Does Magnesium Lower Blood Pressure?

Magnesium is a mineral found in food, supplements, and some medicines. In 2022, the Food and Drug Administration (FDA) approved a qualified health claim allowing foods and supplements with magnesium to include information on their labels that “consuming diets with adequate magnesium may reduce the risk of high blood pressure,” but scientific “evidence is inconsistent and inconclusive.”

While some research has found magnesium reduces blood pressure, there are no conclusive results on how much magnesium to take or what form is best. Magnesium should come from food instead of supplements whenever possible.

This article will look at what magnesium does for the body, its benefits, and foods rich in magnesium. It will also discuss magnesium supplements and their side effects.

What Does Magnesium Do for the Body?

Magnesium plays an important role in keeping the body healthy. It helps to regulate blood pressure, blood sugar, and muscle and nerve function. It assists the body in making protein, bone, and DNA (genetic material).

Higher magnesium intake can help increase bone density, decreasing the risk of osteoporosis (reduced bone density and mass) and bone fractures. It also decreases type 2 diabetes risk and symptoms by helping to regulate blood sugar.

Magnesium Benefits

Blood pressure is raised when blood vessels become stiff and constricted. Magnesium is believed to help lower blood pressure because the mineral works to keep blood vessels relaxed. Magnesium also helps blood vessels stay healthy by working as an antioxidant to counteract blood vessel damage.

Some studies have found magnesium’s benefits in lowering blood pressure to be inconclusive or only providing a small benefit. Certain studies have shown stronger evidence that magnesium may lower blood pressure, but results differ on how much magnesium is needed to have an effect.

One study analyzed the results of 34 different clinical trials. It found that taking oral magnesium supplements significantly reduced blood pressure but was likely only effective in people already deficient in magnesium.

Another study analyzed the results of 49 clinical trials of oral magnesium supplements for high blood pressure. In looking at the 20 studies of people with untreated hypertension, they found that magnesium supplements of 600 milligrams (mg) per day or more were needed to lower blood pressure.

In the 10 studies of people who were being treated for hypertension but whose hypertension was uncontrolled, lowered blood pressure was seen at magnesium doses from 240 to 607 mg/day in the various studies. Studies that included people with controlled hypertension or without hypertension saw no blood pressure reduction with magnesium supplementation in this analysis.

Supplementing with magnesium has also been shown to reduce high blood pressure in people with diabetes (a condition resulting in high blood sugar, or glucose, levels), prediabetes (blood sugar levels not quite high enough to be considered diabetes), insulin resistance (when cells no longer respond well to the hormone insulin and can’t take up glucose from the blood, requiring more insulin), and heart disease.

Magnesium-Rich Foods

It’s recommended to get magnesium through natural foods instead of supplements or fortified foods (such as breakfast cereals) because natural food provides additional nutrients, including fiber, with numerous health benefits.

Foods that are rich in magnesium include:

• Pumpkin seeds
• Chia seeds
• Almonds
• Spinach
• Cashews
• Peanuts
• Black beans
• Edamame
• Peanut butter
• Potatoes

The Recommended Dietary Allowance (RDA) for magnesium is 400 mg for males ages 19 to 30 and 420 mg for males ages 31 and up. The RDA for females is 310 mg for ages 19 to 30 and 320 mg for ages 31 and up. (Note that the terms for sex or gender from the linked source are used in this article.)

Should I Take Magnesium Supplements?

More than half of Americans are low in dietary magnesium. Older adults and those with gastrointestinal (GI) diseases, type 2 diabetes, or long-term alcohol use disorder are more likely to get too little magnesium.

The Dietary Guidelines for Americans advise that dietary supplements may be considered in certain cases if you can’t meet the RDA for nutrients through food.

Magnesium supplements are available in various forms, and how well they are absorbed in the body varies.

Magnesium aspartate, chloride, oxide, pidolate, and amino-acid chelate were found to be effective at lowering blood pressure in people with uncontrolled high blood pressure who were also taking blood pressure–lowering medications. However, they were not effective in those with high blood pressure who were not taking blood pressure–lowering medications.

Some research has shown magnesium taurate is also effective in lowering blood pressure.

Magnesium Side Effects

Magnesium from food isn’t harmful in any quantity and doesn’t need to be limited.

It’s recommended that adults get no more than 350 mg per day of magnesium from dietary supplements or medications. Taking more than the recommended amount can cause diarrhea, nausea, abdominal cramps, and, at extremely high levels, irregular heartbeat.

For many age groups, the upper limit (UL) from supplements and medications appears to be lower than the RDA. This occurs because the RDAs include magnesium from all sources—food, beverages, dietary supplements, and medications. The ULs include magnesium from only dietary supplements and medications; they do not include magnesium found naturally in food and beverages.

Magnesium supplements can also interfere with how some medications work, including:

• Bisphosphonates (used to treat osteoporosis), including Fosamax (alendronate)
• Antibiotics, including tetracyclines such as Declomycin (demeclocycline) and Vibramycin (doxycycline), and quinolones such as Cipro (ciprofloxacin) and Levaquin (levofloxacin)
• Diuretics (water pills), including Lasix (furosemide), Bumex (bumetanide), Aquazide H (hydrochlorothiazide), Edecrin (ethacrynic acid), Midamor (amiloride), and Aldactone (spironolactone)
• Proton pump inhibitors (PPIs) (drugs used to treat ulcers or acid reflux), including Nexium (esomeprazole magnesium) and Prevacid (lansoprazole)

To avoid potential interactions and side effects, always check with a pharmacist or healthcare provider before starting to take magnesium supplements.

Summary

While some studies show that higher levels of magnesium may help lower blood pressure in
certain individuals, there is no conclusive or consistent data on its effectiveness or what dosage or form might be best.

Magnesium performs many important bodily functions and is best consumed through dietary sources. If you have trouble getting enough magnesium through food, supplements may be considered in some cases.

Because magnesium supplements can cause side effects and interact with certain medications, it’s always best to consult a healthcare practitioner before taking magnesium supplements.