Independent supplement ratingsUS and Canada · Updated weekly
A ratings desk for a category that has spent thirty years grading its own homework.
A ratings desk for a category that has spent thirty years grading its own homework.
Magnesium is genuinely essential — it's involved in hundreds of enzyme reactions, from muscle function to sleep — and a meaningful share of adults fall short of the recommended intake. Bisglycinate is magnesium chelated to glycine, which makes it well absorbed and easy on the stomach, so it's the form most people are pointed toward.
The number that matters is elemental magnesium — the actual magnesium, not the weight of the whole compound. Trials generally use 200–400 mg elemental a day. Glycinate is the gentlest common form; oxide is cheap but poorly absorbed, which is why we score it far lower.
A well-evidenced, low-risk supplement if you're short on magnesium. Read the label for the elemental figure, not the headline milligrams. Research on PubMed →
They answer different questions. Oxide carries more magnesium per tablet — roughly 60% by weight — and costs about a fifth as much per gram, but the body absorbs comparatively little of it. Glycinate carries less on the label and delivers more of it, with far less digestive upset. If you are healthy and topping up a modest gap, oxide does the job cheaply. If you are older, already low, or your gut objects, glycinate is worth the difference. The arithmetic is in our forms guide.
Whenever you will actually remember. Glycinate is gentle enough to take on an empty stomach, and evening is a sensible default if you are taking it with sleep in mind — that is when most of the trials dosed it. Splitting the dose across the day slightly improves absorption, because the percentage absorbed falls as the single dose rises.
Yes. Bisglycinate is the more precise name — two glycine molecules bound to one magnesium — and manufacturers use the two words interchangeably on labels. Neither term tells you the elemental dose, which is the number that matters.
The form of the magnesium is the same, so the absorption argument is unchanged. The catch is dose and sugar: gummies generally carry less elemental magnesium per serving than a capsule and often add a few grams of sugar to be palatable. Check the Supplement Facts panel for the elemental figure before assuming a gummy replaces a capsule.
Less than the other common forms. Unabsorbed magnesium draws water into the bowel, so the poorly-absorbed forms — oxide and citrate — produce that effect first. Glycinate is the gentlest of the well-absorbed forms, which is most of why it dominates daily-use products. Keeping supplemental magnesium around 350 mg a day keeps most people comfortable.
Reviewed by the NFS editorial team · Educational only — not medical advice.