Instalab

High Quality Vitamin K Supplements

Vitamin K2 supports bone density and arterial health.

K2-7
Vital Nutrients
K2-7
60 capsules
$31.99
Vitamin K
Thorne
Vitamin K
60 capsules
$31.00
Vitamin K2 180 mcg
Ortho Molecular Products
Vitamin K2 180 mcg
60 capsules
$57.22

Vitamin K FAQs

K1 or K2 — which one matters?

K1 (phylloquinone, from leafy greens) supports clotting. K2 (menaquinone) activates osteocalcin and matrix Gla protein, sending calcium to bones and keeping it out of arteries. K2 is the form most relevant for bone density and cardiovascular protection.

MK-4 or MK-7?

MK-7 has a much longer half-life (3 days vs hours) and provides steady effects from one daily dose. MK-4 needs multiple doses per day at higher amounts. Most modern formulas use MK-7. Trans-MK-7 (the bioactive isomer) is what you want.

Are there interactions with K2?

Yes. K2 can affect warfarin (a vitamin K antagonist), so people on warfarin should consult their clinician before supplementing. Newer anticoagulants (DOACs) don't interact with vitamin K. Aim for consistent K intake if you're on warfarin rather than avoiding it.

How much K2 should I take?

90–180 mcg/day of MK-7 is a common range. Higher doses (180–360 mcg) are used for arterial calcification or significant bone loss. Effects are dose-dependent and well-tolerated up to 1,000 mcg/day in studies.

What foods are highest in K2?

Natto (fermented soybeans) is by far the highest — a 50 g serving has 500+ mcg. Other sources: hard cheeses (especially Edam, Gouda), egg yolks, butter from grass-fed cows, chicken liver, and goose liver. Most Western diets are low in K2.

Will K2 reverse arterial calcification?

Studies suggest 180 mcg MK-7 daily may slow or modestly improve arterial calcification over 1–3 years. It activates matrix Gla protein (MGP), which keeps calcium out of arteries. Effects build slowly — combine with optimized D, magnesium, and lifestyle factors.

Should I take K2 with vitamin D?

Yes — they work synergistically. Vitamin D increases calcium absorption; K2 directs that calcium into bones rather than soft tissues. The combination is preferred for bone density and arterial protection.

Are there side effects of K2?

Generally well-tolerated. Rare reactions include digestive upset or skin reactions. Unlike K1, K2 has no upper limit established. The main precaution is for people on warfarin — talk to a clinician first.

When should I take K2?

With a meal containing fat — K2 is fat-soluble. MK-7 has a 3-day half-life, so once-daily dosing maintains steady levels. MK-4 needs to be taken multiple times per day in higher doses to maintain effect.