Does magnesium supplementation lower blood pressure?

How much does magnesium actually lower blood pressure?

The most comprehensive evidence comes from a 2025 meta-analysis of 38 randomized controlled trials involving 2,709 participants. It found that magnesium supplementation reduced systolic blood pressure (the top number) by an average of 2.81 mmHg and diastolic blood pressure (the bottom number) by 2.05 mmHg compared to placebo [1]. These are modest but real reductions — similar to what you might expect from cutting back on salt or increasing physical activity.

The effect was much larger in specific groups. People with hypertension who were already taking blood pressure medication saw an average systolic reduction of 7.68 mmHg, and those with low magnesium levels (hypomagnesemia) saw a reduction of 5.97 mmHg [1]. This suggests that magnesium is most helpful for people who are deficient or already have elevated blood pressure.

An umbrella meta-analysis from 2024, which pooled results from 10 earlier review papers covering 8,610 participants, confirmed a significant but smaller overall reduction: systolic blood pressure dropped by about 1.25 mmHg and diastolic by 1.40 mmHg [2]. The difference in numbers between the two analyses likely reflects differences in how they combined the data, but both point in the same direction: magnesium works, but the effect is modest for the average person.

Who gets the biggest benefit from magnesium supplements?

The evidence clearly shows that magnesium supplementation is most effective for people with hypertension (high blood pressure) or low magnesium levels. In the 2025 meta-analysis, people with hypertension who were already on blood pressure medication experienced a systolic reduction of 7.68 mmHg — more than double the average effect [1]. Similarly, those with hypomagnesemia (low blood magnesium) saw a 5.97 mmHg reduction [1]. In contrast, people with normal blood pressure did not show a statistically significant reduction [1][3].

This pattern makes physiological sense: if your magnesium levels are already adequate, adding more may not move the needle much. But if you're deficient — which is common in Western diets due to food processing — supplementation can correct that deficiency and help relax blood vessels, which lowers pressure [6].

A 2023 cross-sectional study of over 24,000 US adults found that higher dietary magnesium intake was associated with a 34% lower prevalence of hypertension (odds ratio 0.66) after adjusting for lifestyle factors [5]. This doesn't prove causation, but it supports the idea that magnesium plays a role in blood pressure regulation across the population.

What dose and how long does it take to work?

The studies used a wide range of doses, from about 82 mg to 637 mg of elemental magnesium per day, with a median dose around 365 mg [1]. The umbrella meta-analysis found that doses of 400 mg per day or more produced the largest reductions — systolic blood pressure dropped by 6.38 mmHg and diastolic by 3.71 mmHg at these higher doses [2]. This suggests that a daily dose of at least 300–400 mg of elemental magnesium is likely needed for a meaningful effect.

Duration matters too. Most trials lasted about 12 weeks, and the umbrella analysis found that supplementation for 12 weeks or longer was associated with significant blood pressure reductions [2]. A 2022 trial in people with prediabetes using 250 mg of magnesium oxide for 12 weeks did not find a significant blood pressure effect [4], which may be because the dose was lower or the population was not hypertensive.

Importantly, the 2025 meta-analysis did not find a clear dose-response relationship — meaning that taking more magnesium didn't necessarily lead to greater blood pressure reductions across the whole group [1]. This could be because individual responses vary, or because the studies were too different to detect a pattern. The practical takeaway: aim for a moderate daily dose (300–400 mg) for at least 3 months, and monitor your blood pressure to see if it works for you.

About These Sources

This answer is built on 6 peer-reviewed studies — published from 2022 to 2025, 3 from 2024 or later, 4 in Q1 journals, collectively cited 59 times — selected as the most relevant from 15 studies that passed quality screening, drawn from 69 papers retrieved from a database of over 500 million.

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