Which gut bacteria produce vitamin K2?

Over half of all studied bacteria contain menaquinone, also known as vitamin K2, which is essential for blood clotting, bone health, and cardiovascular function. While dietary intake from fermented foods is a major source, our gut microbiome plays a vital role, with several species of gut bacteria producing vitamin K2 endogenously. This article details the specific microbes and isoforms responsible for this production.

Quick Summary

Several key genera of gut bacteria, including Bacteroides, Escherichia coli, and Lactobacillus, produce different forms of vitamin K2 (menaquinones). Although synthesized in the large intestine, the bioavailability of this bacterially produced vitamin can be limited, making diet a primary source for functionally available K2. Factors like diet, antibiotics, and overall health status influence gut bacterial composition and, therefore, K2 synthesis.

Key Points

• Key Bacterial Producers: Major gut bacteria producing vitamin K2 include Bacteroides (MK-10/11), Escherichia coli (MK-8), and species from Lactobacillus and Bifidobacterium.

• Endogenous Production is Limited: While your gut bacteria produce K2, the amount and location of synthesis often mean dietary intake is essential for meeting full nutritional needs due to poor absorption in the colon.

• Impact of Diet and Health: Diet plays a critical role in supporting K2-producing gut bacteria; a high-fiber diet fosters a healthy microbiome, while poor diets and antibiotic use can disrupt it.

• Better Bioavailability from Diet: Vitamin K2 derived from fermented foods like natto (MK-7) and certain dairy products generally has higher bioavailability and longer half-life compared to endogenous production.

• Improve Gut Health for K2: Supporting your gut bacteria with fermented foods and prebiotic fiber can help enhance your body's natural capacity to synthesize vitamin K2.

• Importance Beyond Coagulation: Gut-produced K2 offers health benefits beyond just blood clotting, impacting bone density and cardiovascular health.

Understanding Menaquinones: The Bacterial Form of Vitamin K2

Vitamin K2 isn't a single molecule, but a family of related compounds called menaquinones (MK-n). These variations are predominantly synthesized by bacteria. Gut-produced vitamin K2 is absorbed primarily in the distal small bowel and colon. Vitamin K2 plays crucial roles in extrahepatic processes like cardiovascular and bone health.

Key Bacterial Producers of Vitamin K2 in the Gut

Several key genera and species of bacteria in the human gut microbiome produce menaquinones. These include Bacteroides species (longer-chain menaquinones like MK-10 and MK-11) and Escherichia coli (primarily the MK-8 isoform). Lactic acid bacteria (Lactobacillus and Lactococcus) and Bifidobacterium species are also known producers. Other producers include Eubacterium lentum (MK-6) and Veillonella (MK-7).

Factors Influencing Gut Production and Availability

Factors such as diet, antibiotic use, health status, and bile salts can affect gut bacteria's K2 production and absorption.

Comparing Gut vs. Dietary Vitamin K2 Sources

Feature	Gut Bacterial Production	Dietary Sources (e.g., Fermented Foods)
Primary Location	Large intestine	Food processing and fermentation
Key Bacteria	Bacteroides, E. coli, Lactobacillus, Bifidobacterium	Bacillus subtilis (natto), Lactic Acid Bacteria (cheese)
MK Isoforms	Often longer-chain varieties (MK-8, MK-10)	Both short-chain (MK-4 from animals) and long-chain (MK-7 from natto)
Bioavailability	Variable and often limited due to production site	Generally high, especially for longer-chain menaquinones like MK-7
Consistency of Supply	Dependent on dynamic gut microbiome composition	More reliable with consistent intake of K2-rich foods
Supplementation	Not easily manipulated directly	Commonly supplemented with specific, bioavailable MK isoforms like MK-7

Improving Your Gut's K2 Production

Supporting your gut microbiome can enhance its natural production capacity. This can include consuming a varied, high-fiber diet, including fermented foods, managing antibiotic use, pairing fats with vitamin K sources, and considering targeted probiotics.

Conclusion

Key gut bacteria such as Bacteroides, Escherichia coli, and lactic acid bacteria produce vitamin K2. While this contributes to overall K2 supply, limited bioavailability often makes diet and supplements essential. Understanding these microbes and factors influencing them helps in supporting the microbiome's capacity to synthesize this vital nutrient for bone, cardiovascular, and overall health.

References

IntechOpen. (2017). Menaquinones, Bacteria, and Foods: Vitamin K2 in the Diet. Open access book, IntechOpen. Smajdor, J., et al. (2023). The impact of gut bacteria producing long chain homologs of vitamin K2 on colorectal carcinogenesis. Cancer Cell International, 10638769. IntechOpen. (2017). Menaquinones, Bacteria, and Foods: Vitamin K2 in the Diet. Open access book, IntechOpen. ResearchGate. (2017). Menaquinones, Bacteria, and Foods: Vitamin K2 in the Diet. ResearchGate. ScienceDirect.com. (2019). Culturable gut bacteria lack Escherichia coli in children with.... ScienceDirect.com. PubMed. (2023). Neuroprotective effect of Vitamin K2 against gut dysbiosis.... National Institutes of Health. ScienceDirect.com. (2024). Review: Bacterially produced vitamin K2 and its potential to.... ScienceDirect.com. Medical News Today. (2023). Vitamin K-2: Functions, sources, benefits, and deficiency.... Medical News Today. Consensus. (2016). Top foods high in Vitamin K2. Consensus Academic Search Engine. Role of gut microbiome in vitamin K2 synthesis. {Link: Consensus consensus.app/search/role-of-gut-microbiome-in-vitamin-k2-synthesis/s2yqaya0RDC5-bML1bgbMQ/}. Feel Gut. (2025). How the gut microbiome helps our body to synthesise vitamins.... Feel Gut Blog. Super Synbiotics. (n.d.). Why you need vitamin K – and the importance of the gut flora. Super Synbiotics. Microbial Cell Factories. (2019). Long-chain vitamin K2 production in Lactococcus lactis is influenced.... Biomed Central. The Relationship Among Intestinal Bacteria, Vitamin K and.... {Link: Frontiers frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.829304/full}.

Frequently Asked Questions

Which specific strains of gut bacteria produce vitamin K2?

Several strains produce vitamin K2, including certain species of Bacteroides (producing MK-10 and MK-11), Escherichia coli (producing MK-8), and members of the Lactobacillus and Bifidobacterium genera.

Is the vitamin K2 produced by gut bacteria enough for my needs?

No, the amount of vitamin K2 produced by gut bacteria is often not sufficient to meet all of the body's needs. While it contributes to the overall supply, absorption can be limited, making a balanced diet rich in K2 a necessity.

How can I support my gut bacteria to produce more vitamin K2?

You can support K2-producing bacteria by consuming a varied, high-fiber diet with plenty of prebiotic-rich vegetables, and by including fermented foods like kefir and sauerkraut in your diet.

What is the difference between dietary and gut-produced vitamin K2?

Dietary vitamin K2 comes from fermented foods and animal products and is often more bioavailable. Gut-produced K2 is synthesized by intestinal bacteria, but its absorption is less efficient because it is produced mostly in the colon.

Can taking antibiotics affect my body's production of vitamin K2?

Yes, long-term antibiotic use can kill beneficial gut bacteria that produce vitamin K2, which can negatively impact your overall vitamin K status.

Do all gut bacteria produce vitamin K2?

No, not all gut bacteria produce vitamin K2. The synthesis is dependent on specific metabolic pathways present in certain species, such as Bacteroides and E. coli, while others do not possess this ability.

What role does vitamin K2 produced by gut bacteria play in health?

Gut-produced vitamin K2 plays a key role in numerous health functions beyond blood clotting, including bone mineralization, cardiovascular health, and potentially modulating inflammation.