Comparison
Magnesium L-Threonate vs Semaglutide
Side-by-side of Magnesium L-Threonate and Semaglutide. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Magnesium L-Threonate
Magnesium l-threonate (Magtein) crosses the blood-brain barrier. Typical dose 1,500-2,000 mg. Sleep and cognitive trial data, side effects.
Semaglutide
Semaglutide for weight loss: GLP-1 agonist (Ozempic, Wegovy) drives 15-17% mean loss at 2.4 mg/week in STEP trials. Watch lean-mass loss.
Effects at a glance
Magnesium L-Threonate
- •Distinct magnesium salt designed for blood-brain barrier penetration; not a higher-quality systemic magnesium
- •Liu 2010 rodent study: elevated CSF magnesium ~15% and increased hippocampal synaptic density
- •Trial portfolio in humans is small and mostly Magtein-funded; cognitive effects are modest where reported
- •Typical dose 1500 to 2000 mg/day delivers only ~108 to 144 mg of elemental magnesium
- •GI tolerability comparable to other magnesium forms; loose stools in a minority at 2000 mg/day
- •Distinct from magnesium glycinate, which is the conventional sleep/anxiety/repletion form
Semaglutide
- •Long-acting GLP-1 receptor agonist with a ~7-day half-life that supports once-weekly subcutaneous dosing
- •STEP trials reported ~15 to 17% mean body-weight loss at 2.4 mg/week over 68 weeks in adults with obesity
- •Lowers HbA1c by ~1.0 to 1.8 percentage points in type 2 diabetes versus placebo
- •SELECT trial showed reduced major cardiovascular events in adults with prior CVD and overweight or obesity
- •Up to 25 to 40% of weight lost can be lean mass; pairing with resistance training and protein intake mitigates this
- •GI effects (nausea, vomiting, constipation) drive most discontinuations and ease with slow titration
Side-by-side
| Attribute | Magnesium L-Threonate | Semaglutide |
|---|---|---|
| Category | supplement | pharmaceutical |
| Also known as | Mg-T, MgT, Magtein, magnesium threonate | Ozempic, Wegovy, Rybelsus |
| Half-life (hr) ↗ | 4 | 168 |
| Typical dose (mg) ↗ | 2000 | 2.4 |
| Dosing frequency | 1 to 3 times daily | weekly (SC); daily (oral Rybelsus) |
| Routes | oral | subcutaneous, oral |
| Onset (hr) | 1 | 24 |
| Peak (hr) | 2 | 72 |
| Molecular weight | 294.5 | 4113.58 |
| Molecular formula | C8H14MgO10 | - |
| Mechanism | Proposed to deliver magnesium across the blood-brain barrier more effectively than other oral salts via threonate-related transporters, raising CNS magnesium and modulating NMDA receptor function and synaptic plasticity. | Long-acting GLP-1 receptor agonist; potentiates glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and acts on hypothalamic satiety centers. |
| Legal status | OTC dietary supplement | Prescription only (FDA-approved, EMA-approved) |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement (not scheduled) | Rx only (not a controlled substance); FDA-approved for type 2 diabetes (2017) and chronic weight management (2021) |
| Pregnancy | Standard magnesium safety; Mg-T-specific data limited | Not recommended; discontinue 2 months before planned pregnancy |
| CAS | 778571-57-6 | 910463-68-2 |
| PubChem CID | 10691810 | 56843331 |
| Wikidata | Q27151568 | Q27089394 |
Safety profile
Magnesium L-Threonate
Common side effects
- loose stools
- mild GI upset
- headache (rare)
- fatigue (rare)
Contraindications
- severe renal impairment (eGFR below 30)
- hypermagnesemia
- myasthenia gravis (high doses)
- concurrent IV magnesium therapy
Interactions
- tetracyclines and fluoroquinolones: magnesium chelation reduces antibiotic absorption; separate by 2 to 4 hours(moderate)
- bisphosphonates: reduced absorption; separate by 2 hours minimum(moderate)
- muscle relaxants and aminoglycosides: potentiated neuromuscular blockade at high doses(moderate)
- antihypertensives: additive blood pressure reduction at high doses(minor)
Semaglutide
Common side effects
- nausea
- vomiting
- diarrhea
- constipation
- decreased appetite
- injection-site reactions
- fatigue
Contraindications
- personal or family history of medullary thyroid carcinoma
- multiple endocrine neoplasia type 2
- pregnancy
- history of pancreatitis (use caution)
Interactions
- insulin: additive hypoglycemia risk; insulin dose typically reduced(major)
- sulfonylureas (glipizide, glyburide): hypoglycemia risk, sulfonylurea dose often reduced(major)
- oral medications (general): delayed gastric emptying can alter absorption kinetics(moderate)
- warfarin: monitor INR due to altered absorption(moderate)
Which Should You Take?
Magnesium L-Threonate comes out ahead for most readers on the criteria we weight: 2 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-B outcome catalogued. Semaglutide is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Magnesium L-Threonate.
- → If your priority is sleep onset or sleep quality, pick Magnesium L-Threonate.
- → If your priority is metabolic health and glucose control, pick Semaglutide.
- → If your priority is fat loss, pick Semaglutide.
Edge case: If you want to avoid prescription-only, Magnesium L-Threonate is the more accessible choice.
Default choice: Magnesium L-Threonate. Lower friction to source, and broader goal coverage. Reach for Semaglutide only if your priority sits squarely in the goals it owns above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Magnesium L-Threonate and Semaglutide?
Magnesium L-Threonate and Semaglutide differ in category (supplement vs pharmaceutical), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Magnesium L-Threonate or Semaglutide?
Magnesium L-Threonate half-life is 4 hours; Semaglutide half-life is 168 hours.
Can you stack Magnesium L-Threonate with Semaglutide?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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