How Much Salt Is Too Much? What the Latest Science Says About Sodium and Blood Pressure

The link between salt and blood pressure has long been a topic of scientific inquiry—and public debate. Two recent meta-analyses (studies that combine the results of multiple studies), examining over a hundred clinical trials between them, provide some of the clearest evidence yet about how different salt-reduction strategies affect blood pressure, who benefits most and how much of a difference it really makes.

Salt is, of course, essential to life and health. But too much is detrimental. The average Singaporean (our home base) consumes close to 2 teaspoons of salt (3,600mg of sodium) daily. This is almost twice the WHO's daily recommendation of 2,000mg of sodium. Similarly, in the USA and UK, people on average consume around approximately 8.5 grams of salt (3,400mg sodium) versus their recommended maximum 2,300 mg of sodium.

As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.

Salt Reduction Works, But How You Do It Matters

A 2022 meta-analysis published in PLOS ONE examined how different salt reduction interventions perform in the real world. Drawing on 50 trials across diverse populations and countries, it showed that the type of intervention matters when it comes to results. The most effective strategy by far was salt substitution, where regular table salt is replaced with alternatives lower in sodium - typically potassium-enriched salts. These lowered systolic blood pressure by an average of 7.4 mmHg, which translates to about a 5–6% reduction.

For individuals with high blood pressure, this kind of drop is associated with significantly lower risk of heart disease and stroke.

Nutrition education interventions were also impactful, especially when delivered to older adults and over longer periods. These programmes included group sessions, personalised counselling, cooking classes, and public awareness campaigns. The effect - an average 2.75 mmHg drop in systolic BP - may seem modest, but even a 2 mmHg reduction in blood pressure has been linked to a 10% decrease in stroke mortality at the population level.

Interestingly, self-help tools like smartphone apps or home sodium test kits had a more inconsistent impact. These were more effective among younger adults and those with hypertension, but results varied, possibly due to short follow-up periods or low user engagement. The least studied approach - food reformulation, where manufacturers reduce salt in products - showed potential but remains under-researched, with only two trials included. The amount of salt hidden in commons foods is shocking, see our comparison of potato chips and bread and separate analysis of instant (packet) noodles.

It's a Sliding Scale: The More You Cut, the More You Gain

The 2021 Circulation study took a quantitative approach to understanding how reductions in sodium intake relate to changes in blood pressure, across 85 controlled trials. Its major strength was the use of a novel statistical method that allowed researchers to chart a dose–response curve, showing how each incremental reduction in sodium impacts both systolic and diastolic blood pressure.

The results were clear: the lower your sodium intake, the lower your blood pressure, and this effect continued even at very low intakes - there was no clear threshold where benefits stopped.

This study also highlighted important differences in who benefits most. Participants with high blood pressure saw significantly larger reductions than those without it. For example, a 2.3g/day (100 mmol) sodium reduction led to a 6.5 mmHg drop in systolic BP in hypertensive individuals, compared to just 2.3 mmHg in those without hypertension. Even more interesting, people taking blood pressure medication experienced further reductions with sodium cuts - suggesting lifestyle changes still offer benefits even when medication is used.

The study further found that dietary interventions - which involve overall eating pattern changes - were more effective than clinical supplementation of sodium (i.e. adding back precise sodium doses via tablets). Real-world dietary changes likely bring synergistic effects from reducing processed foods and improving overall nutrient balance. This highlights the importance of not just targeting sodium, but improving diet quality as a whole. The DASH diet has been shown to be highly effective, learn more here.

Common Ground - and Some Differences

Both studies strongly agree on several key points:

Less sodium = lower blood pressure, across a wide range of people and sodium intakes.
People with high blood pressure benefit the most, but everyone stands to gain.
Salt substitutes and education strategies are effective, especially when tailored.

But they differ slightly in focus. The PLOS ONE study concentrated on the effectiveness of intervention types, offering practical insights for public health programmes and individual lifestyle changes. The Circulation study homed in on dose-response, showing there’s no clear 'safe' threshold above which salt becomes problematic - it’s more of a gradient, as shown in the graph below.

The solid line represents the average change in systolic and diastolic blood pressure based on sodium intake levels at the end of each trial. Dashed lines indicate the expected range of variation. Results are shown for all studies combined, as well as by intervention type: either dietary changes or sodium supplementation. The reference point is set at 2 grams of sodium per day, aligning with common health guidelines.

In practical terms, 2 grams of sodium is just under 1 level teaspoon of table salt.

Another standout from the Circulation study: dietary changes were more effective than sodium supplements in influencing blood pressure. In this context, “sodium supplements” refers to trials where participants first reduced sodium in their diet and then were given specific amounts of sodium back in the form of pills or capsules to test the effects of different intake levels. These controlled additions of sodium - essentially 'salt tablets' - allowed researchers to measure blood pressure responses to precise doses.

While scientifically useful, this method doesn’t mimic real-world eating habits. In contrast, diet-based interventions involved participants cutting back on processed and salty foods or following specific low-sodium meal plans. These real-life changes tended to produce larger and more sustained drops in blood pressure, especially when sodium intake fell below 2 grams per day. This suggests that not only does the amount of sodium matter, but how it's consumed - within a broader dietary context - can influence its impact on blood pressure.

What About Potassium?

A side note: while not the main focus of either study, many of the most effective salt substitutes used in the trials contained potassium, which itself can help lower blood pressure. However, potassium-based substitutes may not be safe for people with kidney disease or on certain medications - another reason to consult your doctor before making changes.

Final Thoughts

Together, these two landmark reviews reaffirm a message we've heard before but now understand better: lowering salt intake helps lower blood pressure. What’s new is how clearly this effect shows up across populations and interventions - and that more substantial reductions yield greater benefits, without a clear cut-off point where gains plateau.

For most people, simply moving towards the recommended daily limit of 2g sodium (5g salt) could significantly reduce the risk of hypertension and its complications. Whether through education, diet swaps, or potassium-based salt substitutes, even small changes can make a measurable difference.

As always, the best strategy is one you can stick with - one that fits your personal health profile. For most people, improving blood pressure is about finding motivation and prioritising self-care - with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle, The Whole Health Practice is here to help.

Whether your interest is healthspan and longevity, to beat chronic illness or to enhance your mental health and well-being, our consultations and programs deliver results that are tailored to your needs.

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Stay Healthy,

Alastair

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Related Studies

Aliasgharzadeh S, Tabrizi JS, Nikniaz L, Ebrahimi-Mameghani M, Lotfi Yagin N. Effect of salt reduction interventions in lowering blood pressure: A comprehensive systematic review and meta-analysis of controlled clinical trials. PLoS One. 2022 Dec 7;17(12):e0277929. doi: 10.1371/journal.pone.0277929. PMID: 36477548; PMCID: PMC9728935.

Filippini T, Malavolti M, Whelton PK, Naska A, Orsini N, Vinceti M. Blood Pressure Effects of Sodium Reduction: Dose-Response Meta-Analysis of Experimental Studies. Circulation. 2021 Apr 20;143(16):1542-1567. doi: 10.1161/CIRCULATIONAHA.120.050371. Epub 2021 Feb 15. PMID: 33586450; PMCID: PMC8055199.