What are the benefits of vitamin K2? Evidence, claims & uses

How it works

Vitamin K2 is a fat-soluble vitamin that belongs to the vitamin K family, which also includes vitamin K1. While vitamin K1 (phylloquinone) is primarily found in leafy green vegetables, vitamin K2 (menaquinones) is present in some animal-derived foods and fermented products, such as natto, certain cheeses, egg yolk, and some meats. The main forms of vitamin K2 in the diet are MK-4 and MK-7, though other menaquinones (MK-5 through MK-13) exist in smaller amounts.

Vitamin K2 is essential for the activation of specific proteins through a process called carboxylation. These proteins are involved in two key physiological processes: blood clotting and bone metabolism. In the liver, vitamin K2 helps activate clotting factors that are necessary for normal blood coagulation, reducing the risk of excessive bleeding. In bones and other tissues, vitamin K2 activates osteocalcin, a protein that binds calcium to the bone matrix, contributing to the maintenance of normal bone structure.

The absorption and transport of vitamin K2 differ from vitamin K1. Vitamin K2 is absorbed in the small intestine and transported in the bloodstream by lipoproteins. Its fat-soluble nature means that dietary fat enhances its absorption. The different forms of vitamin K2 also have varying half-lives in the body, with MK-7 remaining in circulation longer than MK-4, which may influence its biological effects.

Vitamin K2 contributes to normal blood clotting and the maintenance of normal bones, according to authorised health claims.

What the research and authorised claims say

The European Food Safety Authority (EFSA) has evaluated the scientific evidence for vitamin K and authorised two health claims for products that are at least a source of vitamin K:

• Vitamin K contributes to normal blood clotting.
• Vitamin K contributes to the maintenance of normal bones.

These claims apply to both vitamin K1 and K2, provided the product contains at least 15% of the nutrient reference value (NRV) per serving. The NRV for vitamin K in the EU is 75 µg per day for adults, so a product must provide at least 11. 25 µg per serving to use these claims.

Vitamin K2's role in blood clotting is well established. It is required for the synthesis of several proteins involved in the coagulation cascade, including prothrombin and factors VII, IX, and X. Without sufficient vitamin K2, these proteins remain inactive, which can impair the body's ability to form clots when needed.

For bone health, vitamin K2 activates osteocalcin, a protein produced by osteoblasts (bone-forming cells). Activated osteocalcin binds calcium and helps incorporate it into the bone matrix, supporting bone mineral density and structure. This mechanism underlies the authorised claim that vitamin K contributes to the maintenance of normal bones.

While there is ongoing research into additional roles for vitamin K2, such as cardiovascular and metabolic health, only the above claims are currently authorised for use in the European Union.

Comparison of Vitamin K Forms in Tigoo's Range

Form	Number of Products	Typical Dose (µg)	Common Sources
MK-7 (Menaquinone-7)	50	100	Natto, supplements
Menakinon (unspecified)	9	100	Supplements
Other K2 forms	100	Varies	Fermented foods, supplements

Of the 159 vitamin K2 products in Tigoo's range, MK-7 is the most common form, with a median dose of 100 µg per serving. MK-7 is often preferred in supplements due to its longer half-life in the body compared to other forms. Some products contain unspecified menaquinones or blends of different K2 forms, and the dose can vary depending on the intended use and formulation.

MK-7 is the most common form of vitamin K2 in Tigoo's range, typically provided at 100 µg per serving.

Some studies suggest that vitamin K2, especially MK-7, may be more effective at reaching extrahepatic tissues (such as bone) than vitamin K1, but this is still under investigation and is not reflected in current authorised claims.

Key limitations

While research has explored additional roles for vitamin K2, such as cardiovascular health, cognitive function, and metabolic outcomes, only the claims related to normal blood clotting and maintenance of normal bones are authorised for use in the European Union.

The evidence base for other potential effects of vitamin K2 is still developing. For example, some studies have examined the relationship between vitamin K2 intake and markers of arterial health, but these findings have not led to authorised health claims. Similarly, while observational research has linked higher vitamin K2 intake to certain health outcomes, these associations do not establish causality and are not sufficient for regulatory approval of additional claims.

Another limitation is the variability in individual response to vitamin K2 supplementation. Factors such as age, genetics, baseline nutritional status, and concurrent intake of other fat-soluble vitamins (like vitamin D) can influence how the body utilises vitamin K2. The optimal dose and form for different individuals or populations are not fully established, and more research is needed to clarify these aspects.

Finally, it is important to recognise that vitamin K2 supplements are not a substitute for a balanced diet or medical treatment.

How to choose

When selecting a vitamin K2 supplement, several factors should be considered to ensure safety, efficacy, and suitability for your individual needs:

• Form: MK-7 (menaquinone-7) is the most common and well-studied form in supplements. It is derived mainly from bacterial fermentation (such as natto) and is favoured for its longer half-life in the body, which may allow for once-daily dosing. MK-4 (menaquinone-4), found in some animal foods, is also available in supplements but is less common in Tigoo's range.
• Dosage: The median dose in Tigoo's range is 100 µg per serving. To qualify for the authorised health claims, a product must provide at least 15% of the NRV (11. 25 µg per serving). Some products offer higher doses, but higher intake is not necessarily better and should be matched to individual needs and professional guidance.
• Combination with other nutrients: Many vitamin K2 supplements are combined with vitamin D3, calcium, or magnesium. However, the specific benefits of combinations are not covered by authorised claims, so always check the label for exact amounts and forms.
• Dietary preferences: Some vitamin K2 supplements are suitable for vegetarians or vegans, especially those derived from fermented plant sources like natto. Others may be sourced from animal products or use animal-derived capsules. Always check for dietary suitability if this is important to you.
• Quality and certification: Look for products that are tested for purity, potency, and contaminants. Certifications such as GMP (Good Manufacturing Practice) or third-party testing can provide additional assurance of quality.
• Formulation and delivery: Vitamin K2 is fat-soluble, so supplements in oil-based capsules or softgels may enhance absorption. Some tablets or powders may require co-ingestion with a meal containing fat for optimal uptake.

It is also helpful to consider the reputation of the manufacturer and to read product reviews or consult healthcare professionals for recommendations.

Food Sources of Vitamin K2

Food	Approximate K2 Content (µg/100g)	Type of K2
Natto (fermented soybeans)	800–1000	MK-7
Hard cheeses	50–100	MK-8, MK-9
Egg yolk	15	MK-4
Chicken	10	MK-4

Vitamin K2 intake from food varies widely by diet. Fermented foods like natto are particularly rich sources, while animal products such as egg yolk and chicken provide smaller amounts. Cheese, especially hard and aged varieties, can also be a significant source of certain menaquinones, depending on the bacterial cultures used in fermentation. In Western diets, overall intake of vitamin K2 is often lower than in traditional Japanese diets, where natto is commonly consumed.

The bioavailability of vitamin K2 from food can be influenced by factors such as food matrix, fat content, and preparation methods. For example, consuming K2-rich foods with dietary fat can enhance absorption. Individuals following plant-based diets may have lower K2 intake unless they consume fermented plant foods like natto or choose fortified products.

Safety, interactions and risk groups

Vitamin K2 is generally considered safe when consumed in amounts found in food and supplements that do not exceed recommended intakes. Adverse effects are rare, and there is currently no established tolerable upper intake level (UL) for vitamin K2 in the EU. However, certain groups should exercise caution:

• People taking anticoagulant medications (e. g. , warfarin): Vitamin K can interfere with the action of these medicines by promoting clotting factor activation. Even small changes in vitamin K intake can affect the effectiveness of anticoagulant therapy. Always consult a healthcare professional before starting a vitamin K supplement if you are on medication.
• Pregnant or breastfeeding women: Safety data for high-dose supplementation is limited. While dietary intake is considered safe, supplementation should only be undertaken with medical advice.
• Children: Supplement use in children should only occur under medical supervision, as their requirements and safety profiles may differ from adults.
• Allergies and sensitivities: Some supplements may contain allergens such as soy (from natto-derived K2), dairy, or animal-derived gelatin. Check product labels for potential allergens or animal-derived ingredients.
• People with malabsorption syndromes: Conditions that impair fat absorption (such as celiac disease, cystic fibrosis, or chronic pancreatitis) may reduce vitamin K2 uptake and increase the risk of deficiency. These individuals should seek medical advice regarding supplementation.

If you have any medical condition, are taking medication, are pregnant, or are considering giving supplements to children, always seek advice from a qualified healthcare professional before use.

There are no known significant interactions between vitamin K2 and most foods or nutrients at normal intake levels. However, very high doses of vitamin E may interfere with vitamin K metabolism, though this is rarely an issue at typical dietary or supplement doses.

Vitamin K2 supplements should be stored away from heat, light, and moisture to preserve potency, as the vitamin can degrade over time if not properly protected.