AboutThoughts
I never thought much about Vitamin K. I was focused on the usual suspects—Vitamin D, magnesium, and omega-3s.
However, a few years ago, during my quest to improve bone health and reduce inflammation from my chronic conditions, I stumbled upon a research paper about Vitamin K2. That one article changed my understanding of how our bodies regulate calcium and keep our bones and arteries in balance.
What surprised me most wasn’t just the science—it was how little we hear about Vitamin K despite its importance. Since then, I’ve made it a part of my nutrition strategy.
In this article, I’ll break down what Vitamin K actually does, the difference between K1 and K2, and why you should pay attention to this quiet but powerful vitamin.
Vitamin K helps with blood clotting, bone density, and heart health by managing calcium in the body.
K1 is found in dark leafy green vegetables, while K2 is found in fermented and animal-based foods and is more bioavailable for bones and arteries.
Deficiency is rare but possible due to poor vitamin K absorption, liver issues, or certain medications, such as vitamin K antagonists.
Vitamin K2 supplements (like MK-7) may help those at risk for osteoporosis or low bone density.
Always consult with health professionals if you’re on warfarin therapy before changing your dietary vitamin K intake.
Vitamin K is a fat-soluble vitamin that plays a central role in blood clotting proteins, bone metabolism, and regulating calcium in the body.
Unlike water-soluble vitamins, Vitamin K is stored in the liver and fatty tissues and is best absorbed with dietary fat. The Vitamin K cycle in your body ensures proper activation of various proteins that depend on this essential nutrient.
There are two primary forms of Vitamin K:
Vitamin K1 (phylloquinone): Found in green leafy veggies, this form helps with blood clotting.
Vitamin K2 (menaquinone): Found in fermented foods and certain animal products, this form is more active in bone and cardiovascular health.
Your body uses Vitamin K to activate specific glutamic acid residues in vitamin K-dependent proteins that direct calcium into your bones and teeth and away from your arteries and soft tissues, where it could harm you.
Without adequate vitamin K status, this process becomes inefficient and increases the risk of both bone fractures and coronary artery calcification.
Vitamin K plays several vital roles in the body—beyond just blood clotting—that are essential for your overall health.
One of Vitamin K’s most well-known functions is to support the liver in producing clotting factors. Without it, even a small cut could lead to excessive bleeding.
This is why newborns are given a newborn vitamin K shot shortly after birth—to prevent vitamin K deficiency bleeding, a rare but serious disorder.
Vitamin K activates bone Gla protein (osteocalcin), a vitamin K-dependent protein that binds calcium to the bone matrix.
Studies show that people with higher dietary vitamin K intake have greater bone mineral density and a lower risk of bone fractures, especially postmenopausal women who often struggle with low bone density.
Perhaps most surprising is Vitamin K2’s role in preventing coronary heart disease. It activates matrix Gla protein (MGP), which inhibits calcium from depositing in the arteries.
Some long-term studies suggest that higher vitamin K levels are associated with reduced coronary artery calcification and overall better cardiovascular outcomes.
While Vitamin D helps your body absorb calcium, Vitamin K2 helps guide that calcium to the right places. Taking one without the other may be less effective, especially if you have a high calcium intake.
Some research also suggests an interplay between vitamin K and vitamin E, with vitamin E supplements potentially decreasing vitamin K’s effectiveness in certain pathways.
Vitamin K inadequacy is rare in healthy adults but can occur under certain circumstances, especially if fat absorption is impaired or after long-term antibiotic use. Chronic kidney disease can also negatively impact vitamin K status.
Signs of Deficiency:
Easy bruising
Nosebleeds or bleeding gums
Blood in stool or urine
Heavy menstrual bleeding
Weak bones or increased fracture risk
Infants are at greater risk due to low circulating vitamin K at birth and the fact that breast milk contains only modest vitamin K levels, which is why hospitals administer an oral vitamin K or injectable form within hours of delivery.
Conditions like celiac disease, Crohn’s disease, or liver disorders can also lead to poor vitamin K absorption.
Medication like warfarin (Coumadin), which is a vitamin K antagonist that directly interferes with the vitamin K-dependent carboxylation process, can also cause this.
The Food and Nutrition Board has established dietary reference intakes for vitamin K based on adequate intake rather than a more precise RDA. Meeting these targets through food composition choices is vital for overall health.
Vitamin K1 and K2 come from different types of foods, and your body processes them differently. Here’s a quick breakdown:
| Food Item | Serving Size | Vitamin K1 (µg) |
|---|---|---|
| Kale (raw) | 1 cup | 472 |
| Spinach (cooked) | ½ cup | 444 |
| Broccoli (cooked) | ½ cup | 110 |
| Green leaf lettuce | 1 cup | 63 |
| Brussels sprouts | ½ cup | 78 |
| Food Item | Serving Size | Vitamin K2 (µg) |
|---|---|---|
| Natto (fermented soybeans) | 1 tbsp | 150–1000+ |
| Gouda cheese | 1 oz | 75 |
| Chicken liver | 3 oz | 14 |
| Egg yolk | 1 large | 6 |
| Butter | 1 tbsp | 2–3 |
💡 Tip: Vitamin K2 is better absorbed and more active in bone and arterial tissues, even though it’s less abundant in a standard diet. Dairy foods also provide smaller but meaningful amounts of vitamin K2.
For most people, a balanced diet rich in dark green leafy vegetables and fermented foods will provide adequate intake of Vitamin K. However, vitamin K supplementation might be useful for:
People with osteopenia or osteoporosis
Individuals taking high-dose Vitamin D or calcium
Those with fat malabsorption issues
People on long-term antibiotic therapy
Those with inadequate vitamin K status due to dietary patterns
Vitamin K2 (particularly MK-7) is the preferred form in dietary supplements for bone and heart health due to its longer half-life and better bioavailability.
The good news is that, unlike some nutrients, there’s no established tolerable upper intake level for vitamin K, as excessive vitamin K from supplements hasn’t been shown to cause significant adverse effects in most populations.
⚠️ Important: If you’re taking vitamin K antagonists like warfarin, consult your doctor before taking any vitamin K supplementation. Vitamin K affects how these medications work, and consistent nutrient intake of this vitamin is crucial for stable treatment.
The Recommended Dietary Allowance (RDA) for Vitamin K varies by age and gender:
| Age Group | Recommended Daily Allowance |
|---|---|
| Infants (0–6 months) | 2.0 mcg/day |
| Infants (7–12 months) | 2.5 mcg/day |
| Children (1–3 years) | 30 mcg/day |
| Children (4–8 years) | 55 mcg/day |
| Children (9–13 years) | 60 mcg/day |
| Adolescents (14–18) | 75 mcg/day |
| Adult Men (19+ years) | 120 mcg/day |
| Adult Women (19+ years) | 90 mcg/day |
| Pregnant Teens | 75 mcg/day |
| Pregnant Adults | 90 mcg/day |
| Breastfeeding Teens | 75 mcg/day |
| Breastfeeding Adults | 90 mcg/day |
There’s no known toxicity from high intakes of Vitamin K1 or K2 from food, but caution is advised with high-dose supplements especially for those with underlying health conditions or on medications.
Rare to get excessive Vitamin K from food sources. High supplement doses may affect medication efficacy, especially anticoagulants.
Vitamin K1 is plant-based and is essential for blood clotting, while Vitamin K2 is animal-based and fermented food-based and is vital for bone and heart health.
Yes, Vitamin K helps with calcium management, which strengthens bones and reduces osteoporosis risk.
Most healthy individuals don’t need supplements if they have a balanced diet rich in Vitamin K sources.
Vitamin K may not be as flashy as Vitamin D or B12, but don’t let that fool you—it’s a foundation of whole-body health.
Once I started adding more fermented foods like natto and mindful amounts of leafy greens to my diet, I noticed improvements in circulation and even joint comfort.
Not a magic pill. Just a piece missing—one that underlies your bones, blood, and heart. Get it from a salad, a spoonful of natto or a well-chosen supplement.
The information provided on this website is for general informational and educational purposes only and is not intended as medical advice, diagnosis, or treatment. Always consult your physician or other qualified healthcare professional with any questions you may have regarding a medical condition or before starting any health or wellness program.
