{"ok":true,"entry":{"slug":"vitamin-k2","kind":"supplement","name":"vitamin k2","aliases":["menaquinone","MK-7","MK-4","vitamin K"],"brands_sg":["California Gold Nutrition","Futurebiotics","Sports Research","Thorne","NOW Foods"],"class":"vitamin","tags":["bone-joint","heart"],"use_for":"coenzyme for clotting and bone-metabolism proteins","use_after":"no timing rule","use_duration":null,"take_with":"fat-soluble · absorbed like dietary fat, via bile","pros":["no ul — fnb found no reported adverse effects","one rct: mk-7 180 mcg/day × 3 y improved bone strength","meta-analysis: higher lumbar-spine bmd after menopause"],"cons":["on warfarin? a serious clash — steady intake matters","artery calcification / heart evidence still unclear","sg: k capped at 0.12 mg, in multi-vitamin products only"],"dose_note":"ai 120 mcg (men) / 90 mcg (women) — no rda, and no ul; multis usually give under 75% of the 120 mcg dv, while stand-alone products go up to 4,050 mcg; bone trials used mk-4 45 mg/day (a pharmacological dose used in japan) or mk-7 180 mcg/day; the 2022 meta-analysis pooled 16 rcts and found better lumbar-spine bmd but no overall fracture difference; hsa caps vitamin k1/k2 in singapore health supplements at 0.12 mg (120 mcg) a day, in multi-vitamin/mineral products only","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},"ul_status":"none_established","sg_class":null,"cautions":["on warfarin or a similar blood thinner — sudden changes in vitamin k intake alter the drug's effect; hsa's label statement says to consult a healthcare professional first","malabsorption (celiac, ulcerative colitis, cystic fibrosis, short bowel) or past bariatric surgery — vitamin k status may be low; worth a doctor's check","chronic kidney disease — calcification research is ongoing and unsettled; ask your doctor first"],"clashes":[{"src":["nih_ods_k_warfarin"],"note":"serious, potentially dangerous — the drugs antagonise vitamin k; steady intake from food and supplements matters","with":"warfarin (coumadin) and similar anticoagulants"},{"src":["nih_ods_k_drugs"],"note":"can destroy vitamin k-producing gut bacteria; supplements usually not needed unless use is prolonged with poor intake","with":"antibiotics (esp. cephalosporins such as cefoperazone)"},{"src":["nih_ods_k_drugs"],"note":"can reduce vitamin k absorption; clinical significance unclear","with":"bile acid sequestrants (cholestyramine, colestipol)"},{"src":["nih_ods_k_drugs"],"note":"reduces fat-soluble vitamin absorption; with warfarin may raise prothrombin time","with":"orlistat (xenical, alli)"}],"sources":[{"id":"nih_ods_k_intro","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), updated March 29, 2021 — Introduction","quote":"These compounds include phylloquinone (vitamin K1) and a series of menaquinones (vitamin K2) … Vitamin K functions as a coenzyme for vitamin K-dependent carboxylase, an enzyme required for the synthesis of proteins involved in hemostasis (blood clotting) and bone metabolism","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), updated March 29, 2021 — Introduction (absorption)","quote":"Like dietary lipids and other fat-soluble vitamins, ingested vitamin K is incorporated into mixed micelles via the action of bile and pancreatic enzymes, and it is absorbed by enterocytes of the small intestine","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), updated March 29, 2021 — Table 1 Adequate Intakes + DV note","quote":"Insufficient data were available to establish an EAR for vitamin K, so the FNB established AIs … Table 1: Adequate Intakes (AIs) for Vitamin K … 19+ years 120 mcg 90 mcg … The DV for vitamin K is 120 mcg for adults","accessed":"2026-08-27"},{"id":"nih_ods_k_supp","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), updated March 29, 2021 — Dietary supplements","quote":"Vitamin K is present in most multivitamin/mineral supplements, typically at values less than 75% of the DV … some providing 4,050 mcg … both phytonadione and MK-7 supplements are well absorbed, but MK-7 has a longer half-life","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), updated March 29, 2021 — Groups at risk","quote":"People with malabsorption syndromes and other gastrointestinal disorders, such as cystic fibrosis, celiac disease, ulcerative colitis, and short bowel syndrome, might not absorb vitamin K properly … Vitamin K status can also be low in patients who have undergone bariatric surgery","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), updated March 29, 2021 — Osteoporosis","quote":"it is unclear whether supplementation with any form of vitamin K reduces the risk of osteoporosis … MK-4 at either 15 mg/day (1 trial) or 45 mg/day (6 trials) … MK-7 supplementation (180 mcg/day for 3 years) improved bone strength","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), updated March 29, 2021 — Coronary heart disease","quote":"the role of the different forms of vitamin K on arterial calcification and the risk of coronary heart disease is unclear … in the general population and in patients with chronic kidney disease","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), updated March 29, 2021 — 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), updated March 29, 2021 — Interactions: warfarin","quote":"Vitamin K can have a serious and potentially dangerous interaction with anticoagulants such as warfarin (Coumadin) … maintain a consistent intake of vitamin K … because sudden changes in vitamin K intakes can increase or decrease the anticoagulant effect","accessed":"2026-08-27"},{"id":"nih_ods_k_drugs","url":"https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/","label":"NIH ODS — Vitamin K (Health Professional), updated March 29, 2021 — Interactions: antibiotics, bile acid sequestrants, orlistat","quote":"Antibiotics can destroy vitamin K-producing bacteria in the gut … cholestyramine (Questran) and colestipol (Colestid) … can also reduce the absorption of vitamin K … Combining orlistat with warfarin therapy might cause a significant increase in prothrombin time","accessed":"2026-08-27"},{"id":"ma2022","url":"https://europepmc.org/article/PMC/PMC9403798","label":"Efficacy of vitamin K2 in the prevention and treatment of postmenopausal osteoporosis: systematic review and meta-analysis of RCTs (Ma et al., Front Public Health 2022)","quote":"Sixteen RCTs with a total of 6,425 subjects … a significant improvement in lumbar spine BMD (BMD LS) (P = 0.006) with VK2 … no significant difference in fracture incidence between the two groups (RR=0.96, P=0.65)","accessed":"2026-08-27"},{"id":"hsa_hs_guidelines","url":"https://file.go.gov.sg/hsa-hs-guidelines.pdf","label":"HSA Singapore — Health Supplements Guidelines GL-CHPB-3-001 Rev. No. 020 (January 2026), s4.8 general-adult limits, Table 4 Vitamins Limits + List of Health Claims row 99","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 … Table 4: Vitamins Limits … Vitamin K1 / K2 0.12mg … Maintain/support bone health … Vitamin D, K","accessed":"2026-08-27"},{"id":"hsa_prohibited_2025","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev. 001 (October 2025), Annex A rows 116–117","quote":"116. Vitamin K1, Vitamin K2 Restricted use in HS and TM Restricted to oral dosage forms of multi-vitamin/mineral preparations for adults … maximum recommended daily dose should not provide more than 0.12mg … 117. Vitamin K3 (menadione) Prohibited in HS and TM","accessed":"2026-08-27"},{"id":"hsa_prohibited_2025_caution","url":"https://file.go.gov.sg/hsa-chp-prohibited-restricted-ing-guidelines.pdf","label":"HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev. 001 (October 2025), Annex A row 116 cautionary statement","quote":"Cautionary Statement The following statement should be included: “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":"fda_dv","url":"https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels","label":"FDA — Daily Value on the Nutrition and Supplement Facts Labels (Reference Guide: Daily Values for Nutrients), content current as of 03/05/2024","quote":"Vitamin K 120mcg … DVs are the recommended amounts of nutrients to consume or not to exceed each day","accessed":"2026-08-27"},{"id":"iherb_sg","url":"https://sg.iherb.com/c/vitamin-k","label":"iHerb Singapore — Vitamin K category page (default order), first listings","quote":"1 - 48 of 226 results … California Gold Nutrition, Vitamin D3 + K2 as MK-7 … Futurebiotics, Vitamin K2 + D3 … Sports Research, D3 + K2 … Thorne, Vitamin D + K2 … NOW Foods, MK-7 Vitamin K-2, 100 mcg","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."}