Health Reference LibraryMagnesium glycinate vs magnesium citrate: which should you take?
This entry is part of the Nutri Tailor Health Reference Library — cited research on supplements, nutrients and adjacent areas of health.
Summary
Both are well absorbed, so choose on the side effect you want. Magnesium citrate draws water into the bowel, which makes it the better pick if you are also a little constipated and the one to avoid if your gut is already loose. Magnesium glycinate, also sold as bisglycinate, is bound to the calming amino acid glycine, sits easily on the stomach and is the usual choice for the evening and for sleep. In the one randomised comparison of forms, citrate raised blood magnesium more than oxide; glycinate was not in that trial, and no good study puts glycinate and citrate head to head. Many people take citrate by day and glycinate at night.
How it works
Magnesium is absorbed passively along the small intestine and actively at lower intakes. The organic forms, citrate and glycinate among them, stay dissolved for longer than oxide and are taken up more completely. What differs is what the unabsorbed portion does. Unabsorbed citrate holds water in the bowel and speeds transit. Unabsorbed glycinate largely does not. For sleep, the mechanism is the same whichever form you use: magnesium is a cofactor for the enzymes that make GABA and it damps the stress hormone axis, and the 2022 trial found magnesium alone reduced stress scores in people with low magnesium.
Effective dose
The UK reference intake is 300 mg of magnesium a day for men and 270 mg for women, from all sources. The NHS says up to 400 mg a day from supplements is unlikely to cause harm; more than that can cause diarrhoea in the short term, and citrate reaches that point sooner than glycinate. Sleep and stress trials used 250 to 500 mg a day for six to eight weeks. Check the elemental magnesium figure on the label, not the compound weight.
Forms compared
Citrate is magnesium bound to citric acid, the salt behind the sharpness in citrus fruit. It dissolves readily, is one of the best absorbed common forms, and at higher doses pulls water into the large bowel, which is why magnesium citrate is also sold as a laxative. Glycinate is magnesium bound to two molecules of glycine, an amino acid, and is the same compound as bisglycinate. The glycine bond means it does not behave like a salt in the gut, so it is the form least likely to send you to the bathroom, and glycine itself has a mild calming effect. Neither is a bad choice; the question is which side effect suits you.
Timing
Citrate with breakfast or lunch, so the bowel effect lands during the day. Glycinate with dinner or an hour before bed. If you want both effects, split them that way rather than taking a double dose of either. Food does not block absorption and reduces stomach upset.
Safety profile
Citrate above 400 mg a day of magnesium is a laxative for most people. Anyone with reduced kidney function should not take magnesium supplements without their GP. Signs of too much magnesium are loose stools first, then nausea, low blood pressure and drowsiness; stop and seek advice if those appear.
Guideline positions
NHS: 300 mg a day for men and 270 mg for women; up to 400 mg a day from supplements is unlikely to cause harm. NIH Office of Dietary Supplements magnesium fact sheet. Magnesium citrate found more bioavailable than other preparations in a randomised comparison (2003). Bioavailability of magnesium food supplements: systematic review (2021).
Practical framework
Constipated, or want a daytime form: citrate. Trouble sleeping, tense muscles or a sensitive gut: glycinate. Nutri Tailor stocks both as single form capsules made in the UK: [magnesium citrate](/products/magnesium-citrate) at 85 mg of magnesium per capsule, and [magnesium bisglycinate](/products/magnesium-bisglycinate) at 133 mg per capsule, the compound other brands call glycinate, blended with oxide to reach the dose. If you have never taken magnesium, start with one capsule a day and hold for a week before adding a second. This is a summary of published research, not personal health advice. Talk to your GP or a registered nutritional therapist before changing what you take, especially if you are pregnant, have a diagnosed condition or are under ongoing care.
Common misconceptions
That glycinate is better absorbed than citrate: both beat oxide, and there is no trial showing one beats the other. That citrate is only a laxative: at 85 to 170 mg a day most people notice no bowel change at all. That you must pick one: taking citrate by day and glycinate at night is a sensible way to use both.
Forms compared
| Magnesium Citrate | Magnesium Glycinate | |
|---|---|---|
Sources
- Walker AF, Marakis G, Christie S, Byng M 2003. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium Research. PMID: 14596323
- Pardo MR, Garicano Vilar E, San Mauro Martín I, Camina Martín MA 2021. Bioavailability of magnesium food supplements: A systematic review. Nutrition. PMID: 34111673 · DOI: 10.1016/j.nut.2021.111294
- Schuette SA, Lashner BA, Janghorbani M 1994. Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. Journal of Parenteral and Enteral Nutrition. PMID: 7815675 · DOI: 10.1177/0148607194018005430
- Macian N et al 2022. Short-Term Magnesium Therapy Alleviates Moderate Stress in Patients with Fibromyalgia: A Randomized Double-Blind Clinical Trial. Nutrients. PMID: 35631229 · DOI: 10.3390/nu14102088
- NIH Office of Dietary Supplements. NIH Office of Dietary Supplements — Magnesium Fact Sheet for Health Professionals. NIH Office of Dietary Supplements (US government).