Sodium intake and blood pressure across 85 trials
What it found
Across 85 trials in people, eating less sodium lowered blood pressure, and the drop kept getting bigger the more sodium was cut.
The link looked close to a straight line, with no clear point where the benefit stopped.
What they found
Studies in people
Blood pressure drop
Lower sodium intake went hand in hand with lower systolic and diastolic blood pressure. The relationship was close to a straight line across the whole range studied, with no flattening at the lowest or highest sodium levels.
Size of the effect
Every 1 g a day drop in sodium was linked to a fall of 2.42 mm Hg in systolic pressure and 1.01 mm Hg in diastolic pressure. Over the full range of sodium exposure, the difference was more than 15 mm Hg for systolic and nearly 10 mm Hg for diastolic.
With and without hypertension
The pattern was similar in people with and without high blood pressure, but the drop was steeper in those with high blood pressure. In people without high blood pressure, there was little sign of a diastolic effect below 2 g a day.
How sodium was cut
Trials that changed the whole diet produced bigger blood pressure drops than trials that used sodium supplements. For a 100 mmol a day reduction, diet changes gave a 6.63 mm Hg fall in systolic pressure, compared with 4.47 mm Hg for supplement-based studies.
Trial length
Trials lasting 12 weeks or more showed a slightly weaker effect than shorter trials, but the dose-response link was still close to a straight line. The authors say this matters for long-term advice.
Background sodium intake
People who usually ate more sodium showed a stronger blood pressure response when their sodium intake changed. This was seen for both systolic and diastolic pressure.
What the authors conclude
“In this dose-response analysis of sodium reduction in clinical trials, we identified an approximately linear relationship between sodium intake and reduction in both systolic and diastolic BP across the entire range of dietary sodium exposure.”
Also in their conclusions
- They conclude that there is an approximately linear relationship between sodium intake and reduction in both systolic and diastolic blood pressure across the entire range of dietary sodium exposure.
- They say the effect was more pronounced in participants with a higher blood pressure level, but occurred independently of baseline blood pressure.
- They advise that reducing dietary sodium applies not only to adults with hypertension but also to those without hypertension, in whom the expected reduction in blood pressure is smaller but still important.
How it was done
The authors wanted to find out whether the relationship between sodium intake and blood pressure is a straight line or a curve, and whether there is any threshold. They also wanted to look specifically at adults without high blood pressure, the group where the link has been most questioned.
They pooled 85 trials that changed how much sodium people ate and measured blood pressure at the start and end. The trials ran from 4 weeks to 36 months, and sodium intake ranged from 0.4 to 7.6 g a day. Most trials were in people with high blood pressure (65 trials), 11 were in people without it, and 9 included both.
What it can’t tell you
- This paper looked at blood pressure, not at heart attacks, strokes or deaths. It cannot show whether lowering sodium changes those outcomes.
- The trials used different ways to cut sodium and different diets, so the exact size of the effect for any one person is uncertain.
- Some estimates, especially for people without high blood pressure and for the longest trials, were statistically unstable.
Who paid
- Funding
- Funded by NIGMS NIH HHS (from the PubMed record).
- Authors work at
- University of Modena and Reggio Emilia, M.V.; Tulane University School of Public Health and Tropical Medicine, LA (P.K.W.); National and Kapodistrian University of Athens, Greece (A.N.)
The paper
- Title
- Blood Pressure Effects of Sodium Reduction: Dose-Response Meta-Analysis of Experimental Studies
- Type
- Meta-analysis
- Evidence
- Studies in people
- Summarised from
- Full text
- Cite
- Filippini T, Malavolti M, Whelton PK, Naska A, Orsini N, Vinceti M (2021). Blood Pressure Effects of Sodium Reduction: Dose-Response Meta-Analysis of Experimental Studies. Circulation. doi:10.1161/CIRCULATIONAHA.120.050371Free full textPubMed 33586450DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error