The world eats more than twice the sodium WHO advises. Cutting it works in trials.

WHO recommends adults consume less than 2,000 mg of sodium a day, equivalent to less than 5 g of salt or just under a teaspoon [s1]. Global mean adult intake in 2021 was 4,278 mg a day, about 11 g of salt — more than double the recommendation, and WHO describes almost all populations as consuming too much [s1]. Unlike most nutrition targets, this one has both a randomised blood-pressure trial and a randomised hard-outcome trial behind it, which is why it is stated with more confidence than dietary advice usually warrants.

Why sodium is treated differently from other dietary targets

The mechanism is narrow and well characterised. WHO identifies raised blood pressure as the primary health effect of high-sodium diets, which in turn raises the risk of cardiovascular disease, gastric cancer, obesity, osteoporosis, Meniere's disease and kidney disease [s1]. An estimated 1.7 million deaths a year were associated with excess sodium in 2023 [s1]. The agency also notes that sodium deficiency is extremely unlikely in healthy individuals [s1] — a claim that cannot be made about most nutrients where intake advice runs in the other direction.

Where the sodium comes from is not mainly the salt shaker. In many high-income countries, and increasingly in low- and middle-income ones, a significant proportion comes from processed foods: breads, processed meat, snack foods and condiments such as soy and fish sauce [s1]. WHO's four recommended interventions are correspondingly industrial rather than individual — reformulating products to contain less sodium with target levels, supportive food environments in hospitals, schools, workplaces and nursing homes, front-of-pack labelling, and mass media campaigns [s1].

The blood-pressure trial

A crossover trial enrolled 213 community-based adults aged 50 to 75 in two US cities between April 2021 and February 2023, deliberately mixing blood pressure categories: 25% normotensive, 20% with controlled hypertension, 31% with uncontrolled hypertension and 25% untreated [s2]. Median age was 61, 65% were female and 64% were Black [s2]. After a baseline visit on their usual diet, each participant completed one week on a high-sodium diet — roughly 2,200 mg of sodium added daily to their usual intake — and one week on a low-sodium diet totalling roughly 500 mg a day [s2].

Median 24-hour ambulatory systolic blood pressure was 125 mm Hg on the usual diet, 126 on the high-sodium diet and 119 on the low-sodium diet [s2]. The median within-individual change in mean arterial pressure between the high- and low-sodium weeks was 4 mm Hg, with an interquartile range of 0 to 8 [s2]. The trial's conclusion was that dietary sodium reduction significantly lowered blood pressure in the majority of middle-aged to elderly adults, independent of hypertension status and antihypertensive medication use, generally consistent across subgroups, and without excess adverse events [s2].

The interquartile range is the honest detail. A quarter of participants sat at or below zero change. "Majority" is the correct word, and it is not "everyone".

The hard-outcome trial

The Salt Substitute and Stroke Study randomised 600 villages in rural China, enrolling 20,995 people who had either had a stroke or were 60 or older with high blood pressure [s3]. Villages were assigned in a 1:1 ratio to a salt substitute — 75% sodium chloride and 25% potassium chloride by mass — or to continued use of regular salt [s3]. Mean age was 65.4, 49.5% were female, 72.6% had a history of stroke and 88.4% a history of hypertension [s3].

Over a mean 4.74 years of follow-up, the stroke rate was lower with the salt substitute: 29.14 versus 33.65 events per 1,000 person-years, a rate ratio of 0.86 (95% CI 0.77 to 0.96, P = 0.006) [s3]. Major cardiovascular events fell similarly, 49.09 versus 56.29 per 1,000 person-years (0.87, 0.80 to 0.94), and death from any cause was also lower [s3]. WHO now suggests replacing regular table salt with lower-sodium substitutes containing potassium, while noting all salt consumed should be iodised [s1].

The limits worth carrying

SSaSS was conducted in a high-risk rural Chinese population with high baseline sodium intake, most of whom had already had a stroke [s3]. Its results transfer least well to younger, healthier people in countries where most sodium is embedded in packaged food rather than added during cooking — a salt substitute cannot reduce the sodium already in bread. Potassium-containing substitutes are also not appropriate for everyone; SSaSS specified clinical hyperkalaemia as its safety outcome [s3].

The crossover trial ran for one week per arm and measured blood pressure, not events [s2]. And WHO's own figures show why individual advice will not move the aggregate much: the global mean is more than double the target, and the interventions WHO recommends are reformulation and labelling rather than anything a shopper does alone [s1].

This article is informational and is not medical advice. Sodium and potassium intake are clinical questions for anyone with kidney disease, heart failure, or on medications affecting potassium.

Sources

• Sodium reduction (fact sheet) — World Health Organization, updated 2026-05-11
• Effect of Dietary Sodium on Blood Pressure: A Crossover Trial — JAMA, 2023
• Effect of Salt Substitution on Cardiovascular Events and Death — The New England Journal of Medicine, 2021