{"ok":true,"entry":{"slug":"vitamin-k1","kind":"supplement","name":"vitamin K1","aliases":["phylloquinone","phytonadione"],"brands_sg":["California Gold Nutrition","Futurebiotics","Sports Research","Thorne","NOW Foods"],"class":"vitamin","tags":["heart","bone-joint"],"use_for":"vitamin k — k1 is the main dietary form, from greens","use_after":"with a meal — fat improves phylloquinone absorption","use_duration":null,"take_with":"food containing some fat","pros":["the main dietary form of vitamin k","no upper limit set — low potential for toxicity","free-form absorption is about 80%"],"cons":["serious interaction with warfarin and similar drugs","sg caps supplements at 0.12 mg vitamin k a day","bone and heart findings quoted here are for k2 forms"],"dose_note":"the adequate intake is 120 mcg for men and 90 mcg for women; singapore caps health supplements at 0.12 mg (120 mcg) a day and restricts vitamin k to multi-vitamin/mineral preparations for adults","dosage":{"ul":null,"unit":"mcg","fda_dv":120,"rda_ai":"120 mcg men · 90 mcg women (AI, not RDA)","ul_status":"none_established","population":"general adult","hsa_max_daily":"120 mcg (HSA states 0.12mg)"},"ul_status":"none_established","sg_class":null,"cautions":["on warfarin or a similar anticoagulant — medical advice first; sg requires that warning on the label","malabsorption conditions or bariatric surgery — vitamin k status may be low","sg restricts vitamin k to oral multi-vitamin/mineral preparations for adults"],"clashes":[{"src":["nih_ods_k_warfarin"],"note":"sudden changes in vitamin k intake can increase or decrease the anticoagulant effect","with":"warfarin and similar anticoagulants"}],"sources":[{"id":"nih_ods_k_intro","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Introduction","quote":"These compounds include phylloquinone (vitamin K1) and a series of menaquinones (vitamin K2). … Phylloquinone is present primarily in green leafy vegetables and is the main dietary form of vitamin K","accessed":"2026-08-27"},{"id":"nih_ods_k_absorb","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Introduction (absorption)","quote":"The absorption rate of phylloquinone in its free form is approximately 80%, but its absorption rate from foods is significantly lower. … Consuming vegetables at the same time as some fat improves phylloquinone absorption","accessed":"2026-08-27"},{"id":"nih_ods_k_ai","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Table 1 Adequate Intakes","quote":"19+ years | 120 mcg | 90 mcg","accessed":"2026-08-27"},{"id":"nih_ods_k_dv","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Sources of Vitamin K (Daily Value)","quote":"The DV for vitamin K is 120 mcg for adults and children age 4 years and older","accessed":"2026-08-27"},{"id":"nih_ods_k_ul","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Health Risks from Excessive Vitamin K","quote":"The FNB did not establish ULs for vitamin K because of its low potential for toxicity. … 'no adverse effects associated with vitamin K consumption from food or supplements have been reported in humans or animals'","accessed":"2026-08-27"},{"id":"nih_ods_k_warfarin","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Interactions with Medications (warfarin)","quote":"Vitamin K can have a serious and potentially dangerous interaction with anticoagulants such as warfarin (Coumadin) … sudden changes in vitamin K intakes can increase or decrease the anticoagulant effect","accessed":"2026-08-27"},{"id":"nih_ods_k_bone","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Osteoporosis","quote":"Some, but not all, studies also link higher vitamin K intakes with higher bone mineral density and/or lower hip fracture incidence. … MK-4 supplementation significantly reduced rates of hip fractures, vertebral fractures, and all nonvertebral fractures","accessed":"2026-08-27"},{"id":"nih_ods_k_heart","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Coronary heart disease","quote":"Participants in this study who had dietary menaquinone intakes in the mid tertile (21.6–32.7 mcg/day) and upper tertile (>32.7 mcg/day) also had a 27% and 57% lower risk of coronary heart disease mortality","accessed":"2026-08-27"},{"id":"nih_ods_k_risk","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Groups at Risk of Vitamin K Inadequacy","quote":"People with malabsorption disorders (cystic fibrosis, celiac disease, ulcerative colitis, short bowel syndrome) … Patients who have undergone bariatric surgery","accessed":"2026-08-27"},{"id":"nih_ods_k_forms","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), Dietary supplements","quote":"Several forms of vitamin K are used in dietary supplements, including vitamin K1 as phylloquinone or phytonadione (a synthetic form of vitamin K1) and vitamin K2 as MK-4 or MK-7","accessed":"2026-08-27"},{"id":"hsa_hs_limits_k","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines GL-CHPB-3-001 Rev. 020 (January 2026), clause 4.8 and Table 4 Vitamins Limits","quote":"HS for use by the general adult population should not contain vitamins and minerals exceeding the stipulated limits stated in Tables 4 and 5. … Vitamin K1 / K2  0.12mg","accessed":"2026-08-27"},{"id":"hsa_prohibited_k","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in HS and TM (Oct 2025), Annex B row 116 (restriction and maximum daily dose)","quote":"116. Vitamin K1, Vitamin K2 — Restricted use in HS and TM. Restricted to oral dosage forms of multi-vitamin/mineral preparations for adults … should not provide more than 0.12mg","accessed":"2026-08-27"},{"id":"hsa_prohibited_k_warn","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in HS and TM (Oct 2025), Annex B row 116 cautionary statement","quote":"Cautionary Statement … 'This product contains vitamin K. Consult a healthcare professional prior to use if you are taking a blood thinner such as warfarin.'","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/vitamin-k","label":"iHerb Singapore — 'Vitamin K' category page, default order, 226 results","quote":"Vitamin K … 1 - 48 of 226 results … California Gold Nutrition … Futurebiotics … Sports Research … Thorne … NOW Foods","accessed":"2026-08-27"}],"brand_certs":[{"brand":"Sports Research","example":null,"programme":"NSF Certified for Sport","matching_products":0,"brand_total_certified":2},{"brand":"Thorne","example":null,"programme":"NSF Certified for Sport","matching_products":0,"brand_total_certified":66}],"updated_at":"2026-08-30T17:59:38.376296+08:00"},"disclaimer":"kozen-x is not a medical device and does not give medical advice. it lists what published sources have written down. absence of a record is not the same as safe."}