Which Probiotics Produce Vitamin K for Better Gut Health?

Gut bacteria can synthesize vitamin K2, a form of vitamin K essential for bone and cardiovascular health. While our diet provides a primary source of this vital nutrient, certain probiotic bacteria, both in our gut and in fermented foods, significantly contribute to our body's vitamin K levels. This article explores exactly which probiotics produce vitamin K to help you make informed choices for your diet and supplements.

Quick Summary

Several probiotic species synthesize vitamin K2, specifically long-chain menaquinones (MKs). The primary producers are Bacillus subtilis in fermented soybeans and certain Lactococcus lactis strains found in dairy. Gut flora, including some Bacteroides and Eubacterium species, also contribute, though their absorption may be less efficient. This highlights how both diet and a healthy microbiome support vitamin K status.

Key Points

• Specific Bacteria: Probiotic species like Bacillus subtilis (natto), Lactococcus lactis (dairy), and various Propionibacterium species produce vitamin K, specifically the K2 (menaquinone) form.

• Natto is a Top Source: Fermenting soybeans with Bacillus subtilis var. natto yields extremely high levels of MK-7, a highly bioavailable form of vitamin K2.

• Gut Flora Contribution: Your intestinal microbiome, including Bacteroides and Eubacterium species, also synthesizes menaquinones, though the absorption of these is less efficient due to their production site in the colon.

• Fermented Foods are Key: Consuming a variety of fermented foods like natto, cheese, and kefir is an excellent way to introduce vitamin K-producing probiotics into your diet.

• Enhancing Absorption: Since vitamin K is fat-soluble, consuming K2-rich fermented foods with some fat can improve absorption.

• Beyond Coagulation: Vitamin K2, produced by these probiotics, is crucial for functions beyond blood clotting, including bone mineralization and preventing arterial calcification.

Understanding the Vitamin K Family and Bacterial Production

Before exploring which probiotics produce vitamin K, it's crucial to distinguish between the two main natural types: vitamin K1 (phylloquinone) and vitamin K2 (menaquinones). Vitamin K1 comes mainly from leafy green vegetables and is primarily used by the liver for blood clotting factors. Vitamin K2 is predominantly synthesized by bacteria and is more involved in regulating calcium in soft tissues and bones. Probiotic bacteria and the gut microbiome are the primary producers of vitamin K2, particularly the long-chain menaquinones (MKs) such as MK-7 and MK-9.

Key Probiotic Producers of Vitamin K

Numerous bacterial species have the capability to produce menaquinones, but a few stand out in fermented foods and for their potential as probiotic supplements. Their ability to synthesize vitamin K2 varies depending on the strain, fermentation conditions, and food matrix.

• Bacillus subtilis (natto): This is arguably the most well-known probiotic for vitamin K production. The specific strain Bacillus subtilis var. natto is used to ferment soybeans into natto, a traditional Japanese food. This fermentation process yields an exceptionally high concentration of MK-7, a long-chain menaquinone that has a longer half-life in the bloodstream than other forms. Natto is, in fact, one of the richest dietary sources of vitamin K2.
• Lactococcus lactis: Found in fermented dairy products like cheese and kefir, various strains of Lactococcus lactis are efficient producers of menaquinones. Studies show these bacteria can produce MK-8 and MK-9, and the production levels can be enhanced by optimizing fermentation conditions. A recent study even demonstrated that specific starter cultures containing L. lactis can significantly enrich quark products with vitamin K2.
• Propionibacterium species: Used in the production of Swiss-type cheeses, these bacteria produce MK-9(H4). This contributes to the relatively high vitamin K2 content found in certain types of cheese.
• Other Lactic Acid Bacteria (LAB): Some strains of Leuconostoc lactis and Leuconostoc mesenteroides have also been identified as menaquinone producers, contributing to the vitamin K2 content in a variety of fermented foods. Lactobacillus acidophilus has been noted to increase MK-7 content in some fermented dairy products.

Vitamin K Production in the Gut Microbiome

Our own gut flora also plays a significant role in endogenous vitamin K production, though its bioavailability to the body is a topic of ongoing research. The absorption of these bacterially produced menaquinones, which occurs primarily in the large intestine, is generally less efficient than dietary absorption in the small intestine because of the lack of bile salts needed for solubilization.

• Bacteroides species: These are a major component of the human intestinal flora and are known producers of long-chain menaquinones, mainly MK-10 and MK-11.
• Eubacterium lentum: This bacterium is capable of producing MK-6 within the gut.
• Enterobacter species and Escherichia coli: Also found in the intestinal tract, these bacteria produce menaquinones like MK-8.
• Veillonella species: These can produce MK-7 in the intestinal flora.

Comparison of Key Vitamin K Producing Probiotics

Feature	Bacillus subtilis (natto)	Lactococcus lactis	Gut Flora (Bacteroides, Eubacterium, etc.)
Primary Fermented Food Source	Natto (fermented soybeans)	Dairy products (cheese, kefir)	N/A (Endogenous gut production)
Primary Menaquinone Type	MK-7	MK-8, MK-9	MK-6, MK-7, MK-8, MK-10, MK-11
Bioavailability from Food	Very high from natto	Good from fermented dairy	Limited, especially for long-chain MKs from distal colon
Health Benefits from K2	Strong association with bone and cardiovascular health	Contributes to overall K2 status	Supports endogenous vitamin K levels
Supplementation Potential	Often used in dedicated K2 supplements	Can be included in fermented food supplements	Found naturally within a healthy microbiome

Optimizing Vitamin K from Probiotics

To effectively leverage probiotic vitamin K production, consider these strategies:

1. Consume diverse fermented foods: Incorporate a variety of fermented foods into your diet. For a potent boost of MK-7, try natto. For a dairy-based option, quality cheeses, especially hard varieties, and kefir can increase your MK-8 and MK-9 intake.
2. Support overall gut health: Since many vitamin K-producing bacteria reside in your gut, maintaining a healthy and balanced microbiome is crucial. A varied diet rich in fiber and other probiotics helps foster a robust microbial community.
3. Choose targeted probiotic supplements: Some probiotic supplements are specifically formulated to contain strains known for their vitamin K2-producing capabilities. Look for products containing strains like B. subtilis or certain Lactococcus species, as clinical studies show they can effectively raise vitamin K status.
4. Consider pairing with dietary fat: As a fat-soluble vitamin, absorption of menaquinones is enhanced when consumed with fat. Pairing fermented foods or supplements with healthy fats can improve absorption in the small intestine before it reaches the colon.

The Role of Probiotics in Maintaining Optimal Vitamin K Levels

The ability of probiotics to produce vitamin K, especially the highly bioavailable long-chain menaquinones like MK-7, offers a promising avenue for improving vitamin K status. For individuals with limited dietary intake or impaired absorption, these beneficial bacteria can provide a steady and consistent supply of this critical nutrient. For instance, a study in middle-aged adults with elevated cardiovascular risk showed that a 12-week supplementation with K2-producing probiotics led to a significant increase in vitamin K levels in the body. This highlights the potential of probiotic interventions to support bone and cardiovascular health. For the average person, a diet rich in a variety of fermented foods containing these bacterial strains works synergistically with a healthy gut microbiome to ensure adequate vitamin K status. This multifaceted approach to nutrition and gut health offers a more holistic way to manage your vitamin intake.

Conclusion

In conclusion, several probiotic bacteria are capable of producing vitamin K, particularly the menaquinone (K2) form. The most potent producer found in food is the Bacillus subtilis strain used for fermenting natto, which yields a high concentration of MK-7. Other significant producers include various Lactococcus lactis and Propionibacterium species in dairy products like cheese and kefir. Beyond food, our own gut flora, including Bacteroides and Eubacterium species, synthesize a variety of menaquinones, although their absorption is less efficient than dietary intake from the small intestine. By incorporating a range of fermented foods and considering targeted probiotic supplements, you can leverage the power of these microorganisms to boost your body's vitamin K status and support critical physiological functions like bone and cardiovascular health.

Authoritative Outbound Link

For more detailed information on vitamin K and its different forms, you can refer to the National Institutes of Health (NIH) Office of Dietary Supplements.

Frequently Asked Questions

Which specific bacterial strains produce the most vitamin K?

The Bacillus subtilis var. natto strain produces exceptionally high levels of menaquinone-7 (MK-7) during the fermentation of soybeans for natto. Certain strains of Lactococcus lactis, commonly used in cheese and kefir production, are also potent producers of menaquinones like MK-8 and MK-9.

Is the vitamin K produced by my gut bacteria absorbed effectively?

No, the absorption of menaquinones synthesized by gut bacteria is generally considered less efficient than dietary intake. This is because the majority of production occurs in the distal colon, where there are fewer bile salts available to aid in the fat-soluble vitamin's absorption.

Does eating fermented foods provide enough vitamin K2?

Consuming fermented foods can significantly contribute to your vitamin K2 intake, especially if you eat options like natto or certain hard cheeses. However, the exact amount can vary widely based on the specific bacteria strain and fermentation conditions.

Should I take a probiotic supplement specifically for vitamin K production?

Some probiotic supplements are specifically formulated with strains known to produce vitamin K2, and studies have shown they can increase vitamin K status in humans. This can be a beneficial option for those with elevated risk factors for cardiovascular disease or limited dietary intake, but a balanced diet is also crucial.

What is the difference between vitamin K1 and vitamin K2 sources?

Vitamin K1 (phylloquinone) is found primarily in plant foods like leafy greens, while vitamin K2 (menaquinones) is mostly produced by bacteria found in fermented foods and some animal products. Your gut bacteria also produce K2.

Can probiotics help improve my bone health through vitamin K?

Yes, some research suggests that increasing vitamin K2 intake through probiotic-rich fermented foods or supplements can support bone health. Vitamin K2 helps regulate calcium, directing it to bones and away from arteries.

Do all probiotics produce vitamin K?

No, not all probiotic bacteria produce vitamin K. Production is species-specific and even strain-specific, with some, like Bifidobacterium, not producing menaquinones. Certain strains of Bacillus and Lactococcus are the most noted producers.