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Vitamin K2 and Plant-Based Diets: What You Need to Know

Why Is Vitamin K2 Important?


Vitamin K2 is crucial for bone metabolism alongside vitamin D3 and calcium.


Vitamin K2 (menaquinones, particularly MK-4, MK-7, MK-9) is found in fermented foods like cheese and in free range egg yolks.


Vitamin K2 plays a key role in activating proteins that regulate calcium in the body. Specifically, it helps prevent calcium from accumulating in blood vessels (reducing the risk of arterial calcification) while directing it into bones and teeth to maintain strength.


Multiple studies have highlighted concerns about vegan diets in relation to lower bone mineral density and a higher risk of fractures, likely due to a lower intake of calcium from dairy products, among other nutrients like vitamin K2 that support bone health.


Lower intake of calcium, vitamin D3, and vitamin K2 increases the risk of osteoporosis, so vegans are advised to consume fortified plant-based alternatives or top up with supplements to maintain healthy bone density.


Sources of Vitamin K2


While vitamin K1 (phylloquinone) is abundant in leafy green vegetables, vitamin K2 (menaquinone) is found primarily in animal-derived foods like dairy, eggs, and fermented products.


The primary sources of vitamin K2 in a plant-based diet include:

  • Natto (fermented soybeans): The best plant-based source of K2 (MK-7 form), providing a highly bioavailable amount.
  • Other fermented foods (kimchi, sauerkraut, tempeh, miso): These contain some K2, but in significantly lower amounts than natto.
  • Gut bacteria: The human gut microbiota can produce some vitamin K2, but its contribution to overall vitamin K2 status is not well-established and varies among individuals.


Can Vitamin K1 Be Converted to K2?


The body can convert vitamin K1 to K2, but the efficiency of this process is low. Some studies suggest the conversion is minimal, which could mean a higher reliance on dietary K2 sources. However, consuming plenty of leafy greens (rich in K1) may still provide some benefit.


Who may need to supplement with Vitamin K2?
While supplementation is not essential for all individuals following a plant-based diet, some groups may benefit, including:

  • Bone and heart health concerns: Those at risk for osteoporosis or cardiovascular disease may benefit from supplementation.
  • Gut dysbiosis: Imbalance in intestinal flora as well as issues regarding in vivo absorption and/or metabolism may have higher risk for deficiency
  • Lack of sufficient dietary sources: If not consuming natto regularly, supplementation (typically with MK-7 derived from bacterial fermentation) may be a practical option.
  • Imbalanced whole-food diet: A plant-based diet with limited sources of vitamin K1 and fermented foods may increase the risk of deficiency.


If you or your client feel they may be lacking vitamin K2 in their diet or experiencing symptoms of a deficiency, they should speak with their medical provider about getting a vitamin K2 blood test.


If you don’t eat natto or fermented foods regularly, a supplement (MK-7 form) may be beneficial, especially for bone and cardiovascular health.


MK-7 (menaquinone-7) is a long-chain form of vitamin K2 that is more bioavailable and longer-lasting in the body compared to other forms like MK-4. It is primarily found in fermented foods, especially natto (fermented soybeans). Natto contains over 1,000 μg per 100g of MK-7.


Why MK-7 is Preferred Over MK-4

  • Longer Half-Life – MK-7 stays in the bloodstream for up to 72 hours, while MK-4 is cleared within a few hours.
  • Better Absorption – The body absorbs MK-7 more efficiently, meaning lower doses can be effective.
  • Stronger Bone and Heart Benefits – MK-7 is particularly effective in activating osteocalcin (for bone health) and matrix Gla-protein (for arterial health).


Why Should Vitamin D3 Be Paired with Vitamin K2?
Vitamin D3 and K2 work synergistically to regulate calcium metabolism in the body. Taking D3 alone without K2 may lead to improper calcium distribution, increasing the risk of arterial calcification rather than strengthening bones.


Key reasons to pair D3 with K2 include:


  1. Calcium regulation:
  • D3 increases calcium absorption in the gut.
  • K2 ensures calcium is directed to bones and teeth rather than arteries and soft tissues.
  1. Limits arterial calcification: Without sufficient K2, excess calcium absorbed from high-dose D3 may deposit in arteries rather than bones, increasing cardiovascular risk.
  2. Supports bone health:
  • D3 stimulates osteocalcin production (a protein that binds calcium).
  • K2 activates osteocalcin, helping calcium integrate into bones instead of blood vessels.


Optimal Ratio of Vitamin D3 to K2


There is no strict one-size-fits-all ratio, but common recommendations suggest:

  • 100 to 200 mcg of K2 (MK-7) per 5,000 IU of D3
  • If taking lower doses of D3 (e.g., 1,000 to 2,000 IU), aim for about 50 to 100 mcg of K2


This ratio may help support calcium balance while avoiding potential risks.


References:

Updated on: 26/10/2026

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