Systematic review of long term effects of advice to reduce dietary salt in adults.
OBJECTIVE
To assess the long term effects of advice to restrict dietary sodium in adults with and without hypertension.


METHODS
Systematic review and meta-analysis of randomised controlled trials.


METHODS
Cochrane library, Medline, Embase, and bibliographies.


METHODS
Unconfounded randomised trials that aimed to reduce sodium intake in healthy adults over at least 6 months. Inclusion decisions, validity and data extraction were duplicated. Random effects meta-analysis, subgrouping, sensitivity analysis, and meta-regression were performed.


RESULTS
Mortality, cardiovascular events, blood pressure, urinary sodium excretion, quality of life, and use of antihypertensive drugs.


RESULTS
Three trials in normotensive people (n=2326), five trials in those with untreated hypertension (n=387), and three trials in people being treated for hypertension (n=801) were included, with follow up from six months to seven years. The large high quality (and therefore most informative) studies used intensive behavioural interventions. Deaths and cardiovascular events were inconsistently defined and reported. There were 17 deaths, equally distributed between intervention and control groups. Systolic and diastolic blood pressures were reduced (systolic by 1.1 mm Hg, 95% confidence interval 1.8 to 0.4 mm Hg; diastolic by 0.6 mm Hg, 1.5 to -0.3 mm Hg) at 13 to 60 months, as was urinary 24 hour sodium excretion (by 35.5 mmol/24 hours, 47.2 to 23.9). Degree of reduction in sodium intake and change in blood pressure were not related.


CONCLUSIONS
Intensive interventions, unsuited to primary care or population prevention programmes, provide only small reductions in blood pressure and sodium excretion, and effects on deaths and cardiovascular events are unclear. Advice to reduce sodium intake may help people on antihypertensive drugs to stop their medication while maintaining good blood pressure control.
Hooper
Lee
L
MANDEC, University Dental Hospital of Manchester, Manchester M15 6FH. lee.hooper@man.ac.uk
Bartlett
Christopher
C
Davey Smith
George
G
Ebrahim
Shah
S
D000293:Adolescent; D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002318:Cardiovascular Diseases / Q000401:mortality / Q000517:prevention & control; D003376:Counseling; D005260:Female; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D006973:Hypertension / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D011788:Quality of Life; D016032:Randomized Controlled Trials as Topic; D012964:Sodium / Q000652:urine; D017673:Sodium Chloride, Dietary / Q000008:administration & dosage*
D017673:Sodium Chloride, Dietary; D012964:Sodium