Magnesium is found throughout your body. Every cell in your body contains this mineral and needs it to function. About 60% of the magnesium in your body occurs in bone, while the rest is in muscles, soft tissues, and fluids, including blood. One of its main roles is to act as a cofactor — a helper molecule — in the biochemical reactions continuously performed by enzymes. It’s involved in more than 600 reactions in your body. However, many people get less than they need.

You may need more magnesium during exercise than when you’re resting, depending on the activity. Magnesium helps move blood sugar into your muscles and dispose of lactate, which can build up during exercise and cause fatigue. Studies show magnesium supplements may be particularly beneficial for improving exercise performance in older adults and those with a deficiency in this nutrient. 

Magnesium plays a critical role in brain function and mood; low levels are linked to an increased risk of depression. A 2020 review suggested that stress may deplete magnesium, increasing susceptibility to stress and depression. What’s more, supplementing with this mineral may help reduce symptoms of depression. In one small 8-week study, taking 500 mg of magnesium daily led to significant improvements in symptoms of depression in people with a deficiency in this mineral. 

Studies suggest that about 48% of people with type 2 diabetes have low blood levels of magnesium, which may impair the body’s ability to regulate blood sugar levels effectively. Additionally, research indicates that people who consume more magnesium have a lower risk of type 2 diabetes.

Magnesium plays an important role in keeping your heart healthy and strong. A 2021 review shows that magnesium supplements can help lower high blood pressure levels, which may be a risk factor for heart disease. Another review linked high magnesium intake to a lower risk of heart disease, stroke, and high blood pressure.

Low magnesium intake is linked to increased levels of inflammation, which plays a crucial role in aging and chronic disease. One review of 11 studies concluded that magnesium supplements decreased levels of C-reactive protein (CRP), a marker of inflammation, in people with chronic inflammation. Other studies report similar findings, showing that magnesium supplements may reduce CRP and other markers of inflammation, such as interleukin-6.

Migraine headaches can be painful and often cause nausea, vomiting, and sensitivity to light and noise. Some researchers believe that people with migraine are more likely than others to have a magnesium deficiency. Several studies suggest that magnesium may even prevent and treat migraine headaches.

Premenstrual syndrome (PMS) is one of the most common conditions in female-bodied people of childbearing age. It often causes symptoms such as water retention, abdominal cramps, tiredness, and irritability. Some research suggests that magnesium supplements help relieve PMS symptoms and other conditions such as menstrual cramps and migraine attacks.

Magnesium is crucial for maintaining bone health and protecting against bone loss. In fact, 50–60% of your body’s magnesium is found in your bones. Some studies associate lower levels of this mineral with a higher risk of osteoporosis, which causes bones to become brittle and weak. A 3-year study in 358 people undergoing hemodialysis — a treatment to help remove waste and water from the blood — showed that those who consumed the least magnesium experienced three times more fractures than those with the highest intake.

Magnesium supplements are often used as a natural remedy for sleep issues such as insomnia. This is because magnesium regulates several neurotransmitters involved in sleep, such as gamma aminobutyric acid. One review of older adults with insomnia found that magnesium supplements lowered the amount of time it took people to fall asleep by an average of 17 minutes. 

Some research suggests that magnesium helps treat and prevent anxiety. For example, one study of 3,172 Iranian adults associated increased magnesium intake with a lower risk of depression and anxiety. Similarly, a small 6-week study found that taking 248 mg of magnesium daily significantly reduced anxiety symptoms. Other research suggests that magnesium deficiency may increase your body’s susceptibility to stress, which may amplify symptoms of anxiety.