Vitamin K2 vs K1: Differences, Food Sources and MK-4 vs MK-7

Vitamin K1 and K2 do the same basic job: they switch on proteins that help blood clot normally and help direct calcium into bone. The difference is where they come from and how long they last. K1 comes mainly from leafy greens, while K2 comes from fermented and animal foods, and its MK-7 form stays in the blood far longer than K1.

Key Takeaways

• K1 (phylloquinone) is the main form of vitamin K in the diet and comes mostly from green leafy vegetables; K2 (menaquinones) comes from fermented and animal foods (NIH ODS).
• MK-4 is the K2 form your body makes from K1 in its own tissues; MK-7 comes from fermented foods such as natto, with 850 mcg in 3 ounces.
• K1 and MK-7 are both absorbed well, but MK-7 has a much longer half-life and built up to 7 to 8 times higher levels with daily intake (Schurgers et al., 2007).
• Adults need 90 mcg (women) to 120 mcg (men) of vitamin K a day, and no upper limit has been set because vitamin K has a low potential for toxicity.
• Both forms affect how warfarin works, so anyone taking a blood thinner should talk with their clinician before changing vitamin K intake.

Vitamin K1 vs K2: The Main Difference

Vitamin K is a family of compounds that share the same ring structure and differ in the side chain attached to it. Vitamin K1, called phylloquinone, is made by plants. Vitamin K2 is a group called menaquinones, named MK-4 through MK-13 by the length of that chain. Most K2 forms are made by bacteria, which is why fermented foods are a rich source. MK-4 is the exception: your body makes it from K1 in its own tissues (NIH ODS). So the K1 vs K2 question is really a three-way comparison.

Feature	Vitamin K1	K2 as MK-4	K2 as MK-7
Main food sources	Leafy greens such as collards, spinach and kale	Chicken, eggs and cheese, in small amounts	Natto (fermented soybeans)
Where it comes from	Made by plants	Made by your body from K1	Made during fermentation
Key amounts	The main food form; adults need 90 to 120 mcg of vitamin K a day	1.5 mg a day in a 12-month trial; up to 45 mg a day in Japan under medical care	180 mcg a day in a 3-year trial; very long half-life, builds up with daily use
Shared job	Activates clotting proteins, osteocalcin in bone and matrix Gla protein in blood vessel walls

More on the two K2 forms: vitamin K2 MK-4 vs MK-7.

What Both Forms Do in the Body

Every form of vitamin K is a helper for one enzyme, vitamin K-dependent carboxylase, which changes certain proteins so they can bind calcium (NIH ODS). Those proteins include:

• Clotting proteins such as prothrombin, which help blood clot normally.
• Osteocalcin, a protein in bone that binds calcium once it is activated.
• Matrix Gla protein, found in blood vessel walls, bone and cartilage, which helps regulate where calcium is deposited.

Since all three feed the same enzyme, the real differences are food sources, absorption and time in circulation. Vitamin D works on the same task from the other side by helping your gut absorb calcium (NIH ODS, vitamin D). Our guide to vitamin D3 and K2 explains how the two work as a team.

How K1 and K2 Are Absorbed and How Long They Last

Both forms are fat soluble, so they are absorbed best with a meal that contains some fat. Free K1 is absorbed at about 80 percent, but in vegetables it is tightly bound inside the plant cell, and the body absorbs only 4 to 17 percent as much K1 from spinach as from a tablet. Research suggests long-chain menaquinones such as MK-7 may be absorbed better than K1 from green vegetables (NIH ODS).

The bigger difference comes after absorption. In healthy volunteers given K1 or natto-derived MK-7, both peaked in the blood about 4 hours after intake, but MK-7 had a very long half-life, gave much steadier blood levels, built up to 7 to 8 times higher levels with daily intake and activated osteocalcin more completely than K1 (Schurgers et al., 2007).

K1 vs K2 Foods

The NIH food table lists most foods by their K1 content, with a few marked as K2 (NIH ODS):

Food and serving	Vitamin K (mcg)	Form
Natto, 3 ounces	850	K2 (MK-7)
Collards, frozen, boiled, half cup	530	K1
Spinach, raw, 1 cup	145	K1
Kale, raw, 1 cup	113	K1
Soybean oil, 1 tablespoon	25	K1
Chicken breast, rotisserie, 3 ounces	13	K2 (MK-4)
Cheddar cheese, 1.5 ounces	4	K2 (MK-4)
Egg, hard boiled, 1 large	4	K2 (MK-4)

One serving of greens can cover a full day of K1, while large amounts of K2 come from only one common food, natto. Chicken, eggs and cheese add smaller amounts of MK-4. Our guide to vitamin K2 foods lists more options.

MK-4 vs MK-7 vs K1: What Human Studies Have Measured

Much recent human research on vitamin K and bone has used K2:

• MK-7 and bone. In a 3-year trial of 244 healthy postmenopausal women, 180 mcg of MK-7 a day improved vitamin K status and slowed the usual age-related decline in bone mineral density at the lower spine and the femoral neck (the top of the thigh bone) compared with placebo (Knapen et al., 2013).
• MK-7 and activated proteins. In 42 healthy adults aged 18 to 45 who took MK-7 at 10 to 360 mcg a day for 12 weeks, the groups taking amounts around the daily reference intake had more fully activated osteocalcin and matrix Gla protein than placebo, with no change in thrombin generation, a lab measure of clotting (Theuwissen et al., 2012).
• MK-4 and bone. In 48 healthy postmenopausal women aged 50 to 65, 1.5 mg of MK-4 a day for 12 months lowered inactive osteocalcin compared with placebo, and forearm bone density held steady while it fell in the placebo group, without substantial side effects (Koitaya et al., 2014).

MK-4 has also been used at far larger amounts of 45 mg a day in Japan under medical care (NIH ODS).

How Much Vitamin K Do You Need?

US intake guidelines set one amount for vitamin K as a whole. The Adequate Intake for adults is 120 mcg a day for men and 90 mcg a day for women, including during pregnancy and breastfeeding, and there is no Tolerable Upper Intake Level (NIH ODS). Many people get that from vegetables and add K2 for its long time in the blood and its pairing with vitamin D.

Choosing Between K1 and K2

• Get K1 from food. Leafy greens with a little oil give plenty of K1 and help you absorb it.
• Read the K2 label. It should name MK-4, MK-7 or both, with the mcg of each. Our guide to the best vitamin D3 and K2 supplement covers what else to check.
• Take it with a meal. Vitamin K is fat soluble, so some fat in the meal helps.

Safety: Warfarin and Other Medicines

Vitamin K has a low potential for toxicity, and the important cautions are about medicines (NIH ODS):

• Warfarin. It works by blocking vitamin K, so changing your K1 or K2 intake can change how it works. The authors of the K1 and MK-7 comparison noted that 50 mcg a day or more of MK-7 may interfere with oral anticoagulant treatment (Schurgers et al., 2007). If you take warfarin, talk with your clinician before starting a vitamin K supplement or making a big change in how many greens you eat.
• Antibiotics can lower vitamin K status.
• Bile acid sequestrants and orlistat can reduce absorption of vitamin K and other fat-soluble vitamins.

If you are pregnant, breastfeeding or take prescription medicine, check with your healthcare provider first. Our guide to vitamin K2 side effects has more detail.

Where Our Vitamin D3 + K2 Drops Fit

Our Vitamin D3 + K2 Drops give both main K2 forms in a single drop: 300 mcg of vitamin K as menaquinone-7 200 mcg and menaquinone-4 100 mcg, with vegan vitamin D3 from lichen at 50 mcg (2,000 IU), in MCT oil from coconut. Take 1 drop daily, or as directed on the label, with a meal that contains some fat, on your tongue or on a spoonful of food. They are made with third-party tested ingredients, and the warfarin caution above applies.

Vitamin D also supports normal immune function; see our vitamin D3 ingredient page and immune system guide. Our Vitamin D Cofactor Capsules, with magnesium 100 mg, zinc 10 mg and boron 3 mg in every 2 capsules, are made to pair with the drops and are open for pre-order.

Frequently Asked Questions

What is the difference between vitamin K1 and K2?

K1, or phylloquinone, is made by plants and comes mainly from leafy greens. K2 is a group of forms called menaquinones from fermented and animal foods, and one of them, MK-4, is made by your body from K1. All forms activate the same proteins; they differ in food sources and time in the blood.

Is vitamin K2 better than K1?

They do the same job, so it depends on your goal. K1 is the easiest form to get from food. K2 as MK-7 has a much longer half-life, builds up to steadier levels with daily intake and activated osteocalcin more completely than K1 in a comparison study. Many people get K1 from vegetables and add K2.

Can the body convert K1 to K2?

Yes, to one form. Your body makes MK-4 from K1 in its own tissues. It does not make MK-7 this way; MK-7 comes from fermented foods such as natto or from supplements. This is why a K2 label may list both forms.

What foods have K1 vs K2?

K1 is highest in leafy greens: a half cup of boiled collards has 530 mcg, and a cup of raw spinach has 145 mcg. K2 is highest in natto, with 850 mcg of MK-7 in 3 ounces. Chicken, eggs and cheese give smaller amounts of MK-4, from 4 to 13 mcg per serving.

MK-4 vs MK-7 vs K1: what is the difference?

K1 is the plant form in greens. MK-4 is a short-chain K2 your body makes from K1, also found in chicken, eggs and cheese. MK-7 is a long-chain K2 from fermented foods with a very long half-life. A 12-month MK-4 trial used 1.5 mg a day, while a 3-year MK-7 trial used 180 mcg a day.

Do you need K2 if you eat leafy greens?

Leafy greens can cover the daily Adequate Intake of 90 to 120 mcg of vitamin K as K1. People add K2 because MK-7 stays in the blood much longer than K1 and because it pairs with vitamin D3, which works on the same calcium task.

Can you take vitamin K2 if you take warfarin?

Only with your clinician's guidance. Warfarin works by blocking vitamin K, so both K1 and K2 can change how it works, and researchers have noted that 50 mcg a day or more of MK-7 may interfere with this treatment. Ask before you start.

Sources

• NIH Office of Dietary Supplements. Vitamin K: Fact Sheet for Health Professionals. National Institutes of Health, updated 2026. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/
• NIH Office of Dietary Supplements. Vitamin D: Fact Sheet for Health Professionals. National Institutes of Health. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
• Schurgers LJ, Teunissen KJ, Hamulyak K, Knapen MH, Vik H, Vermeer C. Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Blood, 2007. https://pubmed.ncbi.nlm.nih.gov/17158229/
• Knapen MHJ, Drummen NE, Smit E, Vermeer C, et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International, 2013. https://doi.org/10.1007/s00198-013-2325-6
• Theuwissen E, Cranenburg EC, Knapen MH, et al. Low-dose menaquinone-7 supplementation improved extra-hepatic vitamin K status, but had no effect on thrombin generation in healthy subjects. British Journal of Nutrition, 2012. https://doi.org/10.1017/S0007114511007185
• Koitaya N, Sekiguchi M, Tousen Y, et al. Randomized, double-blind, placebo-controlled trial of low-dose vitamin K2 (MK-4), 1.5 mg a day for 12 months, in postmenopausal Japanese women. Journal of Bone and Mineral Metabolism, 2014. https://doi.org/10.1007/s00774-013-0472-7

These statements have not been evaluated by the Food and Drug Administration. This content is for education and is not medical advice. Our products are not intended to diagnose, treat, cure or prevent any disease. Talk with a healthcare provider before starting a new supplement if you are pregnant, breastfeeding or taking medication.