Magnesium

What it is

Magnesium is a nutrient the body needs to stay healthy.

Source: NIH Office of Dietary Supplements: Magnesium - Consumer ↗

How it's thought to work

Magnesium helps run many body processes, including muscle and nerve function, blood sugar levels, and blood pressure.

Source: NIH Office of Dietary Supplements: Magnesium - Consumer ↗

What people use it for

Magnesium is also included in some laxatives and in some products for heartburn and indigestion. Magnesium therapy is used for migraine prevention, under the direction of a health care provider.

Sources: NIH Office of Dietary Supplements: Magnesium - Consumer ↗ · NIH Office of Dietary Supplements: Magnesium - Health Professional Fact Sheet ↗

What the research has found so far

• A review of studies found that magnesium supplements lowered diastolic blood pressure (the bottom number) by only a small amount.
• A review of studies found that each extra 100 mg a day of magnesium in the diet was linked to an 8% lower risk of stroke.
• A review of studies found that 100 mg more magnesium a day was linked to a 15% lower risk of diabetes.
• A 2021 review found that magnesium supplements may improve insulin sensitivity in people at high risk of diabetes.
• Experts at two neurology groups concluded that magnesium therapy is probably effective for preventing migraine.
• Several small studies found that magnesium supplements can modestly reduce how often migraines happen.

Sources: NIH Office of Dietary Supplements: Magnesium - Health Professional Fact Sheet ↗ · NCCIH (NIH): Diabetes and Dietary Supplements: What You Need To Know ↗ · NIH Office of Dietary Supplements: Magnesium - Consumer ↗

On Magnesium and aging, PubMed lists 131 trials in people, 239 studies that watched people over time, 11 animal and lab studies. See the counts and searches

Side effects and risks

• High intakes from supplements and medicines can cause diarrhea, nausea, and belly cramping.
• Extremely high intakes can lead to irregular heartbeat and cardiac arrest.
• Magnesium toxicity can cause low blood pressure, nausea, vomiting, facial flushing, urine retention, depression, and tiredness, then muscle weakness, trouble breathing, and cardiac arrest.
• Very large doses, more than 5,000 mg a day, can be deadly.

Sources: NIH Office of Dietary Supplements: Magnesium - Consumer ↗ · NIH Office of Dietary Supplements: Magnesium - Health Professional Fact Sheet ↗ · NCCIH (NIH): Diabetes and Dietary Supplements: What You Need To Know ↗

Who should be careful, and drug interactions

• The risk of magnesium toxicity rises with poor kidney function or kidney failure, since the body removes less excess magnesium.
• Magnesium-rich supplements or medicines can lower absorption of oral bisphosphonates, which treat osteoporosis.
• Antibiotics might not be absorbed if taken too soon before or after a magnesium supplement.
• Diuretics can either increase or decrease magnesium loss in urine, depending on the type.
• Prescription acid reflux and ulcer drugs can cause low blood magnesium when taken over a long period.
• Very high doses of zinc supplements can interfere with how the body absorbs and regulates magnesium.

Sources: NIH Office of Dietary Supplements: Magnesium - Health Professional Fact Sheet ↗ · NIH Office of Dietary Supplements: Magnesium - Consumer ↗

Amounts used in studies

What studies or labels describe, not a recommendation.

Studies of blood pressure have used magnesium doses from about 243 to 973 mg a day. Supplements come in forms including magnesium oxide, citrate, and chloride.

Source: NIH Office of Dietary Supplements: Magnesium - Health Professional Fact Sheet ↗

Roughly what it costs

The 3 products we list that contain Magnesium cost from $21.99 to $26, as read from the makers' pages. See the products

Questions to ask your doctor

• Is Magnesium a sensible option for me, given my health and the medicines I take?
• Could Magnesium interact with any medicine or supplement I already take?
• What side effects should I watch for, and when should I stop or call you?
• Supplements aren't checked by the FDA before sale. Is there a brand or a third-party test seal you would trust?
• How would we tell whether it is helping, and when should we review it?