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Magnesium Oxide 500 mg

Best Naturals
4.7
★ ★ ★ ★ ★
(120 ratings)
Magnesium 500 mg
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Score74
A cheap, high-dose magnesium oxide tablet may help bowel regularity but is a weak choice for absorbed magnesium support.
How scoring works
Quantity:180 Tablet(s) • (180 servings)
Goals:
Energy
Stress Relief

Score 74

A cheap, high-dose magnesium oxide tablet may help bowel regularity but is a weak choice for absorbed magnesium support.
How scoring works
$9.93($0.05 per serving)
iHerb
$ 11.99
Vitacost
$ 9.93
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Analysis

The 500 mg elemental amount looks impressive, but it comes entirely from magnesium oxide. Oxide tends to remain in the digestive tract more than citrate, glycinate, or malate, so the label amount overstates likely systemic uptake compared with better-absorbed forms.

A one-tablet serving and low cost are practical strengths. The same high amount may act mainly as an osmotic laxative and can cause cramping or urgent bowel movements.

It may suit someone deliberately using magnesium oxide for bowel effects. People seeking dependable magnesium support for muscles, sleep, or dietary repletion have better form choices.

Who is it for
  • Adults intentionally seeking magnesium oxide
  • People prioritizing low cost
  • Users who tolerate laxative effects
Best for
  • Occasional bowel-support use
  • One-tablet convenience
  • Budget-focused supplementation

Pros

  • Clearly discloses 500 mg elemental magnesium
  • Single-tablet serving
  • Very low serving cost
  • Simple active profile

Cons

  • Oxide has low systemic absorption
  • 500 mg is a high supplemental amount
  • High likelihood of loose stools or cramping
  • Poor fit for targeted magnesium repletion

Warnings

  • The 500 mg oxide serving of supplemental magnesium may cause loose stools, cramping, or nausea; a smaller divided amount may be easier to tolerate.
  • Magnesium can reduce absorption of tetracycline or quinolone antibiotics; follow the prescriber or pharmacist’s spacing instructions.
  • Magnesium can interfere with levothyroxine absorption and should be separated according to medication guidance.
  • People with significantly reduced kidney function can accumulate magnesium and need clinician-guided use.

Nutrient quality

65 Moderate impact

Magnesium oxide is inexpensive but has weak systemic absorption compared with citrate or chelated forms. The listed amount is large, though the poorly absorbed form limits how much is likely to be retained, while a large oxide dose may cause diarrhea or stomach discomfort.

Ingredient transparency

81 Highest impact

The magnesium amount and oxide form are clearly identified. Serving totals are apparent, but full directions and inactive ingredients are not supplied.

Customer satisfaction

63 Moderate impact

The supplied average rating is favorable. The moderate rating base offers some confidence but is not extensive, while complaint and firsthand experience details are unavailable.

Value for money

85 Highest impact

Formula quality provides partial support for the asking position. The serving value is reasonably competitive within the category.

Report analysis

Goals

Energy
Energy
Impact
High effect
A- Goal FitD+ Strength of SupportD- CoverageB+ Formula Quality
Magnesium · 500 mg

Magnesium is relevant to cellular energy production, but oxide is a poorly absorbed form for systemic support. The clearly disclosed 500 mg amount is high enough to create more digestive exposure without ensuring proportionate absorption.

The single-ingredient formula is simple but offers no alertness, stress-resilience, or complementary metabolic pathway. Magnesium oxide at this amount may cause diarrhea or abdominal discomfort, limiting practical daily use.

Study evidence
Magnesium Supportive 4 studies
Stress Relief
Stress Relief
Impact
High effect
B Goal FitD+ Strength of SupportD+ CoverageA- Formula Quality
Magnesium · 500 mg

Magnesium is relevant to nervous system regulation, but the oxide form limits its usefulness for systemic stress support. The single mineral also lacks adaptogenic or direct calming neurotransmitter coverage.

The amount is clearly disclosed but higher than the usual supplemental target. Low absorption and a greater chance of digestive upset weaken an otherwise focused formula.

Study evidence
Magnesium Supportive 13 studies
Digestive Health
Digestive Health
Impact
Moderate effect
C Goal FitC+ Strength of SupportF CoverageA- Formula Quality
Magnesium · 500 mg

Magnesium oxide can draw water into the bowel, so it may help occasional constipation. Its low absorption and substantial dose also make loose stools, cramping, or stomach discomfort more likely.

The single-pathway formula does not support enzymes, the gut lining, the microbiome, or fiber intake. Clear dosing is useful, but the oxide form is a blunt motility option rather than broad digestive support.

Study evidence
Magnesium Supportive 50 studies
Cardiovascular Support
Cardiovascular Support
Impact
Moderate effect
B- Goal FitD- Strength of SupportD+ CoverageA Formula Quality
Magnesium · 500 mg

Magnesium supports vascular tone and normal cardiac rhythm, giving it a direct but narrow cardiovascular role. Human evidence supports magnesium for blood-pressure and rhythm support, especially when intake is inadequate.

The magnesium amount exceeds the usual target range and may be harder to tolerate. Magnesium oxide has low absorption despite clear amount disclosure.

Study evidence
Magnesium Supportive 123 studies
General Health
General Health
Impact
Moderate effect
B+ Goal FitD Strength of SupportF CoverageB Formula Quality
Magnesium · 500 mg

The formula provides a large, clearly stated magnesium amount for a nutrient with broad roles in muscle, nerve, and energy function. Its single-ingredient design is straightforward.

Magnesium oxide is poorly absorbed compared with citrate or chelated forms, limiting its value for systemic magnesium support. The 500 mg amount may also cause loose stools or stomach discomfort without delivering proportionate absorption.

Study evidence
Magnesium Supportive 114 studies
Heart Health
Heart Health
Impact
Moderate effect
B- Goal FitD- Strength of SupportF CoverageB+ Formula Quality
Magnesium · 500 mg

Magnesium supports vascular tone, heart rhythm, and cellular energy, giving the mineral a clear cardiovascular role. The 500 mg amount is substantial, but magnesium oxide is poorly absorbed and limits reliable systemic support.

The high supplemental amount may cause diarrhea or abdominal cramping without delivering the expected absorbed magnesium. The focused formula also leaves lipid management, vascular signaling, and other heart pathways uncovered.

Study evidence
Magnesium Supportive 158 studies
Testosterone Support
Testosterone Support
Impact
Moderate effect
C- Goal FitF Strength of SupportF CoverageA+ Formula Quality
Magnesium · 500 mg

Magnesium is relevant to endocrine function when low intake contributes to poor status. Magnesium oxide is poorly absorbed, so the large label amount is not a strong systemic hormone-support dose.

The 500 mg amount also exceeds the usual supplemental target and may cause diarrhea or cramping. A single tablet is convenient, but form quality sharply limits its practical contribution.

Study evidence
Magnesium Disputed 5 studies

Ingredients

IngredientAmount per serving
Magnesium (Magnesium Oxide)
 500 mg
Gluten Free Adults 18–50 Sugar Free
Report overview
Magnesium (Magnesium Oxide) · 500 mg OverallScore44
F Active Ingredient Quality & BioavailabilityB Dose, Safety & Label TransparencyD- Value

The clearly stated elemental dose is higher than the usual target range and may be harder to tolerate. Magnesium oxide has low absorption potential, which limits its fit for systemic magnesium support. Its very low cost per serving does not fully offset that form-quality drawback.

View ingredientView products
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Magnesium Bisglycinate Powder

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<p>Magnesium bisglycinate supplies a well-absorbed form at a practical, moderate amount. Compared with the original, its magnesium form, dose clarity, and focused design offer a stronger quality-oriented option.</p>
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Magnesium Bisglycinate 200 mg

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Magnesium Citrate Pure Powder

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<p>A well-aligned amount of magnesium citrate delivers useful absorption in a focused powder. Its lower supplied serving cost makes it a more economical magnesium option than the original.</p>
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Magnesium Bisglycinate Chelate

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<p>TRAACS magnesium bisglycinate provides high-quality absorption quality, a useful elemental amount, and strong serving value in a clean powder. The supplied serving cost is not lower; it is included only because fewer than three eligible lower-cost choices from different brands are available.</p>
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Krebs Magnesium Potassium Complex

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<p>Magnesium lysinate and malate provide favorable forms at a useful amount, with a modest potassium contribution. The supplied serving cost is not lower; it is included only because fewer than three eligible lower-cost choices from different brands are available.</p>
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Magnesium Glycinate

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<p>Magnesium glycinate is a well-absorbed form that is often gentle on digestion. Its stated magnesium form and dose may improve formulation value, although the supplied serving cost is not lower than the original.</p>
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Magnesium Citrate 420 mg

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<p>A substantial amount of magnesium citrate offers useful absorption and a focused formula. Its stated magnesium form and dose may improve formulation value, although the supplied serving cost is not lower than the original.</p>
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Magnesium Citrate 200 mg

Best Naturals
<p>A substantial amount of magnesium citrate combines useful absorption with a focused single-active design. Its stated magnesium form and dose may improve formulation value, although the supplied serving cost is not lower than the original.</p>
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Sources

Published studies used for the product analysis and the top-ranked studies for each ingredient and goal.

  1. Magnesium status and magnesium therapy in critically ill patients: A systematic review.
    Fairley J; Glassford NJ; Zhang L; Bellomo R · Journal of critical care · 2016
    Systematic review34 studies pooledGeneral Health forMagnesium
  2. Hospital-Acquired Dysmagnesemia and In-Hospital Mortality.
    Cheungpasitporn W; Thongprayoon C; Chewcharat A; Petnak T; Mao MA; Davis PW; Bathini T; Vallabhajosyula S; Qureshi F; Erickson SB · Medical sciences (Basel, Switzerland) · 2024
    Cohort study26,020 participantsGeneral Health forMagnesium
  3. Association of magnesium sulfate use with mortality in critically ill patients with sepsis: a retrospective propensity score-matched cohort study.
    Gu WJ; Duan XJ; Liu XZ; Cen Y; Tao LY; Lyu J; Yin HY · British journal of anaesthesia · 2023
    Cohort study10,999 participantsGeneral Health forMagnesium
  4. Hypomagnesemia and Mortality in Incident Hemodialysis Patients.
    Li L; Streja E; Rhee CM; Mehrotra R; Soohoo M; Brunelli SM; Kovesdy CP; Kalantar-Zadeh K · American journal of kidney diseases : the official journal of the National Kidney Foundation · 2016
    Cohort study9,359 participantsGeneral Health forMagnesium
  5. Perioperative systemic magnesium to minimize postoperative pain: a meta-analysis of randomized controlled trials.
    De Oliveira GS; Castro-Alves LJ; Khan JH; McCarthy RJ · Anesthesiology · 2013
    Meta-analysis1,257 participants20 studies pooledGeneral Health forMagnesium
  6. The association between circulating magnesium and clinically relevant outcomes in patients with chronic kidney disease: A systematic review and meta-analysis.
    Leenders NHJ; Vermeulen EA; van Ballegooijen AJ; Hoekstra T; de Vries R; Beulens JW; Vervloet MG · Clinical nutrition (Edinburgh, Scotland) · 2021
    Meta-analysis348,059 participants33 studies pooledGeneral Health forMagnesium
  7. Serum magnesium, mortality, and cardiovascular disease in chronic kidney disease and end-stage renal disease patients: a systematic review and meta-analysis.
    Xiong J; He T; Wang M; Nie L; Zhang Y; Wang Y; Huang Y; Feng B; Zhang J; Zhao J · Journal of nephrology · 2020
    Meta-analysis200,934 participants20 studies pooledGeneral Health Cardiovascular Support forMagnesium
  8. Magpie Trial in the UK: methods and additional data for women and children at 2 years following pregnancy complicated by pre-eclampsia.
    Smyth RM; Spark P; Armstrong N; Duley L · BMC pregnancy and childbirth · 2009
    Randomized trial1,601 participantsGeneral Health forMagnesium
  9. Long-term outcome after intravenous magnesium sulphate in suspected acute myocardial infarction: the second Leicester Intravenous Magnesium Intervention Trial (LIMIT-2).
    Woods KL; Fletcher S · Lancet (London, England) · 1994
    Randomized trial2,316 participantsGeneral Health forMagnesium
  10. Effects of oral magnesium therapy on exercise tolerance, exercise-induced chest pain, and quality of life in patients with coronary artery disease.
    Shechter M; Bairey Merz CN; Stuehlinger HG; Slany J; Pachinger O; Rabinowitz B · The American journal of cardiology · 2003
    Randomized trial187 participantsGeneral Health forMagnesium
  11. The effect of food, vitamin, or mineral supplements on chronic constipation in adults: A systematic review and meta-analysis of randomized controlled trials.
    van der Schoot A; Creedon A; Whelan K; Dimidi E · Neurogastroenterology and motility · 2023
    Meta-analysis787 participants8 studies pooledDigestive Health forMagnesium
  12. Lactobacillus casei rhamnosus Lcr35 in children with chronic constipation.
    Bu LN; Chang MH; Ni YH; Chen HL; Cheng CC · Pediatrics international : official journal of the Japan Pediatric Society · 2007
    Randomized trial45 participantsDigestive Health forMagnesium
  13. A Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic Constipation.
    Mori S; Tomita T; Fujimura K; Asano H; Ogawa T; Yamasaki T; Kondo T; Kono T; Tozawa K; Oshima T; Fukui H; Kimura T; Watari J; Miwa H · Journal of neurogastroenterology and motility · 2022
    Randomized trial34 participantsDigestive Health forMagnesium
  14. Ca:Mg ratio, medium-chain fatty acids, and the gut microbiome.
    Fan L; Zhu X; Sun S; Yu C; Huang X; Ness R; Dugan LL; Shu L; Seidner DL; Murff HJ; Fodor AA; Azcarate-Peril MA; Shrubsole MJ; Dai Q · Clinical nutrition (Edinburgh, Scotland) · 2022
    Randomized trial240 participantsDigestive Health forMagnesium
  15. Magnesium-Rich Mineral Water Improves Stool Consistency and Bowel Habits in Healthy Subjects: A Randomized Controlled Trial.
    Yoneda H; Tomita T; Kitano T; Morishita D; Kodani M; Nishii N; Sei H; Eda H; Sato T; Kawai M; Yokoyama Y; Igeta M; Okugawa T; Fukui H; Shinzaki S · Neurogastroenterology and motility · 2026
    Randomized trial40 participantsDigestive Health forMagnesium
  16. Lactobacillus reuteri DSM 17938 and Magnesium Oxide in Children with Functional Chronic Constipation: A Double-Blind and Randomized Clinical Trial.
    Kubota M; Ito K; Tomimoto K; Kanazaki M; Tsukiyama K; Kubota A; Kuroki H; Fujita M; Vandenplas Y · Nutrients · 2020
    Randomized trial60 participantsDigestive Health forMagnesium
  17. Diagnosis of magnesium-induced diarrhea.
    Fine KD; Santa Ana CA; Fordtran JS · The New England journal of medicine · 1991
    Clinical trial19 participantsDigestive Health forMagnesium
  18. The Magnesium-Rich Formula for Functional Constipation in Infants: a Randomized Comparator-Controlled Study.
    Benninga MA; MENA Infant Constipation Study Group; Vandenplas Y · Pediatric gastroenterology, hepatology & nutrition · 2022
    Randomized trial286 participantsDigestive Health forMagnesium
  19. Effect of the laxative magnesium oxide on gastrointestinal functional recovery in fast-track colonic resection: a double-blind, placebo-controlled randomized study.
    Andersen J; Christensen H; Pachler JH; Hallin M; Thaysen HV; Kehlet H · Colorectal disease : the official journal of the Association of Coloproctology of Great Britain and Ireland · 2012
    Randomized trial49 participantsDigestive Health forMagnesium
  20. Efficacy of oral magnesium therapy in the treatment of chronic constipation in spastic cerebral palsy children: a randomized controlled trial.
    Hassanein SMA; Deifallah SM; Bastawy HA · World journal of pediatrics : WJP · 2021
    Randomized trial100 participantsDigestive Health forMagnesium
  21. Circulating and dietary magnesium and risk of cardiovascular disease: a systematic review and meta-analysis of prospective studies.
    Del Gobbo LC; Imamura F; Wu JH; de Oliveira Otto MC; Chiuve SE; Mozaffarian D · The American journal of clinical nutrition · 2013
    Meta-analysis313,041 participants16 studies pooledCardiovascular Support forMagnesium
  22. Magnesium and the risk of cardiovascular events: a meta-analysis of prospective cohort studies.
    Qu X; Jin F; Hao Y; Li H; Tang T; Wang H; Yan W; Dai K · PloS one · 2013
    Meta-analysis532,979 participants19 studies pooledCardiovascular Support forMagnesium
  23. Quantitative Association Between Serum/Dietary Magnesium and Cardiovascular Disease/Coronary Heart Disease Risk: A Dose-Response Meta-analysis of Prospective Cohort Studies.
    Zhao L; Hu M; Yang L; Xu H; Song W; Qian Y; Zhao M · Journal of cardiovascular pharmacology · 2020
    Meta-analysis544,581 participants18 studies pooledCardiovascular Support Heart Health forMagnesium
  24. Comparative Efficacy of Nutraceuticals on Endothelial Function: A Systematic Review and Network Meta-Analysis.
    Norouzzadeh M; Rashedi MH; Mahdavi-Mazdeh G; Kosari A; Shahinfar H · Current atherosclerosis reports · 2026
    Meta-analysisCardiovascular Support Heart Health forMagnesium
  25. Magnesium treatment increases gut microbiome synthesizing vitamin D and inhibiting colorectal cancer: results from a double-blind precision-based randomized placebo-controlled trial.
    Sun E; Zhu X; Ness RM; Murff HJ; Sun S; Yu C; Fan L; Azcarate-Peril MA; Shrubsole MJ; Dai Q · The American journal of clinical nutrition · 2025
    Randomized trial240 participantsDigestive Health forMagnesium
  26. Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial.
    Hausenblas HA; Lynch T; Hooper S; Shrestha A; Rosendale D; Gu J · Sleep medicine: X · 2025
    Randomized trial80 participantsEnergy forMagnesium
  27. Total magnesium intake and risk of frailty in older women.
    Struijk EA; Fung TT; Bischoff-Ferrari HA; Willett WC; Lopez-Garcia E · Journal of cachexia, sarcopenia and muscle · 2024
    Cohort study81,524 participantsEnergy forMagnesium
  28. Red blood cell magnesium and chronic fatigue syndrome.
    Cox IM; Campbell MJ; Dowson D · Lancet (London, England) · 1991
    Randomized trial32 participantsEnergy forMagnesium
  29. Exercise, magnesium and immune function.
    Laires MJ; Monteiro C · Magnesium research · 2008
    Narrative reviewEnergy forMagnesium
  30. The effects of magnesium supplementation on abnormal uterine bleeding, alopecia, quality of life, and acne in women with polycystic ovary syndrome: a randomized clinical trial.
    Jaripur M; Ghasemi-Tehrani H; Askari G; Gholizadeh-Moghaddam M; Clark CCT; Rouhani MH · Reproductive biology and endocrinology : RB&E · 2022
    Randomized trial64 participantsGeneral Health forMagnesium
  31. Effects of magnesium supplementation on improving hyperglycemia, hypercholesterolemia, and hypertension in type 2 diabetes: A pooled analysis of 24 randomized controlled trials.
    Xu L; Li X; Wang X; Xu M · Frontiers in nutrition · 2023
    Meta-analysis1,325 participants24 studies pooledHeart Health forMagnesium
  32. The effect of lowering blood pressure by magnesium supplementation in diabetic hypertensive adults with low serum magnesium levels: a randomized, double-blind, placebo-controlled clinical trial.
    Guerrero-Romero F; Rodríguez-Morán M · Journal of human hypertension · 2009
    Randomized trial82 participantsHeart Health forMagnesium
  33. Positive effects of magnesium supplementation in metabolic syndrome.
    Kisters S; Kisters K; Werner T; Vormann J; Tokmak F; Westhoff T; Gröber U; Predel HG; Reuter H · International journal of clinical pharmacology and therapeutics · 2024
    Randomized trial54 participantsHeart Health forMagnesium
  34. Role of magnesium supplementation in the treatment of depression: A randomized clinical trial.
    Tarleton EK; Littenberg B; MacLean CD; Kennedy AG; Daley C · PloS one · 2017
    Randomized trial126 participantsStress Relief forMagnesium
  35. Effects of Intravenous Esketamine or Magnesium Sulfate on Early Postoperative Negative Emotions and Pain in Patients Undergoing Endoscopic Sinus Surgery: A Randomized Controlled Trial.
    Wang L; Zhou J; Liu Q; Qian K; Wang L; Xie C · Therapeutics and clinical risk management · 2026
    Randomized trial137 participantsStress Relief forMagnesium
  36. Effect of short-term magnesium supplementation on anxiety, depression and sleep quality in patients after open-heart surgery.
    Saba S; Faizi F; Sepandi M; Nehrir B · Magnesium research · 2022
    Non-randomized trial60 participantsStress Relief forMagnesium
  37. Effects of dry needling compared to magnesium infiltration in trigger points for patients with myofascial pain syndrome: a randomized controlled study in Tunisia.
    Dhouibi J; Moncer R; Kalbousi N; Gaddour M; Laayouni S; Ouanes W; Kacem B; Jemni S · Korean journal of family medicine · 2026
    Randomized trial45 participantsStress Relief forMagnesium
  38. Effect of magnesium and vitamin B6 supplementation on mental health and quality of life in stressed healthy adults: Post-hoc analysis of a randomised controlled trial.
    Noah L; Dye L; Bois De Fer B; Mazur A; Pickering G; Pouteau E · Stress and health : journal of the International Society for the Investigation of Stress · 2021
    Randomized trialStress Relief forMagnesium
  39. Magnesium and anabolic hormones in older men.
    Maggio M; Ceda GP; Lauretani F; Cattabiani C; Avantaggiato E; Morganti S; Ablondi F; Bandinelli S; Dominguez LJ; Barbagallo M; Paolisso G; Semba RD; Ferrucci L · International journal of andrology · 2012
    Cohort study399 participantsTestosterone Support forMagnesium
  40. Analysis of the relationship between the blood concentration of several metals, macro- and micronutrients and endocrine disorders associated with male aging.
    Rotter I; Kosik-Bogacka DI; Dołęgowska B; Safranow K; Kuczyńska M; Laszczyńska M · Environmental geochemistry and health · 2017
    Cross-sectional study313 participantsTestosterone Support forMagnesium
  41. Effect of magnesium supplementation in improving hyperandrogenism, hirsutism, and sleep quality in women with polycystic ovary syndrome: A randomized, placebo-controlled clinical trial.
    Gholizadeh-Moghaddam M; Ghasemi-Tehrani H; Askari G; Jaripur M; Clark CCT; Rouhani MH · Health science reports · 2024
    Randomized trial64 participantsTestosterone Support forMagnesium
  42. The effects of trace element supplementation on glycolipid metabolism in PCOS: a systematic review and meta-analysis.
    Yang L; Gao Y; Zhao W; Qi Y; Duo X; Wang H · Frontiers in nutrition · 2025
    Meta-analysis1,600 participants25 studies pooledTestosterone Support forMagnesium
  43. Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion.
    Cinar V; Polat Y; Baltaci AK; Mogulkoc R · Biological trace element research · 2011
    Non-randomized trial20 participantsTestosterone Support forMagnesium