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Vitamin K1 for Health & Longevity

Evidence Review created on 08/12/2026 using AI4L / Grok 4.5

Also known as: Phylloquinone, Phytomenadione, Phytonadione

Motivation

Vitamin K1 is the plant form of vitamin K, found mainly in green leafy vegetables and some plant oils. The body uses it as a helper molecule to finish building several proteins that control blood clotting and help place calcium where it belongs—in bone rather than in soft tissues. For people focused on long-term health, the interest is not only avoiding rare deficiency, but whether higher intakes support denser bones, quieter arteries, and lower long-term risk.

Observational work links higher dietary vitamin K1 and higher circulating levels with fewer fractures and lower all-cause death rates in some cohorts. Controlled trials, by contrast, show clearer effects on blood markers of vitamin K status than on hard clinical events, and results for artery calcium and bone density are mixed. The form also differs from vitamin K2 (menaquinones), which has a longer presence in blood and different tissue preference.

This review examines the human evidence on vitamin K1 for health and longevity: mechanisms, expected benefits and risks, who may gain or lose, practical dosing and sourcing, monitoring, and how the evidence base currently stands.

Benefits - Risks - Protocol - Conclusion

High-level overviews and expert commentary that place vitamin K1 in a broader bone, vascular, and nutrition context.

Four high-level sources are listed (priority expert and academic monographs). No substantial dedicated content on vitamin K1 was found from Peter Attia or Andrew Huberman; Lifespan.io material focuses on vitamin K2 rather than K1-specific protocols.

Grokipedia

  • Phytomenadione

    Dedicated Grokipedia entry on phytomenadione (vitamin K1), covering structure, absorption, and cofactor role in clotting proteins.

Examine

  • Vitamin K

    Examine’s vitamin K monograph summarizing evidence grades, typical K1 dose ranges, bone and cardiovascular outcomes, and safety.

ConsumerLab

Systematic Reviews

PubMed-indexed systematic reviews and meta-analyses most relevant to vitamin K1 intake, status, bone outcomes, cardiovascular risk, and anticoagulant interaction.

Mechanism of Action

Vitamin K1 (phylloquinone) is a fat-soluble cofactor for the enzyme γ-glutamyl carboxylase. That enzyme converts specific glutamic acid residues on vitamin K-dependent proteins (VKDPs; proteins that require vitamin K to function) into γ-carboxyglutamic acid (Gla) residues, which bind calcium. In the liver, this activates clotting factors II, VII, IX, and X and regulatory proteins C and S—the classic “koagulation” role. Extrahepatic VKDPs include osteocalcin (bone matrix protein from bone-building cells) and matrix Gla protein (MGP; a local inhibitor of soft-tissue calcification in vessel walls and cartilage).

After carboxylation, vitamin K is oxidized to vitamin K epoxide and recycled by vitamin K epoxide reductase (VKORC1; the enzyme blocked by warfarin-type anticoagulants). Hepatic needs for clotting are met at relatively low intake; full carboxylation of osteocalcin and MGP appears to require higher intake. Oral phylloquinone is absorbed with dietary fat via chylomicrons, preferentially taken up by the liver, and shows a short plasma half-life (roughly 1–4 hours after oral dosing), so serum levels fluctuate with meals. Compared with long-chain menaquinone-7 (MK-7; a vitamin K2 form), K1 accumulates less and carboxylates extrahepatic proteins less efficiently at equal microgram doses. Pharmacokinetics vary with VKORC1 genotype. Metabolism does not depend primarily on cytochrome P450 (CYP) enzymes in the usual drug-interaction sense; the clinically decisive pathway is VKORC1-mediated recycling.

Historical Context & Evolution

Vitamin K was identified in the 1930s when chicks on low-fat diets developed bleeding; the “K” comes from the Danish/German word for coagulation. Early work by Dam and Doisy established the antihemorrhagic factor and led to Nobel recognition. Phylloquinone from plants and menaquinones from bacteria were distinguished chemically, and synthetic phytonadione became standard for newborn prophylaxis against vitamin K deficiency bleeding and for reversing excess anticoagulation from vitamin K antagonists (VKAs; warfarin-type drugs that block vitamin K recycling).

From the 1980s onward, discovery of osteocalcin and MGP shifted attention beyond clotting to bone and vascular biology. Japanese research on high-dose menaquinone-4 (MK-4; a vitamin K2 form) for osteoporosis and Dutch observational work (e.g., Rotterdam) linking menaquinones to less coronary calcification and heart disease raised longevity interest. Parallel cohorts examined dietary phylloquinone and circulating K1 against fractures, coronary disease, and death—with mixed but often favorable associations for higher K1 status. Randomized trials of K1 (often 200 µg–10 mg/day) have repeatedly improved carboxylation markers; effects on bone mineral density, fractures, and imaging calcification have been modest or inconsistent, especially outside deficient or high-risk groups (postmenopausal bone loss, chronic kidney disease on dialysis). The field has not settled on one “correct” form: some researchers emphasize K1 from greens as sufficient insurance; others argue K2 better reaches bone and vessel wall. Both positions rest on incomplete hard-endpoint trial data rather than a closed consensus.

Expected Benefits

High 🟩 🟩 🟩

Prevention and Correction of Vitamin K Deficiency Coagulopathy

Vitamin K1 is the established medical form used to restore γ-carboxylation of hepatic clotting factors when deficiency or VKA excess impairs coagulation. Newborn intramuscular prophylaxis with phylloquinone sharply reduces vitamin K deficiency bleeding; oral or intravenous phytonadione is standard to reverse supratherapeutic anticoagulation from warfarin-class drugs when clinically indicated. For longevity-oriented adults without malabsorption or anticoagulant use, frank deficiency is uncommon if leafy greens are eaten, but the coagulation role remains the highest-certainty physiologic benefit of the molecule.

Magnitude: Clinical use restores coagulability; newborn prophylaxis largely prevents classic vitamin K deficiency bleeding in covered populations.

Medium 🟩 🟩

Lower Fracture Risk with Higher Dietary Phylloquinone

Meta-analysis of cohort and nested case-control data (~80,982 participants; 1,114 fracture cases) found higher dietary vitamin K1 intake associated with lower fracture risk (highest vs lowest RR 0.78, 95% confidence interval (CI) 0.56–0.99), with dose-response of RR 0.97 per +50 µg/day. Longer-follow-up strata were stronger. Residual confounding by overall vegetable-rich diet quality remains possible; fracture-endpoint RCTs of K1 alone are limited.

Magnitude: About 22% lower relative fracture risk (highest vs lowest intake strata); ~3% lower per additional 50 µg/day dietary K1.

Lower All-Cause Mortality with Higher Circulating Phylloquinone

Participant-level meta-analysis of three U.S. cohorts (Health ABC, MESA, Framingham Offspring; n=3,891; median follow-up 13 years) found fasting phylloquinone ≤0.5 nmol/L associated with 19% higher all-cause mortality vs >1.0 nmol/L after full adjustment (hazard ratio (HR) 1.19, 95% CI 1.03–1.38). Incident cardiovascular disease was not significantly associated. Mechanism may involve extrahepatic vitamin K-dependent proteins, broader nutritional status, or residual confounding.

Magnitude: Fully adjusted HR 1.19 for death at low (≤0.5 nmol/L) vs higher (>1.0 nmol/L) circulating phylloquinone.

Modestly Lower Coronary Heart Disease Risk (Dietary Intake)

Pooled prospective studies reported higher dietary phylloquinone associated with modestly lower total coronary heart disease (pooled HR 0.92, 95% CI 0.84–0.99; four studies). Associations for stroke, cardiovascular death, and all-cause mortality by intake were weaker or null in the same synthesis. Menaquinone intake showed larger coronary point estimates in fewer studies.

Magnitude: Pooled HR ~0.92 for total coronary heart disease (top vs bottom tertile of dietary phylloquinone).

Low 🟩

Bone Mineral Density and Turnover (Supplementation)

RCTs of phylloquinone (often 200–1000 µg/day), alone or with calcium and vitamin D, reliably lower undercarboxylated osteocalcin and sometimes yield modest, site-specific bone mineral density (BMD) gains. Large hip BMD or fracture effects in general Western populations are not established.

Magnitude: Site-specific BMD increases in some RCTs; fracture reduction from K1 alone not consistently quantified.

Slowing Coronary or Vascular Calcification in High-Risk Chronic Kidney Disease ⚠️ Conflicted

Small dialysis RCTs of high-dose K1 report slower coronary or aortic calcification versus control. A broader K1/K2 trial review found inconsistent prevention; benefit may cluster where calcification is already present. Healthy-adult imaging data remain thin.

Magnitude: Up to ~55–68% relative reduction in calcification progression in small dialysis trials; general-population effect not established.

Speculative 🟨

Improved Insulin Sensitivity and Cardiometabolic Profile

Some trials report small HOMA-IR (insulin-resistance index) gains with vitamin K, often K2-driven; lipids and glucose are largely unchanged. Diabetes associations remain observational.

Benefit-Modifying Factors

  • Baseline vitamin K status: Individuals with low circulating phylloquinone or high undercarboxylated osteocalcin/MGP markers have more headroom for carboxylation and, observationally, higher mortality risk when status is low.

  • Dietary pattern: High leafy-green intake already supplies substantial K1; supplemental absolute benefit is likely smaller than in low-vegetable consumers.

  • APOE genotype: Apolipoprotein E variants affect chylomicron clearance and vitamin K delivery to bone; APOE4 carriers may clear vitamin K-rich lipoproteins faster, potentially lowering bone availability.

  • VKORC1 genotype: Promoter polymorphism c.-1639 G>A alters oral phylloquinone bioavailability and half-life; AG carriers showed higher area under the curve and longer half-life than GG/AA in one pharmacokinetic study.

  • Age and bone status: Older adults and postmenopausal women with low bone mass are the populations most studied for skeletal endpoints; absolute fracture risk reduction matters more as baseline risk rises.

  • Chronic kidney disease: Dialysis populations show severe vitamin K insufficiency markers and high calcification burden; calcification-slowing signals cluster here more than in healthy adults.

  • Sex: Adequate intake targets differ (90 µg/day women, 120 µg/day men in U.S. tables); most bone RCTs enroll postmenopausal women—male skeletal data are thinner.

Potential Risks & Side Effects

High 🟥 🟥 🟥

Antagonism of Vitamin K Antagonist Anticoagulation

Supplemental or high dietary vitamin K1 directly opposes warfarin, phenprocoumon, and related vitamin K antagonists by restoring carboxylation of clotting factors, which can lower the international normalized ratio (INR; a lab measure of anticoagulant effect) and increase thrombosis risk. Stable day-to-day intake is preferred over avoidance; large unannounced dose changes are hazardous. This is the dominant, clinically proven risk of vitamin K1 for adults on these drugs.

Magnitude: Clinically relevant INR shifts reported with substantial intake changes; systematic review notes effects more detectable above ~150 µg/day dietary swings in some settings.

Medium 🟥 🟥

Anaphylactoid Reactions with Intravenous Phytonadione

Intravenous vitamin K1 (especially older formulations) has been associated with rare but serious hypersensitivity and anaphylactoid (severe allergy-like) reactions, including hypotension and cardiac arrest. Oral and intramuscular routes used for routine nutrition or mild correction carry far lower acute reaction risk. Longevity supplementation is oral; intravenous risk applies to medical use.

Magnitude: Rare but serious intravenous reactions documented in pharmacovigilance; not a typical oral-supplement adverse event.

Low 🟥

Gastrointestinal Discomfort at High Oral Doses

High milligram-range oral phytonadione is generally well tolerated in clinical use. Occasional nausea or stomach upset appears in product labeling and case reports. There is no characteristic organ-toxicity syndrome for oral K1 at nutritional or usual supplemental doses.

Magnitude: Uncommon; no UL (tolerable upper intake level) established for phylloquinone from diet or supplements.

Speculative 🟨

Theoretical Over-Carboxylation Concerns at Extreme Doses

No established toxicity syndrome exists for high-dose phylloquinone in humans. Synthetic menadione (vitamin K3) is the toxic form and is not used in nutrition. “Too much K1” concerns lack clinical support at usual doses.

Risk-Modifying Factors

  • VKA therapy: Absolute driver of clinically important risk; any supplemental K1 requires coordinated INR monitoring or avoidance.

  • Baseline INR instability: Patients with labile anticoagulation are more sensitive to diet and supplement swings.

  • Malabsorption and cholestasis: Fat-malabsorption states and cholestasis (impaired bile flow) raise deficiency risk more than toxicity risk; dosing routes and monitoring differ.

  • Age: Older adults more often use VKAs and have higher fall/fracture and calcification burdens—both benefit and interaction risk rise together.

  • Sex: No major sex-specific toxicity of oral K1; warfarin management patterns differ by indication and age mix.

  • Liver disease: Impaired synthetic function and altered vitamin K handling change both bleeding risk and response to phytonadione.

  • Genetic VKORC1/CYP2C9 variants: Variants in vitamin K recycling and warfarin-metabolizing enzymes strongly affect dose needs and interaction severity more than K1 toxicity itself.

Key Interactions & Contraindications

  • Vitamin K antagonists (warfarin, acenocoumarol, phenprocoumon): Absolute caution / relative contraindication for unsupervised supplementation — reduces anticoagulant effect, raises clot risk; requires clinician-managed stable intake and INR checks.

  • Orlistat and bile-acid sequestrants (cholestyramine, colesevelam): Caution — impair fat-soluble vitamin absorption; may lower K1 status over time; separate dosing and monitor if prolonged use.

  • Mineral oil and severe fat restriction: Caution — reduce absorption of phylloquinone with meals.

  • High-dose vitamin E (e.g., ~1000 IU (international units)/day): Caution — may antagonize vitamin K-dependent carboxylation and raise bleeding risk when vitamin K status or VKA therapy is marginal.

  • High-dose vitamin A: Caution — can interfere with vitamin K absorption/utilization in experimental and clinical observation contexts.

  • Broad-spectrum antibiotics (prolonged): Monitor — reduce menaquinone-producing gut bacteria; usually minor for K1 if diet is adequate, more relevant when intake is low.

  • Additive bone-support stack (vitamin D, calcium, magnesium): Potentiating for skeletal goals — co-use is common in protocols; does not replace attention to K1–VKA interaction.

  • Direct oral anticoagulants (DOACs; apixaban, rivaroxaban, dabigatran, edoxaban): No vitamin K mechanism — K1 does not reverse DOACs; interaction profile differs entirely from VKAs.

Populations who should avoid Vitamin K1:

  • Individuals on vitamin K antagonist anticoagulants without explicit clinician coordination and INR monitoring
  • Anyone with a documented severe hypersensitivity to phytonadione formulations (especially prior intravenous reaction)
  • People with active unexplained clotting disorders until evaluated (supplemental high-dose K1 may be inappropriate depending on diagnosis)

Risk Mitigation Strategies

  • Stable intake on VKAs: Keep dietary K1 consistent day to day rather than eliminating greens; never start/stop high-dose supplements without INR plans—limits INR swings and thrombosis risk.

  • Prefer oral over intravenous for nutrition: Use oral phylloquinone for repletion; reserve IV phytonadione for monitored medical care to avoid rare anaphylactoid reactions.

  • Take with dietary fat: Pair with oil, egg, or avocado so absorption is not wasted and status markers respond more reliably.

  • Start near dietary-equivalent doses: Begin around 100–200 µg/day if supplementing to limit unnecessary high-dose exposure and interaction risk.

  • Separate from sequestrants/orlistat: Dose vitamin K several hours apart from binders that block fat-soluble vitamins and lower K1 status.

  • Coordinate with vitamin E use: Avoid chronic very high vitamin E when vitamin K intake is low or on VKAs to limit bleeding-risk antagonism.

  • Third-party tested products: Prefer USP/NSF/ConsumerLab-checked products to reduce label-accuracy and contaminant risk for chronic use.

Therapeutic Protocol

  • Dietary foundation: Prioritize phylloquinone-rich greens (kale, spinach, collards, broccoli); U.S. adequate intakes are 90 µg/day (women) and 120 µg/day (men).

  • Supplemental range used in practice: Longevity/bone stacks commonly use 100–1000 µg/day K1; bone RCTs often used 200 µg–1 mg/day; medical phytonadione doses for INR reversal are higher and indication-specific.

  • Timing: Take once daily with a fat-containing meal; plasma half-life is short (~1–4 hours oral), so meal pairing matters more than split dosing for nutrition goals.

  • Single vs split dose: Single daily dose is standard for microgram–low milligram supplemental K1; split dosing is unnecessary for most non-medical uses.

  • With vitamin D and calcium: Combinations showed more consistent skeletal marker/BMD signals than K1 alone in several trials; many clinicians co-supplement when bone is the goal.

  • K1 vs K2 choice: Food-first K1 (e.g., Kresser / LPI framing) vs add-on MK-4 or MK-7 for extrahepatic targets; evidence does not mandate one universal default.

  • VKORC1 / APOE considerations: Genotype may alter levels and bone delivery; not routinely required before dietary optimization, but relevant in research-minded personalization.

  • Sex and age: Follow sex-specific adequate-intake floors; older adults with osteoporosis or low vegetable intake are typical candidates for higher intentional intake.

  • Baseline markers: Low undercarboxylated osteocalcin improvement after repletion confirms biological response; circulating phylloquinone is labile and meal-dependent.

  • Avoid self-supplementation on warfarin: Protocol is clinician-directed stable diet, not ad hoc high-dose K1.

Discontinuation & Cycling

  • Duration of use: Nutritional K1 is compatible with long-term or lifelong intake at dietary or modest supplemental levels when not on VKAs.

  • Withdrawal: No classic withdrawal syndrome; carboxylation markers revert toward baseline over days to weeks as body stores turn over.

  • Tapering: Not required for microgram-range supplements; on VKAs, any planned change must be tapered only under INR supervision.

  • Cycling: Not required for efficacy; continuous steady intake matches physiology better than on/off cycles.

  • After stopping high doses: Resume food-first patterns; clotting factor status in healthy people remains adequate if diet includes greens.

Sourcing and Quality

  • Form: Look for vitamin K1 / phylloquinone / phytonadione on the label; do not confuse with MK-4 or MK-7 (vitamin K2), which are different molecules.

  • Dose accuracy: Prefer third-party tested brands (e.g., Thorne, Pure Encapsulations, NOW; USP, NSF, or ConsumerLab) because label miss rates occur in category testing.

  • Matrix: Oil-based softgels or formulas designed for fat-soluble vitamins aid absorption versus dry tablets taken fat-free.

  • Food sources: Frozen and fresh dark leafy greens remain the primary natural source; cooking oils (soybean, canola) contribute smaller amounts.

  • Avoid menadione (K3): Not appropriate for human supplementation; stick to K1/K2 vitamers.

  • Combination products: D3+K formulas are common; verify each component’s dose and that K form matches intent (K1 vs K2).

Practical Considerations

  • Time to effect: Carboxylation markers (e.g., undercarboxylated osteocalcin) improve within weeks; BMD or calcification imaging changes, if any, require many months to years.

  • Common pitfalls: Starting high-dose K1 while on warfarin without INR plans; taking K1 fat-free; assuming K1 and K2 are interchangeable for every endpoint; expecting large BMD gains from K1 alone.

  • Regulatory status: Dietary supplement and food nutrient in the U.S./EU; prescription phytonadione products exist for medical coagulation indications.

  • Cost and access: Inexpensive as a standalone microgram-dose softgel; greens are widely accessible; specialty tested combos cost more but remain far cheaper than prescription bone drugs.

  • Taste/format: Softgels are neutral; high-green diets are the main lifestyle “format” cost in meal planning.

Interaction with Foundational Habits

  • Sleep: No direct sleep disruption or promotion established for vitamin K1; indirect benefit only if overall diet quality improves.

  • Nutrition: Strongly potentiating with leafy-green and adequate-fat dietary patterns; K1 is itself a diet quality marker. Severe low-fat diets reduce absorption.

  • Exercise: No evidence that K1 blunts hypertrophy or endurance; bone-loading exercise remains primary for skeletal strength alongside nutrient sufficiency.

  • Stress management: No direct cortisol pathway effect established; vascular and bone benefits, if present, are not stress-hormone mediated in clinical data.

Monitoring Protocol & Defining Success

Before intentional high-dose supplementation—especially with bone or vascular goals—establish bleeding and clotting context (medication review for vitamin K antagonists), usual vegetable intake, and, when available, functional vitamin K markers. Circulating phylloquinone is highly meal-dependent and is a weaker chronic-status tool than undercarboxylated protein markers. Ongoing monitoring is light for healthy adults on food-level or low supplemental doses, and intensive if any vitamin K antagonist is involved (INR-driven schedules set by the prescribing clinician). Reassess bone-oriented labs and dual-energy X-ray absorptiometry (DXA) on the same cadence used for osteoporosis care (often every 1–2 years), not with weekly vitamin checks. Define success by stable safe use, improved carboxylation markers when measured, and maintained bone density appropriate to age—not by short-term energy changes.

Biomarker Optimal Functional Range Why Measure It? Context/Notes
ucOC or %ucOC Toward lower % after repletion; lab-specific Functional vitamin K status in bone ucOC = undercarboxylated osteocalcin; not standardized everywhere; trends beat single cutoffs
dp-ucMGP Lower values reflect better vessel vitamin K status Functional marker linked observationally to heart/vessel death dp-ucMGP = desphospho-uncarboxylated matrix Gla protein; specialty labs; not universal
Serum phylloquinone (vitamin K1) Often >0.5–1.0 nmol/L fasting in cohort analyses Direct circulating K1 Strongly affected by recent intake; fasting sample
INR (if on VKA) Target set by indication (e.g., 2–3) Detect K1–warfarin interaction INR = international normalized ratio; any K1 change requires repeat INR per clinician
25-hydroxyvitamin D Often 40–60 ng/mL in functional practice Co-factor context for bone protocols Conventional sufficiency often ≥20–30 ng/mL
DXA BMD (hip/spine) T-score goals individualized Hard skeletal outcome for bone-focused use DXA = dual-energy X-ray absorptiometry; every 1–2 years if treating low bone mass

Qualitative markers:

  • Consistency of leafy-green intake across the week
  • Absence of abnormal bruising/bleeding (or, on VKAs, absence of out-of-range INR symptoms)
  • Adherence with fat-containing meal timing for supplements
  • Fracture-free status and maintained height/posture over years (skeletal)

Success for a longevity-oriented user is usually defined as adequate carboxylation status, stable safe use relative to any anticoagulants, and maintenance of bone density appropriate to age and sex—not a short-term energy change.

Emerging Research

  • Knee osteoarthritis K1 trial: NCT06385275 is recruiting for vitamin K1 500 µg in knee osteoarthritis outcomes (phase 1/2; n≈55)—could extend K1 beyond classic bone density endpoints.

  • Dialysis calcification signals: The VitaVasK RCT (Saritas et al., 2022) of oral K1 in hemodialysis reported slower calcification progression; larger multicenter confirmation would strengthen or weaken chronic kidney disease (CKD)–specific use.

  • InterVitaminK and MK-7 programs: NCT05259046 (MK-7; active) will inform form-specific cardiovascular and bone effects and, by comparison, how much K1-only strategies can claim.

  • VITAL vitamin D–K bone ancillary: NCT04573946 examines vitamin D and vitamin K interrelationship on bone in a large trial platform—relevant to combination protocols.

  • Mendelian and status work: Larsson et al., 2018 used genetic instruments for circulating phylloquinone; refined dp-ucMGP studies may still clarify whether mortality associations are causal or confounded by diet quality.

Conclusion

Vitamin K1 is the main plant form of vitamin K and the standard medical form used to restore clotting proteins that depend on it. For health- and longevity-focused adults, the strongest case is meeting needs that fully support those proteins and, at higher food intakes, observational links with fewer fractures and lower overall death rates when blood levels are not low. Links with coronary disease are modest; controlled trials improve lab markers of vitamin K status more reliably than they change bone density or artery calcium in general populations.

The main practical risk is not organ damage—oral vitamin K1 has no established upper limit and is usually well tolerated—but interference with warfarin-type blood thinners. Outside that setting, food-first intake from leafy greens, with optional modest supplements often paired with vitamin D and calcium for bone goals, matches how leading nutrition sources frame use. Claims that vitamin K1 alone matches longer-acting vitamin K2 for every vessel outcome go beyond current randomized evidence; both forms turn on the same enzyme but differ in half-life and tissue reach.

Overall, the evidence is mature for clotting, intermediate for dietary K1 with fracture or mortality links, and still developing for imaging and hard clinical events. Uncertainty is highest where marketing is loudest: large, rapid longevity gains from K1 capsules in well-nourished adults. The molecule remains a rational part of a vegetable-rich, bone-conscious pattern, with care around interactions when vitamin K–blocking blood thinners are used.

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