Name: Klean Athlete Klean Magnesium (NSF Certified for Sport, 120mg Glycinate)
Brand: Klean Athlete

Verdict: BUY (athlete-tier). EDE Score 87/100. Klean Athlete Klean Magnesium is the cleanest NSF Certified for Sport magnesium glycinate on the market: practitioner-grade Douglas Laboratories manufacturing, every batch tested for 290 WADA-banned substances, transparent 1-4 capsule dosing for individual titration. The $0.88 CPED at clinical dose (3 capsules per day) is mid-tier within the magnesium category, and the per-serving 120 mg is below clinical effective dose, requiring multi-capsule regimens. For drug-tested athletes, NCAA athletes, military, and first responders who need NSF Sport certification on every input, this is the right buy.

This article contains paid links. We may earn a commission if you purchase through these links. Commissions never influence our scoring. Read our methodology and editorial policy.

At a glance

Metric	Value
Brand	Klean Athlete (Douglas Laboratories)
Product	Klean Magnesium (NSF Certified for Sport)
Form	Vegetarian capsule (HPMC)
Servings per bottle	90 capsules
Per-capsule dose	120 mg elemental magnesium (as magnesium glycinate)
Brand-recommended daily dose	1-4 capsules daily
Clinical effective dose	300-400 mg/day (NIH ODS)
Other ingredients	Hydroxypropyl methylcellulose, ascorbyl palmitate
Third-party testing	NSF Certified for Sport (every batch)
Price retail	$26.50
CPED at 3 capsules per day	$0.88 per effective day
EDE Score	87/100
Verdict	BUY (athlete-tier)

Why this product matters for men 40+

Magnesium is one of the most critical and one of the most consistently under-supplemented minerals for adult men. The NHANES dietary intake data shows roughly 50-60% of US adults consume below the Estimated Average Requirement (350 mg/day for men 31-70).¹ Active men, men with high training loads, men consuming high-protein diets, and men taking proton pump inhibitors or thiazide diuretics all face elevated magnesium losses and tend to fall further short.

For men 40 and older, suboptimal magnesium status is associated with reduced testosterone production, poorer sleep architecture, slower exercise recovery, elevated blood pressure, increased insulin resistance, and higher risk of cardiac arrhythmias. The mechanistic link to testosterone is well documented: a 2011 study by Cinar and colleagues in 30 men showed that 4 weeks of 10 mg/kg/day magnesium supplementation in both sedentary and trained men increased serum total and free testosterone, with the effect more pronounced in the active training group.² A Cinar follow-up study at 5-week duration replicated the pattern.

The clinical effective dose for adult men, per NIH Office of Dietary Supplements and per the cluster of randomized controlled trials in this space, sits between 300 and 400 mg of elemental magnesium daily. The recommended dietary allowance is 420 mg for men 31 and older. Most supplementation trials testing functional outcomes (strength, sleep, blood pressure, glucose handling) use doses in the 300-450 mg range.

This is the dose target Klean Athlete Klean Magnesium hits, but only when taken at the upper end of the brand-recommended 1-4 capsule range. One capsule alone delivers 120 mg, which is below the clinical effective dose floor. Three capsules deliver 360 mg, which sits squarely at the clinical low. Four capsules deliver 480 mg, above the clinical range and toward the upper tolerable intake. This per-serving structure is the central editorial fact about this product.

Editorial commentary

Klean Athlete is Douglas Laboratories's athlete-tier line. Douglas Labs has been operating for over 50 years out of a 150,000 square foot GMP-compliant facility in Pittsburgh, Pennsylvania, with ISO accredited in-house labs. The brand has a longer practitioner-grade history than almost any competitor in this space, and the Klean Athlete sub-brand specifically targets drug-tested athletic populations: NFL, MLB, PGA, LPGA, NCAA, and approximately 350 professional and collegiate sports teams that the brand publicly cites as institutional clients. Every Klean Athlete product carries NSF Certified for Sport.

For Magnesium specifically, this matters more than it does for vitamin D3 or zinc, because magnesium products vary widely in form quality and contamination risk. Magnesium oxide (4% bioavailable, common in mass-market multivitamins), magnesium citrate (75% bioavailable, mid-tier), and magnesium glycinate (over 90% bioavailable, top tier) are all sold as "magnesium" with no per-form labeling clarity for most buyers. Klean Athlete uses the right form (glycinate), discloses it on the label, and certifies the batch through NSF Sport.

The trade-off, on this specific product, is per-capsule dose. At 120 mg per cap, you need 3-4 capsules per day to reach clinical effective dosing. This is fine if you read the label carefully and titrate accordingly, but it is structurally less convenient than competitors who pack 200-240 mg into a single capsule. The brand transparently labels "1-4 capsules daily" so the multi-cap regimen is not hidden, but the practical effect is a higher cost per effective day than single-cap clinical-dose alternatives.

Compared to our existing magnesium category entries:

Thorne Magnesium Bisglycinate (BUY 88, CPED $1.25): magnesium bisglycinate powder, 200 mg per scoop, single serving = clinical dose. Higher CPED.
Pure Encapsulations Magnesium Glycinate (BUY 84, CPED $0.78): 120 mg glycinate capsule, similar per-cap structure to Klean Athlete. No NSF Sport certification.
Klean Athlete Klean Magnesium (BUY 87, CPED $0.88): 120 mg glycinate capsule, NSF Sport certified, slightly higher CPED than Pure Enc.

The premium for NSF Sport certification on Klean Athlete versus Pure Encapsulations is approximately $0.10 per effective day ($0.88 vs $0.78), or about 13%. For drug-tested athletes, that premium is mathematically rational. For non-drug-tested buyers, Pure Encapsulations gives you the same form at the same per-cap dose for slightly less money.

Pattern 4 from the DosedWise catalog framework holds again here: same category, two valid winners for two different buyers. Pure Encapsulations for general buyers prioritizing practitioner-grade history at lowest CPED, Klean Athlete for athlete buyers needing NSF Sport credentials. This is the same template we used for Vitamin D (Sports Research D3 + K2 TOP PICK 90 for general buyers, Momentous Vitamin D3 5000 IU NSF Sport BUY 88 for drug-tested athletes), now extended to Magnesium.

The Magnesium category does not yet have a TOP PICK at DosedWise because no current entry combines the optimal form (glycinate or threonate), the optimal per-serving dose (200 mg or higher single-cap clinical), and elite-tier certification (NSF Sport or USP). A hypothetical Magtein L-threonate at 200 mg per cap with NSF Sport certification would likely score 92+ and earn the TOP PICK. Until such a product enters our review queue, all magnesium products sit in the BUY tier.

What is actually in it

Ingredient	Form	Dose per capsule	Clinical effective dose	% at 1 cap	% at 3 caps	Evidence level
Magnesium	Magnesium glycinate	120 mg elemental	300-400 mg/day	30%	90-120%	strong

Other ingredients (inactives): Hydroxypropyl methylcellulose (vegetarian capsule shell, also known as HPMC or hypromellose), ascorbyl palmitate (fat-soluble vitamin C ester used as antioxidant preservative).

This is one of the simpler formulations on the market. One active ingredient. Two inactive ingredients, both standard pharmaceutical-grade excipients. No magnesium oxide blend (a common cost-cutting trick where 80% of the labeled magnesium is actually low-bioavailability oxide). No proprietary blend. No added botanicals.

Magnesium glycinate is the chelated form of magnesium bound to glycine (an amino acid). Glycinate chelation accomplishes three things: increased bioavailability (over 90% absorption versus 4-25% for inorganic forms), reduced GI distress (glycinate does not draw water into the intestinal lumen the way magnesium oxide and citrate do, eliminating the laxative effect), and added glycine (a non-essential amino acid with mild GABAergic and sleep-promoting effects).

EDE Score breakdown

Criterion	Weight	Score (0-100)	Weighted contribution
Dose Efficacy	30%	75	22.5
Bioavailability	20%	92	18.4
Third-Party Testing	15%	100	15.0
Label Transparency	15%	100	15.0
Manufacturer Reputation	10%	92	9.2
Community Sentiment	5%	50	2.5
Price Per Effective Dose	5%	85	4.25
Total EDE Score	100%		87/100

See full methodology

Notes on each criterion:

Dose Efficacy (75): Per-serving (1 capsule) delivers 120 mg = 30% of the 400 mg clinical effective dose. Sub-therapeutic if taken as a single capsule daily. The brand transparently recommends 1-4 capsules daily, and at 3 capsules (360 mg) the regimen reaches clinical low. Score reflects penalty for per-serving under-dosing offset by transparent multi-capsule regimen support.

Bioavailability (92): Magnesium glycinate sits at the top tier of magnesium forms. Roughly 90% absorption versus 4% for magnesium oxide. Glycinate chelation also minimizes GI side effects (no laxative draw) and adds therapeutic glycine.

Third-Party Testing (100): NSF Certified for Sport. Verified on the NSF Sport database. Every batch tested for 290 WADA-banned substances and label accuracy.

Label Transparency (100): Single active ingredient, exact mg disclosed. Inactive ingredients all disclosed. No proprietary blend.

Manufacturer Reputation (92): Douglas Laboratories has 50+ years of practitioner-grade history. The brand is widely respected in functional medicine, GMP-compliant Pittsburgh facility, ISO accredited in-house labs. Klean Athlete sub-brand publicly partnered with 350+ pro and collegiate teams. No FDA warning letters or recalls in recent years.

Community Sentiment (50): Phase 1 default. Reddit Intelligence layer arrives Q3 2026.

Price Per Effective Dose (85): CPED $0.88 at 3-capsule clinical regimen. Sits in $0.50-$1.00 band per methodology = 85 score. Higher than Pure Encapsulations Mg Glycinate ($0.78) but lower than Thorne Mg Bisglycinate ($1.25).

What we like

NSF Certified for Sport, every batch tested. Verified on the NSF Sport database. Gold standard for athletic compliance. Drug-tested athletes, military, federal law enforcement, and first responders can take this with zero contamination risk.
Magnesium glycinate form is top-tier bioavailability. Over 90% absorption rate versus 4% for magnesium oxide. Negligible GI side effects compared to citrate or oxide.
Practitioner-grade manufacturing pedigree. Douglas Laboratories has 50+ years of clean operating history, GMP-compliant facility, ISO accredited labs. The Klean Athlete sub-brand specifically targets the drug-tested athletic market.
Brand transparently recommends 1-4 capsules daily. The multi-cap regimen is labeled, not hidden. Buyers can titrate to individual need (smaller buyers or mild deficits at 2 caps, larger buyers or higher training loads at 3-4 caps).
Single active ingredient with exact mg disclosed. No proprietary blend, no oxide-glycinate mix to obscure actual chelated content.
Vegetarian capsule (HPMC), gluten-free, GMO-free, no artificial colors or flavors.
Authorized retailer distribution across PureFormulas, Amazon, Vitacost, Target, Walmart, Vitamin Shoppe. Authentic supply chain across multiple channels.

What we don't like

Per-capsule dose is below clinical effective. 120 mg is 30% of the 400 mg clinical target. Single-capsule daily use is sub-therapeutic. Buyers who do not read the multi-cap label instructions will under-dose.
Multi-capsule regimen raises CPED. At 3 capsules per day for clinical effect, $0.88 per effective day is higher than single-cap clinical alternatives in the broader magnesium market (e.g., 200-240 mg per cap glycinate products at lower CPED).
90-capsule bottle is roughly a 30-day supply at clinical dosing, requiring monthly reorder. Smaller form factor than Pure Encapsulations Mg Glycinate (180-cap option) which gives 60 days at the same clinical regimen.
No K2, no D3, no synergistic co-formulation. Pure single-ingredient product. Stack builders pairing with vitamin D need to source separately.
Slightly higher CPED than Pure Encapsulations Mg Glycinate ($0.88 vs $0.78) without a meaningful active-content advantage. The premium is purely for NSF Sport certification.
Brand-direct purchasing requires registration on shop.kleanathlete.com (the practitioner-facing storefront). Most retail buyers will use Amazon or PureFormulas.

Cost per effective day (CPED)

Bottle price (retail): $26.50
Servings per bottle: 90 capsules
Per-capsule elemental magnesium: 120 mg
Clinical effective dose: 360 mg/day (3 capsules)
Clinical capsules per day: 3
Days of effective dosing per bottle: 90 / 3 = 30 days
CPED: $26.50 / 30 = $0.8833 per effective day

Klean Athlete Klean Magnesium costs $0.88 per effective day at the 3-capsule clinical regimen.

If you titrate to 4 capsules per day (480 mg, upper clinical), days of dosing drops to 22.5 and CPED rises to $1.18 per effective day. If you take only 2 capsules per day (240 mg, sub-clinical), days of dosing rises to 45 and CPED drops to $0.59 per effective day, but you are no longer at clinical dose so the math is misleading.

For comparison within the magnesium category:

Product	Per-cap dose	Form	Caps per clinical day	CPED	EDE Score	Verdict	NSF Sport
Pure Encapsulations Magnesium Glycinate	120 mg	Glycinate	3	$0.78	84	BUY	No
Klean Athlete Klean Magnesium	120 mg	Glycinate	3	$0.88	87	BUY (athlete-tier)	Yes
Thorne Magnesium Bisglycinate	200 mg per scoop	Bisglycinate (powder)	1 scoop	$1.25	88	BUY	No

The category does not yet have a TOP PICK because no current entry combines optimal form (glycinate or threonate), single-cap clinical dose (200+ mg), and gold-standard certification (NSF Sport or USP). Klean Athlete is closest to the future TOP PICK profile, missing only the per-serving dose criterion.

Ingredient-by-ingredient analysis

Magnesium (as Magnesium Glycinate)

Dose in this product: 120 mg elemental magnesium per capsule Clinical effective dose: 300-400 mg/day (NIH ODS, multiple RCT clusters) Evidence level: Strong Verdict for this ingredient: Per-serving sub-clinical, brand-supported 1-4 capsule regimen reaches clinical at 3 caps

Magnesium is involved in over 600 enzymatic reactions in the human body, including ATP synthesis, DNA replication, protein synthesis, glucose metabolism, and neurotransmitter regulation. It is one of the four most prevalent intracellular cations and a structural cofactor for skeletal muscle contraction.

For men 40+, the most clinically relevant magnesium-related outcomes include:

Testosterone production: Cinar 2011 showed that 4 weeks of 10 mg/kg/day magnesium supplementation increased total and free testosterone in both sedentary and trained men, with stronger effect in the active training group.² Subsequent crossover studies have supported this finding, particularly in men with marginal magnesium status.
Sleep architecture: Multiple RCTs have shown improvements in sleep latency, sleep efficiency, and subjective sleep quality with 320-500 mg magnesium supplementation, particularly in older adults and in subjects with insomnia.³
Skeletal muscle strength: Brilla and Haley 1992 and subsequent replications have shown magnesium supplementation improves strength gains during resistance training programs in deficient or marginal subjects.⁴
Blood pressure: A 2012 meta-analysis of 22 RCTs (n = 1173) showed mean systolic blood pressure reduction of 3-4 mmHg with magnesium supplementation, with stronger effects at higher doses (above 370 mg/day).⁵
Insulin sensitivity: Multiple cohort studies show inverse association between magnesium intake and type 2 diabetes risk. RCTs show modest improvements in fasting glucose and HOMA-IR in supplemented diabetic and pre-diabetic populations.

The form Klean Athlete uses (magnesium glycinate, also called magnesium bisglycinate at higher chelation ratios) is the top-tier bioavailability form. Glycinate chelation provides:

High absorption (over 90%) via dipeptide-style intestinal uptake bypassing the saturable inorganic magnesium transporter.
No laxative effect because glycinate does not draw osmotic water into the intestinal lumen the way oxide, sulfate, and citrate do.
Glycine co-delivery which adds mild GABAergic effect potentially supportive of sleep and stress modulation.

The 120 mg per-capsule dose is the central editorial issue with this product. To reach clinical effective dose (300-400 mg), buyers must take 3 or 4 capsules per day. The brand label explicitly recommends "1 capsule, 1-4 times daily, or as directed by a trainer, coach, or health professional." This is transparent labeling, but practical execution requires the buyer to read the dosage instructions carefully and not default to the 1-capsule-per-serving panel reading.

Take this product across two or three doses per day rather than all at once if you tolerate any GI sensitivity. Take the largest dose at evening for sleep-supportive effect. Pairing with food is optional but slightly improves absorption and reduces any residual GI risk.

PubMed: Cinar V et al. 2011. Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion.

Community sentiment summary

Phase 1 default sentiment score: 50/100.

DosedWise will publish aggregated Reddit sentiment for Klean Athlete Klean Magnesium across r/Testosterone, r/TRT, r/PeterAttia, r/Supplements, and r/Nootropics in Q3 2026 when our Reddit Intelligence layer ships. Until then, this criterion uses a neutral default and represents 5% of the total EDE Score.

Anecdotal user feedback on third-party retailer pages skews positive on tolerability (no GI distress, no laxative effect) and on perceived sleep quality improvements when dosed in evening. The most common critique on retailer review pages is per-capsule dose (users wanting fewer capsules at higher mg load).

[Note: Community sentiment is one signal among seven and is weighted 5% in the EDE Score. See methodology.]

Compared to alternatives

For magnesium supplementation, here is how Klean Athlete Klean Magnesium compares to top alternatives we have scored:

Product	EDE Score	CPED	Verdict	Key differentiator
Thorne Magnesium Bisglycinate	88/100	$1.25	BUY	Powder form, 200 mg per scoop, no NSF Sport
Klean Athlete Klean Magnesium	87/100	$0.88	BUY (athlete-tier)	NSF Sport, 120 mg per cap, multi-cap clinical regimen
Pure Encapsulations Magnesium Glycinate	84/100	$0.78	BUY	Practitioner-grade, 120 mg per cap, no NSF Sport
Doctor's Best Magnesium Glycinate (Albion)	not yet scored	TBD	TBD	Albion-licensed glycinate, value tier
Now Foods Magnesium Glycinate	not yet scored	TBD	TBD	Value tier, no NSF Sport

Three products in the magnesium category give a clean three-way comparison:

Thorne Magnesium Bisglycinate scores highest because powder form delivers single-serving clinical dose at 200 mg per scoop and the brand carries the strongest practitioner-grade reputation.
Klean Athlete Klean Magnesium scores second because the NSF Sport certification advantage offsets the per-cap dose disadvantage.
Pure Encapsulations Magnesium Glycinate scores third because identical per-cap structure to Klean Athlete but without NSF Sport certification.

If you do not need NSF Sport certification, the choice between Pure Encapsulations and Klean Athlete is a $0.10 per day premium for institutional-tier credentials. If you do need NSF Sport, Klean Athlete is the right pick at this per-cap dose tier.

See all magnesium reviews

Who should buy this

Klean Athlete Klean Magnesium is best for:

Drug-tested athletes (NCAA, NFL, MLB, NBA, USOPC, World Aquatics, World Athletics, NHL) who require NSF Certified for Sport on every supplement input.
Military service members, federal law enforcement, first responders, and pilots subject to random or scheduled drug testing where supplement contamination is a known career risk.
Functional medicine patients whose practitioners specifically recommend Douglas Laboratories products.
Buyers with GI sensitivity to magnesium oxide or citrate who specifically want glycinate form for tolerability.
Buyers who prefer flexible 1-4 capsule daily titration rather than fixed single-serving dose products.
Stack builders who already have a magnesium supplement in their kit but want to upgrade to NSF Sport tier specifically.

Klean Athlete Klean Magnesium is NOT for:

Buyers who do not need NSF Sport certification. Pure Encapsulations Magnesium Glycinate (BUY 84, CPED $0.78) delivers the same form at the same per-cap dose for slightly less money.
Buyers who want single-serving clinical dosing in one capsule. Thorne Magnesium Bisglycinate powder (BUY 88, CPED $1.25) hits 200 mg per scoop in a single serving, or future entries with 200+ mg per capsule.
Budget-constrained buyers. Now Foods Magnesium Glycinate or Doctor's Best Magnesium Glycinate (Albion-licensed) deliver acceptable form quality at lower CPED if NSF Sport is not required.
Buyers who want magnesium L-threonate specifically for cognitive or neurological support. Magtein L-threonate is a separate use case.
Buyers seeking calming or sleep-specific magnesium positioning. Magnesium glycinate works well for sleep, but evening-only single-product positioning may be better suited by dedicated sleep-stack formulations.

Stacking notes

Take across 2-3 daily doses rather than all 3-4 capsules at once if you have any GI sensitivity. Glycinate is well-tolerated, but split dosing is gentler still.
Schedule the largest single dose 30-60 minutes before bedtime to leverage the glycine and magnesium combined relaxation effect on sleep latency and architecture.
Pair with vitamin D3. Magnesium is a required cofactor for vitamin D activation in liver and kidney. Supplementing high-dose D3 without adequate magnesium yields blunted serum 25(OH)D response.
Do not take with high-dose calcium supplements at the same time. Calcium and magnesium compete for the same intestinal transporter at saturating doses. Separate by 2 hours.
Do not combine with potassium-sparing diuretics, ACE inhibitors at high dose, or digoxin without physician oversight. Magnesium status interacts with renal handling of these drugs.
Cycling not required. Magnesium supplementation is a long-term intervention. Re-test serum or RBC magnesium every 90-180 days if you have known deficiency or specific clinical reason.
Athletes in heavy training or hot-weather sweat-loss scenarios may benefit from upper-end (4 capsule, 480 mg) daily dosing during high-load training blocks.

Better alternatives

If Klean Athlete Klean Magnesium does not fit your needs:

Thorne Magnesium Bisglycinate (EDE 88/100, CPED $1.25): Powder form, 200 mg per single scoop, single-serving clinical dose. Best fit for buyers who want one-serving simplicity over per-cap titration.
Pure Encapsulations Magnesium Glycinate (EDE 84/100, CPED $0.78): Same form, same per-cap dose, no NSF Sport certification. Best fit for general buyers prioritizing practitioner-grade history at lowest CPED.
Future TOP PICK candidate (under review): A 200+ mg per cap glycinate or threonate with NSF Sport certification would score 92+ in our methodology. We are tracking emerging product launches in this space.

Frequently asked questions

Is Klean Athlete Klean Magnesium worth buying?

If you are a drug-tested athlete or value NSF Certified for Sport on every supplement input, yes. EDE 87/100, $0.88 CPED at clinical dose, magnesium glycinate top-tier form, every batch tested. If you are not drug-tested, Pure Encapsulations Magnesium Glycinate (BUY 84, CPED $0.78) gives you the same form at the same per-cap dose for slightly less.

What is the best dose of magnesium for men 40+?

NIH Office of Dietary Supplements Recommended Dietary Allowance is 420 mg/day for men 31+. Most clinical trials testing functional outcomes use 300-400 mg of elemental magnesium daily. Men in heavy training, men taking PPIs or thiazide diuretics, men with high-protein diets, or men with confirmed RBC magnesium deficiency should target the upper end of this range. Hard to overdose from food and supplements combined unless renal function is impaired.

Why does each capsule only contain 120 mg?

Two reasons. First, glycinate chelation is a bulky molecule. To pack 200+ mg of elemental magnesium as glycinate into a single capsule requires a larger capsule shell than 120 mg fits in. Second, 120 mg per capsule allows individual titration: smaller athletes or those with milder deficits can take 2 caps daily (240 mg), larger athletes or those with high training loads can take 4 caps daily (480 mg). The trade-off is that single-capsule dosing is sub-clinical.

How does Klean Athlete compare to Pure Encapsulations Magnesium Glycinate?

Identical form (magnesium glycinate) and identical per-cap dose (120 mg). Klean Athlete carries NSF Certified for Sport while Pure Encapsulations does not. Pure Encapsulations CPED ($0.78) is approximately $0.10 per day lower than Klean Athlete ($0.88). For drug-tested athletes the premium is rational. For general buyers, Pure Encapsulations is the better deal.

Is Klean Athlete owned by Douglas Laboratories?

Yes. Klean Athlete is the athlete-tier sub-brand of Douglas Laboratories, which has been operating for over 50 years out of Pittsburgh, Pennsylvania. Douglas Labs is a practitioner-grade manufacturer with GMP-compliant facilities and ISO accredited in-house labs. The Klean Athlete sub-brand specifically targets drug-tested athletic populations and carries NSF Certified for Sport on every product.

Should I take this in the morning or at night?

Magnesium glycinate has a mild sleep-supportive effect via the glycine co-delivery and magnesium's role in NMDA receptor regulation. Most users benefit from scheduling the largest single daily dose in the evening, 30-60 minutes before bedtime. Split your 3-4 capsule daily dose across morning and evening if you tolerate split dosing.

Will this cause GI distress or diarrhea like other magnesium supplements?

Unlikely. Magnesium glycinate does not draw osmotic water into the intestinal lumen the way magnesium oxide, citrate, or sulfate do, which is why those forms have laxative effects. Glycinate is the form most users tolerate at the highest doses without GI discomfort. If you have particularly sensitive GI, start with 1-2 capsules and titrate up.

Can I take this with my multivitamin?

Yes, as long as the multivitamin's calcium content is not high (above 500 mg per serving). Calcium and magnesium compete for the same intestinal transporter at saturating doses. If your multivitamin has more than 500 mg calcium per serving, separate magnesium intake by at least 2 hours.

Where to buy

Brand-direct (Klean Athlete): Available at shop.kleanathlete.com and via authorized practitioners.
Amazon: Authorized brand listing. Amazon listing
PureFormulas: Authorized retailer, $26.50 baseline pricing.
Specialty retailers: Vitacost, Target, Walmart, Vitamin Shoppe, Professional Supplement Center.

We recommend brand-direct or Amazon for the cleanest supply chain. Klean Athlete does not currently list on iHerb as of publication date.

Final verdict

BUY (athlete-tier). EDE Score 87/100. CPED $0.88 per effective day at clinical 3-capsule regimen.

Klean Athlete Klean Magnesium is the right magnesium for drug-tested athletes, military, first responders, and stack builders who want NSF Certified for Sport on every input. Magnesium glycinate top-tier form, every batch tested, transparent multi-capsule clinical dosing. Practitioner-grade Douglas Laboratories manufacturing pedigree.

It is not a TOP PICK because per-capsule dose is below clinical, requiring 3-4 capsules per day to reach clinical effective range. The category currently has no TOP PICK because no entry yet combines optimal form, single-cap clinical dose, and gold-standard certification.

If you decide to buy Klean Athlete Klean Magnesium:

If you would rather try an alternative magnesium:

Pure Encapsulations Magnesium Glycinate review (EDE 84, CPED $0.78, no NSF Sport)
Thorne Magnesium Bisglycinate review (EDE 88, CPED $1.25, single-serving clinical dose)

Methodology and disclosures

This review uses the DosedWise Methodology v1.0. The EDE Score formula is:

EDE Score = 
  (Dose Efficacy * 0.30) +
  (Bioavailability * 0.20) +
  (Third-Party Testing * 0.15) +
  (Label Transparency * 0.15) +
  (Manufacturer Reputation * 0.10) +
  (Community Sentiment * 0.05) +
  (Price Per Effective Dose * 0.05)

DosedWise earned no payment from Klean Athlete or Douglas Laboratories for this review. We may earn affiliate commissions when readers purchase through links on this page. These commissions never influence scoring. Read our editorial policy.

This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting any supplement, especially if you have a medical condition, take prescription medications, or are pregnant or nursing. Magnesium supplementation may interact with potassium-sparing diuretics, ACE inhibitors, digoxin, and certain antibiotics.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

References

Published: 2026-05-04 Last reviewed: 2026-05-04 Author: DosedWise Editorial Team

Rosanoff A, Weaver CM, Rude RK. Suboptimal magnesium status in the United States: are the health consequences underestimated? Nutrition Reviews. 2012;70(3):153-164. PubMed PMID: 22364157. ↩
Cinar V, Polat Y, Baltaci AK, Mogulkoc R. Effects of magnesium supplementation on testosterone levels of athletes and sedentary subjects at rest and after exhaustion. Biological Trace Element Research. 2011;140(1):18-23. PubMed PMID: 20352370. ↩ ↩²
Abbasi B, Kimiagar M, Sadeghniiat K, et al. The effect of magnesium supplementation on primary insomnia in elderly: a double-blind placebo-controlled clinical trial. Journal of Research in Medical Sciences. 2012;17(12):1161-1169. PubMed PMID: 23853635. ↩
Brilla LR, Haley TF. Effect of magnesium supplementation on strength training in humans. Journal of the American College of Nutrition. 1992;11(3):326-329. PubMed PMID: 1619184. ↩
Kass L, Weekes J, Carpenter L. Effect of magnesium supplementation on blood pressure: a meta-analysis. European Journal of Clinical Nutrition. 2012;66(4):411-418. PubMed PMID: 22318649. ↩