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Marine Based Magnesium 500 mg

4.7
★ ★ ★ ★ ★
(1784 ratings)
Magnesium 500 mg
Product Image
Score65
A large marine-derived dose looks appealing, but hydroxide absorption and digestive tolerance are significant limitations.
How scoring works
Capsule
Quantity:90 Capsule(s) • (45 servings)
Goals:
Heart Health
Stress Relief
Digestive Health
General Health
Cardiovascular Support
Energy
Testosterone Support
Bone Health

Score 65

A large marine-derived dose looks appealing, but hydroxide absorption and digestive tolerance are significant limitations.
How scoring works
$17.19($0.38 per serving)
Vitacost
$ 18.19
iHerb
$ 17.24
Amazon
$ 17.19
Pure Formulas
$ 17.24
Report prices

Analysis

Aquamin seawater supplies a large labeled magnesium amount and a small calcium contribution. The marine source is identifiable, but the active is largely magnesium hydroxide.

Hydroxide is less useful for systemic replenishment than citrate, malate, or glycinate. Its bowel effect may be more noticeable than its absorbed magnesium contribution.

Two capsules provide a substantial label amount at moderate cost. The product fits users who tolerate hydroxide, but it is not the strongest choice for efficient absorption.

Who is it for
  • Adults comfortable with magnesium hydroxide
  • People seeking a marine mineral source
Best for
  • General magnesium intake with digestive effects in mind
  • Marine mineral supplementation

Pros

  • Clearly stated magnesium amount
  • Named marine source
  • Small calcium contribution

Cons

  • Hydroxide has limited systemic absorption
  • Two-capsule serving
  • Poor fit for efficient replenishment

Warnings

  • The 500 mg magnesium hydroxide amount may cause loose stools, urgency, or abdominal cramping

Nutrient quality

52 Moderate impact

A large label amount cannot overcome the low systemic absorption of magnesium hydroxide. The same high amount raises a meaningful risk of digestive discomfort.

.

Ingredient transparency

71 High impact

The elemental amount is clear, but repeated marine-source entries obscure each form’s contribution. No blend hides ingredients, while directions and non-active ingredients are absent.

.

Customer satisfaction

71 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

68 High impact

The low cost is offset by weak absorption for systemic magnesium support. A simple formula avoids extras but competes poorly with better-absorbed forms.

.
Report analysis

Goals

Heart Health
Heart Health
Impact
High effect
B Goal FitB Strength of SupportC- CoverageA- Formula Quality
Magnesium · 500 mg

A 500 mg magnesium amount provides substantial support for heart rhythm and vascular tone. The marine source is identified, but magnesium hydroxide is included and the usable share from each listed form is unclear.

The two-capsule formula is focused and contains little unrelated material. Magnesium hydroxide can have a laxative effect, and the full amount may cause diarrhea or abdominal discomfort in sensitive users.

Study evidence
Magnesium Supportive 158 studies
Stress Relief
Stress Relief
Impact
High effect
B Goal FitC+ Strength of SupportD+ CoverageB+ Formula Quality
Magnesium · 500 mg

A high magnesium amount can support nerve and muscle relaxation, especially when intake is inadequate. The mineral-only design is focused but does not address adaptogenic or immediate mental-calming pathways.

Magnesium hydroxide is less absorbable and more laxative than preferred glycinate forms. The 500 mg amount may cause diarrhea or abdominal cramping and may be difficult to tolerate as a single serving.

Study evidence
Magnesium Supportive 13 studies
Digestive Health
Digestive Health
Impact
High effect
B- Goal FitB+ Strength of SupportD CoverageB- Formula Quality
Magnesium · 500 mg

A substantial magnesium amount may support bowel motility through the osmotic effect of magnesium hydroxide. The magnesium amount is strong and likely sufficient to affect bowel function.

The marine source is identified, but mixed source labeling makes its absorption profile less certain. The marine mineral combination is coherent, though calcium adds little to the digestive purpose.

Study evidence
Magnesium Supportive 50 studies
General Health
General Health
Impact
High effect
A Goal FitD+ Strength of SupportD CoverageB+ Formula Quality
Magnesium · 500 mg

Magnesium is a foundational mineral involved in energy metabolism, muscle function, and nervous-system regulation, and the label reports a high amount. The marine source is primarily magnesium hydroxide, which has limited systemic absorption compared with well-formed organic or chelated options.

The high amount and hydroxide form may cause loose stools or abdominal cramping. Small calcium and sodium amounts add little to the central goal, while clear elemental labeling helps users understand what is supplied.

Study evidence
Magnesium Supportive 114 studies
Cardiovascular Support
Cardiovascular Support
Impact
High effect
B+ Goal FitD+ Strength of SupportD CoverageA Formula Quality
Magnesium · 500 mg

The large magnesium amount is relevant to normal vascular relaxation and cardiac rhythm. Magnesium hydroxide has limited systemic absorption, so the label amount may overstate its practical value for improving magnesium status.

The elemental amount and marine source are disclosed, but the formula is less suitable for targeted cardiovascular magnesium support than better-absorbed forms. The high hydroxide amount may cause loose stools or abdominal cramping.

Study evidence
Magnesium Supportive 123 studies
Energy
Energy
Impact
High effect
A Goal FitD+ Strength of SupportD- CoverageB Formula Quality
Magnesium · 500 mg

Magnesium supports ATP-dependent enzymes and physical-energy functions when intake is inadequate. The serving clearly lists a large elemental amount from a marine source.

Magnesium hydroxide has limited systemic absorption and may act mainly as an osmotic laxative at this dose. Loose stools or abdominal cramping are practical concerns with 500 mg from this form.

Study evidence
Magnesium Supportive 4 studies

Ingredients

IngredientAmount per serving
Calcium (Aquamin Red Algae, Seawater)
 25 mg
Magnesium (Aquamin Seawater, Magnesium Hydroxide)
 500 mg
Sodium
15 mg
Gluten Free Adults 18–50 Vegan Vegetarian
Report overview
Magnesium (Aquamin Seawater, Magnesium Hydroxide) · 500 mg OverallScore45
F Active Ingredient Quality & BioavailabilityB Dose, Safety & Label TransparencyD- Value

The marine magnesium comes primarily from magnesium hydroxide, a form with limited systemic absorption. Its 500 mg elemental dose is clearly stated and costs less than the collection median, but the form limits its value for raising magnesium status. The high dose and hydroxide form may cause loose stools or abdominal cramping.

View ingredientView products
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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. What is the impact of daily oral supplementation of vitamin D3 (cholecalciferol) plus calcium on the incidence of hip fracture in older people? A systematic review and meta-analysis.
    Manoj P; Derwin R; George S · International journal of older people nursing · 2023
    Meta-analysis12,620 participants7 studies pooledBone Health forCalcium
  6. Calcium supplementation prevents seasonal bone loss and changes in biochemical markers of bone turnover in elderly New England women: a randomized placebo-controlled trial.
    Storm D; Eslin R; Porter ES; Musgrave K; Vereault D; Patton C; Kessenich C; Mohan S; Chen T; Holick MF; Rosen CJ · The Journal of clinical endocrinology and metabolism · 1998
    Randomized trial60 participantsBone Health forCalcium
  7. The effects of calcium supplementation (milk powder or tablets) and exercise on bone density in postmenopausal women.
    Prince R; Devine A; Dick I; Criddle A; Kerr D; Kent N; Price R; Randell A · Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research · 1995
    Randomized trial168 participantsBone Health forCalcium
  8. The efficacy of calcium supplementation alone in elderly Thai women over a 2-year period: a randomized controlled trial.
    Rajatanavin R; Chailurkit L; Saetung S; Thakkinstian A; Nimitphong H · Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2014
    Randomized trial404 participantsBone Health forCalcium
  9. Calcium-enriched foods and bone mass growth in prepubertal girls: a randomized, double-blind, placebo-controlled trial.
    Bonjour JP; Carrie AL; Ferrari S; Clavien H; Slosman D; Theintz G; Rizzoli R · The Journal of clinical investigation · 1997
    Randomized trial149 participantsBone Health forCalcium
  10. 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
  11. 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
  12. 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
  13. 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
  14. 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
  15. 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
  16. 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
  17. 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
  18. 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
  19. 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 pooledCardiovascular Support 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. 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
  22. 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
  23. 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
  24. 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
  25. 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
  26. Red blood cell magnesium and chronic fatigue syndrome.
    Cox IM; Campbell MJ; Dowson D · Lancet (London, England) · 1991
    Randomized trial32 participantsEnergy forMagnesium
  27. Exercise, magnesium and immune function.
    Laires MJ; Monteiro C · Magnesium research · 2008
    Narrative reviewEnergy forMagnesium
  28. 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
  29. 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
  30. 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
  31. 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
  32. 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
  33. 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
  34. 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
  35. 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
  36. 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
  37. 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
  38. 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
  39. 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
  40. 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
  41. 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
  42. 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
  43. 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
  44. 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