Magnesium Citrate vs Selenium (Selenomethionine)
Sleep vs Mineral · evidence-backed comparison
- • Magnesium Citrate has the broader effect profile across the 9 effect categories.
- • Selenium (Selenomethionine) is cheaper per serving ($0.10 vs $0.12).
- • Magnesium Citrate has a slightly cleaner safety profile.
- • Selenium (Selenomethionine) has higher bioavailability (better absorption).
Side-by-side traits
| Trait | Magnesium Citrate | Selenium (Selenomethionine) |
|---|---|---|
Category | Sleep | Mineral |
Active compound | Magnesium citrate | Selenomethionine |
Form available | Capsule, Powder, Tablet, Liquid | Capsule, Tablet |
Source | synthetic | synthetic |
Typical dose | 200–400 mg elemental Mg | 100–200 mcg daily |
Dose range | 200–400 mg | 100–200 mcg |
Loading protocol | — | — |
Best taken with | any time, with water | with food |
Best time of day | any | any |
Bioavailability How efficiently the body absorbs and utilizes the compound. | High (4/5) | Very High (5/5) |
Onset time | Acute: 1–3 hours | Cumulative: 4–12 weeks |
Half-life | — | ~252 days (long body store) |
Evidence level Quality and quantity of human research. | Moderate (some RCTs) | Moderate (some RCTs) |
Overall effect Subjective effect magnitude. | Moderate (3/5) | Low (2/5) |
Muscle / strength | Low (2/5) | Very Low (1/5) |
Physical energy | Low (2/5) | Low (2/5) |
Focus / cognition | Very Low (1/5) | Very Low (1/5) |
Mood / stress | Low (2/5) | Low (2/5) |
Sleep quality | Moderate (3/5) | Very Low (1/5) |
Immunity | Very Low (1/5) | Moderate (3/5) |
Recovery Post-exercise recovery support. | Low (2/5) | Low (2/5) |
Longevity / healthspan | Moderate (3/5) | Moderate (3/5) |
Safety rating 5 = exceptionally well-tolerated; 1 = significant risk profile. | High (4/5) | Moderate (3/5) |
Price per serving Approximate USD per typical daily dose. | $0.12 | $0.10 |
Vegan friendly | Yes | Yes |
Gluten free | Yes | Yes |
3rd-party tested | Yes | Yes |
About Magnesium Citrate
Most affordable absorbable magnesium. Doubles as a mild laxative — useful if constipated, less ideal if not.
About Selenium (Selenomethionine)
Cofactor for glutathione peroxidase and thyroid hormone activation. Two Brazil nuts per day already meet requirements; toxicity above 400 mcg.
Vetted brands, third-party testing, ships worldwide.
Vetted brands, third-party testing, ships worldwide.
Magnesium Citrate safety
Common side effects:
- • Loose stools (often desired)
- • GI cramps
Avoid if:
- • Severe kidney disease
Drug interactions:
- • Bisphosphonates
Selenium (Selenomethionine) safety
Common side effects:
- • Selenosis (>400 mcg/day): hair loss, garlic breath, brittle nails
Avoid if:
- • Already eating Brazil nuts daily
Drug interactions:
- • Anticoagulants
Common uses
- • General magnesium repletion
- • Constipation
- • Sleep
Stacks well with: Vitamin D3
Common uses
- • Thyroid support
- • Hashimoto's
- • Antioxidant
Stacks well with: Iodine (Potassium Iodide)
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Medical disclaimer
SupplementDuel is for educational purposes only and is not medical advice. Consult a physician before starting, stopping, or combining supplements — especially if you are pregnant, breastfeeding, take prescription medication, or have a chronic condition.