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Magnesium Caps 420 mg

4.7
★ ★ ★ ★ ★
(1515 ratings)
Magnesium 420 mg
Product Image
Score70
Excellent value and convenience cannot fully offset magnesium oxide's weak absorption and higher digestive burden.
How scoring works
Capsule
Quantity:200 Capsule(s) • (200 servings)
Goals:
Bone Health
Cardiovascular Support
Heart Health
General Health
Stress Relief

Score 70

Excellent value and convenience cannot fully offset magnesium oxide's weak absorption and higher digestive burden.
How scoring works

Also available as

1 option
100 servings Magnesium 420 mg • 100 Capsule(s) • 100 servings $10.99 ($0.10 per serving)
$16.71($0.08 per serving)
iHerb
$ 16.71
Vitacost
$ 18.39
Amazon
$ 16.71
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Analysis

The formula uses only magnesium oxide at a substantial labeled amount. The form is compact and inexpensive but not absorbed as well as glycinate, citrate, or malate.

Some users may value its bowel effect, yet that same property can cause urgency or cramping. The product's stress, energy, and heart support is therefore less dependable than its large number suggests.

One capsule and a very long supply make it exceptionally economical. It fits users who already know they tolerate oxide and value cost above form quality.

Who is it for
  • Value-focused adults who tolerate oxide
  • People seeking a long one-capsule supply
Best for
  • Economical magnesium intake
  • Users who accept a bowel effect

Pros

  • Substantial labeled amount
  • One capsule daily
  • Very large supply
  • Excellent serving value

Cons

  • Less-absorbable oxide form
  • Poorer fit for replenishment
  • Digestive effects are likely at the full amount

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.

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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

72 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.

.
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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.

Heart Health
Heart Health
Impact
High effect
C+ Goal FitC+ Strength of SupportD+ CoverageA- Formula Quality
Magnesium · 420 mg

Magnesium oxide provides foundational support for vascular tone, blood-pressure regulation, and normal heart rhythm. It does not address lipids, nitric oxide, or cardiac cellular energy.

The 420 mg amount is substantial, but oxide is clearly named but is less bioavailable than citrate or bisglycinate. Magnesium oxide at this amount may cause diarrhea or abdominal cramping.

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 supports energy metabolism, muscle function, and normal nerve signaling. The label clearly provides 420 mg, but magnesium oxide is poorly absorbed for systemic use.

The concentrated amount does not fully overcome the form limitation. A simple one-capsule serving is convenient, although more bioavailable magnesium forms are better aligned with ongoing foundational support.

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 substantial magnesium amount supports nervous-system regulation in principle, but oxide is a weakly absorbed form. Effective stress support may therefore be much lower than the label amount suggests.

The capsule is simple and fully disclosed, with no irrelevant active ingredients. No chelate, cofactor, or complementary calming pathway improves the formulation.

Study evidence
Magnesium Supportive 13 studies
Digestive Health
Digestive Health
Impact
Moderate effect
C Goal FitC+ Strength of SupportF CoverageA- Formula Quality
Magnesium · 420 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

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>
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 Budget

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. 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>
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>
83 Value

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. 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
  2. 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
  3. Diagnosis of magnesium-induced diarrhea.
    Fine KD; Santa Ana CA; Fordtran JS · The New England journal of medicine · 1991
    Clinical trial19 participantsDigestive Health forMagnesium
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. Red blood cell magnesium and chronic fatigue syndrome.
    Cox IM; Campbell MJ; Dowson D · Lancet (London, England) · 1991
    Randomized trial32 participantsEnergy forMagnesium
  20. Exercise, magnesium and immune function.
    Laires MJ; Monteiro C · Magnesium research · 2008
    Narrative reviewEnergy forMagnesium
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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
  26. 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
  27. 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
  28. 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
  29. 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
  30. 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
  31. 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
  32. 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
  33. 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
  34. 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
  35. 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
  36. 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
  37. 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
  38. 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
  39. 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
  40. 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