Vitamin B12 (Methylcobalamin) vs L-Carnitine (Tartrate)
Vitamin vs Performance · evidence-backed comparison
- • Vitamin B12 (Methylcobalamin) has the stronger evidence base (strong (multiple rcts / meta-analyses)).
- • Vitamin B12 (Methylcobalamin) is cheaper per serving ($0.12 vs $0.60).
- • Vitamin B12 (Methylcobalamin) has a slightly cleaner safety profile.
- • Vitamin B12 (Methylcobalamin) has higher bioavailability (better absorption).
Side-by-side traits
| Trait | Vitamin B12 (Methylcobalamin) | L-Carnitine (Tartrate) |
|---|---|---|
Category | Vitamin | Performance |
Active compound | Methylcobalamin | L-carnitine L-tartrate |
Form available | Tablet, Capsule, Liquid | Powder, Capsule, Liquid |
Source | microbial | synthetic |
Typical dose | 500–1000 mcg daily | 1–3 g daily |
Dose range | 500–1000 mcg | 1–3 g |
Loading protocol | — | — |
Best taken with | sublingual or with food | carbs (improves absorption) |
Best time of day | morning | post-workout |
Bioavailability How efficiently the body absorbs and utilizes the compound. | Very High (5/5) | Moderate (3/5) |
Onset time | Cumulative: 2–8 weeks | Cumulative: 4–12 weeks |
Half-life | ~6 days | ~15 hours |
Evidence level Quality and quantity of human research. | Strong (multiple RCTs / meta-analyses) | Moderate (some RCTs) |
Overall effect Subjective effect magnitude. | Low (2/5) | Low (2/5) |
Muscle / strength | Very Low (1/5) | Moderate (3/5) |
Physical energy | High (4/5) | Moderate (3/5) |
Focus / cognition | Moderate (3/5) | Low (2/5) |
Mood / stress | Moderate (3/5) | Low (2/5) |
Sleep quality | Very Low (1/5) | Very Low (1/5) |
Immunity | Low (2/5) | Very Low (1/5) |
Recovery Post-exercise recovery support. | Low (2/5) | High (4/5) |
Longevity / healthspan | Moderate (3/5) | Moderate (3/5) |
Safety rating 5 = exceptionally well-tolerated; 1 = significant risk profile. | Very High (5/5) | High (4/5) |
Price per serving Approximate USD per typical daily dose. | $0.12 | $0.60 |
Vegan friendly | Yes | No |
Gluten free | Yes | Yes |
3rd-party tested | Yes | Yes |
About Vitamin B12 (Methylcobalamin)
Active 'methylated' form of B12 that bypasses MTHFR variants. Essential for vegans, the elderly, and metformin/PPI users.
About L-Carnitine (Tartrate)
Shuttle for fatty acids into mitochondria. Modest fat-burning effects; stronger evidence for recovery and androgen receptor density.
Vetted brands, third-party testing, ships worldwide.
Vetted brands, third-party testing, ships worldwide.
Vitamin B12 (Methylcobalamin) safety
Common side effects:
- • Generally none
Avoid if:
- • Leber's optic atrophy
Drug interactions:
- • Metformin (depletes)
- • PPIs (reduces absorption)
L-Carnitine (Tartrate) safety
Common side effects:
- • Fishy body odor (high doses)
- • GI upset
Avoid if:
- • Hypothyroidism
- • Seizure disorders
Drug interactions:
- • Warfarin
- • Thyroid hormone
Common uses
- • Vegan supplementation
- • Energy
- • Cognitive function
- • Anemia
Stacks well with: Methylfolate (5-MTHF), Betaine Anhydrous
Common uses
- • Fat loss
- • Recovery
- • Endurance
- • Cognitive (acetyl-L-carnitine form)
Stacks well with: Creatine Monohydrate
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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.