Vitamin K1 And K2
Also known as: Vitamin K1, Phylloquinone, Vitamin K2, Menaquinone, MK-4, MK-7, MK-8, MK-9, MK-10, MK-11, MK-12, MK-13, Phylloquinone and Menaquinone
Overview
Vitamin K encompasses a group of fat-soluble vitamins essential for blood clotting, bone health, and cardiovascular function. Phylloquinone (Vitamin K1) is primarily involved in coagulation and is abundant in leafy green vegetables and vegetable oils. Menaquinones (Vitamin K2), including subtypes like MK-4 and MK-7, play a crucial role in calcium metabolism, directing calcium to bones and preventing arterial calcification. K2 is found in fermented foods and animal products. While K1's benefits are mainly related to blood clotting, K2, particularly MK-7, has shown promise in maintaining bone mineral density and potentially reducing cardiovascular risk. Supplementation with Vitamin K2, especially MK-7, is increasingly recognized for its potential to support bone health, particularly when combined with Vitamin D3 and calcium. Research suggests that K2 has a longer half-life in the body compared to K1, potentially leading to more sustained benefits.
Benefits
Vitamin K offers several potential health benefits, primarily related to bone and cardiovascular health. Vitamin K2 (specifically MK-4 and MK-7) has demonstrated the ability to maintain or increase lumbar spine bone mineral density (BMD), with studies showing a mean difference of 1.02 to 1.97 (95% CI 0.30–3.74, P ≤ 0.03). Vitamin K1 primarily supports coagulation. Some studies suggest that K2 may reduce arterial stiffness, although meta-analyses have shown inconsistent effects on blood pressure and C-reactive protein (CRP). Vitamin K1 has not demonstrated significant cardiovascular benefits. The combination of K2 with calcium and Vitamin D3 may further improve BMD. Observational data suggests that low vitamin K intake correlates with an increased risk of hip fractures.
How it works
Vitamin K's mechanism of action revolves around activating proteins involved in blood clotting, calcium metabolism, and vascular health. Specifically, Vitamin K2 carboxylates osteocalcin, a protein that binds calcium to the bone matrix, thereby promoting bone mineralization. Additionally, K2 activates matrix Gla protein (MGP), which inhibits vascular calcification by binding calcium in the arteries. The bioavailability of different forms of Vitamin K varies; MK-7 has a longer half-life (approximately 72 hours) compared to K1 (approximately 1.5 hours), potentially leading to more sustained effects. Vitamin D3 enhances osteocalcin synthesis, working synergistically with Vitamin K2 to support bone health.
Side effects
Vitamin K is generally considered safe at recommended doses. Common side effects are rare, with no adverse effects reported at doses up to 45mg/day for K1 or up to 360μg/day for MK-7. Allergic reactions are very rare, occurring in less than 0.1% of users. However, Vitamin K can interact with certain medications, particularly warfarin, an anticoagulant. Vitamin K can antagonize the effects of warfarin, requiring careful monitoring and stable Vitamin K intake for individuals on anticoagulant therapy. Vitamin K supplementation is contraindicated for individuals on anticoagulant therapy without medical supervision. It is crucial to maintain consistent Vitamin K intake to avoid fluctuations in anticoagulant effectiveness. Individuals taking blood thinners should consult their healthcare provider before starting Vitamin K supplementation.
Dosage
The recommended daily intake of Vitamin K1 is 70–120μg. For Vitamin K2 (MK-7), a dosage of 90–180μg per day is typically recommended for bone health. Vitamin K supplements should be taken with fat-containing meals to enhance absorption. Vitamin D3 can be taken as a cofactor to enhance osteocalcin synthesis. While specific upper limits for Vitamin K2 are not well-established, it is generally advised to adhere to recommended dosages to minimize potential risks. Individuals on warfarin or other anticoagulants should consult their healthcare provider to determine a safe and appropriate dosage, as Vitamin K can interfere with these medications.
FAQs
Which is better for bones, K1 or K2?
Meta-analyses suggest that Vitamin K2 (specifically MK-7) has superior effects on bone mineral density compared to Vitamin K1. Therefore, K2 is generally preferred for bone health.
How long does it take to see results from Vitamin K supplementation?
Changes in bone mineral density typically require at least 6–12 months of consistent Vitamin K supplementation. It's important to maintain a regular intake and monitor progress over time.
Is Vitamin K safe to take with blood thinners?
Vitamin K can interact with blood thinners like warfarin. If you are taking blood thinners, consult your doctor before taking Vitamin K supplements, as it requires medical supervision.
What foods are high in Vitamin K?
Vitamin K1 is abundant in leafy green vegetables like spinach and kale. Vitamin K2 is found in fermented foods like natto and some animal products, such as cheese and egg yolks.
Research Sources
- https://pmc.ncbi.nlm.nih.gov/articles/PMC11631259/ – This 2024 meta-analysis of 17 RCTs found that Vitamin K2 maintains lumbar bone mineral density (BMD) with a mean difference of 1.02 (P=0.006). However, the study noted heterogeneity in K2 subtypes and doses, and did not find consistent cardiovascular benefits. The overall quality of the meta-analysis was considered moderate due to subgroup heterogeneity.
- https://pubmed.ncbi.nlm.nih.gov/38282652/ – A 2022 meta-analysis of 10 RCTs indicated that Vitamin K2, when combined with calcium and Vitamin D3, improves bone mineral density (MD=1.97, P=0.03). The study acknowledged limitations due to small sample sizes (30–500 participants) in the included trials. Despite these limitations, sensitivity analysis confirmed the robustness of the findings, suggesting a high-quality result.
- https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/410550 – This Cochrane-adjacent review from 2018 found a correlation between low vitamin K intake and an increased risk of hip fracture (OR=1.45–2.17). The review noted that the available data was predominantly observational, limiting the strength of the conclusions. The overall quality of the evidence was considered moderate due to the limited availability of RCT evidence.
- https://www.cambridge.org/core/journals/journal-of-nutritional-science/article/effect-of-vitamin-k-supplementation-on-cardiovascular-risk-factors-a-systematic-review-and-metaanalysis/0F16EF6952E35875EE28AC0DA5974B5E – This systematic review and meta-analysis investigates the effect of vitamin K supplementation on cardiovascular risk factors. It provides a comprehensive overview of the current evidence regarding the potential cardiovascular benefits of vitamin K supplementation, contributing to a better understanding of its role in cardiovascular health.
- https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2022.979649/full – This article discusses the importance of vitamin K in public health, highlighting its roles in bone health, cardiovascular function, and blood coagulation. It emphasizes the need for adequate vitamin K intake to maintain overall health and prevent related diseases, providing valuable insights for public health strategies.
Recommended Articles
Herbal Boosters & COVID-19 Antivirals: Safe Mix?
Herbal supplements may interact with COVID-19 antivirals, requiring careful consideration and further research.
2025's Top Vegan Protein Powders: A Buyer's Guide
In 2025, the best vegan protein powders are third-party tested, ensuring purity, safety, and high nutritional content.
Immune Supplements & Pregnancy Safety 2025
The safety of immune-boosting supplements during pregnancy in 2025 hinges on supplement type, dosage, and health conditions.
Top Immune Support Ingredients: What Works?
Vitamin D, zinc, and echinacea are key ingredients in immune support supplements, backed by scientific evidence.