A mix of nuts, seeds and dried fruit including walnuts, pecans, pistachios and almonds

Does Magnesium Lower Blood Pressure?

9 min read

Magnesium is one of the most popular supplements on the shelf, and lowering blood pressure is one of the main reasons people reach for it. The mineral is involved in how blood vessels relax, so the idea is reasonable. The question is whether taking more of it moves the number on the cuff.

The honest answer from the trials is yes, a little. Across dozens of randomised controlled trials the average drop is small. For some groups, though, it is large enough to matter, and that is where the detail counts.

Here is what the evidence says magnesium does to blood pressure, who gets the biggest effect, how much you need, and why food should come before a pill.

2.8 mmHg
Lower systolic blood pressure on average
2025 Hypertension review, 38 RCTs
7.7 mmHg
Lower systolic BP in adults on BP medication
Argeros 2025, hypertensive subgroup
368 mg/day
Median dose that lowered blood pressure
Zhang 2016 review, 34 trials
300 mg
UK daily magnesium target for men, 270 mg for women
NHS recommendation

Sources: Argeros Z et al. Hypertension 2025. Zhang X et al. Hypertension 2016. NHS, Vitamins and minerals.

The honest answer: a small average drop

The best current summary is a 2025 systematic review and meta-analysis in the journal Hypertension by Argeros and colleagues. The team pooled 38 randomised controlled trials covering 2,709 participants, with magnesium doses from 82 mg up to 637 mg a day, a median dose of 365 mg, and a median trial length of 12 weeks.

Across all of those trials, magnesium lowered systolic blood pressure, the top number, by 2.81 mmHg (95% confidence interval 1.29 to 4.32) and diastolic pressure, the bottom number, by 2.05 mmHg (95% confidence interval 0.88 to 3.23) compared with placebo. In plain terms, the average effect is a drop of roughly 2 to 3 mmHg. That is modest, well short of what a blood pressure medication delivers.

A small average is not the same as a pointless one. Blood pressure sits on a continuous scale, so even a slight reduction is still worth having, especially when it stacks on top of the bigger changes. The honest way to see magnesium is as a minor contributor, not a substitute for the main drivers of blood pressure.

Who gets the biggest effect

The average hides the most useful finding. The 2025 review split the trials by group, and the effect was far from even. In people who already had high blood pressure and were on BP-lowering medication, magnesium lowered systolic pressure by 7.68 mmHg. In people with hypomagnesemia, meaning low blood magnesium to begin with, it lowered systolic pressure by 5.97 mmHg. In people with normal blood pressure, the change did not reach statistical significance.

That pattern is the practical heart of the topic. Magnesium behaves less like a general tonic and more like a correction. The further your starting point sits from where it should be, through raised pressure or a genuine shortfall of the mineral, the more room there is to move. If your blood pressure and your magnesium status are already fine, the trials suggest a supplement does little for your numbers.

Systolic blood pressure drop with magnesium, by group
Fall in systolic pressure (mmHg) All adults 2.8 Low in magnesium 6.0 On BP medication 7.7 Average effect is small. It grows where BP is high or magnesium is low.
Systolic reductions versus placebo, rounded. Values 2.81, 5.97 and 7.68 mmHg. Source: Argeros Z et al. Hypertension 2025, 38 randomised controlled trials.

Two reviews, one consistent signal

The 2025 analysis is not alone. An earlier meta-analysis in the same journal, by Zhang and colleagues in 2016, pooled 34 randomised, double-blind, placebo-controlled trials covering 2,028 participants. At a typical dose of 368 mg a day over about three months, magnesium lowered systolic pressure by 2.00 mmHg and diastolic pressure by 1.78 mmHg.

Two independent teams, nearly a decade apart, landed on the same place: a real but modest average fall of around 2 mmHg in systolic pressure. The Zhang review went further and concluded that the data "indicate a causal effect of Mg supplementation on lowering BPs in adults." Agreement between reviews is what turns a single hopeful result into a dependable one.

Average systolic drop found by each review
Fall in systolic pressure (mmHg) 2.0 2016 review 34 trials, 2,028 people 2.8 2025 review 38 trials, 2,709 people
Pooled systolic reductions versus placebo. Sources: Zhang X et al. Hypertension 2016 (2.00 mmHg). Argeros Z et al. Hypertension 2025 (2.81 mmHg).

How magnesium may lower pressure

The mechanism is plausible, which is part of why the finding holds up. Magnesium acts as a natural counterweight to calcium inside the smooth muscle that lines artery walls. Calcium drives those muscles to contract and narrow the vessel. Magnesium opposes that action, which lets it relax a little and widen. Blood-pressure drugs called calcium channel blockers work on the same system from a different angle.

Magnesium also supports the lining of blood vessels, the endothelium, which releases nitric oxide to help vessels dilate. When magnesium is low, that relaxing signal tends to weaken. The Zhang review noted that the fall in blood pressure tracked with a rise in blood magnesium, which fits the idea that correcting a shortfall is where most of the benefit sits. These are proposed pathways rather than settled fact, so treat them as the reason the numbers make sense, not as a guarantee.

How much, and from food first

The NHS sets the daily requirement at 300 mg for men and 270 mg for women aged 19 to 64. Most of the trials that moved blood pressure used a bit more than that as a supplement. The 2025 review reported a median dose of 365 mg a day, and the 2016 review a median of 368 mg. Zhang and colleagues added that around 300 mg a day was enough to raise blood magnesium and begin lowering pressure, with the benefit appearing within about a month.

Food is the sensible starting point, because magnesium comes packaged with fibre, potassium and other nutrients that help the heart in their own right. The NHS lists spinach, nuts and wholemeal bread among good sources. Add pumpkin seeds, beans, lentils and wholegrains, and a daily target is well within reach from the plate. A diet built this way also raises potassium, which has its own blood-pressure benefit, so the gains compound.

If you do choose a supplement, keep the dose sensible. The NHS advises that 400 mg or less a day of magnesium from supplements is unlikely to cause harm, and that higher short-term doses can cause diarrhoea. More is not better here, and the trials give no reason to chase large amounts.

A practical plan

1. Fill the plate before the pillbox
Build meals around magnesium-rich foods: dark leafy greens, nuts, seeds, beans, lentils and wholegrains. Food delivers the mineral alongside fibre and potassium, which support blood pressure in their own right.
2. Match the expectation to the group
If your blood pressure is raised or your magnesium is genuinely low, expect a worthwhile drop. If both are already healthy, expect very little change in the number.
3. Keep any supplement modest
If you use a supplement, a dose in the range used by the trials, around 300 to 365 mg a day, covers it. The NHS flags 400 mg a day from supplements as the point to stay under. Larger doses add side effects, not benefit.
4. Stack it on the bigger changes
Magnesium is a minor addition. The large moves on blood pressure come from losing excess weight, cutting salt, staying active, moderating alcohol and taking prescribed medication. Treat magnesium as a top-up, not a swap.

Who should be cautious

For most healthy adults, magnesium from food carries no risk and a modest supplement is well tolerated. Two groups should take more care. People with reduced kidney function clear magnesium less well, so it can build up to unsafe levels, and they should only supplement under medical advice. Magnesium can also interact with some medicines, including certain antibiotics and drugs for osteoporosis, by changing how they are absorbed.

If you already take blood-pressure medication, do not change it on the strength of a supplement. Speak to your GP or pharmacist first, keep taking what you are prescribed, and let them guide any adjustment based on your actual readings.

Common mistakes

  • Treating it as a drug. The average drop is around 2 to 3 mmHg. That helps at the margins, but it will not control high blood pressure on its own.
  • Chasing a high dose. The trials used moderate amounts. Going well above 400 mg a day from supplements brings diarrhoea, not a bigger effect.
  • Skipping food sources. Reaching for a tablet while ignoring greens, nuts and wholegrains misses the nutrients that travel with magnesium and help the heart.
  • Stopping prescribed medication. No supplement replaces a blood-pressure drug. Any change belongs with your GP, guided by real readings.

Frequently asked questions

How much does magnesium actually lower blood pressure?
Across 38 trials in the 2025 Hypertension review, magnesium lowered systolic pressure by 2.81 mmHg and diastolic by 2.05 mmHg on average. The effect was larger in people on blood-pressure medication, at 7.68 mmHg systolic, and in those with low magnesium, at 5.97 mmHg.
What type of magnesium is best?
The trials used several forms, and no single salt stands out for blood pressure. Well-absorbed forms such as magnesium citrate are a reasonable choice. The dose and your starting magnesium status matter more than the exact form.
Can I get enough magnesium from food?
Yes, for most people. Spinach, nuts, seeds, beans, lentils and wholemeal bread are all good sources, and a varied diet meets the 300 mg target for men and 270 mg for women set by the NHS. Food also delivers potassium and fibre that help blood pressure.
Is a magnesium supplement safe?
For healthy adults, 400 mg or less a day from supplements is unlikely to cause harm, per the NHS, while higher short-term doses can cause diarrhoea. People with kidney problems or those on certain medicines should check with a GP or pharmacist first.
Will it help if my blood pressure is already normal?
Probably not much. In the 2025 review, the reduction in people with normal blood pressure did not reach statistical significance. Magnesium works best as a correction for raised pressure or a genuine shortfall, so a healthy starting point leaves little to gain.

Bottom line

Magnesium does lower blood pressure, by a small average amount of around 2 to 3 mmHg, and two large reviews agree on it. The gain is bigger for the people with the most room to move, those on blood-pressure medication and those who are genuinely low in the mineral, and close to nothing for people whose pressure and magnesium are already fine. Build your intake from food first, keep any supplement modest and under 400 mg a day, and treat magnesium as a useful top-up to the main changes rather than a replacement for them.

Work with DT Fitness London

Diet and training move blood pressure far more than any single supplement. For a plan that pulls the big levers together, book a consultation at www.dtfitnesslondon.com.

Dushyanta Tomar, MSc Applied Sport and Exercise Physiology, CIMSPA Accredited Personal Trainer.

Sources

  • Argeros Z, Xu X, Bhandari B, Harris K, Touyz RM, Schutte AE. Magnesium Supplementation and Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Hypertension. 2025, vol 82, issue 11, pages 1844 to 1856. PMID 41000008. pubmed.ncbi.nlm.nih.gov/41000008
  • Zhang X, Li Y, Del Gobbo LC, Rosanoff A, Wang J, Zhang W, Song Y. Effects of Magnesium Supplementation on Blood Pressure: A Meta-Analysis of Randomized Double-Blind Placebo-Controlled Trials. Hypertension. 2016, vol 68, issue 2, pages 324 to 333. PMID 27402922. pubmed.ncbi.nlm.nih.gov/27402922
  • NHS. Vitamins and minerals: Others (including magnesium). nhs.uk/conditions/vitamins-and-minerals/others
Back to blog