Phylloquinone.
The plant form of vitamin K that keeps your blood clotting properly and helps calcium get into your bones. Vitamin K1 switches on the proteins that your clotting cascade and your bone matrix both rely on, by letting specific residues in them bind calcium.
Reviewed March 2026
- Category
- Vitamin
- Also filed under
- Essential for blood clottingSupports bone mineralizationActivates osteocalcin for calcium depositionRequired for normal wound healing
What Phylloquinone is, and what it does.
- Does it work
- If leafy greens are a regular part of your week, food covers this. It suits people who rarely eat greens, and anyone building a bone routine around calcium and vitamin D.
- How much to take
- 90 mcg (women) to 120 mcg (men) as adequate intake. One cup of cooked spinach or kale provides 500+ mcg, so food is the easiest source. Supplements typically contain 100-120 mcg.
- Time to feel it
- There is no onset to feel. Carboxylation picks up within days of steady intake, and it reads on functional markers rather than in how your day goes.
- The first dose
- Zero noticeable effects. K1 is absorbed and used to activate clotting factors in the liver. This is invisible to you.
- With regular use
- Steady daily intake keeps carboxylation of clotting and bone proteins running. It shows on markers such as uncarboxylated osteocalcin rather than as a sensation.
- How well tolerated
- Well tolerated, with no upper limit set from food or supplements. If you take warfarin, keep your intake steady and talk to your doctor before changing it.
- How it feels
- Invisible. K1 is a metabolic utility player that you'll never consciously notice. It's essential for life (you'd die without it), but your experience of taking it is completely neutral.
- The overlooked benefit
- K1 is recycled. Each carboxylation turns it into an epoxide that an enzyme regenerates, so a small amount of the vitamin gets used over and over again.
90 to 120mcg a day is where Phylloquinone works.
Source: IOM DRI 2001; Booth, 2012
The proof, claim by claim.
These words describe the research, not the molecule's worth. Research strength is how much work stands behind one claim, and it is never a product score.
- Essential for blood clotting
- Supports bone health
- Protects against arterial calcification
Questions people ask about Phylloquinone.
- What's the difference between K1 and K2?
- K1 (phylloquinone) is from plants and primarily supports blood clotting. K2 (menaquinone, especially MK-7) is from fermented foods and bacteria, and has stronger evidence for bone and cardiovascular health. Ideally, get both.
- Can I take K1 if I'm on blood thinners?
- If you're on warfarin: yes, but keep your intake CONSISTENT. Don't suddenly eat a huge kale salad one day and nothing the next. Warfarin doses are calibrated to your usual K1 intake. For other blood thinners (DOACs like Eliquis/Xarelto), K1 isn't a concern.
- Should I take K1 or K2 for bone health?
- Both help, but K2 (MK-7) has stronger evidence for bone density and reducing fracture risk. K1 activates osteocalcin too, but K2 does it more efficiently and has a longer half-life. A combo supplement with D3+K2+K1 is the gold standard for bone support.
- Do I need a K1 supplement if I eat salads?
- Probably not. One cup of spinach, kale, or other leafy greens provides many times the daily adequate intake. If you eat greens several times a week, you're almost certainly getting enough K1.
- Is there an upper limit for K1?
- No established upper limit. Unlike fat-soluble vitamins A and D, K1 hasn't shown toxicity even at high doses. That said, there's no benefit to mega-dosing either.
- Why do newborns get a vitamin K shot?
- Babies are born with very low vitamin K stores, and breast milk is a poor source. Without the injection, about 1 in 60 newborns would develop serious bleeding (VKDB). It's one of the most well-justified routine medical interventions.
Why these belong in the same formula. Each row says what the basis is, from settled biochemistry through to a trial that measured the pair.
Phylloquinone is cleared mainly by the liver and part of it is converted to menaquinone-4 in tissues, while MK-7 circulates far longer and reaches bone and vessel wall. Taken together they cover both the hepatic and the peripheral pools of the same carboxylation cofactor.
Both forms drive the same gamma-glutamyl carboxylase reaction but distribute differently, K1 to the liver and menaquinones to extrahepatic tissue. Doses of the two add into one functional vitamin K supply.
Vitamin K1 carboxylates glutamate residues on osteocalcin and matrix Gla protein, and it is those carboxylated residues that bind calcium ions. Calcium handling in bone matrix depends on that step being complete.
Vitamin D drives intestinal calcium absorption and raises osteocalcin expression, and vitamin K1 carboxylates that osteocalcin so it can bind mineral. One supplies the protein and the mineral, the other activates the protein.
High alpha-tocopherol intake lowers vitamin K status and blunts vitamin K-dependent carboxylation, an established antagonism at the level of normal clotting factor activation. This is an anti-synergy to declare, not a benefit.
Vitamin K1 supports synthesis of active clotting factors while long-chain omega-3s shift platelet aggregation the other way. The two pull normal clotting in opposite directions and should be recorded as an offsetting pair.
EPA and DHA reduce platelet aggregation, whereas phylloquinone is the cofactor that activates clotting factors II, VII, IX and X. Combining them means two settled, opposite influences on the same physiology.
Ginkgo constituents act on platelet aggregation while phylloquinone activates clotting factor synthesis. The direction of the interaction is established even where its size is not well quantified.
Garlic sulfur compounds dampen platelet aggregation, the opposite direction to vitamin K1's role in activating clotting factors. Formulas carrying both should record the offset.
Phylloquinone needs bile salts and mixed micelles to cross the enterocyte, and phospholipids improve micelle formation for fat-soluble vitamins. This is emulsification chemistry rather than a metabolic link.
Vitamin K1 uptake rises when it is taken with dietary fat because absorption is micelle-dependent. A lipid carrier in the same dose raises the fraction absorbed.
Activated charcoal adsorbs fat-soluble compounds in the intestinal lumen, so a phylloquinone dose taken at the same time is partly bound and not absorbed. Separating the two by several hours removes the competition.
Phylloquinone is fat-soluble and must be incorporated into mixed micelles with bile salts before it crosses the enterocyte membrane. Where bile delivery is reduced, uptake of the vitamin falls accordingly. Supplemental bile components are used in formulas for that reason, and the underlying dependence is textbook physiology.
Triglyceride must be hydrolysed to monoglyceride and free fatty acid before micelles can form and carry phylloquinone into the enterocyte. Lipase performs that hydrolysis. The dependency is settled digestive biochemistry, which is why the vitamin is taken with a fat-containing meal.
Phospholipids are a structural part of the mixed micelles that ferry fat-soluble vitamins across the unstirred water layer of the gut. Phosphatidylcholine is used in formulations to disperse phylloquinone into that phase. Established micelle chemistry. The size of any absorption difference in people is not something to state without a number.
Fat-soluble vitamins share micellar transport and chylomicron packaging, and high doses of retinol have been described as antagonising vitamin K-dependent clotting factor activity. The direction of the interaction is recognised in clinical nutrition references. The dose at which it matters is not something to assert without a figure. Worth flagging in a stack that carries a large vitamin A amount.
Phylloquinone enables gamma-carboxylation of osteocalcin, the vitamin K-dependent bone matrix protein, while magnesium is a structural component of the hydroxyapatite lattice and a cofactor across the enzymes of bone turnover. The two act at different points of the same tissue process. Both mechanisms are established. A combination trial for bone density measures was not located.
Phylloquinone supports the carboxylation of factors II, VII, IX and X, which raises coagulation capacity, while nattokinase acts on fibrin and raises clot breakdown. The two work in opposite directions on the same haemostatic balance. That opposition is worth flagging in any formula carrying both, particularly for anyone whose clotting is being managed clinically.
Bromelain has been described as reducing platelet aggregation and degrading fibrin, again the opposite direction from vitamin K-supported coagulation capacity. Neither cancels the other cleanly, and the net effect on haemostasis is not predictable from the pairing. Flag it rather than formulate around it.
Salicylates inhibit platelet cyclooxygenase and reduce thromboxane-driven aggregation. Phylloquinone acts on the coagulation cascade rather than on platelets, so the two touch different arms of haemostasis pushing opposite ways. Recorded so a stack carrying both is visible.
Gut bacteria including Bacteroides and Escherichia species produce long-chain menaquinones, which contribute to total vitamin K available to the body alongside dietary phylloquinone. Changing the microbial population therefore changes that contribution. Whether a given probiotic raises measured vitamin K status in people has not been established, so the row sits at Promising and describes a modulating relationship, not an additive one.
Inulin is fermented in the colon and shifts which bacterial genera dominate, and some of those genera are menaquinone producers. That gives a plausible route by which a prebiotic could alter endogenous vitamin K supply. The link runs through several steps without human status data behind it, so it is Early.
Boron is described as influencing calcium and magnesium handling and appears in bone-focused formulas alongside vitamin K forms. Phylloquinone's contribution there is the carboxylation of osteocalcin and matrix Gla protein. The pairing is formulation practice supported by separate mechanisms, not a measured combination, so it stays Early.
Alkaline phosphatase, a marker and participant in bone mineralisation, is a zinc metalloenzyme. Vitamin K-dependent carboxylation of osteocalcin is a separate step in the same tissue. Both facts are established. The additive value of combining them has not been measured, so this is recorded at Early.
Ascorbate is the cofactor for prolyl and lysyl hydroxylases that build the collagen scaffold of bone, while phylloquinone enables carboxylation of the Gla proteins that bind calcium to that scaffold. Matrix and mineral binding are sequential requirements, not competing ones. Both mechanisms are established. The combination itself has not been trialled for bone measures.
Talk to a doctor before taking Phylloquinone if any of these apply to you: CRITICAL: Interacts with warfarin/Coumadin (keep intake consistent), Fat-soluble, requires dietary fat for absorption, K2 may be more effective for bone health specifically. These are flags to check first, not effects Phylloquinone is known to cause.
Not medical advice. Show the label to your pharmacist.What Phylloquinone actually does.
Phylloquinone is vitamin K1, the form made by plants and the main type of vitamin K found in leafy greens.
Its one known job is to act as a helper for an enzyme that modifies certain proteins so they can bind calcium.
The proteins this enzyme modifies include several blood clotting factors as well as proteins in bone and in blood vessel and cartilage tissue.
Each time the enzyme does its job it uses up a bit of vitamin K, but another enzyme recycles it back to its active form, so a small amount goes a long way.
Where Phylloquinone comes from.
Most vitamin K1 in supplements is made in a factory by attaching a long fatty tail to a simpler ring molecule, which gives the same compound plants make. Some is pulled straight out of green plant material instead. Either way it ends up in oil or a dispersible powder, in packaging that keeps light out.
The same molecule is reached more than one way. Which route a given product used is a manufacturing choice, and the finished compound is the same either way.
The synthetic route starts from menadione, a naphthoquinone with no side chain. The extraction route starts from leafy plant tissue where phylloquinone sits in chloroplast membranes
Menadione is condensed with a phytyl group under acid catalysis to build the C20 saturated side chain that defines phylloquinone
Dried green material is extracted with a lipophilic solvent to pull the vitamin out of the membrane lipid it is bound to
The trans isomer is separated from cis and from reaction by-products by chromatography or crystallisation, since biological activity is isomer-dependent
Content is quantified by HPLC and the material is diluted into oil or a dry carrier to a declared microgram-per-serving figure
Filled under light protection and often with an antioxidant, because phylloquinone degrades on exposure to light
Labels seldom state the isomer specification, whether the material is synthetic or plant-extracted, or the antioxidant and packaging measures protecting it, and all three affect how much active vitamin is present at the end of shelf life.
Getting Phylloquinone from food.
The whole-food sources on file. A supplement closes the gap, it does not replace dinner.
A gram-for-gram figure (how much of each you would eat to match a dose) will appear here once it is sourced and reviewed. This page will not print a number it cannot cite.
The forms it comes in.
The essence, in one line each.
- A controlled supplementation trial that measured markers of glucose handling, including fasting glucose and insulin measures, and reported no detectable between-group difference overall. That is a failure to detect a difference on intermediate markers, not evidence that none exists.Randomised trial. Kumar R et al., 2010 (The American Journal of Clinical Nutrition). PMID 20881072 ↗
- A double-blind placebo-controlled trial that measured serum lipid markers before and after phylloquinone supplementation in a defined clinic population. Lipid concentrations are intermediate measures, so the paper speaks to markers rather than to any clinical endpoint.Randomised trial. Kolahi S et al., 2015 (Nutrition Research and Practice). PMID 25861426 ↗
- Serum concentrations of retinol, cholecalciferol, alpha-tocopherol and phylloquinone were quantified and compared between affected and unaffected animals, confirming that phylloquinone is measurable in circulation alongside the other fat-soluble vitamins.Case-control. Bilgiç B et al., 2025 (Animals). PMID 40941272 ↗
These are the studies our verdict leans on, chosen from the 3 we read for Phylloquinone. The full linked list is below.
The studies, linked.
2 sources behind our Phylloquinone verdict: peer-reviewed studies and registered clinical trials. Every one links straight to PubMed, the journal, or ClinicalTrials.gov. Read them yourself.
- Clinical trialInhibit Progression of Coronary Artery Calcification With Vitamin K in HemoDialysis Patients: The iPACK-HD StudyClinicalTrials.gov ↗Phase 2, 85 participants, Completed
- Clinical trialVitamin K1 to Slow Progression of Vascular Calcification in Hemodialysis PatientsClinicalTrials.gov ↗Phase 3, 63 participants, Terminated
Evidence surfaced via Semantic Scholar (Allen Institute for AI) and ClinicalTrials.gov. Ranked by study type and citation weight, not cherry-picked.
Problems people have reported.
Read this carefully. These are 37 voluntary, unverified reactions reported to the FDA (openFDA). The number mostly reflects how popular Phylloquinone is, not how risky it is. A report is not proof Phylloquinone caused anything. It is a signal of what to watch for, nothing more.
Source: openFDA adverse-event reports. Voluntary reporting, not an incidence rate.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. This information is for educational purposes only and is not intended to diagnose, treat, cure, or prevent any disease. Consult your healthcare provider before starting any supplement regimen.


