photo from Freepik

by Reed Mangels, PhD, RD

Vitamin K is an essential vitamin that plays important roles in blood clotting and in bone health. Most people in the United States get enough vitamin K from foods. The bacteria in our large intestines make some vitamin K, which we can absorb. Vitamin K deficiency can occur in people with medical conditions such as ulcerative colitis, celiac disease, and cystic fibrosis, that affect their ability to absorb nutrients.

Vitamin K is a complex molecule and has several different forms that are found in foods and supplements. Phylloquinone (vitamin K1) is the main form of vitamin K that is found in foods. Menaquinone (vitamin K2) is made by bacteria and is found in small amounts in some animals foods and in fermented foods.

The Adequate Intake (AI) for vitamin K is:

Birth to 6 months: 2 micrograms/day

7-12 months: 2.5 micrograms/day

1-3 years: 30 micrograms/day

4-8 years: 55 micrograms per day

9-13 years: 60 micrograms/day

14-18 years: 75 micrograms/day

19 years and older: 120 micrograms/day (male); 90 micrograms/day (female)

Pregnancy and Lactation: 75 micrograms/day (14-18 years); 90 micrograms/day (19 years and older)

Many whole plant foods supply us with vitamin K. As you can see, a small (1/2 cup portion) of cooked greens provides all the vitamin K we need for a day.

10 Good Sources of Vitamin K for Vegans

1. Kale, 573 micrograms of vitamin K in ½ cup cooked
2. Collard greens, 530 micrograms of vitamin K in ½ cup cooked
3. Spinach, 494 micrograms of vitamin K in ½ cup cooked
4. Turnip greens, 426 micrograms of vitamin K in ½ cup cooked
5. Mustard greens, 415 micrograms of vitamin K in ½ cup cooked
6. Swiss chard, 286 micrograms of vitamin K in ½ cup cooked
7. Brussels sprouts, 150 micrograms of vitamin K in ½ cup cooked
8. Cabbage, 82 micrograms of vitamin K in ½ cup cooked
9. Broccoli, 81 micrograms of vitamin K in ½ cup cooked
10. Asparagus, 72 micrograms of vitamin K in ½ cup cooked

Fat helps our bodies absorb more vitamin K and eating vitamin K-rich vegetables along with a source of fat can increase the amount of vitamin K absorbed 3-fold (1).

The sources of vitamin K listed above all provide vitamin K in the form of vitamin K1. Natto, a food made from fermented soybeans and used in traditional Japanese cuisine, is one of the few plant-based sources of vitamin K2. There is no evidence to suggest that vegans whose diets contain adequate amounts of vitamin K1 need to be concerned about low dietary vitamin K2 (2).

Some studies find that vitamin K2 supplements that provide much higher amounts than could be obtained from food reduce the risk of fractures and increase bone mineral density in older women (3,4) but do not have a significant effect on bone mineral density in older men (5). Additional research is needed on the effects of vitamin K2 supplements on bone health and heart disease in those following vegan diets (2).

References

1. Gijsbers BL, Jie KS, Vermeer C. Effect of food composition on vitamin K absorption in human volunteers. Br J Nutr. 1996;76:223-229.
2. Goldman DM, Warbeck CB, Barbaro R, et al. Assessing the roles of retinol, vitamin K2, carnitine, and creatine in plant-based diets: A narrative review of nutritional adequacy and health implications. Nutrients. 2025;17:525.
3. Shiraki M, Shiraki Y, Aoki C, et al. Vitamin K2 (menatetrenone) effectively prevents fractures and sustains lumbar bone mineral density in osteoporosis. J Bone Miner Res. 2000;15:515-521.
4. Knapen MH, Drummen NE, Smit E, et al. Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporos Int. 2013;24:2499-2507.
5. Zhang Y, Liu Z, Duan L, et al. Effect of low-dose vitamin K2 supplementation on bone mineral density in middle-aged and elderly Chinese: A randomized controlled study. Calcif Tissue Int. 2020;106:476-485.

To read more about vitamin K see:

Vitamin K Fact Sheet for Consumers (from National Institutes of Health; contains nonvegan sources of vitamin K)

Nutrition Hotline from Vegetarian Journal about vitamin K

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The contents of this website and our other publications, including Vegetarian Journal and Vegan Journal, are not intended to provide personal medical advice. Medical advice should be obtained from a qualified health professional. We often depend on product and ingredient information from company statements. It is impossible to be 100% sure about a statement, info can change, people have different views, and mistakes can be made. Please use your best judgment about whether a product is suitable for you. To be sure, do further research or confirmation on your own.