{"url":"https://whatshealthyandwhy.com/magnesium/types-of-magnesium","path":"/magnesium/types-of-magnesium","alternates":{"json":"https://whatshealthyandwhy.com/api/articles/magnesium/types-of-magnesium.json","markdown":"https://whatshealthyandwhy.com/magnesium/types-of-magnesium.md"},"topic":{"slug":"magnesium","name":"Magnesium","url":"https://whatshealthyandwhy.com/magnesium"},"slug":"types-of-magnesium","order":2,"title":"Types of Magnesium","question":"Which type of magnesium supplement is best?","answer":"Citrate and glycinate are likely absorbed better than oxide, and glycinate is gentlest on the stomach, but form-specific health benefits are not proven.","description":"Glycinate vs citrate vs oxide vs threonate — which forms work best for what","confidence":3,"confidenceNote":"Small human absorption studies (urinary excretion) and reviews support citrate over oxide; threonate's brain benefit is shown in animals, with limited human trials.","evidenceSummary":{"metaAnalysisCount":0,"replicated":true,"newestStudyYear":2024},"category":{"categoryTitle":"What's Good For You","categorySlug":"good-for-you","subcategoryName":"Supplements & Vitamins","subcategorySlug":"supplements","url":"https://whatshealthyandwhy.com/explore/good-for-you/supplements"},"actions":["Choose citrate for general use: absorption is significantly higher than oxide, and it also helps regularity at higher doses [1][4].","Choose glycinate if you have a sensitive stomach or need higher doses; it has the fewest digestive side effects [4].","Use oxide mainly for constipation, not to correct low magnesium; absorption is only about 4–5% [1]."],"cautions":["The NIH upper limit for supplemental magnesium is 350 mg a day from any form; it does not apply to magnesium from food [5].","Oxide and citrate can loosen stools, especially at higher doses [4].","Magnesium threonate's memory benefits come from animal research; human trials are limited [2]."],"simpleText":"Not all magnesium supplements are the same. The mineral is always bonded to another molecule (like citrate, glycinate, or oxide), and that pairing affects how well your body absorbs it, what it does best, and what side effects it might cause. Magnesium oxide is cheap but poorly absorbed. Magnesium citrate absorbs better and helps with constipation. Magnesium glycinate is gentle on the stomach and popular for sleep and relaxation. Magnesium threonate is a newer form studied specifically for brain health [2][4].","mediumText":"The bioavailability of magnesium varies substantially between forms. Organic salts, where magnesium is bound to an organic compound such as citrate, can show better absorption than inorganic salts such as magnesium oxide: in volunteers, magnesium citrate was more soluble and bioavailable than magnesium oxide [1], and a comparison of two magnesium oxide formulations found that the preparation also affects absorption [3].\n\nMagnesium oxide contains the highest percentage of elemental magnesium by weight (about 60 percent) but has the lowest bioavailability, with absorption rates estimated at only 4 to 5 percent [1]. It has an osmotic laxative effect, making it useful for constipation but a poor choice for correcting systemic deficiency [3].\n\nMagnesium citrate offers a strong balance between cost, bioavailability, and tolerability. Studies show absorption rates significantly higher than oxide [1]. It retains a mild laxative effect at higher doses, which makes it a common recommendation for people who want both supplementation and digestive regularity [4].\n\nMagnesium glycinate (also called bisglycinate) bonds magnesium to the amino acid glycine. This chelated form is well absorbed and has the least gastrointestinal side effects, making it the preferred option for people with sensitive stomachs or those taking higher doses [4]. Glycine itself has calming properties, which may add to the relaxation benefits.\n\nMagnesium L-threonate was developed specifically to cross the blood-brain barrier more effectively than other forms. Animal research demonstrated that it elevates brain magnesium levels and enhances synaptic plasticity, learning, and memory [2]. Human trials are still limited but early results are promising for cognitive support, particularly in older adults.","deepText":"Lindberg et al. (1990) conducted one of the foundational bioavailability comparisons, administering equimolar doses of magnesium citrate and magnesium oxide to healthy subjects and measuring urinary magnesium excretion as a proxy for absorption [1]. Magnesium citrate produced significantly higher bioavailability, a finding that has been replicated in subsequent studies and fundamentally shaped clinical supplementation recommendations [1].\n\nSiener et al. (2011) published a bioavailability study in Urological Research comparing two pharmaceutical formulations of magnesium oxide (MgO), capsules and effervescent tablets, in thirteen healthy male volunteers (22–31 years) [3]. In a crossover design, each preparation supplied 450 mg of magnesium, and under standardized conditions urinary magnesium excretion increased by 40% after the effervescent tablets but by only 20% after the capsules [3]. The authors concluded that magnesium from the effervescent tablets was more bioavailable, and suggested this may be because the tablets are dissolved in water before ingestion, so that magnesium becomes ionized, an important precondition for absorption [3].\n\nThe magnesium L-threonate story originates from Slutsky et al. (2010), who showed in a landmark Neuron paper that increasing brain magnesium with this newly developed compound (MgT) enhanced learning abilities, working memory, and both short-term and long-term memory in rats, and improved pattern completion in aged rats [2]. MgT-treated rats had a higher density of synaptophysin- and synaptobrevin-positive puncta in the DG and CA1 subregions of the hippocampus, which correlated with memory improvement, and the authors concluded that an increase in brain magnesium enhances both short-term synaptic facilitation and long-term potentiation [2].\n\nGröber, Schmidt, and Kisters (2015) provided clinical guidance on form selection: oxide for constipation and when cost is the primary concern, citrate as a general-purpose supplement, glycinate for patients needing high-dose therapy without GI disturbance, and threonate when cognitive endpoints are the target [4]. They emphasized that the \"best\" form depends entirely on the clinical context, and that switching forms can sometimes resolve non-response in patients who appear resistant to supplementation [4]. The NIH recommends that the Tolerable Upper Intake Level of 350 mg per day applies to supplemental magnesium from any form, not magnesium from food sources [5].","deepTruncated":false,"references":[{"id":"1","title":"Magnesium bioavailability from magnesium citrate and magnesium oxide","authors":"Lindberg JS, Zobitz MM, Poindexter JR, Pak CY","year":1990,"journal":"Journal of the American College of Nutrition","pmid":"2407766","url":"https://pubmed.ncbi.nlm.nih.gov/2407766/"},{"id":"2","title":"Enhancement of learning and memory by elevating brain magnesium","authors":"Slutsky I, Abumaria N, Wu LJ, Huang C, Zhang L, Li B, Zhao X, Govindarajan A, Zhao MG, Zhuo M, Tonegawa S, Liu G","year":2010,"journal":"Neuron","pmid":"20152124","url":"https://pubmed.ncbi.nlm.nih.gov/20152124/"},{"id":"3","title":"Bioavailability of magnesium from different pharmaceutical formulations","authors":"Siener R, Jahnen A, Hesse A","year":2011,"journal":"Urological Research","pmid":"20862466","url":"https://pubmed.ncbi.nlm.nih.gov/20862466/"},{"id":"4","title":"Magnesium in prevention and therapy","authors":"Gröber U, Schmidt J, Kisters K","year":2015,"journal":"Nutrients","pmid":"26404370","url":"https://pubmed.ncbi.nlm.nih.gov/26404370/"},{"id":"5","title":"Magnesium: Fact Sheet for Health Professionals","authors":"National Institutes of Health, Office of Dietary Supplements","year":2024,"journal":"NIH Office of Dietary Supplements","url":"https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/"}],"wordCount":687,"source":{"path":"src/content/topics/magnesium/types-of-magnesium.md"},"citeAs":"“Which type of magnesium supplement is best?.” What's Healthy and Why. https://whatshealthyandwhy.com/magnesium/types-of-magnesium","notice":"General information backed by peer-reviewed research, not medical advice."}