Magnesium glycinate

Also called magnesium bisglycinate, chelated magnesium.

Dr Chad OkayFounder, Suna Health

3 min read. Updated .

Magnesium glycinate is a chelated form where each magnesium atom is bound to two glycine amino acids. It is well-absorbed, gentle on the gut (does not cause the loose stools magnesium oxide or citrate can), and the form most often used for sleep, muscle cramps, anxiety and PMS. Trials typically used 200 to 400 mg of elemental magnesium in the evening; supplemental magnesium is capped at 400 mg a day by UK guidance.

Why glycinate specifically

  • Bioavailability is reasonable but not exceptional, Schuette 1994 measured magnesium diglycinate absorption around 23.5%. The 80% figure that circulates online is a marketing claim with no published evidence.
  • Glycine itself has a calming effect on the brain (small but measurable).
  • Does not pull water into the gut like citrate or oxide, so no laxative effect.
  • Well-tolerated even at higher doses.
  • More expensive than oxide, similar price to citrate.

What it actually helps

  • Sleep onset and quality: modest evidence (low-quality trials) at 200 to 400 mg before bed.
  • Muscle cramps and twitches.
  • PMS symptoms in the luteal phase.
  • Migraines (some evidence at 400 mg daily as prophylaxis).
  • Anxiety and stress (mixed evidence; effect probably small).
  • Constipation: NOT this form. Use citrate or oxide if constipation is the goal.

Forms of magnesium and what they're for

  • Glycinate: sleep, cramps, anxiety. Gentle on gut.
  • Citrate: constipation, mild laxative effect.
  • Oxide: cheap, poorly absorbed, mostly used as a laxative or antacid.
  • Threonate: small evidence for memory and cognition; expensive.
  • Malate: muscle pain and fatigue (some evidence in fibromyalgia).
  • Sulfate: Epsom salts; topical for muscle aches, oral as a strong laxative.

Amounts: what the references say

  • UK adult reference intake from food: 270 to 300 mg/day. Most people get 200 to 250 from diet.
  • Trials of supplements used 200 to 400 mg of ELEMENTAL magnesium. Watch labels carefully: 1000 mg of magnesium glycinate yields only about 140 mg of elemental magnesium.
  • The sleep trials dosed in the evening, usually with food.
  • Upper limit for supplements (UK EVM safe upper level): 400 mg per day. A pharmacist can advise on a starting amount, especially if you take other medicines.

Foods rich in magnesium

  • Pumpkin seeds (around 550 to 590 mg per 100 g for dried kernels).
  • Spinach (79 mg per 100 g).
  • Almonds (270 mg per 100 g).
  • Dark chocolate 70%+ (228 mg per 100 g).
  • Black beans (70 mg per 100 g cooked).
  • Avocado (29 mg per 100 g).

Why it matters for the long run

For the long run, the magnesium that matters most is the food kind: seeds, nuts, leafy greens, beans and dark chocolate, eaten routinely for years, cover most people without a capsule in sight. Supplements are patches for specific moments; the dietary pattern is the maintenance plan, and it brings fibre and polyphenols along for free.

Common questions

Should I take it every night?
Reasonable for chronic poor sleep, regular muscle cramps or PMS in the luteal phase. Otherwise occasional use is fine. There is no addiction risk and no rebound on stopping.
Will it interact with other medications?
Magnesium can reduce absorption of some antibiotics (tetracyclines, quinolones), bisphosphonates, and thyroid medication. Take at least 2 hours apart, and at least 4 hours apart from thyroid medication (levothyroxine). Check with a pharmacist if on multiple medications.
Is more better?
No. Above 400 mg/day supplemental, you start seeing diarrhoea even with glycinate. Kidneys excrete excess. Sticking to 200 to 400 mg covers most use cases.
Can I get enough from food?
Most people technically can but most do not. UK women average about 238 mg/day from food and men about 302 mg/day, against a 270 to 300 mg target, so many women fall short. A 200 mg supplement is a low-risk way to top up. Ask a pharmacist first if you take other medicines.

Sources

Written by Dr Chad Okay. Contributor: Dr Parisah Hussain, MBChB, BSc (Hons), DRCOG, MRCGP. Last updated 15 September 2026. From Digests.

Digests explains how the body works in general, everyday terms. It is not medical advice. It is not a substitute for someone who can examine you and knows your history, and we do not tell you what dose of any medicine to take.

Where we describe how something is checked or looked after, we follow UK guidance from NICE and the NHS. If you are reading this outside the UK, the same concerns are worth taking to your own doctor, though the tests and routes where you live may differ.

Suna Health is building a wearable wellness device for gut health, and you will see it advertised alongside these pages. That commercial interest does not decide what the content says.

If you think we have got something wrong, tell us at digests@suna.health. It goes to the editor. Full terms, including our liability position, are at suna.health/terms.