Vitamin K: Are You “Kovered?”
When it comes to vitamin K, are you “kovered?” If you’re consuming leafy greens such as kale, spinach, and collard greens on a daily basis, you most likely reach your daily needs. We turned the spotlight on vitamin K to share more about other foods containing this vitamin, what it does, how much we need, and recipes with vitamin K-rich ingredients.
Family of Compounds and Food Sources
Quinones are the family of compounds known as vitamin K.
- Vitamin K1 (phylloquinones) is the most biologically active and main dietary form of vitamin K. Rich sources of vitamin K1 include leafy greens such as kale, spinach, Brussels sprouts, and broccoli, as well as vegetable oils.
- Vitamin K2 (menaquinones) is found in fish oils, dairy, meat, and some fermented foods. Also, the bacteria in the human colon can synthesize vitamin K2, although not enough to reach daily needs.
- Vitamin K3 (menadione) is a synthetic form of vitamin K1 that can be converted to K2 in the body. However, vitamin K3 is no longer used in supplements because it was shown to have detrimental health effects.
The Adequate Intake for vitamin K is 90 micrograms/day for adult women and 120 micrograms/day for adult men. The Daily Value for vitamin K, which you will find on supplement labels, is 80 micrograms/day. Foods that contain more than 100% of the Daily Value for vitamin K include: ½ cup collard greens or turnip greens, 1 cup raw spinach or kale, and ½ cup of broccoli.
Vitamin K is essential for blood clotting through its role in the synthesis and activation of blood clotting factors in the liver, which prevent excess bleeding through forming clots. Vitamin K is also involved in synthesizing proteins involved in bone metabolism. Furthermore, independent of its role in blood clotting and bone metabolism, vitamin K is being explored for potential anti-inflammatory effects.
For those on anticoagulants such as Warfarin, vitamin K supplements should be avoided and dietary intake should be consistent because the drug interacts with vitamin K’s role in activating blood-clotting factors in the liver. Please check with your doctor before adjusting your intake of vitamin K-rich foods.
Because vitamin K is a fat-soluble vitamin, meaning that it is absorbed along with dietary fat, we pair vitamin K-rich foods with health fats such as plant oils, avocado, and nuts. Try these seasonal dishes to make sure you are A-O-K!
- Roasted Sweet Potato and Kale Salad
- Chard, Tomato, and Zucchini Frittata
- Pumpkin Vegetable Curry with Spinach
- Brussels Sprout Salad With Pear And Pomegranate
Byrd-Bredbrenner C, Moe G, Berning J, Kelley D. Wardlaw’s Perspectives in Nutrition. McGraw-Hill Education 2016; 10: 425-29.
Harshman SG, Shea MK. The Role of Vitamin K in Chronic Aging Disease: Inflammation, Cardiovascular Disease, and Osteoarthritis. Curr Nutr Rep 2016;5(2):90-98.
Vitamin K: Fact Sheet for Health Professionals. National Institutes of Health Office of Dietary Supplements. 2016. Available from: https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/