The short answer
Magnesium supports normal muscle and nerve function, and both glycinate and oxide give you it, but they suit different people. Glycinate is the popular pick for everyday use, especially if your stomach is sensitive. Oxide packs more magnesium into a smaller, cheaper tablet, but it's more likely to loosen your stools. Whichever you choose, keep supplements under 350mg of elemental magnesium a day. Not sure which suits you? Try our Supplement Finder.
In this article
Maybe you're new to magnesium and the labels all look the same, or you've tried a cheap tablet that didn't sit well. Maybe you train and want it for your muscles, or you don't train and just want to cover your intake. This guide explains how the two forms differ, which one suits you and how much to take.
What's the difference?
Both are magnesium bound to something else. In glycinate, it's the amino acid glycine. In oxide, it's oxygen. Oxide carries more magnesium by weight, so tablets can be smaller or fewer.
Oxide is generally absorbed less well than forms that dissolve easily, like citrate and chloride. [1] Direct evidence for glycinate is thinner than the marketing suggests, so don't count on "twice as absorbed" claims. [2]
Which one is gentler on the stomach?
For many people, glycinate. Magnesium that isn't absorbed stays in your gut and draws in water, which can loosen stools or cause cramps. Oxide is one of the forms known for doing that, especially at higher doses. [1] Everyone's gut is different, though, so see how you go.
Which one should I pick?
Glycinate if your stomach is sensitive, oxide if you'd rather take fewer, cheaper tablets and your gut handles it well. Not both: doubling up adds to your total and makes stomach upsets more likely.
Side by side
Glycinate or oxide?
Glycinate
- Bound to
- The amino acid glycine
- Tablet size and cost
- Less magnesium by weight than oxide
- Absorption
- Direct absorption evidence is thinner than the marketing suggests, so don't count on "twice as absorbed" claims [2]
- Gut comfort
- Gentler on the stomach for many people
- Best for
- The popular pick for everyday use
- Label tip
- Want straight glycinate? Skip "buffered", which can include oxide as well.
Oxide
- Bound to
- Oxygen
- Tablet size and cost
- More magnesium by weight, so tablets can be smaller, fewer and cheaper
- Absorption
- Absorbed less well than forms that dissolve easily, like citrate and chloride [1]
- Gut comfort
- More likely to loosen stools or cause cramps, especially at higher doses [1]
- Best for
- Smaller, fewer and cheaper tablets
- Label tip
- It can turn up in "buffered" formulas alongside other forms.
Want to skip oxide altogether? Look for a formula built on forms that dissolve easily, like citrate [1].
Our pick
For an oxide-free everyday magnesium: Sanderson Magnesium FX. Four organic forms of magnesium (amino acid chelate, citrate, aspartate and orotate), with no magnesium oxide or phosphate, giving 160mg of elemental magnesium per tablet. Supports normal muscle and nerve function and energy metabolism, with vitamin B6, vitamin D3 and selenium added. Take one to two tablets daily, preferably in the evening; two tablets is 320mg, which keeps you under the 350mg supplement limit as long as you're not taking magnesium anywhere else.
Save 42%For an oxide-free everyday magnesium
Sanderson Magnesium FX 120 Tablets
- Rating
- New
How much do I take?
Adults need roughly 310 to 320mg a day for women and 400 to 420mg for men, from food and supplements together. [3]
The upper limit for adults is 350mg a day from supplements, not counting food. It's set around diarrhoea, and it's a ceiling, not a target. [3] Wholegrains, beans, nuts, seeds and green veges already give you some, so a supplement only needs to cover the rest.
These amounts are for elemental magnesium, the actual magnesium you get. "Magnesium glycinate 1,000mg" is the weight of the whole compound, magnesium plus glycine, so it gives you much less than 1,000mg of magnesium.
Is glycinate better for sleep?
No form has strong evidence of being better for sleep than another. Our magnesium for sleep guide covers what the research shows and how magnesium fits into a better night's sleep.
Check first
Who should check first?
Magnesium can reduce how well some medicines are absorbed, including tetracycline and quinolone antibiotics, osteoporosis medicines (bisphosphonates) and thyroid replacement. You may need to space them apart, so ask your pharmacist. [1]
Also check first if you have kidney disease, take diuretics or long-term reflux medicines, or already use a laxative. If you're taking magnesium for ongoing constipation or long-running sleep trouble, see your GP rather than relying on a supplement.
Want a plan built around you?
Inception Nutrition builds your minerals, supplements and lifestyle into one plan around your goals, your routine and the foods you like, with weekly check-ins wherever you are in NZ. Not sure where to start? Take their free metabolic audit. Not sure which product suits you? Try our Supplement Finder or email us at info@supplementsolutions.co.nz. No question is too basic.
References
3 sources
- 1.NIH Office of Dietary Supplements: magnesium fact sheet for health professionals Forms, absorption, medicine interactions and side effects.
- 2.Pardo et al. (2021). Bioavailability of magnesium food supplements: a systematic review How different forms compare, and the limits of the evidence.
- 3.Australia and New Zealand Nutrient Reference Values: magnesium Adult intakes and the 350mg upper limit for supplements.
Sources shown: the research is linked in the references. Product details and doses come from the brand. Product suggestions show what’s available now. Last updated 22 October 2026.
This guide is general information, not a diagnosis or medical advice. Take products as directed, and check with a qualified health professional first if you're pregnant, breastfeeding, taking medication or managing a health condition.
