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Check vitamin K intake vs AI — see mcg/day, % of AI and food sources.
Check vitamin K intake vs AI — see mcg/day, % of AI and food sources.
Enter values above and click Calculate — results will appear here with the formula explained.
Vitamin K Adequate Intake is 120 mcg daily for men and 90 mcg for women 19+ — set from median intakes since dose-response data is insufficient for an RDA. K1 (phylloquinone) from greens drives clotting-factor carboxylation; K2 (menaquinones) from fermented foods and gut bacteria is studied for bone and vascular roles. This calculator checks intake as percent of AI.
One serving rewrites the math: a cup of cooked kale (~500 mcg), spinach (~440 mcg) or collards overshoots AI several-fold, while iceberg lettuce and fruit contribute little. Because K1 concentrates so heavily in dark greens, vegetarians routinely exceed AI while fast-food patterns fall to 30–60 mcg — the gap is one salad, not a supplement regimen.
The warfarin interaction dominates clinical relevance: warfarin thins blood by antagonizing vitamin K, so sudden K swings destabilize INR — a kale binge after weeks of fries can drop INR into clot risk, and vice versa. The rule is consistency, not avoidance: stable daily greens plus regular INR checks beat both binges and bans. DOACs (apixaban, rivaroxaban) lack this interaction.
Bone and vascular research extends beyond clotting: K-dependent osteocalcin and matrix Gla protein need carboxylation to bind calcium properly, and observational data link higher K2 intake to better bone density and less arterial calcification. Trials are mixed (K1 supplementation shows modest bone effects), so food-first remains the guidance — natto (1,000+ mcg K2 per serving) leads, then hard cheeses and egg yolks.
Deficiency in healthy adults is rare (gut bacteria plus recycling cover baseline needs) and usually signals fat malabsorption, long broad-spectrum antibiotics, or warfarin mismanagement — presenting as easy bruising, nosebleeds or prolonged bleeding. Newborns get prophylactic K shots precisely because placental transfer and gut colonization start at zero.
No Upper Limit is set — even gram-level K1 shows little toxicity — but that safety doesn't extend to changing warfarin patients' intake abruptly. This is general information; anticoagulated patients should coordinate diet changes with their INR clinic, not this calculator.
Check vitamin K intake vs AI — see mcg/day, % of AI and food sources. Formula: AI: M 120, F 90 mcg. Example: With 100 mcg intake, male AI 120: 83% — add half a cup of cooked kale (~250 mcg) to exceed 290%.
Vitamin K Adequate Intake is 120 mcg daily for men and 90 mcg for women 19+ — set from median intakes since dose-response data is insufficient for an RDA. K1 (phylloquinone) from greens drives clotting-factor carboxylation; K2 (menaquinones) from fermented foods and gut bacteria is studied for bone and vascular roles. This calculator checks intake as percent of AI.
One serving rewrites the math: a cup of cooked kale (~500 mcg), spinach (~440 mcg) or collards overshoots AI several-fold, while iceberg lettuce and fruit contribute little. Because K1 concentrates so heavily in dark greens, vegetarians routinely exceed AI while fast-food patterns fall to 30–60 mcg — the gap is one salad, not a supplement regimen.
The warfarin interaction dominates clinical relevance: warfarin thins blood by antagonizing vitamin K, so sudden K swings destabilize INR — a kale binge after weeks of fries can drop INR into clot risk, and vice versa. The rule is consistency, not avoidance: stable daily greens plus regular INR checks beat both binges and bans. DOACs (apixaban, rivaroxaban) lack this interaction.
Bone and vascular research extends beyond clotting: K-dependent osteocalcin and matrix Gla protein need carboxylation to bind calcium properly, and observational data link higher K2 intake to better bone density and less arterial calcification. Trials are mixed (K1 supplementation shows modest bone effects), so food-first remains the guidance — natto (1,000+ mcg K2 per serving) leads, then hard cheeses and egg yolks.
Deficiency in healthy adults is rare (gut bacteria plus recycling cover baseline needs) and usually signals fat malabsorption, long broad-spectrum antibiotics, or warfarin mismanagement — presenting as easy bruising, nosebleeds or prolonged bleeding. Newborns get prophylactic K shots precisely because placental transfer and gut colonization start at zero.
No Upper Limit is set — even gram-level K1 shows little toxicity — but that safety doesn't extend to changing warfarin patients' intake abruptly. This is general information; anticoagulated patients should coordinate diet changes with their INR clinic, not this calculator.
With 100 mcg intake, male AI 120: 83% — add half a cup of cooked kale (~250 mcg) to exceed 290%. A natto breakfast alone (~1,000 mcg K2) covers a week of AI in one bowl.
Last reviewed: September 2026 · Report an error