Suplmnt

Magnesium Glycinate vs Magnesium Citrate

Evidence Level: promising

If you want daily magnesium without looser stools, choose glycinate. If you need constipation relief or don't mind a mild laxative effect, choose citrate. Evidence for sleep/stress benefits is modest regardless of form [3][4][7][9].

Both raise magnesium; citrate has stronger human data for absorption vs oxide and for laxative use, while glycinate is favored for GI tolerability and nightly routines. Start with 100–200 mg elemental Mg/day, pick glycinate if stool-sensitive, and pick citrate if regularity is desired. Keep supplemental Mg ≤350 mg/day unless supervised, separate from interacting meds, and avoid high doses with kidney disease [3][7][9][10][11].

Magnesium glycinate (magnesium bisglycinate) Products

Magnesium citrate Products

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The Comparison

A Magnesium glycinate (magnesium bisglycinate)

Standardization: Chelated form; typical pure chelate ~14% elemental Mg by mass; beware “buffered” blends with added oxide that raise % Mg but lower chelate purity [^1][^2].

Dosage: 100–200 mg elemental Mg/day for general use; stay ≤350 mg/day supplemental per NIH unless supervised [^3].

Benefits

  • •Generally gentler on GI tract vs osmotic salts at comparable elemental doses (clinical lore; limited direct trials) [3].
  • •Chelate form commonly used for nightly routines (sleep/stress) when diarrhea is a concern; evidence for magnesium helping sleep is modest overall [4].

Drawbacks

  • •Fewer direct head-to-head bioavailability data vs citrate; quality varies (buffered products) [1][2].

Safety:Same magnesium interactions/UL as other forms; separate from tetracyclines/quinolones and bisphosphonates; caution in CKD [3].

B Magnesium citrate

Standardization: Often supplied as trimagnesium dicitrate (anhydrous ~16% Mg) or nonahydrate (~11% Mg). Labels should declare elemental Mg [^5][^6].

Dosage: 100–200 mg elemental Mg/day for supplementation; higher single doses used short‑term as saline laxative per OTC labeling/clinical practice [^7][^8].

Benefits

  • •Well-studied organic salt with good solubility and higher bioavailability than oxide in RCTs [9][10].
  • •Effective osmotic laxative; widely used in bowel prep (multiple RCTs and monograph support) [7][8][11][12].

Drawbacks

  • •More likely to loosen stools at typical doses (osmotic effect), which some users find limiting [7][8].

Safety:Avoid or use cautiously in CKD; risk of electrolyte shifts and rare hypermagnesemia with excess or laxative use [3][13].

Head-to-Head Analysis

Efficacy for common goals (sleep, stress, general repletion) Critical

Winner:Tie• Importance: high

Meta-analysis shows small benefits of oral magnesium for insomnia in older adults; effects are form-agnostic and low-certainty. No robust head-to-head glycinate vs citrate for sleep/stress; both deliver elemental Mg [4].

Constipation/regularity Critical

Winner:Magnesium citrate• Importance: high

Citrate is an established saline laxative and component of bowel-prep regimens in RCTs and the OTC monograph; glycinate lacks laxative evidence [7][11][12].

GI tolerability at typical supplemental doses Critical

Winner:Magnesium glycinate (magnesium bisglycinate)• Importance: high

Chelated forms are generally chosen to minimize diarrhea; citrate's osmotic effect more often loosens stools at comparable elemental doses (indirect evidence, clinical practice) [3][7][8].

Bioavailability/absorption evidence

Winner:Magnesium citrate• Importance: medium

Citrate shows superior bioavailability vs oxide in crossover RCTs and is among organic salts with better absorption than poorly soluble forms; direct glycinate head-to-head data are limited [9][10][3].

Standardization/label clarity

Winner:Tie• Importance: medium

Both should list elemental Mg. Citrate percent Mg varies by hydrate; glycinate is ~14% when pure but is often "buffered" with oxide—check labels [5][6][1][2].

Cost/value per effective dose

Winner:Tie• Importance: low

Prices vary widely by brand and form; value depends more on elemental Mg per serving and tolerability than salt type (no consistent, high-quality cost advantage across markets).

Which Should You Choose?

Nightly supplement for sleep/stress without laxative effect

Choose: Magnesium glycinate (magnesium bisglycinate)

Pick glycinate for gentler GI profile; overall sleep evidence for magnesium is modest, so prioritize tolerability and routine use [3][4].

Occasional constipation or preference for looser stools

Choose: Magnesium citrate

Citrate acts as an osmotic laxative and is widely used in bowel-prep protocols; start with label-directed doses and hydrate [7][11][12].

General magnesium repletion when absorption is a concern

Choose: Magnesium citrate

Citrate has human data showing better bioavailability than oxide and is a well-soluble organic salt [9][10][3].

Taking antibiotics (tetracyclines/quinolones) or bisphosphonates

Choose: Either option

Either form can chelate these drugs; separate dosing (2 h before or 4–6 h after for antibiotics; ≥2 h for bisphosphonates) or defer supplementing during therapy [3].

Safety Considerations

  • UL for supplemental magnesium in adults is 350 mg/day unless medically supervised; GI upset and diarrhea increase with dose [3].
  • Drug interactions: separate from tetracyclines/quinolones (2 h before or 4–6 h after), and from oral bisphosphonates (≥2 h); consider timing with thyroid meds as well [3].
  • Kidney disease, heart block, and bowel obstruction: avoid or use only with clinician guidance; osmotic salts (e.g., citrate) carry higher risk of electrolyte shifts [3][8].
  • Laxative/colon-prep use: follow labeled or clinician-directed dosing; rare severe hypermagnesemia reported with excessive magnesium-containing laxatives [13].
  • Labeling: ensure dose is stated as elemental Mg; for glycinate, prefer "fully reacted/chelated" products and avoid "buffered" blends if GI gentleness is the goal [2][5].

Common Questions

How much should I take daily?

Commonly 100–200 mg elemental magnesium/day. Keep supplemental Mg ≤350 mg/day unless prescribed. Adjust based on GI tolerance and dietary intake [3].

Will glycinate help me sleep better than citrate?

Evidence for magnesium improving sleep is small and low-certainty, with no head-to-head data between these forms. Choose based on tolerability [4].

Which is better absorbed?

Citrate shows good human data and outperforms oxide; glycinate likely similar to other organic salts but has less direct head-to-head research [9][3].

Can I take magnesium with my medications?

Separate from tetracyclines/quinolones by 2–6 hours and from bisphosphonates by ≥2 hours; ask your clinician if unsure [3].

How do I read labels for elemental magnesium?

Look for "Magnesium (as ...) — X mg." That X is elemental Mg. Beware glycinate products "buffered" with oxide that inflate % Mg [5][2].

Sources

  1. 1.
    Magnesium glycinate (bisglycinate) contains ~14.1% Mg by mass (2025) [link]
  2. 2.
    NOW Foods testing note on buffered magnesium glycinate claims (2022) [link]
  3. 3.
    NIH ODS Magnesium—Health Professional Fact Sheet (UL, interactions, forms, absorption notes) (2022) [link]
  4. 4.
    Oral magnesium for insomnia in older adults: Systematic review & meta‑analysis (2021) [link]
  5. 5.
    ConsumerLab explainer on elemental Mg in citrate (11–16% depending on form) and label reading (2023) [link]
  6. 6.
    Magnesium citrate nonahydrate elemental % reference (2023) [link]
  7. 7.
    FDA OTC monograph listing magnesium citrate as a saline laxative active ingredient (2024) [link]
  8. 8.
    Magnesium citrate dosing/precautions for laxative and bowel prep (clinical reference) (2024) [link]
  9. 9.
    Crossover RCT: Magnesium citrate shows higher bioavailability vs oxide (2017) [link]
  10. 10.
    In vitro solubility/in vivo absorbability: citrate vs oxide (1990) [link]
  11. 11.
    RCTs with sodium picosulfate + magnesium citrate for colon cleansing (efficacy/tolerability) (2014) [link]
  12. 12.
    Review: Sodium picosulfate/magnesium citrate as colorectal cleanser (2009) [link]
  13. 13.
    Fatal hypermagnesemia due to magnesium‑containing laxatives (case report) (2018) [link]