What is the best form of vitamin k?
4 forms compared by what actually reaches your bloodstream. Absorption ranges from 60% to 85% — a difference that matters more than the milligrams on the label.
Ranked by absorption
Higher means more of the dose reaches youShort answer
Vitamin K2 (MK-9) absorbs best — 85%.
Extended-release bone & heart support. Typical dose 50-200 mcg (experimental), about $120 a month. The cheapest option is Vitamin K1 (Phylloquinone) at $8, but its absorption score is only 80 of 100.
Which form for which goal
Best absorbed option that covers each useSame compound, different carrier — the goal changes which trade-off matters, not what the mineral does.
Every form side by side
| Form | Absorbed | Elemental | Cost / 100 mg delivered | Per month | Dose |
|---|---|---|---|---|---|
| Vitamin K2 (MK-9) | 85% | — | $3,764.71 | $120 | 50-200 mcg (experimental) |
| Vitamin K2 (MK-7) | 80% | — | $694.44 | $25 | 100-200 mcg |
| Vitamin K1 (Phylloquinone) | 80% | — | $317.46 | $8 | 90-120 mcg |
| Vitamin K2 (MK-4) | 60% | — | $6.48 | $35 | 15-45 mg (divided doses) |
What not to take with vitamin k
Same rules for every form — the interaction belongs to the mineral, not the carrierSeparating the two by two to four hours removes most of these: they compete for the same transporters in the gut, not in the bloodstream. Splitting the day is what solves a conflict — dropping one of the two is rarely necessary.
Medication interactions
May reduce anticoagulant effectiveness · Consult physician, may need dose adjustment
May increase K1 requirements · Monitor for bleeding, consider supplementation
May reduce gut bacteria production of MK-9 · Consider supplementation during antibiotic use
Interaction potential unknown for MK-9 · Extreme caution, avoid without medical supervision
Prescription medicine is your doctor's call, not ours — this is what the records list.
How much is too much
33 reports to the FDA name vitamin-k as the suspect product.
Most reported: pain (3), chest pain (3), death (3), nephrolithiasis (3). Serious outcomes: 85% of them.
Counted from FDA CAERS by parsing each report's product list, not by keyword — a report where the product was merely present does not count.
How to read this
- Absorption is the share of the dose that reaches your bloodstream — the number that decides whether the milligrams on the label mean anything.
- A cheaper form at half the absorption is not cheaper per unit delivered.
- Safety here reflects tolerance at normal doses, not toxicity risk.
- Evidence A means the form itself was studied, not just the parent compound.
Compiled by Denis, who maintains this database and holds no medical qualification. Absorption figures and cost-per-absorbed values are derived by published formulas from cited sources — see the arithmetic.
Common questions
What is the best form of vitamin k?
Vitamin K2 (MK-9) — it scores 85 of 100 on absorption, the highest of the 4 forms here. Extended-release bone & heart support. Typical dose 50-200 mcg (experimental).
Which form of vitamin k is worst absorbed?
Vitamin K2 (MK-4) at 60%. It is usually the cheapest option, which is exactly why it ends up in budget products.
Is the expensive form of vitamin k worth it?
Compare per unit delivered, not per bottle. Vitamin K1 (Phylloquinone) costs $8 a month at 80% absorption, Vitamin K2 (MK-9) costs $120 at 85%.
How much vitamin k should you take?
Doses differ by form: Vitamin K2 (MK-9) 50-200 mcg (experimental); Vitamin K2 (MK-7) 100-200 mcg; Vitamin K1 (Phylloquinone) 90-120 mcg; Vitamin K2 (MK-4) 15-45 mg (divided doses).