Magnesium: Which Form, and Why So Many People Run Low

Magnesium is worth a look before most other supplements, because the shortfall is common and the mechanism is plain. Roughly half of American adults take in less than the recommended amount from food. The target is about 400 to 420 milligrams a day for men and 310 to 320 for women, and the foods that carry it, leafy greens, nuts, seeds, beans and whole grains, are the foods most people eat least of.

What it does

Magnesium sits inside hundreds of enzyme reactions. The ones that matter day to day are muscle relaxation, nerve signaling, blood sugar handling and the production of energy inside the cell. Calcium tells a muscle fiber to contract. Magnesium helps it let go. That is why a true deficiency can show up as cramps, twitches and muscle tightness, although most everyday leg cramps have other causes.

A blood level is a weak test for this. Only about 1% of the body's magnesium is in the blood, and the body defends that number by pulling from bone and muscle. A normal serum magnesium does not rule out a low intake, which is why we ask about diet rather than relying on the lab.

Which form

The forms differ mostly in how well they absorb and what they do to the gut.

• Magnesium oxide is the cheapest and the most common in drugstore bottles. It absorbs poorly, so most of it stays in the gut and pulls water in. It is a poor way to raise magnesium.
• Magnesium citrate absorbs reasonably well and still loosens stool at higher doses. A fair choice for someone who is also constipated.
• Magnesium glycinate absorbs well and is gentle on the gut. This is the form we usually suggest for sleep, muscle tension and a general shortfall.

A reasonable dose is 200 to 350 milligrams of elemental magnesium in the evening, and 350 is the upper limit for supplements in adults. Read the label for the word elemental, because a 500 milligram capsule of a magnesium salt may contain far less actual magnesium. Someone with kidney disease needs their kidney function checked first, since the kidney is how the excess leaves the body.

What it will not do

Magnesium will not fix sleep that is short because of a late bedtime. Its effect on blood pressure is small, a few points at most, and shows up mainly in people who were low to begin with. In someone who is genuinely low it can nudge blood sugar handling in the right direction, and some people find it helps cramps and sleep, although the trials there are small and mixed.

The bigger point is that magnesium is a food problem before it is a pill problem. If greens, nuts and beans are rare on your plate, the supplement is a patch, not the fix.

That's the kind of thing we ask about before anyone buys a bottle. When a supplement is the right call, we use our online dispensary for professional grade products, and clinic members get 35% off.

This article is educational and is not medical advice.

Shop the HYBRD Health supplement dispensary