Vitamin B12 (Methylcobalamin) vs Glycine
Vitamin vs Sleep · evidence-backed comparison
- • Vitamin B12 (Methylcobalamin) has the stronger evidence base (strong (multiple rcts / meta-analyses)).
- • Vitamin B12 (Methylcobalamin) has the broader effect profile across the 9 effect categories.
- • Glycine is cheaper per serving ($0.10 vs $0.12).
Side-by-side traits
| Trait | Vitamin B12 (Methylcobalamin) | Glycine |
|---|---|---|
Category | Vitamin | Sleep |
Active compound | Methylcobalamin | Glycine |
Form available | Tablet, Capsule, Liquid | Powder, Capsule |
Source | microbial | synthetic |
Typical dose | 500–1000 mcg daily | 3 g before bed |
Dose range | 500–1000 mcg | 3–5 g |
Loading protocol | — | — |
Best taken with | sublingual or with food | water, 30 min before bed |
Best time of day | morning | evening |
Bioavailability How efficiently the body absorbs and utilizes the compound. | Very High (5/5) | Very High (5/5) |
Onset time | Cumulative: 2–8 weeks | Acute: 30–60 min |
Half-life | ~6 days | ~1 hour |
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) | Low (2/5) |
Physical energy | High (4/5) | Very Low (1/5) |
Focus / cognition | Moderate (3/5) | Low (2/5) |
Mood / stress | Moderate (3/5) | Moderate (3/5) |
Sleep quality | Very Low (1/5) | High (4/5) |
Immunity | Low (2/5) | Very Low (1/5) |
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. | Very High (5/5) | Very High (5/5) |
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 Vitamin B12 (Methylcobalamin)
Active 'methylated' form of B12 that bypasses MTHFR variants. Essential for vegans, the elderly, and metformin/PPI users.
About Glycine
Sweet-tasting amino that lowers core body temperature for deeper sleep. Cheap, well-tolerated, and especially useful with magnesium glycinate.
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)
Glycine safety
Common side effects:
- • Generally none
Avoid if:
- • Clozapine therapy
Drug interactions:
- • Clozapine
Common uses
- • Vegan supplementation
- • Energy
- • Cognitive function
- • Anemia
Stacks well with: Methylfolate (5-MTHF), Betaine Anhydrous
Common uses
- • Deep sleep
- • Sleep quality
- • Collagen synthesis
Stacks well with: Magnesium Glycinate, Melatonin
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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.