2) | -0.03 mmHg | ||||
| DBP: 72 (95% CI: 70–74) mmHg |
1
*P < 0.05. **P < 0.01. ***P < 0.001. †Not included in current meta-analysis because it is a quasi-experimental trial. BMI, body mass index; CI, 95% confidence interval; DBP, diastolic blood pressure; HT, hypertensive; Pre-HT, pre-hypertensive; NR: not reported; SBP, systolic blood pressure.
2
Body mass index is Mean ± SD unless otherwise indicated.
3
Blood pressure is Mean ± SD unless otherwise indicated.
4
Mean ± SD (all such values).
5
Mean ± SD values or changes.
6
Quality rating: P = Positive, Ø = Neutral, − = Negative.
7
NHMRC (National Health and Medical Research Council) rating is classified as I, III-1, III-2, III-3 or IV.