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Magnesium Caps 420 mg

4.6
★ ★ ★ ★ ★
(482 ratings)
Magnesium 420 mg
Product Image
Score69
Low cost and a large label dose are appealing, but oxide absorption and digestive effects make it a weaker systemic magnesium option.
How scoring works
Capsule
Quantity:100 Capsule(s) • (100 servings)
Goals:
Bone Health
Cardiovascular Support
Digestive Health
Heart Health
General Health
Stress Relief

Score 69

Low cost and a large label dose are appealing, but oxide absorption and digestive effects make it a weaker systemic magnesium option.
How scoring works

Also available as

1 option
200 servings Magnesium 420 mg • 200 Capsule(s) • 200 servings $16.71 ($0.08 per serving)
$10.99($0.10 per serving)
iHerb
$ 10.99
Vitacost
$ 10.99
Pure Formulas
$ 10.99
Amazon
$ 37.95
Walmart
$ 12.65
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Analysis

The capsule supplies a large amount of magnesium oxide in a simple formula. Oxide contains much magnesium by weight but is absorbed less efficiently than citrate, malate, or glycinate.

The dose may still contribute to general intake and can have a noticeable bowel effect. It is less convincing for energy, stress, or deficiency replenishment than the label amount suggests.

One capsule and a long supply provide strong convenience and value. Users should choose it with digestive tolerance rather than label potency alone in mind.

Who is it for
  • Budget-focused adults who tolerate magnesium oxide
  • People wanting a one-capsule high-label-dose product
Best for
  • General magnesium intake with bowel effects in mind
  • Economical long-term supply

Pros

  • Large labeled amount
  • One-capsule serving
  • Strong serving value

Cons

  • Oxide has limited absorption
  • Weak fit for efficient replenishment
  • High amount may be hard to tolerate

Warnings

  • Magnesium oxide at 420 mg may cause diarrhea, urgency, or abdominal cramping

Nutrient quality

54 Moderate impact

The large label amount is undermined by the weak absorption of magnesium oxide. Digestive side effects are a meaningful concern at the full serving.

.

Ingredient transparency

84 Highest impact

The active form and elemental amount are specific, with no hidden blend. Intake directions and non-active ingredients were not included in the supplied details.

.

Customer satisfaction

68 High impact

The available satisfaction metric and sample size provide the clearest evidence for general acceptance. Specific experience details are absent, so repeated complaints and purpose fit remain uncertain.

.

Value for money

70 High impact

A very low serving cost improves affordability but not absorption. Better-formed magnesium products provide stronger effective value.

.
Report analysis

Goals

Bone Health
Bone Health
Impact
Highest effect
A+ Goal FitA- Strength of SupportA CoverageA+ Formula Quality
Magnesium · 420 mg

The formula directly targets mineral structure, absorption, and remodeling with multiple bone-specific actives. Hydroxyapatite calcium, vitamin D, vitamin K, magnesium, and boron have strong complementary skeletal rationale.

The formula provides useful amounts across calcium, magnesium, vitamin D, K2, boron, and phosphorus. The formula covers mineral structure, absorption, remodeling, and trace-mineral support.

Study evidence
Magnesium Supportive 48 studies
Cardiovascular Support
Cardiovascular Support
Impact
Highest effect
A Goal FitA- Strength of SupportC CoverageA+ Formula Quality
Magnesium · 420 mg

Ubiquinone supports mitochondrial energy production in heart muscle and provides lipid-phase antioxidant activity. The standard amount may be especially relevant when statin use or low CoQ10 status is a concern.

The focused capsule clearly discloses the ubiquinone amount and form. CoQ10 may reduce warfarin’s anticoagulant effect, so stable use requires clinical monitoring.

Digestive Health
Digestive Health
Impact
High effect
B- Goal FitB- Strength of SupportD- CoverageA+ Formula Quality
Magnesium · 420 mg

Magnesium oxide can promote bowel movements through poor absorption, giving it a narrow motility role. The magnesium amount is substantial enough to influence bowel function.

Its low solubility makes delivery less predictable and less suitable for nutritional magnesium support. The single-ingredient design is clear and coherent.

Study evidence
Magnesium Supportive 50 studies
Heart Health
Heart Health
Impact
High effect
B- Goal FitC Strength of SupportD+ CoverageA Formula Quality
Magnesium · 420 mg

The formula supplies a substantial magnesium amount for vascular tone and normal cardiac rhythm. Magnesium oxide is poorly absorbed, which limits the effective systemic contribution.

Its focused design avoids unrelated ingredients but covers only one cardiovascular pathway. Magnesium oxide commonly causes digestive discomfort or loose stools at this amount.

Study evidence
Magnesium Supportive 158 studies
General Health
General Health
Impact
High effect
B+ Goal FitD+ Strength of SupportD- CoverageB+ Formula Quality
Magnesium · 420 mg

Magnesium is important for energy production, muscle function, and nervous-system regulation. The 420 mg amount is clearly stated, but magnesium oxide has low systemic absorption.

The nominal dose looks substantial while the weak form limits how much may be usefully absorbed. A low-cost, simple capsule is practical, yet people seeking foundational magnesium support have better-form options.

Study evidence
Magnesium Supportive 114 studies
Stress Relief
Stress Relief
Impact
High effect
B Goal FitD+ Strength of SupportD CoverageB+ Formula Quality
Magnesium · 420 mg

The high labeled magnesium amount is relevant to nervous-system regulation, but oxide is poorly absorbed for systemic use. The low-quality form limits how much of the stated amount may contribute to stress resilience.

The single-mineral formula is transparent and free of unrelated actives. It offers no cofactor, chelate, adaptogen, or direct calming ingredient to compensate for the weak form.

Study evidence
Magnesium Supportive 13 studies

Ingredients

IngredientAmount per serving
Magnesium (Magnesium Oxide)
 420 mg
Adults 18–50
Report overview
Magnesium (Magnesium Oxide) · 420 mg OverallScore52
F Active Ingredient Quality & BioavailabilityA Dose, Safety & Label TransparencyD+ Value

The clearly stated 420 mg elemental amount fits the target range, but magnesium oxide has low absorption for systemic use. The simple formula has no absorption-supporting cofactor or specialized processing. Its low serving cost improves affordability, though the weak form limits effective value.

View ingredientView products
Loading alternative details
91 Performance

Krebs Magnesium Potassium Complex

Nature's Way
<p>Magnesium lysinate and malate provide favorable forms at a useful amount, with a modest potassium contribution. Compared with the original, its magnesium form, dose clarity, and focused design offer a stronger quality-oriented option.</p>
88 Performance

Magnesium Bisglycinate Powder

NOW
<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>
85 Performance

Cal/Mag 500 mg/250 mg

NaturesPlus
<p>Chelated calcium and magnesium provide a focused, balanced mineral formula with strong form quality. Compared with the original, its magnesium form, dose clarity, and focused design offer a stronger quality-oriented option.</p>
83 Budget

Magnesium Citrate Pure Powder

Best Naturals
<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>
84 Budget

Potassium + Magnesium

Nutricost
<p>A meaningful magnesium citrate amount anchors a simple two-mineral electrolyte formula. Its lower supplied serving cost makes it a more economical magnesium option than the original.</p>
80 Budget

Magnesium Caps 500 mg

Life Extension
<p>Citrate, succinate, and a named glycinate chelate strengthen a multi-form magnesium blend, while oxide lowers average absorption. Its lower supplied serving cost makes it a more economical magnesium option than the original.</p>
85 Value

Magnesium Bisglycinate Chelate

Healthy Origins
<p>TRAACS magnesium bisglycinate provides high-quality absorption quality, a useful elemental amount, and strong serving value in a clean powder. Its stated magnesium form and dose may improve formulation value, although the supplied serving cost is not lower than the original.</p>
84 Value

Magnesium Glycinate

NOW
<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>
83 Value

Magnesium Citrate 420 mg

Nutricost
<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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Sources

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

  1. 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
  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. 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
  4. Diagnosis of magnesium-induced diarrhea.
    Fine KD; Santa Ana CA; Fordtran JS · The New England journal of medicine · 1991
    Clinical trial19 participantsDigestive Health forMagnesium
  5. Association between Serum Magnesium and Fractures: A Systematic Review and Meta-Analysis of Observational Studies.
    Dominguez LJ; Veronese N; Ciriminna S; Pérez-Albela JL; Vásquez-López VF; Rodas-Regalado S; Di Bella G; Parisi A; Tagliaferri F; Barbagallo M · Nutrients · 2023
    Meta-analysis119,755 participants4 studies pooledBone Health forMagnesium
  6. Bioabsorbable Magnesium-Based Materials Potential and Safety in Bone Surgery: A Systematic Review.
    Hung CH; Kwok YC; Yip J; Wong HH; Leung YY · Craniomaxillofacial trauma & reconstruction · 2025
    Systematic review386 participants8 studies pooledBone Health forMagnesium
  7. Vascularized bone grafting fixed by biodegradable magnesium screw for treating osteonecrosis of the femoral head.
    Zhao D; Huang S; Lu F; Wang B; Yang L; Qin L; Yang K; Li Y; Li W; Wang W; Tian S; Zhang X; Gao W; Wang Z; Zhang Y; Xie X; Wang J; Li J · Biomaterials · 2016
    Randomized trial48 participantsBone Health forMagnesium
  8. An update on magnesium and bone health.
    Rondanelli M; Faliva MA; Tartara A; Gasparri C; Perna S; Infantino V; Riva A; Petrangolini G; Peroni G · Biometals : an international journal on the role of metal ions in biology, biochemistry, and medicine · 2022
    Narrative reviewBone Health forMagnesium
  9. Sex-specific differences in the association of magnesium intake with femoral neck bone mineral density among older adults.
    Wang B; Tan X; Yao X; Zhu Z · Endocrine connections · 2025
    Cross-sectional study1,343 participantsBone Health forMagnesium
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. Red blood cell magnesium and chronic fatigue syndrome.
    Cox IM; Campbell MJ; Dowson D · Lancet (London, England) · 1991
    Randomized trial32 participantsEnergy forMagnesium
  17. Exercise, magnesium and immune function.
    Laires MJ; Monteiro C · Magnesium research · 2008
    Narrative reviewEnergy forMagnesium
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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 pooledHeart Health forMagnesium
  23. 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
  24. 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
  25. 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
  26. 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-analysisHeart Health forMagnesium
  27. 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
  28. 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
  29. 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
  30. 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
  31. 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
  32. 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
  33. 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
  34. 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
  35. 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
  36. 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