Comparison
Citicoline vs Vitamin D3 + K2
Side-by-side of Citicoline and Vitamin D3 + K2. 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.
Citicoline
Citicoline supplement profile: CDP-choline as a phosphatidylcholine precursor, Cognizin dosing 250-2000 mg, cognition trials, stroke recovery evidence.
Vitamin D3 + K2
Vitamin D3 K2 supplement profile: cholecalciferol at 1000-4000 IU/day corrects deficiency, MK-7 directs calcium to bone, away from arteries.
Effects at a glance
Citicoline
- •Choline donor and phosphatidylcholine precursor; oral bioavailability roughly 99%
- •Standard prescription medication for stroke recovery and vascular cognitive impairment in much of the world
- •Healthy-adult cognitive trials (Cognizin) report small gains in attention and working memory at 250 to 500 mg/day
- •ICTUS trial (n=2,298) was negative on stroke recovery in the modern thrombolysis era
- •Lower per-gram choline content than alpha-GPC (~18% vs ~40%), meaning smaller TMAO load at equivalent dose
- •Long uridine half-life (~56 hours) supports once or twice daily dosing
Vitamin D3 + K2
- •Reduces non-vertebral fractures 10-20% in older adults at 800 IU/day or above when combined with calcium
- •VITAL trial showed neutral results on primary CV and cancer endpoints at 2000 IU/day over 5 years
- •Vitamin D supplementation reduces respiratory infection incidence ~10-20% in deficient populations
- •K2 MK-7 has 72-hour plasma half-life vs 1-2 hours for MK-4; once-daily dosing is sufficient
- •Synergy hypothesis is largely preclinical; dedicated combination RCTs are limited
- •Daily dosing outperforms bolus dosing for immune and infection outcomes
Side-by-side
| Attribute | Citicoline | Vitamin D3 + K2 |
|---|---|---|
| Category | supplement | supplement |
| Also known as | CDP-choline, cytidine 5'-diphosphocholine, Cognizin | cholecalciferol + menaquinone, D3/K2, vitamin D3 with MK-7 |
| Half-life (hr) ↗ | 56 | 360 |
| Typical dose (mg) ↗ | 500 | 0.05 |
| Dosing frequency | 1 to 2 times daily | daily with a fat-containing meal |
| Routes | oral, intravenous | oral |
| Onset (hr) | 1 | 24 |
| Peak (hr) | 2 | 168 |
| Molecular weight | 488.32 | 384.64 |
| Molecular formula | C14H26N4O11P2 | C27H44O (D3); C46H64O2 (MK-7) |
| Mechanism | Hydrolyzed to cytidine and choline after absorption; both cross the blood-brain barrier and are recombined intracellularly to reform CDP-choline, supporting phosphatidylcholine synthesis and acetylcholine production. | D3 converts to calcidiol then calcitriol, activating the vitamin D receptor (VDR) to increase intestinal calcium absorption and modulate immune and bone gene transcription. K2 carboxylates osteocalcin and matrix Gla protein, directing calcium toward bone and inhibiting vascular calcification. |
| Legal status | Dietary supplement (US, Cognizin GRAS); prescription medication in most of the world | Dietary supplement (global) |
| WADA status | allowed | allowed |
| DEA / Rx | OTC supplement (US); Rx in most of the world | Not scheduled |
| Pregnancy | Insufficient data for routine use | Recommended at standard doses for fetal bone development; consult clinician at higher doses |
| CAS | 987-78-0 | 67-97-0 |
| PubChem CID | 13804 | 5280795 |
| Wikidata | Q411470 | Q139347 |
Safety profile
Citicoline
Common side effects
- mild GI upset
- headache
- restlessness
- occasional insomnia with evening dosing
Contraindications
- concurrent strong anticholinergic therapy
- established cardiovascular disease (TMAO concern, smaller than alpha-GPC)
Interactions
- anticholinergic medications: partial mutual antagonism(minor)
- cholinesterase inhibitors: additive cholinergic effect(minor)
- antimetabolite chemotherapy (5-FU): theoretical cytidine pathway interaction(minor)
Vitamin D3 + K2
Common side effects
- GI upset at high doses
- headache (rare)
- hypercalcemia (only at sustained very high D3 doses)
Contraindications
- hypercalcemia
- sarcoidosis
- active hyperparathyroidism
- warfarin therapy (K2 component requires stable intake)
Interactions
- warfarin: K2 component can affect anticoagulation; maintain stable intake and inform anticoagulation clinic(moderate)
- thiazide diuretics: additive calcium retention; hypercalcemia risk with high-dose D3(moderate)
- digoxin and calcium channel blockers: additive effects from D3-induced hypercalcemia(moderate)
- glucocorticoids: reduced vitamin D efficacy and bone effects(moderate)
- cholestyramine and orlistat: bind fat-soluble vitamins; separate dosing by 2 to 4 hours(moderate)
Which Should You Take?
Vitamin D3 + K2 comes out ahead for most readers on the criteria we weight: 3 catalogued goals, OTC dietary supplement, oral dosing, with a Tier-A outcome catalogued. Citicoline is the right call when one of the conditionals below applies.
- → If your priority is focus or working memory, pick Citicoline.
- → If your priority is stroke recovery, pick Citicoline.
- → If your priority is bone density, pick Vitamin D3 + K2.
- → If your priority is healthspan extension, pick Vitamin D3 + K2.
Edge case: Half-lives differ materially (Citicoline ~56 hr vs Vitamin D3 + K2 ~360 hr). Vitamin D3 + K2 reaches steady state faster; Citicoline is easier to dial in if tolerability is uncertain.
Default choice: Vitamin D3 + K2. Lower friction to source, a Tier-A evidence outcome catalogued, and broader goal coverage. Reach for Citicoline 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 Citicoline and Vitamin D3 + K2?
Citicoline and Vitamin D3 + K2 differ in category (supplement vs supplement), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Citicoline or Vitamin D3 + K2?
Citicoline half-life is 56 hours; Vitamin D3 + K2 half-life is 360 hours.
Can you stack Citicoline with Vitamin D3 + K2?
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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