vitamin · for chronic inflammation
Vitamin K1
Meant to turn down the switch that makes inflammatory signals.
Say that in clinical terms
Modulates NF-kB signaling pathway, reducing production of inflammatory cytokines IL-1beta and IL-6.
How strong is the research?
No Benefit evidence
A 3-year trial in 379 older adults found no reduction in inflammation markers.
Studies disagreeDifferent group studied
4 papers read, 2 supporting, 2 against.
Who was studied: Adults aged 60 to 81, not middle-aged adults.
How much to take
daily
500–1000 mcg
Found in leafy greens. Supplementation may benefit those with low dietary intake.
Before you take it
- No Tolerable Upper Intake Level (UL) has been established for vitamin K in any form by the National Academy of Medicine, due to insufficient data on adverse effects at high intakes; absence of a UL does not imply unlimited safety at supplemental doses.
- Critical anticoagulant drug interaction: Vitamin K1 (phylloquinone) is the functional antagonist of warfarin (Coumadin) and all vitamin K antagonist (VKA) anticoagulants (acenocoumarol, phenprocoumon). Supplemental K1 can reduce anticoagulant efficacy and significantly destabilize INR. Users on VKA anticoagulants must not supplement K1 without physician supervision.
- Adequate Intake (AI) set by the National Academy of Medicine: 90 mcg/day for adult women, 120 mcg/day for adult men. Doses of 500–1000 mcg/day represent approximately 4–8× the AI.
- Antibiotic interaction: Broad-spectrum antibiotics (especially cephalosporins) reduce gut-bacterial vitamin K synthesis and may directly inhibit vitamin K-dependent clotting factor carboxylation; concurrent K1 supplementation warrants clinical monitoring, particularly in patients also on anticoagulants.
- Fat-absorption drug interactions: Bile acid sequestrants (cholestyramine, colestipol) and orlistat impair intestinal absorption of fat-soluble vitamins including K1; concurrent use may substantially reduce K1 bioavailability and, in anticoagulant users, complicate INR management.
- Small RCT signal (Kristensen et al. 2008, PMID 18807108, n=31 postmenopausal women): Phylloquinone 500 mcg/day for 6 weeks was associated with a 15% increase in triglycerides and 5% decrease in HDL-C; this has not been confirmed in larger trials and requires replication, but is a reported safety observation.
What we make of it
The three-year supplementation arm found nothing.
The detail
The study had two parts: a snapshot comparison and a three-year trial giving 500 mcg a day. The trial arm — the part that can actually show cause — found no reduction in inflammation.