Salt restriction among hypertensive patients: Modest blood pressure effect and no adverse effects

Figures & data

Table I.  Characteristics at inclusion of 46 drug-treated hypertensive patients (23 in each study group) with inadequately controlled hypertension.

Variable	Salt-supplemented group Mean or proportion	Placebo group Mean or proportion	95% CI of mean or proportional difference
Age (yrs)	55	57	−1.8, 2.3
Body Mass Index	29	29	−2.2, 3.7
24 h urine sodium secretion (mmol)	98	93	−19, 29
Systolic blood pressure (mmHg)	155	157	−11, 6
Diastolic blood pressure (mmHg)	92	93	−5, 4
Fasting se-glucose (mmol/l)	5.5	6.6	−2.2, 0.1
Se glucose after oral glucose (mmol/l)	8.9	10.3	−3.0, 0.1
Fasting insulin-C-peptide (nmol/l)	1.2	0.9	−0.1, 0.5
Insulin-C-peptide after oral glucose (nmol/l)	2.0	1.8	−0.1, 0.5
Total se-cholesterol (mmol/l)	6.1	6.4	−0.9, 0.5
Se-HDL-cholesterol (mmol/l)	1.2	1.3	−0.3, 0.1
Se-triglyceride (mmol/l)	2.2	1.7	−0.2, 1.4
Skin conductance (µmho)	1.2	1.2	−0.5, 0.3
Total peripheral resistance	266	262	−45, 53
Female gender	0.26	0.26	−0.25, 0.25
On thiazide diuretics	0.78	0.57	−0.05, 0.48
On beta-blockers	0.35	0.26	−0.18, 0.35
On ACE inhibitors	0.17	0.17	−0.22, 0.22

Table II.  Urine electrolyte secretion, body weight, and blood pressure changes after four and eight weeks on a moderate salt-restricted diet with double blind provision of salt or placebo capsules in the two study groups (values at four and eight weeks are subtracted from inclusion values).

Variable	Salt-supplemented group, mean difference compared with inclusion	Placebo group, mean difference compared with inclusion	95% CI of mean difference (p-value^1)
Na^+ excretion after 8 weeks (mmol)	−28	10	−84, 9 (0.11)
K^+ excretion after 8 weeks (mmol)	3	−9	−1, 26 (0.08)
Body weight (kg)	−1	0	−2, 0.5 (0.2)
Systolic blood pressure after 4 weeks (mmHg)	−1	2	−9, 3 (0.3)
Diastolic blood pressure after 4 weeks (mmHg)	0	2	−6, 1 (0.1)
Systolic blood pressure after 8 weeks (mmHg)	0	5	−11, 0 (0.07)
Diastolic blood pressure after 8 weeks (mmHg)	−2	3	−7, −1 (0.02)

¹t-test for independent samples.

Table III.  Between-group differences of changes relating to important measures of claimed unwanted side effects of salt restriction after eight weeks on a moderate salt-restricted diet with double-blind provision of salt or placebo capsules (values at eight weeks are subtracted from inclusion values).

Variable	Salt-supplemented group, mean difference compared with inclusion	Placebo group, mean difference compared with inclusion	95% CI of mean difference (p-value)
Fasting se-glucose (mmol/l)	−0.2	−0.1	−0.5, 0.3 (0.5^1)
Se glucose after oral glucose (mmol/l)	−0.5	0.1	−1.4, 0.2 (0.12^1)
Fasting insulin-C-peptide (nmol/l)	0.03	0.04	−0.28, 0.26 (0.6^2)
Insulin-C-peptide after oral glucose (nmol/l)	−0.05	−0.09	−0.15, 0.23 (0.7^1)
Total se-cholesterol (mmol/l)	0.0	0.2	−0.6, 0.3 (0.4^2)
Se-HDL-cholesterol (mmol/l)	0.00	0.05	−0.25, 0.15 (0.9^2)
Se-triglyceride (mmol/l)	−0.2	0.1	−0.6, 0.2 (0.3^1)
Se-aldosterone (pmol/l)	34	96	−236, 111 (0.4^2)
Skin conductance (µmho)	0.24	0.01	−0.11, 0.56 (0.13^2)
Total peripheral resistance	−23	3	−58, 6 (0.11^1)

¹t-test for independent samples; ²Mann–Whitney U-test.