Best Vitamin K Supplements 2026: Cost per Effective Dose
Top pick for Vitamin K: NOW Foods Vitamin K-2 100 mcg, Menaquinone-4 (MK-4) — 100mcg per 1 veg capsule, $0.07/day.
All Vitamin K Supplements Compared
Vitamin K comes as K1 (phylloquinone, the form in leafy greens, mainly for clotting) and K2 (menaquinones, associated with bone and arterial research). Products labelled simply “vitamin K” may be either, or a blend, so check which menaquinone and how much before comparing prices. ⚠ Vitamin K in any form directly opposes warfarin, and changing your intake changes your anticoagulation — that conversation belongs with your prescriber, not a supplement label.
| Product | Brand | Dose / Serving | Cost / Day | Certification (as labelled) | Pick | Buy |
|---|---|---|---|---|---|---|
| NOW Foods Vitamin K-2 100 mcg, Menaquinone-4 (MK-4) | NOW Foods | 100mcg / 1 veg capsule | $0.07 | None | Buy | |
| Bluebonnet Vitamin K1 100 mcg | Bluebonnet | 100mcg / 1 caplet | $0.10 | None | Buy | |
| Nutricost Vitamin D3 (5,000 IU) + K2 (MK-7 100 mcg) | Nutricost | 100mcg / 1 softgel | $0.12 | None | Buy | |
| Thorne Vitamin K (K1 + MK-4 + MK-7) | Thorne | 100mcg / 1 capsule | $0.52 | Third-party tested | Buy |
Registry check · Vitamin K
Does anyone independently verify Vitamin K supplements?
1 of the 4 Vitamin K products on this page is confirmed in NSF/ANSI 173: Thorne Vitamin K (K1 + MK-4 + MK-7). Thorne Vitamin K (K1 + MK-4 + MK-7) does not show the mark on the listing, so the table’s certification column, which repeats the listing, does not show it either. For the others, the listing may name a certification, but we did not find it in a public registry — that is not evidence against them, only an absence of independent confirmation.
Certification is not a dosing guarantee. Across the whole catalogue, certified products reach the clinically studied dose 57% of the time and uncertified ones 71% — a gap too small to mean anything (Fisher p = 0.185). Read the Vitamin K dose column either way.
The 4 products on this page checked against all 5,317 US NSF, USP and Informed Sport listings, 2026-08-25. Full method and limitations.
What Vitamin K labels show
Priced per day, these vitamin K products run $0.07 to $0.52 — a 7.4× gap between the cheapest and dearest vitamin K here, across 4 brands.
Servings here are close enough to compare directly, so the gap is a real one: NOW Foods at $0.07 states about the same dose per serving as Thorne at $0.52.
In-Depth Vitamin K Guides
Go deeper on vitamin K — by goal, by form, and what the evidence actually supports:
Our Picks
Lowest Cost: NOW Foods Vitamin K-2 100 mcg, Menaquinone-4 (MK-4)
100mcg per 1 veg capsule. $0.07/day. 100 servings per container at $7.47.
The shelf · Vitamin K
A Vitamin K day costs 7.4× more at one end of this table than the other
NOW Foods Vitamin K-2 100 mcg, Menaquinone-4 (MK-4) is the cheapest day on this page at $0.07 and Thorne Vitamin K (K1 + MK-4 + MK-7) the priciest at $0.52. Both state about the same dose per serving, so paying 7.4× more does not buy more Vitamin K. Check what the pricier product can actually be shown to contain before you pay for it.
Method: the 4 Vitamin K products above, compared on label facts, serving size, servings per container, form, price. Not a dosing recommendation.
How these 4 Vitamin K products were ranked
1 of these 4 is confirmed in a certifier's registry — the only vitamin K row where the claim is independently backed — and the rest are ranked on cost per day at the labelled serving. Commission does not enter it: the rate is the same whichever vitamin K you buy. Full methodology.