Can Magnesium Supplements Help Lower Your Blood Pressure?

Almost half of the adults in the United States have high blood pressure. And many people are curious about ways — beyond prescription medication — to lower their blood pressure. 

This includes foods, drinks, and supplements. Magnesium is a dietary supplement touted to have heart and blood pressure benefits. But is it really helpful? Let’s take a look at the evidence. 

How are magnesium and blood pressure related? 

There are two main ways that magnesium affects blood pressure:

1. Magnesium counterbalances the effects of calcium on your blood vessels. Calcium helps blood vessels to constrict. When this happens, your blood pressure goes up. But magnesium binds to the blood vessel wall instead of the calcium. This keeps your blood vessels from tightening, and keeps your blood pressure lower. 

2. Magnesium prevents injury to your blood vessel walls. It’s normal for blood vessels to have some wear and tear over time. And this causes the blood vessels to become stiffer, which causes your blood pressure to be higher. Magnesium helps bind up harmful substances that injure your blood vessels, and may help some in the repair process.

But just because magnesium plays a role in blood pressure regulation, does that mean that taking extra magnesium will lower your blood pressure? Let’s take a look.

What does the research say about magnesium and low blood pressure? 

Studies suggest that magnesium supplements can help lower your blood pressure.

One large review of several different studies on magnesium showed a small but noticeable reduction in blood pressure. Researchers looked at a range of different magnesium dosages and found that magnesium supplements lowered both systolic and diastolic blood pressure. 

Here are a few important takeaways:

• Magnesium supplements lowered blood pressure by just a few points. 

• The effect on blood pressure increased at doses over 370 mg per day. 

• It typically took about 3 to 4 weeks for people to see an effect. 

A more recent review study in 2021 showed that certain people may benefit more from magnesium supplements than others. More specifically, magnesium is more likely to lower someone’s blood pressure if they have high blood pressure that’s not controlled. Researchers saw this effect at dosages:

• Above 240 mg per day when someone was already taking a blood pressure medication 

• Above 600 mg for those who were not taking any blood pressure medications 

Does this mean that low levels of magnesium in your blood can cause high blood pressure? There’s less research on this topic. A study in rats showed that very low levels of magnesium made it more likely for the rats to have higher blood pressure. But there’s limited evidence on whether this is true in humans. 

Does magnesium have other benefits for your heart health? 

Besides direct benefits to your blood pressure, magnesium may be beneficial to your health in other ways. Research suggests it may:

• Decrease risk for heart disease: Magnesium helps to keep blood vessel walls healthy. It prevents injury and stiffness (atherosclerosis) of your blood vessels that leads to heart disease. 

• Decrease risk for stroke: The studies here are more limited. But increasing your intake of magnesium by 100 mg a day could decrease your risk of strokes that happen from atherosclerosis by 8%.

• Help insulin work better: Magnesium can help the natural insulin in your body work more effectively. This can be particularly helpful for people who have or are at risk for diabetes. 

• Help with mood: While more study in this area is needed, some research suggests that magnesium may help with depressive symptoms. And that people with lower magnesium levels may be more likely to develop depression. 

What are the side effects of taking magnesium? 

It’s important to keep in mind that there can also be some side effects from magnesium supplements. They can include:

• Diarrhea

• Nausea

• Abdominal pain

• Low blood pressure

But most people tolerate magnesium supplements well. In fact, there have been studies looking at magnesium dosages of up to 972 mg per day that didn’t result in significant adverse effects. 

How much magnesium do you need? 

The recommended amount of magnesium is:

• 420 mg per day in male adults

• 320 mg per day in female adults

In the studies looking at blood pressure reduction, a dosage of at least 370 mg per day was needed. And in the most recent review, dosages over 600 mg per day showed more benefit. Magnesium supplements come in many forms. But from the studies, the type of magnesium is less important than the actual dosage (number of milligrams a day). 

If you’re considering taking more than the recommended daily supplement dosage, it’s best to consult with your healthcare provider to make sure this is safe to do with your other health conditions and medications. 

Sarah Samaan, MD, FACC, FACP, FASE, a board-certified cardiologist for over 30 years, says that when it comes to taking supplements it's better to get vitamins and minerals from food.

“That's because your body can usually absorb these nutrients more easily when they come from the diet,” Samaan says. “Plus, magnesium-rich foods are full of good nutrition, including fiber and antioxidants.”

Samaan recommends doing a blood test first if you’re considering taking a magnesium supplement. 

“Some conditions, including kidney problems, can affect the way your body handles magnesium,” she says.

Foods that contain magnesium

Most people don’t need a magnesium supplement to keep their magnesium level in a healthy range. And while dietary magnesium may not improve blood pressure in people who have hypertension, there’s some evidence to suggest it may help somewhat in preventing high blood pressure. 

There are many foods that are rich in magnesium. Some examples include:

• Beans

• Nuts

• Green leafy vegetables

• Breakfast cereals and breads 

• Whole grains

• Soy and soy-based foods

• Dairy products like yogurt

• Bananas

Because there are so many different foods that are rich in magnesium, it’s likely that most people can get what they need from their diets. 

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Written by:

Jill L. Jaimes, MD

Jill L. Jaimes, MD, is a board-certified pediatric emergency medicine physician with over 20 years of clinical experience. She received her medical degree from Baylor College of Medicine and completed her residency and fellowship training at Texas Children’s Hospital.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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