{
  "dataset": "magnesium-forms-comparison",
  "title": "Magnesium Forms Compared: magnesium share, what absorption studies show, side effects, cost per 300 mg",
  "sourcePage": "https://verifiedsupplementdata.com/magnesium/forms-compared/",
  "license": "CC BY 4.0",
  "licenseUrl": "https://creativecommons.org/licenses/by/4.0/",
  "attribution": "Verified Supplement Data (2026), Magnesium Forms Comparison",
  "dateModified": "2026-10-15",
  "methodology": "Magnesium share is by molecular weight. Absorption is reported only where a human study or the NIH Office of Dietary Supplements fact sheet (updated 2026-01-06) says something; forms NIH does not name are marked so. Oxide 4% fractional absorption: Firoz & Graber 2001. Product cost is per 300 mg of elemental magnesium at each brand's own list price.",
  "forms": [
    {
      "name": "Magnesium Glycinate",
      "aka": "Bisglycinate",
      "elementalPct": 14,
      "elemental": "~14%",
      "bioavailability": "Not in the absorption studies NIH cites; about the same as oxide in one small trial (Schuette 1994)",
      "bestFor": "Everyday magnesium when other forms upset your stomach",
      "sideEffects": "Better tolerated than oxide in one small trial (Schuette 1994); not on NIH’s list of forms most linked to diarrhea",
      "costTier": "Middle",
      "notes": "Magnesium bound to glycine, an amino acid. In the one trial that compared it with oxide at the same dose (12 people), absorption was about the same and glycinate was better tolerated (Schuette 1994).",
      "evidence": "Few trials tested glycinate itself: a 2025 sleep trial (Schuster 2025), a pregnancy leg-cramp trial (Supakatisant 2015) and that small absorption trial. No trial shows it works better than citrate."
    },
    {
      "name": "Magnesium Citrate",
      "aka": "",
      "elementalPct": 16,
      "elemental": "~16%",
      "bioavailability": "Absorbed better than oxide in small studies (NIH)",
      "bestFor": "Everyday magnesium at a lower cost; also sold as a laxative",
      "sideEffects": "Can loosen stools at higher doses; not on NIH’s list of forms most linked to diarrhea",
      "costTier": "Low",
      "notes": "Magnesium bound to citric acid. The most common form on labels. Liquid magnesium citrate sold at pharmacies is a bowel prep, a much bigger dose.",
      "evidence": "Small studies found it absorbed better than oxide (NIH)."
    },
    {
      "name": "Magnesium Chloride",
      "aka": "",
      "elementalPct": 12,
      "elemental": "~12% (hexahydrate)",
      "bioavailability": "Absorbed better than oxide; equal to lactate and aspartate (Firoz 2001)",
      "bestFor": "Oral tablets and topical oils or sprays",
      "sideEffects": "One of the forms most often linked to diarrhea (NIH)",
      "costTier": "Not priced (we track no chloride product)",
      "notes": "Sold as tablets, flakes and “magnesium oil” sprays. Whether magnesium sprayed on the skin raises body levels has not been shown.",
      "evidence": "Absorbed as well as lactate and aspartate in one small study (Firoz 2001)."
    },
    {
      "name": "Magnesium Malate",
      "aka": "",
      "elementalPct": 15,
      "elemental": "~15%",
      "bioavailability": "Not in the absorption studies NIH cites",
      "bestFor": "General use; marketed for fibromyalgia and energy",
      "sideEffects": "Not on NIH’s list of forms most linked to diarrhea",
      "costTier": "Not priced (we track no malate product)",
      "notes": "Magnesium bound to malic acid, which the body uses to make energy. That is a reason it is sold, not a trial result.",
      "evidence": "For fibromyalgia, magnesium with malic acid made little or no difference to pain (Ferreira 2019, PMID 31150373)."
    },
    {
      "name": "Magnesium Taurate",
      "aka": "",
      "elementalPct": 9,
      "elemental": "~9%",
      "bioavailability": "Not in the absorption studies NIH cites",
      "bestFor": "Marketed for heart health",
      "sideEffects": "Not on NIH’s list of forms most linked to diarrhea",
      "costTier": "Not priced (we track no taurate product)",
      "notes": "Magnesium bound to taurine, an amino acid. The case for pairing them comes from a 1996 hypothesis paper (McCarty, PMID 8692051).",
      "evidence": "We found no human trial of magnesium taurate itself."
    },
    {
      "name": "Magnesium L-Threonate",
      "aka": "Magtein",
      "elementalPct": 7.2,
      "elemental": "~7% (144 mg in 2,000 mg Magtein)",
      "bioavailability": "Not in the absorption studies NIH cites",
      "bestFor": "Marketed for memory and focus",
      "sideEffects": "Not on NIH’s list of forms most linked to diarrhea",
      "costTier": "High",
      "notes": "Developed to raise magnesium in the brain. The study that showed this was in rats (Slutsky 2010, PMID 20152124). A full serving gives only 144 mg of magnesium.",
      "evidence": "The brain claim rests on rat work and two small human trials paid for by the maker (Liu 2016; Lopresti 2026), which found gains on memory and thinking tests."
    },
    {
      "name": "Magnesium Oxide",
      "aka": "",
      "elementalPct": 60,
      "elemental": "~60%",
      "bioavailability": "About 4% absorbed in one study (Firoz 2001); less than citrate in small studies (NIH)",
      "bestFor": "Constipation and heartburn; the cheapest magnesium per mg",
      "sideEffects": "One of the forms most often linked to diarrhea (NIH)",
      "costTier": "Very low",
      "notes": "The most magnesium per tablet and the lowest cost, which is why many bottles with big numbers use it. Most of it is not absorbed, and what stays in the gut draws in water.",
      "evidence": "For constipation, 68% improved on oxide vs 19% on placebo in 2 trials (van der Schoot 2023)."
    },
    {
      "name": "Magnesium Sulfate",
      "aka": "Epsom salt",
      "elementalPct": 10,
      "elemental": "~10% (heptahydrate)",
      "bioavailability": "Absorbed less well than citrate by mouth (NIH); skin absorption not shown",
      "bestFor": "Bath soaks; given by IV in hospitals",
      "sideEffects": "A strong laxative when swallowed",
      "costTier": "Not priced (bath salt, not a supplement)",
      "notes": "Epsom salt is for baths. Do not use it as a daily supplement.",
      "evidence": "Hospital IV use is a medical treatment, not a supplement result."
    }
  ],
  "products": [
    {
      "slug": "nutricost-magnesium-glycinate-360",
      "form": "Glycinate",
      "magnesiumMgPerServing": 210,
      "serving": "3 capsules",
      "costPer300mgUsd": 0.297,
      "testingList": null
    },
    {
      "slug": "nature-made-magnesium-glycinate",
      "form": "Glycinate",
      "magnesiumMgPerServing": 200,
      "serving": "2 capsules",
      "costPer300mgUsd": 1.099,
      "testingList": "USP Verified"
    },
    {
      "slug": "doctors-best-magnesium",
      "form": "Glycinate",
      "magnesiumMgPerServing": 200,
      "serving": "2 tablets",
      "costPer300mgUsd": 0.3,
      "testingList": null
    },
    {
      "slug": "now-magnesium-bisglycinate-powder",
      "form": "Glycinate",
      "magnesiumMgPerServing": 300,
      "serving": "1 level teaspoon",
      "costPer300mgUsd": 0.316,
      "testingList": null
    },
    {
      "slug": "thorne-magnesium-bisglycinate",
      "form": "Glycinate",
      "magnesiumMgPerServing": 120,
      "serving": "1 capsule (label allows 1 to 4 a day)",
      "costPer300mgUsd": 0.722,
      "testingList": "NSF/ANSI 173"
    },
    {
      "slug": "now-magnesium-glycinate-240-tabs",
      "form": "Glycinate",
      "magnesiumMgPerServing": 200,
      "serving": "2 tablets",
      "costPer300mgUsd": 0.533,
      "testingList": null
    },
    {
      "slug": "nature-made-magnesium-citrate",
      "form": "Citrate",
      "magnesiumMgPerServing": 250,
      "serving": "2 softgels",
      "costPer300mgUsd": 0.472,
      "testingList": "USP Verified"
    },
    {
      "slug": "now-magnesium-citrate-200",
      "form": "Citrate",
      "magnesiumMgPerServing": 400,
      "serving": "2 tablets",
      "costPer300mgUsd": 0.24,
      "testingList": null
    },
    {
      "slug": "natural-vitality-calm",
      "form": "Citrate",
      "magnesiumMgPerServing": 350,
      "serving": "2 tsp (4 g) powder in water",
      "costPer300mgUsd": 0.272,
      "testingList": null
    },
    {
      "slug": "nature-made-magnesium-oxide",
      "form": "Oxide",
      "magnesiumMgPerServing": 250,
      "serving": "1 tablet",
      "costPer300mgUsd": 0.071,
      "testingList": null
    },
    {
      "slug": "double-wood-magnesium-l-threonate",
      "form": "L-threonate",
      "magnesiumMgPerServing": 144,
      "serving": "4 capsules",
      "costPer300mgUsd": 2.149,
      "testingList": null
    },
    {
      "slug": "life-extension-neuro-mag",
      "form": "L-threonate",
      "magnesiumMgPerServing": 144,
      "serving": "3 capsules",
      "costPer300mgUsd": 2.188,
      "testingList": null
    },
    {
      "slug": "now-magtein",
      "form": "L-threonate",
      "magnesiumMgPerServing": 144,
      "serving": "3 capsules",
      "costPer300mgUsd": 3.471,
      "testingList": null
    },
    {
      "slug": "nature-made-magnesium-glycinate-gummies",
      "form": "Gummy",
      "magnesiumMgPerServing": 100,
      "serving": "2 gummies",
      "costPer300mgUsd": 3.148,
      "testingList": "USP Verified"
    },
    {
      "slug": "vitamatic-magnesium-citrate-gummies-600",
      "form": "Gummy",
      "magnesiumMgPerServing": 70,
      "serving": "2 gummies",
      "costPer300mgUsd": 2.856,
      "testingList": null
    },
    {
      "slug": "bulksupplements-magnesium-glycinate",
      "form": "Glycinate + oxide",
      "magnesiumMgPerServing": 300,
      "serving": "¾ teaspoon (2.2 g)",
      "costPer300mgUsd": 0.193,
      "testingList": "NSF/ANSI 173"
    },
    {
      "slug": "vitamin-shoppe-magnesium-glycinate",
      "form": "Glycinate",
      "magnesiumMgPerServing": 400,
      "serving": "3 tablets",
      "costPer300mgUsd": null,
      "testingList": null
    },
    {
      "slug": "kal-magnesium-glycinate-400",
      "form": "Glycinate",
      "magnesiumMgPerServing": 350,
      "serving": "4 capsules",
      "costPer300mgUsd": null,
      "testingList": null
    },
    {
      "slug": "natures-bounty-magnesium-glycinate-240",
      "form": "Glycinate",
      "magnesiumMgPerServing": 240,
      "serving": "2 capsules",
      "costPer300mgUsd": null,
      "testingList": null
    }
  ],
  "pricesCheckedOn": "2026-10-14",
  "citations": [
    "https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/",
    "PMID:11794633",
    "PMID:34111673",
    "PMID:31150373",
    "PMID:8692051",
    "PMID:20152124",
    "PMID:26519439",
    "PMID:41601871",
    "PMID:40918053",
    "PMID:37243443",
    "PMID:33865376"
  ]
}