What Happens to Your Blood Pressure When You Take Magnesium

• Magnesium may help lower blood pressure, but results are mixed. Research suggests it may benefit people with high blood pressure or a magnesium deficiency.
• Magnesium supports other aspects of health, such as blood sugar, muscle and nerve function, bone health, and energy production.
• Food sources are best. Include magnesium-rich foods, such as seeds, nuts, beans, and leafy greens, in your diet.

Magnesium plays a key role in keeping blood vessels relaxed, which may help lower blood pressure.1 However, research is mixed on how much magnesium you need for this effect and whether supplements actually work.

Does Magnesium Lower Blood Pressure?

Magnesium is believed to help lower blood pressure by keeping blood vessels relaxed. Magnesium also helps maintain healthy blood vessels by acting as an antioxidant to counteract damage to the blood vessels.

Some studies report that magnesium’s effect on lowering blood pressure is inconclusive or minimal. Others show stronger evidence of a benefit, but findings vary on the amount of magnesium required to see an effect.

Research findings suggest that magnesium may:

• Lower blood pressure in people who are magnesium deficient: An analysis of 34 studies found that taking magnesium significantly lowered blood pressure, but its effectiveness was likely limited to those with a deficiency.2
• Lower blood pressure in those with untreated hypertension (high blood pressure).3
• Reduce blood pressure in people with uncontrolled but treated hypertension.3

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)
• Heart disease

Magnesium showed no benefit for people with controlled hypertension or normal blood pressure.

What Does Magnesium Do for the Body?

Magnesium is a mineral found in food, supplements, and some medicines. It plays an important role in:

• Regulating blood pressure, blood sugar, and muscle and nerve function
• Making protein, bone, and DNA (genetic material)5
• Keeping bones healthy by increasing body density, decreasing the risk of osteoporosis (reduced bone density and mass) and bone fractures

National Institutes of Health Office of Dietary Supplements. Magnesium: fact sheet for consumers.

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.”

Magnesium-Rich Foods to Add to Your Diet

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.

Should I Take Supplements?

Ideally, you can get the vitamins and minerals your body needs with a nutrient-dense diet.7 However, dietary supplements may be necessary in some cases if you can’t meet the RDA for nutrients through diet alone.9 Lab tests can determine if you’re deficient in magnesium.

Magnesium deficiency is more likely to occur in those:

• 65 years and older
• With gastrointestinal diseases
• With type 2 diabetes
• With long-term alcohol use disorder

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist (RD or RDN), pharmacist, or healthcare provider. These supplements can cause side effects and interact with certain medications. No supplement is intended to treat, cure, or prevent disease.

Potential 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
• At extremely high levels, irregular heartbeat

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

• Bisphosphonates (used to treat osteoporosis), including Fosamax (alendronate)
• Antibiotics, including tetracyclines such as demeclocycline and Vibramycin (doxycycline), and quinolones such as Cipro (ciprofloxacin) and 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. (verywellhealth)