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Marine Based Cal-Mag 500/250 mg

4.6
★ ★ ★ ★ ★
(103 ratings)
Calcium 500 mg
Magnesium 250 mg
Product Image
Score70
A useful marine-sourced liquid calcium-magnesium formula with good amounts. Duplicated source entries, magnesium hydroxide, and notable carbohydrate limit precision.
How scoring works
Liquid
Quantity:16 Liquid(s) • (32 servings)
Goals:
Bone Health
General Health
Energy

Score 70

A useful marine-sourced liquid calcium-magnesium formula with good amounts. Duplicated source entries, magnesium hydroxide, and notable carbohydrate limit precision.
How scoring works
$26.24($0.82 per serving)
Vitacost
$ 26.24
iHerb
$ 26.24
Pure Formulas
$ 26.24
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Analysis

The liquid lists 500 mg calcium from red algae and seawater plus 250 mg magnesium from seawater and magnesium hydroxide. These amounts are relevant to bone, muscle, and nerve function when dietary intake is low.

Marine sourcing is distinctive, but the repeated amount under multiple sources makes the true elemental breakdown uncertain. Magnesium hydroxide may loosen stools, while eight grams of carbohydrate makes the formula less streamlined.

It fits adults who prefer liquid minerals and accept the carbohydrate content. The serving should be measured carefully and separated from medicines whose absorption is reduced by calcium or magnesium.

Who is it for
  • Adults who prefer liquid minerals
  • Users interested in marine-derived calcium
  • People seeking combined calcium and magnesium
Best for
  • Bone-mineral support
  • Muscle and nerve nutrient support
  • Liquid mineral supplementation

Pros

  • Provides useful calcium and magnesium amounts
  • Uses marine mineral sources
  • Liquid format suits users avoiding tablets

Cons

  • Source amounts appear duplicated
  • Uses magnesium hydroxide
  • Contains eight grams of carbohydrate
  • Inactive details are incomplete

Warnings

  • Calcium and magnesium can reduce absorption of levothyroxine and certain antibiotics
  • Magnesium hydroxide may cause diarrhea or cramping
  • People with kidney disease should review this mineral load with a clinician

Nutrient quality

77 High impact

Less absorbable mineral forms are the main quality weakness. Non-active carbohydrate also reduces formula efficiency.

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Ingredient transparency

80 High impact

Active amounts are fully disclosed without a hidden blend. Missing full directions and inactive ingredients keep the supplied label information incomplete.

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Customer satisfaction

61 Moderate impact

The supplied average is generally favorable and rests on a limited review count. No review text was provided to assess repeated complaints or specific user experiences.

.

Value for money

58 Moderate impact

Serving efficiency is limited for the disclosed mineral profile. Non-active carbohydrate or formula limitations weaken competitiveness.

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Report analysis

Goals

Bone Health
Impact
Highest effect
A Goal FitA Strength of SupportB+ CoverageA- Formula Quality
Magnesium · 250 mgCalcium · 500 mg

Marine calcium and magnesium provide substantial structural minerals in a liquid Aquamin formula. Both nutrients have established roles in maintaining bone tissue.

The mineral pairing is focused and easier to adjust than a fixed tablet serving. It lacks vitamin D, vitamin K, and protein-matrix support, while the added carbohydrate is not relevant to bone health.

Study evidence
Calcium Supportive 144 studies
Magnesium Supportive 48 studies
Impact
High effect
A- Goal FitC+ Strength of SupportC- CoverageB- Formula Quality
Magnesium · 250 mg

Magnesium and calcium contribute to foundational muscle, nerve, and bone function in an easy-to-measure liquid. The formula is relevant to daily health but is held back by limited mineral absorption.

The 250 mg magnesium amount is suitable for routine use, while magnesium hydroxide is a weak form for systemic delivery. Added carbohydrates and the absence of vitamin D or related cofactors make the liquid less streamlined than the core minerals suggest.

Study evidence
Magnesium Supportive 114 studies
Energy
Impact
High effect
B Goal FitB- Strength of SupportD+ CoverageC+ Formula Quality
Magnesium · 250 mg

Magnesium reaches a meaningful amount for ATP-related enzyme activity and muscle function. The elemental amount is clearly disclosed in a liquid format.

Magnesium hydroxide has limited systemic absorption, while large calcium and carbohydrate amounts reduce focus. The bone-mineral formula offers little support for alertness or stress resilience.

Study evidence
Magnesium Supportive 4 studies
Impact
Moderate effect
C Goal FitB- Strength of SupportD CoverageC+ Formula Quality
Magnesium · 250 mg

A meaningful magnesium amount supports normal rhythm and vascular function, but hydroxide has limited absorption. Calcium dominates the mineral balance and the formula lacks more targeted heart actives.

The disclosed serving supports one established mineral pathway rather than broad cardiovascular coverage. The liquid format does not overcome the limitations of the basic mineral forms.

Study evidence
Magnesium Supportive 158 studies
Stress Relief
Impact
Moderate effect
C Goal FitC Strength of SupportD- CoverageB Formula Quality
Magnesium · 250 mg

Magnesium supports nervous-system regulation and muscle relaxation, with the clearest benefit when intake is inadequate. Its physiological role is established, while human evidence for reducing perceived stress in otherwise replete users is less robust than for targeted adaptogens or theanine.

The 250 mg magnesium amount sits in a meaningful supplemental range. Magnesium hydroxide is poorly absorbed even though the marine source and amount are disclosed.

Study evidence
Magnesium Supportive 13 studies
Digestive Health
Impact
Moderate effect
C Goal FitB- Strength of SupportD- CoverageC- Formula Quality
Magnesium · 250 mg

Magnesium hydroxide can support stool softening, while the larger calcium amount may promote constipation in some users. The formula is a calcium-magnesium supplement rather than a dedicated digestive product.

The 250 mg magnesium amount is visible, but hydroxide has low systemic absorption and can produce loose stools. Calcium may reduce the net motility effect, making individual response less predictable.

Study evidence
Magnesium Supportive 50 studies
Cardiovascular Support
Impact
Moderate effect
C- Goal FitC- Strength of SupportF CoverageC+ Formula Quality
Magnesium · 250 mg

Magnesium provides direct support for vascular tone and normal cardiac electrical activity. Human evidence is relevant, but the product does not address lipid management, nitric oxide production, or cardiac energy.

The magnesium amount is practical, but hydroxide has low systemic absorption and four capsules create a larger serving burden. Twice as much calcium shifts the formula toward bone support rather than cardiovascular use.

Study evidence
Magnesium Supportive 123 studies

Ingredients

IngredientAmount per serving
Calories
32 Calorie(s)
Total Carbohydrates
8 Gram(s)
Calcium (Aquamin Red Algae, Seawater)
500 mg
Magnesium (Aquamin Seawater, Magnesium Hydroxide)
250 mg
Sodium
15 mg
Gluten Free Adults 18–50 Vegan Vegetarian
Report overview
A+ Active Ingredient Quality & BioavailabilityA+ Dose, Safety & Label TransparencyF Value

Red-algae Aquamin supplies a high-quality marine calcium source in a liquid format. The serving amount fits efficient calcium absorption and includes magnesium as a useful companion mineral. Its high serving cost limits value, and the listed carbohydrate content may matter to people monitoring carbohydrate intake.

F Active Ingredient Quality & BioavailabilityB+ Dose, Safety & Label TransparencyF Value

The elemental magnesium amount is clear and suitable for routine supplementation, but hydroxide has low absorption potential. Calcium is present at exactly twice the magnesium amount without a listed vitamin D, boron, or vitamin B6 cofactor. The costly liquid serving offers poor value for these basic mineral forms.

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Sources

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

  1. Calcium supplementation provides an extended window of opportunity for bone mass accretion after menarche.
    Rozen GS; Rennert G; Dodiuk-Gad RP; Rennert HS; Ish-Shalom N; Diab G; Raz B; Ish-Shalom S · The American journal of clinical nutrition · 2003
    Randomized trial100 participantsBone Health forCalcium
  2. Calcium supplementation and bone mineral density in postmenopausal women using estrogen replacement therapy.
    Haines CJ; Chung TK; Leung PC; Hsu SY; Leung DH · Bone · 1995
    Randomized trialBone Health forCalcium
  3. Relationship between bone mineral density changes and risk of fractures among patients receiving calcium with or without vitamin D supplementation: a meta-regression.
    Rabenda V; Bruyère O; Reginster JY · Osteoporosis international : a journal established as result of cooperation between the European Foundation for Osteoporosis and the National Osteoporosis Foundation of the USA · 2011
    Meta-analysis47,365 participants15 studies pooledBone Health forCalcium
  4. Bone turnover and the response to alendronate treatment in postmenopausal osteoporosis.
    Gonnelli S; Cepollaro C; Pondrelli C; Martini S; Montagnani A; Monaco R; Gennari C · Calcified tissue international · 1999
    Randomized trial100 participantsBone Health forCalcium
  5. Calcium and osteoporosis.
    Nordin BE · Nutrition (Burbank, Los Angeles County, Calif.) · 1998
    Meta-analysis20 studies pooledBone Health forCalcium
  6. 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
  7. Magnesium intake, bone mineral density, and fractures: results from the Women's Health Initiative Observational Study.
    Orchard TS; Larson JC; Alghothani N; Bout-Tabaku S; Cauley JA; Chen Z; LaCroix AZ; Wactawski-Wende J; Jackson RD · The American journal of clinical nutrition · 2014
    Cohort study73,684 participantsBone Health forMagnesium
  8. Dialysate Magnesium and Coronary Artery Calcification, Bone Mineral Density, and Cramping in Maintenance Hemodialysis: A Quasi-experimental Study.
    Srisuwarn P; Sethakarun S; Nongnuch A; Jongjirasiri S; Sritara C; Klyprayong P; Disthabanchong S · Kidney medicine · 2022
    Non-randomized trial40 participantsBone Health forMagnesium
  9. Association between magnesium deficiency scores and hip bone health in adults: a population-based study.
    Li S; Chang W; Wu G; Wang K; Sun X; Sun H; Zhou J · Magnesium research · 2025
    Cross-sectional study13,259 participantsBone Health forMagnesium
  10. 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
  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 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
  13. 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
  14. Diagnosis of magnesium-induced diarrhea.
    Fine KD; Santa Ana CA; Fordtran JS · The New England journal of medicine · 1991
    Clinical trial19 participantsDigestive Health forMagnesium
  15. 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
  16. 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
  17. 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
  18. 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
  19. 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
  20. 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
  21. 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
  22. 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
  23. 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
  24. 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
  25. 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
  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 pooledCardiovascular Support Heart Health forMagnesium
  27. 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
  28. 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
  29. 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
  30. 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
  31. 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
  32. 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
  33. 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
  34. 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
  35. 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
  36. Red blood cell magnesium and chronic fatigue syndrome.
    Cox IM; Campbell MJ; Dowson D · Lancet (London, England) · 1991
    Randomized trial32 participantsEnergy forMagnesium
  37. Exercise, magnesium and immune function.
    Laires MJ; Monteiro C · Magnesium research · 2008
    Narrative reviewEnergy forMagnesium
  38. 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
  39. 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
  40. 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
  41. 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
  42. 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
  43. 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
  44. 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
  45. 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
  46. 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
  47. 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
  48. 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
  49. 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
  50. 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