Magnesium has become the supplement of the moment. Sleep coaches recommend it. Functional-medicine doctors recommend it. Your favourite podcast host probably has a discount code for it. And yet, when we walked into three different UK pharmacies and read the back of the box, the form, the dose, and the marketing story were all over the place.
Here's the short version of what most articles won't tell you: not all magnesium is created equal. The form matters more than the milligram count on the front of the bottle.
The four forms you'll see on UK shelves
Magnesium oxide is the cheapest, and it's the form most often used in budget multivitamins. It's also the one your gut absorbs the least of — most people get a fraction of the dose listed on the box.
Magnesium citrate is the middle ground. It's better absorbed than oxide, and it's well-tolerated by most people. It's also mildly laxative at higher doses, which is either a feature or a bug depending on what you're using it for.
Magnesium glycinate (also sold as bisglycinate) is the form most commonly recommended for sleep, anxiety, and muscle relaxation. It's gentle on the gut and absorbs well — the go-to for unwinding in the evening.
Magnesium malate is the form most commonly recommended for exercise and physical performance. The "malate" part — malic acid — plays a role in your body's energy production cycle, which is why this form gets singled out for active people, athletes, and anyone training regularly. It's gentle on the stomach and absorbs well.
What we found when we tried them
We tried each form for a week. The honest answer is there isn't one winner — there's a winner for what you're actually using it for.
Glycinate was the clear pick for evenings — easier on the stomach, and a noticeable difference in how settled we felt before sleep. Malate was the standout on training days — better recovery, less of the next-morning soreness after harder sessions. Citrate did the job but was less subtle than either. Oxide we wouldn't bother with again.
If you're picking one to keep in the cupboard and you train regularly, malate is the one we'd reach for. If your priority is sleep and stress, glycinate. The full write-up, with the specific UK brands we'd buy and the ones we wouldn't, will be published in the next issue.
This article is part of an ongoing series. See our most recent report: The Top 5 Creatine Supplements for 2026 →