Minerals and Blood Pressure: Potassium, Magnesium, Calcium and Sodium Compared
What meta-analyses and trials found for sodium, potassium, magnesium and calcium and blood pressure, how food differs from pills, and who needs a clinician first.
Content last updated . This page has not been medically reviewed.
What the research found
| Mineral | What the source found | Label |
|---|---|---|
| Sodium (lowering it) | A Cochrane review of sodium-reduction trials found the biggest drop in people with high blood pressure, and a small one in people with normal readings [1] | Established recommendation |
| Potassium (raising it) | A meta-analysis of 22 trials found lower blood pressure in people with hypertension but not in those without [2] | Promising, with good-quality trials in hypertension |
| Magnesium (supplements) | A meta-analysis of 34 placebo-controlled trials found small average reductions [3] | Promising but limited |
| Calcium (supplements) | A Cochrane review in people with normal blood pressure found small average reductions [4] | Promising but limited |
Sodium
The 2020 Cochrane review included 195 references. In white participants, cutting sodium from about 203 to 65 mmol a day lowered systolic blood pressure (the top number) by 1.14 mmHg in people with normal pressure and by 5.71 mmHg in people with hypertension. [1] The authors translated this to a mean arterial pressure fall of about 4 mmHg in people with hypertension. [1]The same review also recorded rises in the hormone aldosterone and in cholesterol during sodium reduction. [1] The abstract we read does not say what those changes mean for health, so treat them as an open question rather than a verdict.
Official advice: the World Health Organization recommends adults take in less than 2000 mg of sodium a day, equal to less than 5 g of salt, and notes that 1 gram of salt equals 400 mg of sodium. [5] The NHS (UK) says no more than 6 g of salt (2.4 g of sodium) a day. [6] The DASH eating plan from the US National Heart, Lung, and Blood Institute lists 2,300 mg of sodium a day and says 1,500 mg lowers blood pressure further. [7]
Potassium
The BMJ meta-analysis pooled 22 randomized trials (1,606 participants). Higher potassium intake lowered systolic pressure by 3.49 mmHg overall, an effect seen in people with hypertension but not in those without it. [2] It also found no significant harm to kidney function, blood lipids or stress-hormone levels in adults. [2] In cohort studies, higher intake went with a 24% lower stroke risk, which is observational and cannot prove cause. [2]Salt substitutes are one way potassium reaches people. The SSaSS trial gave villages in rural China a salt substitute (75% sodium chloride, 25% potassium chloride) or regular salt. Participants had a history of stroke or were 60 or older with high blood pressure. [8] Stroke was less common with the substitute (rate ratio 0.86), and serious events attributed to high potassium were not significantly higher. [8] The trial was open-label (people knew which salt they used). [8] Who should avoid potassium-based substitutes is covered in salt substitutes and blood pressure.
Magnesium
The 2016 meta-analysis of 34 trials (2,028 participants) found that magnesium at a median of 368 mg a day for a median of 3 months lowered systolic pressure by 2.00 mmHg. [3] The authors noted that differences between trials may still be affecting the result. [3] The abstract gives milligrams of magnesium without saying whether this is elemental magnesium or compound weight, so compare labels carefully. See magnesium, blood pressure and diabetes.Calcium
The Cochrane review of calcium supplements in people with normal blood pressure included 20 trials (3,512 participants). [4] Systolic pressure fell by 1.37 mmHg and diastolic by 1.45 mmHg on average, rated high-certainty evidence for the pooled result. [4] That is a very small change. For calcium pills in people who already have hypertension, Proper evidence not found: a PubMed search for Cochrane reviews of calcium and hypertension returned this review and pregnancy-related ones only.Food or supplements?
The DASH eating plan is built around vegetables, fruit, whole grains and low-fat dairy, and describes food rich in potassium, calcium, magnesium, fiber and protein. [7] It is a whole eating pattern, so its effect cannot be credited to any single mineral. Most of the pill findings above came from specific amounts in trials, not from advice for the general public.Official intake levels (UK, adults 19 to 64, NHS, page reviewed 2020)
| Mineral | Amount the NHS gives | Source |
|---|---|---|
| Potassium | 3,500 mg a day needed; 3,700 mg or less from supplements is unlikely to have obvious harmful effects [6] | NHS, 2020 |
| Magnesium | 300 mg (men), 270 mg (women) a day; 400 mg or less from supplements unlikely to cause harm [6] | NHS, 2020 |
| Calcium | 700 mg a day; 1,500 mg or less unlikely to cause harm [9] | NHS, 2020 |
US and EU figures differ. We could not read the US National Institutes of Health fact sheets this session, so no US figure is given here.
Frequently asked questions
Does potassium lower blood pressure?
In a meta-analysis of 22 trials, higher potassium intake lowered blood pressure in people with hypertension but not in those without it. [2]
Does magnesium lower blood pressure?
A 2016 meta-analysis found an average systolic drop of 2.00 mmHg, with caveats about differences between trials. [3]
Does calcium lower blood pressure?
In people with normal blood pressure, a Cochrane review found a small average fall of about 1.4 mmHg. [4]
Is cutting salt worth it if my blood pressure is normal?
The Cochrane review found a much smaller drop in people with normal pressure (1.14 mmHg systolic) than in people with hypertension (5.71 mmHg). [1]
Who should be careful with potassium salt substitutes or pills?
The NHS says older people may be at more risk because their kidneys may remove potassium less well. [6] Anyone with kidney problems or on regular medicines should ask a clinician or pharmacist first.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: established recommendation, promising but limited, mixed, insufficient evidence. Where we looked and found nothing usable, we say "Proper evidence not found".
Safety
- Kidney disease and potassium. The NHS says older people may be at more risk because their kidneys may remove potassium less well, and should not take potassium supplements unless a doctor advises it. [6] See high potassium and kidney disease and minerals and kidney disease.
- Medicines. If you take medicines for blood pressure, the heart or the kidneys, ask a pharmacist before adding any mineral: medication interactions. The sources we read for this page do not list specific interactions.
- Pregnancy, children, liver conditions and surgery. The sources we read for this page do not cover these groups, so ask a clinician before using supplements.
- Quality. Pills vary in what they contain: quality testing and certifications.
References
- Graudal NA and others. Effects of low sodium diet versus high sodium diet on blood pressure, renin, aldosterone, catecholamines, cholesterol, and triglyceride. Cochrane Database of Systematic Reviews 2020. PubMed abstract (PMID 33314019). Read 2026-10-23.
- Aburto NJ and others. Effect of increased potassium intake on cardiovascular risk factors and disease: systematic review and meta-analyses. BMJ 2013. PubMed abstract (PMID 23558164). Read 2026-10-23.
- Zhang X and others. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension 2016. PubMed abstract (PMID 27402922). Read 2026-10-23.
- Cormick G and others. Calcium supplementation for prevention of primary hypertension. Cochrane Database of Systematic Reviews 2022. PubMed abstract (PMID 35014026). Read 2026-10-23.
- World Health Organization. Salt reduction (fact sheet). Read 2026-10-23.
- NHS (UK). Vitamins and minerals: Others (magnesium, potassium, selenium, salt, zinc, chromium, copper). Page last reviewed 3 August 2020. Read 2026-10-23.
- NHLBI, NIH (US). DASH eating plan. Page updated 25 February 2026. Read 2026-10-23.
- Neal B and others. Effect of salt substitution on cardiovascular events and death (SSaSS trial). New England Journal of Medicine 2021. PubMed abstract (PMID 34459569). Read 2026-10-23.
- NHS (UK). Vitamins and minerals: Calcium. Page last reviewed 3 August 2020. Read 2026-10-23.