Magnesium

What it is

Magnesium is a mineral your body needs for energy production, muscle and nerve signaling, blood-sugar control, and bone structure. Many people fall short of the recommended intake through diet alone, especially with lower intakes of leafy greens, nuts, and whole grains.

How it works

Magnesium is a cofactor for more than 300 enzyme systems. It helps your cells produce energy (ATP), lets muscles relax after they contract (it acts opposite calcium, which signals contraction), steadies nerve signaling, and supports the systems that regulate blood pressure and blood sugar. When magnesium runs low, muscles and nerves become more excitable — part of why a shortfall can show up as cramps, twitching, or restless sleep.

What it's been studied for

Commonly used to support sleep quality, relaxation and stress, healthy blood pressure, muscle function and cramps, bone health, and regularity.

What the evidence shows

Evidence is strongest for a few uses: a placebo-controlled trial found magnesium bisglycinate improved sleep in poor sleepers, a meta-analysis found supplementation produced a small reduction in blood pressure, and higher intake is linked to better bone density. Effects are generally modest and most noticeable when your intake was low to begin with.

Who should consider it

The people most likely to benefit are those running low, which is common. Higher risk includes people who eat few leafy greens, nuts, and whole grains; heavy alcohol users; people with type 2 diabetes or digestive conditions that reduce absorption (like Crohn's or celiac); older adults; and those on long-term acid-reducing medication or certain diuretics. Poor sleep, muscle cramps, and high stress are frequent reasons people try it.

Amounts commonly studied

Studies commonly use 200-400 mg of elemental magnesium per day. Needs vary by form, since the elemental magnesium content differs between salts.

How to take it

Most people take 200-400 mg of elemental magnesium once daily, often in the evening since it can feel relaxing. Take it with food to reduce the chance of loose stools. Glycinate and citrate absorb well; if one form upsets your stomach, try another. Space magnesium a couple of hours apart from certain antibiotics (tetracyclines, quinolones) and from thyroid medication, which it can bind. Read the 'elemental magnesium' amount, not just the total compound weight.

Forms & absorption

Glycinate and citrate are well absorbed and gentle; oxide is cheap but poorly absorbed and more likely to loosen the bowels; threonate is marketed for the brain. The form on the label matters more than the total weight.

Food sources

Rich sources include pumpkin seeds, chia and flax, almonds and cashews, spinach and Swiss chard, black beans, edamame, whole grains, and dark chocolate. A diet built around these often meets needs without a supplement.

Safety & interactions

Generally well tolerated; the main side effect is loose stools at higher doses. People with kidney disease should check with a provider, as magnesium can accumulate. It can interact with certain antibiotics and other medications, so space them apart.

Common questions

Which form of magnesium is best?

For general use and sleep, glycinate is gentle and well absorbed; citrate is also well absorbed and can help regularity. Oxide is cheap but poorly absorbed and most likely to cause loose stools. Threonate is marketed for the brain but is early in its evidence.

Can I take magnesium with calcium?

Yes — they're often combined and work as partners in muscle and bone. Very large single doses of either can compete a little for absorption, so splitting them across the day is reasonable if you take high amounts.

Will it help cramps or restless legs?

Many people find magnesium helps, especially if their intake was low, though trial evidence is mixed. It's low-risk to try for a few weeks and see.