Salt, Sodium & Potassium and Blood Pressure: Independent Evidence

Table of contents

• Evidence summary
• What salt, sodium and potassium are, and the official targets
• How sodium and potassium affect blood pressure
• What works and what does not
• The evidence by question
• Risks and side effects
• Interactions
• Who should be cautious
• Intakes and doses studied
• The UK salt reduction programme
• Follow the money: who funds the salt evidence
• Related research
• Frequently asked questions
• Sources and funding notes

Evidence summary

Independent evidence and credibility scorecard

Independence tiers: 1 = regulator, government or intergovernmental body; 2 = academic or Cochrane team with no declared commercial funding for the work; 3 = authors with an advocacy role, or a programme with some declared industry or pharmaceutical funding; 4 = trade-body or manufacturer-linked. Credibility runs from A (highest) to D.

Convergence and country clustering. Sources with opposed leanings agree on direction: the Danish reviewer sceptical of broad population targets (Graudal) and the UK campaigners (He) both find a blood-pressure fall, largest in hypertension. They differ on size in normotensive people and on harm signals. The trials are widely spread (US, China, Australia), but the policy and review voices cluster in the UK and US, plus a WHO process led from Switzerland. Chinese trial sites supply the hard-outcome evidence on salt substitutes.

What salt, sodium and potassium are, and the official targets

Table salt is sodium chloride. Most evidence is measured in sodium: 1 g of sodium is about 2.5 g of salt. The review by He and colleagues expressed 75 mmol of urinary sodium as about 4.4 g of salt (Cochrane 2013).

• WHO: under 2,000 mg sodium a day, which is under 5 g of salt. WHO says average adult intake was about 4,278 mg sodium (roughly 11 g salt) in 2021 (WHO fact sheet).
• NHS (UK): adults should have no more than 6 g of salt a day. The page we opened was last reviewed in April 2023 and was due for review in April 2026 (NHS). The 6 g goal goes back to the UK SACN review in 2003 (SACN/COT).
• US/Canada: the National Academies set a "chronic disease risk reduction" level of 2,300 mg sodium a day; above it, cutting intake is expected to help (National Academies 2019). Its potassium adequate intakes range from 2,300 to 3,400 mg a day by sex and age group, and it found too little evidence to set an upper limit for apparently healthy people.

Potassium-enriched ("lower-sodium") salt replaces part of the sodium chloride with potassium chloride. SSaSS used 75% sodium chloride and 25% potassium chloride (Neal 2021); DECIDE-Salt used 62.5% and 25% (Yuan 2023). The Cochrane review found trials replacing from 3% to 77% of sodium (Brand 2022).

Legal and guideline status. WHO published a conditional recommendation in 2025 that adults in the general population use lower-sodium, potassium-enriched salt instead of regular salt; the recommendation does not cover salt in processed food (Lancet Public Health correspondence). We could not open the guideline text, so details come from that correspondence and from a Resolve to Save Lives summary; that organisation promotes the approach. In the UK, SACN and COT judged in 2017 that putting potassium-based replacers in processed food gives a net population benefit (SACN/COT).

How sodium and potassium affect blood pressure

Proven in humans. Controlled-feeding and crossover trials show blood pressure falls when sodium is lowered, with a graded response in DASH-Sodium (Sacks 2001). In a 2023 crossover trial of 213 adults aged 50 to 75, a one-week low-sodium diet (about 500 mg a day) lowered 24-hour mean arterial pressure by a median of 4 mmHg compared with a high-sodium week, and 73.4% of people had a fall (Gupta 2023). The He review estimated a 5.8 mmHg fall in systolic pressure for each 100 mmol (about 6 g of salt) fall in urinary sodium (95% CI 2.5 to 9.2) (Cochrane 2013).

Body response. Less sodium triggers the kidney hormone system. Both Cochrane reviews found rises in renin and aldosterone; Graudal also reported rises in cholesterol and triglyceride, which He found were not significant in longer trials (Cochrane summary; BMJ 2013). Whether these hormone changes matter for outcomes is not settled.

Potassium. A WHO-funded systematic review of 22 trials found higher potassium intake lowered systolic pressure by 3.49 mmHg (95% CI 1.82 to 5.15) in adults, in people with hypertension but not those without, and linked higher intake to a 24% lower stroke risk in cohort studies. People with impaired kidney handling of potassium were not included (Aburto 2013, BMJ). Potassium chloride in salt substitutes therefore acts twice: less sodium and more potassium. Trials cannot separate the two effects.

Not proven. Whether individual "salt sensitivity" can guide advice is unsettled. Gupta's trial showed that individual responses vary: 46% crossed a 5 mmHg threshold often used to label "salt sensitive" (Gupta 2023).

What works and what does not

The evidence by question

Does cutting salt lower blood pressure, and by how much?

Yes. In DASH-Sodium, 412 adults ate a control diet typical of the US or the DASH diet at three sodium levels for 30 days each. Going from intermediate to low sodium lowered systolic pressure by 4.6 mmHg on the control diet and 1.7 mmHg on DASH. At the lowest sodium, DASH was 7.1 mmHg lower than control in people without hypertension and 11.5 mmHg lower in those with it (Sacks 2001). The first number shows the sodium effect; the second shows the extra effect of the diet pattern. This is why we link to our guide on heart-healthy dietary patterns.

The Graudal versus He debate

The two reviews are both Cochrane reviews. Graudal, Hubeck-Graudal and Jürgens (2020) pooled 195 trials with 12,296 people, lasting 3 days to about 3 years; average salt intake fell from 11.5 to 3.8 g a day (Cochrane summary). He, Li and MacGregor (2013) pooled 34 trials with 3,230 people, all lasting 4 weeks or more, with a milder cut of about 4.4 g of salt a day (Cochrane 2013). The He group argues that very short trials with large salt cuts are irrelevant to public-health advice and that lipid rises appear only in them. Graudal found hormone and fat rises that were more consistent than the blood-pressure result.

In 2011 the same UK group published a re-analysis in The Lancet of the earlier Taylor Cochrane review and said the review and its press release had misled the public (FoodNavigator, 2011). The 2014 update (Adler) kept a cautious message: too few events to be sure either way (Adler 2014). In 2022 a group of 25 authors including He, MacGregor, Cappuccio, Sacks and Appel wrote that claims that low sodium harms are poorly founded and that some such claims come from researchers with food-industry funding that was not always declared (Cappuccio 2022). That paper is an expert opinion piece by people with a public stance on the question. It does not itemise each funder in the text we opened.

How should a reader weigh this? Both Cochrane reviews declare no food-industry funding for their authors (Graudal; He). The disagreement is largely about which trials to include, not about hidden money. Graudal's own review notes that only 6 of 195 included trials were food-industry-supported, and the authors judged that influence negligible (Cochrane 2020).

Does cutting salt prevent heart attacks, strokes and deaths?

The best direct evidence is thin. The 2014 Cochrane review (8 trials, 7,284 people) found no reduction in all-cause death (hypertensives RR 1.00, 95% CI 0.86 to 1.15; normotensives end of trial RR 0.67, 0.40 to 1.12). Pooled cardiovascular events had a risk ratio of 0.77 (0.63 to 0.95) across six trials, but this was driven by one trial in retirement homes where the kitchen reduced salt without residents changing behaviour (Adler 2014). The authors concluded the trials lacked power. The National Academies reached a different judgement from wider evidence, with the blood-pressure effect of sodium forming part of the evidence behind its 2,300 mg level (National Academies).

Is very low salt harmful? The J-curve claim

The PURE cohort of 101,945 people in 17 countries estimated sodium intake from morning urine samples. Compared with 4 to 5.99 g sodium a day, intakes of 7 g or more were linked to more events (OR 1.15, 95% CI 1.02 to 1.30) and under 3 g to more events (OR 1.27, 1.12 to 1.44). Higher potassium excretion was linked to fewer events (O'Donnell 2014). The campaign-group paper by Cappuccio and colleagues says this approach is flawed (Cappuccio 2022); a trade body, the Salt Institute, cited a 2018 Lancet study in support of its position that Americans eat the right amount of salt (Food Dive). Observational data cannot show cause. Randomised trials of very low salt that report death are lacking.

Do potassium-enriched salt substitutes prevent strokes?

SSaSS randomised 600 villages in rural China to a salt substitute (75% sodium chloride, 25% potassium chloride) or regular salt. Among 20,995 people (mean age 65.4, 72.6% with prior stroke) followed for 4.74 years, stroke occurred at 29.14 versus 33.65 per 1,000 person-years (rate ratio 0.86, 95% CI 0.77 to 0.96), cardiovascular events 0.87 (0.80 to 0.94) and death 0.88 (0.82 to 0.95) (Neal 2021). The design paper confirms the substitute was provided free and the trial was open-label (Neal 2017 design paper). DECIDE-Salt added care-home evidence: systolic pressure 7.1 mmHg lower and cardiovascular events HR 0.60 (0.38 to 0.96), but no clear effect on total death (HR 0.84, 0.63 to 1.13) (Yuan 2023). The Cochrane review rated the effect on blood pressure and non-fatal events as moderate certainty but small at an individual level (Brand 2022).

Limits: nearly all participants had prior stroke or high stroke risk, the trial was in rural China, and WHO's recommendation does not address salt in processed food (Lancet Public Health).

Risks and side effects

• Hormone changes on lower sodium: small rises in renin, aldosterone and noradrenaline; Graudal also reports cholesterol and triglyceride rises (Cochrane summary).
• Adverse events in the 2023 sodium-diet trial: mild, 9.9% on high sodium and 8.0% on low sodium (Gupta 2023).
• Low sodium blood level (hyponatraemia): SACN/COT note it has been described clinically, especially in older people, but they judged it a lesser concern for the potassium-replacer question (SACN/COT). We did not find trial data on it in this review.

Interactions

Medicines that raise potassium or reduce its removal are the key concern. Trial exclusions included potassium-sparing diuretics, potassium supplements and serious kidney disease (Brand 2022). Whether potassium-enriched salt is safe alongside ACE inhibitors or ARBs is not settled in the evidence we could open: a 2025 research letter from the SSaSS team addressed it (PubMed record), but we could not read its findings, so we make no safety claim. For specific drugs, see our guides to losartan and ramipril, which cover potassium monitoring.

Blood-pressure tablets work alongside, not instead of, diet. In Gupta's trial the sodium effect on mean arterial pressure did not differ by antihypertensive use (Gupta 2023). Sodium restriction should not be used to stop or reduce prescribed medicines without advice.

Who should be cautious

• Chronic kidney disease, advanced or unknown stage: excluded from the substitute trials; WHO advises an advisory label (Brand 2022; RTSL summary). See Chronic Kidney Disease and the Heart.
• People taking potassium-sparing diuretics or potassium supplements: excluded from trials (Brand 2022).
• Pregnancy: no eligible trials of salt substitutes in pregnant women (Brand 2022). One small trial of 92 children measured pressure but reported no safety outcomes for potassium.
• Older adults and people with diabetes: kidney function falls with age and some diabetes complications, and SACN/COT flag both groups for hyperkalaemia risk (SACN/COT).

Intakes and doses studied

These are intakes used in trials and official targets, not personal advice.

• Targets: WHO under 5 g salt a day; NHS no more than 6 g; US/Canada sodium 2,300 mg (WHO; NHS; National Academies).
• Trial diets: DASH-Sodium used three sodium levels, each for 30 days (Sacks 2001). Gupta used about 500 mg sodium a day (low) and 2,200 mg added on top of usual diet (high), for one week each (Gupta 2023).
• Salt substitutes in trials: 75% sodium chloride with 25% potassium chloride in SSaSS; 62.5% sodium chloride with 25% potassium chloride in DECIDE-Salt (Neal 2021; Yuan 2023).
• Where salt comes from: in the UK, most dietary salt comes from processed foods, which is why the household substitute approach covers only part of intake (Lancet Public Health).

The UK salt reduction programme

The programme set voluntary, progressively lower salt targets for food makers, retailers and caterers. Public Health England published its 2024 targets on 7 September 2020 (GOV.UK). A Wolfson Institute (Queen Mary University of London) analysis found England's salt intake, measured by 24-hour urine, fell from 9.38 g a day in 2003 to 7.58 in 2014, then rose to 8.39 in 2018. Blood pressure and stroke and heart-disease mortality fell over 2003 to 2014 and then plateaued (Song 2023, J Hypertens). The authors blame the stall on handing responsibility to industry. A university press release adds a modelled estimate that more than 38,000 deaths could have been prevented in 2014-2018 if the decline had continued; this is a model, not a count (QMUL).

An independent Oxford analysis of grocery sales found sales-weighted salt content of packaged foods fell from 1.04 to 0.90 g per 100 g between 2015 and 2020, a 4.2% fall that was not statistically significant (p=0.13), with salt sold falling 6.7% per person per day (p=0.54). Its authors declared no competing interests and were supported by NIHR (Bandy 2022). The two analyses use different data and agree the pace slowed. Neither shows that the slowdown caused the change in blood pressure; the Song authors say the association "may" be causal.

Government-appointed experts also considered an extra step: SACN and COT concluded in 2017 that potassium-based replacers in foods give a net benefit to the UK population, noting the food industry had asked for the question to be reconsidered because sodium reduction alone was hard in some products (SACN/COT).

Follow the money: who funds the salt evidence

Who profits either way

Salt producers and food manufacturers benefit if salt targets stay voluntary or low. Salt substitute sellers, charities that campaign on salt, and some research groups that built careers on salt reduction benefit if salt cuts are endorsed. The Salt Institute, a trade body for salt producers (road, industrial and food salt), operated from 1914 until it closed at the end of March 2019; its former president said fewer than a dozen member companies funded it when he left in 2010 (Food Dive, 2019).

Documented industry funding of salt research

BuzzFeed News reported in 2018 that a researcher, David McCarron, received US$21,875 in October 2017 from the Salt Institute via the Academy of Nutrition and Dietetics' foundation for early planning of a prison salt trial. A May 2018 essay in Hypertension proposing that trial did not disclose it; the Center for Science in the Public Interest found it. The researcher said the money was unspent and would not shape the trial, and the trial lead said he would not knowingly accept food-industry funding. The Salt Institute said it had called for proper clinical trials and did not try to influence findings (BuzzFeed News, 2018). This is one reported case. Funding does not show that any conclusion is wrong.

Of the 195 trials in Graudal's 2020 Cochrane review, 6 were supported by food-industry organisations and 12 by the pharmaceutical industry; 129 had public-foundation support and 46 gave no support statement (Cochrane 2020).

Funding of the main trials and reviews

• DASH-Sodium: NHLBI grants (US) (Sacks 2001).
• SSaSS: Australia's NHMRC, with a UK MRC grant also on record (Neal 2021). We could not confirm the manufacturer of the salt substitute or the full conflict statements.
• DECIDE-Salt: UK MRC and China's Ministry of Science and Technology (Yuan 2023).
• Cochrane reviews: Denmark (hospital salary, A.P. Møller Foundation for one author) for Graudal; Queen Mary University of London and the China Scholarship Council for He; NIHR for Adler; WHO and UK aid for Brand (Graudal; He; Adler; Brand).
• US recommendations: the 2019 National Academies report was sponsored by Health Canada, NIH, the Public Health Agency of Canada, CDC, USDA and FDA (National Academies).

The campaign side: Action on Salt, CASH and Resolve to Save Lives

Action on Salt is the campaign group working from the Wolfson Institute at Queen Mary University of London, linked to the charity Consensus Action on Salt, Sugar and Health (CASSH) (Action on Salt). The group says it works to reach consensus with the food industry and government. Its 2022-23 annual report lists a funding package of over £200,000 from Resolve to Save Lives, WHO regional-office funding, NIHR and MRC funding for work in China, and trust funding for its sugar work (CASSH annual report 2022-23). Resolve to Save Lives lists Bloomberg Philanthropies, the Gates Foundation and Gates Philanthropy Partners as initial funders (RTSL), and its summary of the WHO guideline promotes lower-sodium salt (RTSL summary). The same research group (Wolfson) authored the main analysis of the UK programme (Song 2023). These are documented relationships; they do not show the findings are wrong. They do mean the strongest advocates are not neutral on the policy question.

Documented integrity events and disputes

• 2011: UK campaigners publicly challenged a Cochrane review and its press release (FoodNavigator).
• 2018: undisclosed Salt Institute-routed funding in a proposed salt trial, as reported by BuzzFeed News (BuzzFeed News).
• 2019: closure of the Salt Institute (Food Dive).

Related research

For wider, evidence-graded context, see these Pure City Research guides:

• Hypertension: Accurate Measurement, Treatment, Safety and Evidence Funding
• High Blood Pressure: Prevention and Management Evidence
• Heart-Healthy Dietary Patterns: DASH, Food Choices and Medicine Safety
• Home Blood Pressure Monitoring: Technique, Readings, Devices and Safety
• Blood Pressure Medicines: Types, Monitoring, Side Effects and Safety
• Blood Pressure Supplements: Benefits, Limits and Safety
• Supplements and Heart Medicines: Blood Thinners, Potassium, Herbs and Test Interactions
• Chronic Kidney Disease and the Heart: Cardiorenal Risks, Tests and Medicine Safety
• Losartan: Uses, Potassium, Monitoring and Pregnancy Safety
• Ramipril: Uses, Kidney Monitoring, Cough and Safety
• Resistant Hypertension: Confirming the Diagnosis, Treatment and Funding
• Stroke: Emergency Signs, Ischaemic and Haemorrhagic Types, Treatment and Recovery

Frequently asked questions

Sources and funding notes

What we could not verify: The full text and full conflict-of-interest statements of the SSaSS trial (we confirmed the abstract, results and grant numbers through PubMed, but not the full text); the supplier of the SSaSS salt substitute; the findings of the 2025 Circulation research letter on SSaSS participants on renin-angiotensin blockers (PubMed has no abstract; we make no claim about its result); the full text of the WHO 2025 guideline (details come from a Lancet Public Health reply and a Resolve to Save Lives summary, and search summaries agree it is conditional and excludes people with impaired potassium excretion); the full list of "others" funding the 2014 PURE paper beyond the Population Health Research Institute and CIHR; the funders behind Action on Salt beyond those named in its 2022-23 report; the NICE and MHRA positions on potassium salt substitutes; other food-industry or salt-company funding of salt research beyond the Salt Institute case. Figures such as the 1% of the UK population with CKD are SACN/COT's own numbers from 2017 and may have changed. The NHS salt page we opened was past its stated review date.

1. Sacks et al., DASH-Sodium, NEJM 2001 — trial; US NHLBI.
2. Gupta et al., JAMA 2023, sodium crossover trial — trial; NHLBI/NIH and American Heart Association.
3. Graudal et al., Cochrane review CD004022 (2020) — systematic review; Copenhagen University Hospital, A.P. Møller Foundation.
4. Cochrane plain-language summary of CD004022 — summary of the above.
5. He, Li, MacGregor, Cochrane review CD004937 (2013) — systematic review; Queen Mary University of London, China Scholarship Council.
6. He, Li, MacGregor, BMJ 2013 — same review, BMJ version; authors at Queen Mary.
7. Adler et al., Cochrane review CD009217 (2014) — systematic review; NIHR grant.
8. Neal et al., SSaSS, NEJM 2021 — trial; Australian NHMRC, UK MRC grant.
9. Neal et al., SSaSS design paper, Am Heart J 2017 — trial design; salt substitute provided free.
10. Yuan et al., DECIDE-Salt, Nature Medicine 2023 — trial; UK MRC, China Ministry of Science and Technology.
11. Brand et al., Cochrane review CD015207 (2022) — systematic review; WHO, UK aid.
12. Yin et al., Circulation 2025 (PubMed record) — research letter on SSaSS; no abstract; conflict statement none, funding not seen.
13. WHO, Use of lower-sodium salt substitutes: WHO guideline (2025) — guideline; WHO.
14. Pineda and Beaney, Lancet Public Health 2025 reply — correspondence on WHO guideline; authors at Imperial College/George Institute.
15. Resolve to Save Lives overview of the WHO guideline — promoter summary; funded by Bloomberg Philanthropies, Gates Foundation.
16. Resolve to Save Lives, About — funder disclosure.
17. WHO salt reduction fact sheet — intergovernmental; WHO.
18. NHS, salt in your diet — UK national health service.
19. SACN/COT, Potassium-based sodium replacers (2017) — UK government expert committees.
20. National Academies news release, sodium and potassium DRIs (2019) — sponsors: Health Canada, NIH, PHAC, CDC, USDA, FDA.
21. O'Donnell et al., PURE, NEJM 2014 — cohort; funding statement not opened.
22. Aburto et al., BMJ 2013, potassium intake — systematic review; WHO funds, Kidney Evaluation Association Japan, Japan and Korea governments.
23. Song et al., J Hypertension 2023, salt intake in England — analysis; MRC and NIHR (authors campaign for salt reduction).
24. Queen Mary University of London news release (2023) — university press release.
25. Bandy et al., PLOS Medicine 2022 — repeated cross-sectional study; NIHR, University of Oxford.
26. Public Health England, Salt reduction targets for 2024 (2020) — government.
27. Consensus Action on Salt, Sugar and Health, Annual Report 2022-23 — charity; funders as listed in the report.
28. Action on Salt, About — campaign group.
29. Cappuccio et al., Curr Nutr Rep 2022 — expert opinion paper by campaigning authors.
30. BuzzFeed News, 18 September 2018 — investigative journalism on Salt Institute funding.
31. Food Dive, 2 April 2019 — trade press on Salt Institute closure.
32. FoodNavigator, 1 August 2011 — trade press on the Cochrane/Lancet dispute.

Educational research reviewed 6 October 2026. This article is not medical advice; talk to a qualified clinician or pharmacist before starting, stopping or combining treatments.