Your Clotting and Calcium Director
Vitamin K does two critical jobs: it activates clotting proteins that stop you from bleeding, and it activates proteins (osteocalcin, MGP) that direct calcium into your bones and AWAY from your arteries. Without enough vitamin K, calcium ends up in your arteries instead of your bones—arterial calcification and weak bones simultaneously.
What is Vitamin K?
Vitamin K exists as K1 (phylloquinone, from green vegetables) and K2 (menaquinone, from fermented foods and gut bacteria). K1 primarily supports clotting. K2 primarily directs calcium. Both are fat-soluble.
↑ What High Vitamin K Means
Vitamin K toxicity from food is essentially impossible. However, high vitamin K intake interferes with warfarin (blood thinner)—if you're on warfarin, keep vitamin K intake consistent rather than avoiding it.
Common symptoms:
No known toxicity from food forms · Interference with warfarin (maintain consistent intake)
↓ What Low Vitamin K Means
Impaired blood clotting (easy bruising, bleeding) and calcium mismanagement (osteoporosis + arterial calcification). Newborns are at particular risk—that's why they receive a vitamin K shot at birth.
Common symptoms:
Easy bruising · Excessive bleeding from cuts · Blood in urine or stool · Heavy menstrual periods · Osteoporosis (long-term) · Arterial calcification (long-term)
Why It Matters
When normal:
Essential for blood clotting (activates factors II, VII, IX, X)
Directs calcium into bones (activates osteocalcin)
Keeps calcium OUT of arteries (activates MGP)
Supports bone density
Risks if abnormal:
Deficiency: bleeding, bruising, osteoporosis, arterial calcification
Interacts with warfarin (must maintain consistent intake)
Newborns born with minimal stores
What Can Cause Abnormal Levels?
Low Dietary Intake
45% likelyK1 from greens and K2 from fermented foods. People who eat few vegetables and no fermented foods miss both.
Fat Malabsorption
35% likelyFat-soluble vitamin. Celiac, Crohn's, cholestasis, and pancreatic insufficiency impair absorption.
Antibiotics
Broad-spectrum antibiotics kill gut bacteria that produce vitamin K2.
Warfarin Therapy
Warfarin works BY blocking vitamin K—patients are functionally K-deficient by design.
Liver Disease
The liver makes vitamin K-dependent clotting factors.
What You Can Do
K1 foods: kale, spinach, broccoli, Brussels sprouts, collard greens
Impact: Dark leafy greens are the richest K1 sources \u00B7 Timeline: 2-4 weeks
K2 foods: natto (richest source), hard cheeses, egg yolks, butter
Impact: K2 specifically directs calcium to bones \u00B7 Timeline: 4-8 weeks
Eat with fat for absorption
Impact: Fat-soluble vitamin needs dietary fat \u00B7 Timeline: Immediate
If lifestyle changes aren't enough:
Vitamin K2 (MK-7): 100-200mcg daily
Impact: MK-7 has the longest half-life and best evidence for bone and arterial health \u00B7 Timeline: 3-6 months
Pair with vitamin D (synergistic for calcium management)
Impact: D increases calcium absorption, K2 directs where it goes \u00B7 Timeline: 3-6 months
Recommended retest: 3-6 months
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