Magnesium Forms Explained: Which One Do You Actually Need?

Magnesium is one of those supplements where the form matters as much as the dose. Walk into any store and you’ll see magnesium oxide, citrate, glycinate, threonate, taurate, malate — and they all do slightly different things at very different absorption rates.

Here’s what you actually need to know.

Why magnesium matters

Magnesium is involved in over 300 enzymatic reactions in your body. It plays a role in muscle and nerve function, blood sugar regulation, blood pressure, and protein synthesis. Despite this, an estimated 50% of Americans don’t get enough from their diet alone.

Common signs of low magnesium include muscle cramps, trouble sleeping, increased stress response, headaches, and fatigue. If any of that sounds familiar, your magnesium levels are worth checking.

The forms, ranked by what they’re good for

Magnesium Glycinate

Best for: General supplementation, sleep, anxiety, muscle recovery

This is magnesium bound to glycine, an amino acid that itself has calming properties. It’s one of the most bioavailable forms — your body absorbs a high percentage of what you take. It’s also the gentlest on your stomach, which makes it a good default choice for most people.

If you’re only going to take one form, this is probably it.

Magnesium Citrate

Best for: Constipation relief, general supplementation

Magnesium bound to citric acid. Good absorption, widely available, affordable. The downside: it has a mild laxative effect, which is either a feature or a bug depending on your situation. Not the best choice if your GI system is already sensitive (looking at you, GLP-1 users).

Magnesium Threonate (Magtein)

Best for: Cognitive function, brain health

This form was specifically developed to cross the blood-brain barrier. Research suggests it may support memory and cognitive function. It’s more expensive and contains less elemental magnesium per dose, so it’s not a great choice for correcting a general deficiency — but it’s interesting for brain-specific goals.

Magnesium Oxide

Best for: Honestly, not much

This is the form you’ll find in most cheap supplements and multivitamins. It has roughly 4% bioavailability — meaning your body uses almost none of it. It’s inexpensive to manufacture, which is why it’s everywhere. If your supplement label just says “magnesium” without specifying the form, it’s probably oxide.

Magnesium Taurate

Best for: Heart health, blood pressure

Magnesium bound to taurine, which supports cardiovascular function. Some research suggests this form may help with blood pressure regulation. Less studied than glycinate or citrate, but worth considering if heart health is a priority.

Magnesium Malate

Best for: Energy, muscle pain, fibromyalgia

Magnesium bound to malic acid, which is involved in energy production. Some people with chronic fatigue or fibromyalgia report benefit from this form. Good absorption, minimal GI issues.

How to choose

For most people, magnesium glycinate is the right starting point. It absorbs well, it’s gentle, and it covers the most common reasons people supplement magnesium — sleep, stress, cramps, and general deficiency.

If you have a specific goal (cognitive function, heart health, constipation), a targeted form might make sense.

The one to avoid: magnesium oxide. If that’s what’s in your current supplement, you’re paying for something your body can barely use.

Dosing

The RDA is 310-420mg of elemental magnesium per day. Most people benefit from 200-400mg of supplemental magnesium, depending on how much they get from food. Start lower and increase gradually — your gut will tell you if you’ve gone too high.