Magnesium barely moves the needle for healthy adults. But in people who already take blood pressure medication, the same supplement was linked to a systolic drop of nearly 8 mmHg, according to a new pooled analysis of 38 randomized trials.
The meta-analysis was published in Hypertension, the American Heart Association journal.
A team at the University of New South Wales in Sydney combined 38 randomized controlled trials covering 2,709 participants and compared magnesium supplementation against placebo.
Where the effect was largest
Across all participants, magnesium cut systolic blood pressure by 2.81 mmHg and diastolic by 2.05 mmHg. That is a small, if statistically meaningful, shift.
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The subgroup analyses tell a more interesting story. Among people already on antihypertensive medication, systolic blood pressure fell by 7.68 mmHg and diastolic by 2.96 mmHg.
Among participants with low blood magnesium, known as hypomagnesemia, the reductions were 5.97 and 4.75 mmHg.
In healthy adults with normal blood pressure, magnesium showed no statistically significant effect.
The authors call the drop in medicated patients clinically important, pointing to earlier work showing that a 5 mmHg cut in systolic pressure lowers the risk of major cardiovascular events by roughly 10 percent.
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Dose and duration in the trials
The trials used doses of elemental magnesium ranging from 82.3 to 637 mg, with a median of 365 mg per day. The median treatment length was 12 weeks.
One notable finding: higher doses did not translate into bigger drops.
The researchers reported no dose-response relationship, meaning blood pressure reductions stayed roughly constant as doses climbed.
The authors also cautioned that heterogeneity between studies was high, so results should be read as directional rather than final.
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Talk to your doctor before adding magnesium
The analysis does not license anyone to swap or skip prescribed medication.
Blood pressure drugs are the backbone of treatment, and missing more than one in five doses can erase most of the heart benefit.
Magnesium supplements can also interact with certain medications, including some antibiotics and diuretics, so the practical step is a conversation with a doctor or pharmacist before starting.
That conversation may be worth having for many Americans. According to the Centers for Disease Control and Prevention, close to half of US adults have high blood pressure, and nearly half of Americans fall short on magnesium intake from food alone.
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Food first, if you can
The Harvard T.H. Chan School of Public Health notes that magnesium helps regulate blood pressure, though the FDA has called the overall evidence for supplements inconsistent and inconclusive.
The Recommended Dietary Allowance for adults sits between 310 and 420 mg per day, depending on age and sex, an amount reachable through food.
According to Cleveland Clinic, an ounce of hulled pumpkin seeds delivers about 150 mg of magnesium, an ounce of almonds around 80 mg, a half cup of cooked spinach 78 mg, and a half cup of black beans 60 mg. Chia seeds, cashews, edamame, avocado, and dark chocolate round out the list.
A typical starting dose in the trials was 365 mg per day for about three months. Anyone on blood pressure medication who is considering that step should bring the study to their next appointment rather than start on their own.
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This article is made and published by Mie Hermansen, who may have used AI in the preparation.