Which Probiotics Produce Vitamin K for Better Health?

An estimated 50% of the bacterial species in the gut can produce vitamin K2, specifically menaquinones. This critical nutrient, known for its roles in blood clotting, bone health, and cardiovascular wellness, can be influenced by the presence of certain probiotics in your diet.

Quick Summary

This article explores which probiotic strains produce vitamin K2, including key species like Bacillus subtilis, Lactococcus lactis, and certain Bifidobacterium. It also details the fermented foods rich in these beneficial bacteria and their contributions to vitamin K synthesis.

Key Points

• Key Strains: Key probiotics that produce vitamin K2 (menaquinone) include Bacillus subtilis, Lactococcus lactis, and certain species of Lactobacillus and Bifidobacterium.

• Best Food Source: Natto, a Japanese fermented soybean dish, is the most potent food source of vitamin K2 due to the fermentation process involving Bacillus subtilis natto.

• Gut Contribution: Bacteria within the human large intestine, such as Bacteroides and E. coli, also contribute to the body's endogenous production of menaquinones.

• Food Variety: Other fermented foods, including certain cheeses (like Gouda), kefir, and unpasteurized sauerkraut, provide beneficial probiotic strains that synthesize vitamin K2.

• Dietary Importance: While gut bacteria produce some vitamin K2, dietary intake of K1 (from greens) and K2 (from fermented foods) is essential because colonic absorption of bacterially produced K2 is limited.

• Supplementation: Some dietary supplements specifically include high-yielding K2-producing probiotic strains to help improve vitamin K status.

Understanding Vitamin K and Its Bacterial Production

Vitamin K is a fat-soluble vitamin essential for human health, existing in two primary forms: vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). While K1 is found predominantly in leafy green vegetables, K2 is largely of microbial origin, with long-chain menaquinones (MK-7, MK-8, MK-9) synthesized by specific bacteria. These bacterial strains can be found both in fermented foods and within the human gut microbiome.

The Role of Probiotics in Vitamin K2 Synthesis

Probiotic bacteria, particularly those used in food fermentation and residing in the gut, are key producers of vitamin K2. Their ability to synthesize this vitamin is not universal across all strains but is a specific metabolic function of certain species and subspecies. The availability and form of vitamin K2 produced vary significantly depending on the microbial source and environmental conditions. For instance, some bacteria produce different lengths of menaquinone side chains, which can influence bioavailability and function.

Key Probiotic Strains That Produce Vitamin K

Several well-researched bacterial strains are known for their ability to synthesize vitamin K2. These include both species commonly used in fermentation and those naturally found in the human intestine.

• Bacillus subtilis: The strain Bacillus subtilis natto is a highly prolific producer of menaquinone-7 (MK-7) and is the active fermenting agent in the Japanese food natto. The high concentration of MK-7 found in natto makes it one of the richest dietary sources of vitamin K2.
• Lactococcus lactis: A lactic acid bacterium (LAB) often used in cheesemaking and dairy fermentation, Lactococcus lactis produces various menaquinones, including MK-8 and MK-9. Research has shown that different subspecies, like L. lactis ssp. cremoris and L. lactis ssp. lactis, have varying capacities for vitamin K2 production.
• Lactobacillus species: While not all Lactobacillus species are significant K2 producers, specific strains have demonstrated this capability. For example, some Lactobacillus plantarum and Lactobacillus reuteri strains have been identified as contributors to vitamin K2 synthesis.
• Bifidobacterium species: Certain members of the Bifidobacterium genus, major inhabitants of the large intestine, have been recognized for their ability to produce vitamin K, along with other essential nutrients. For example, Bifidobacterium longum has been noted as a contributor to K2 production.
• Escherichia coli: A common resident of the mammalian lower intestine, many strains of E. coli are capable of synthesizing menaquinone, primarily MK-8. While some pathogenic strains exist, the production of K2 is a common metabolic function in many benign versions.

The Best Fermented Food Sources of Vitamin K-Producing Probiotics

Including certain fermented foods in your diet can be a natural and effective way to increase your intake of these vitamin K-producing probiotics.

• Natto: This traditional Japanese fermented soybean dish is unparalleled as a food source of vitamin K2, specifically MK-7. The fermentation process with Bacillus subtilis is responsible for this incredibly high concentration.
• Kefir: A fermented milk drink made with kefir grains (a culture of yeast and bacteria), kefir is rich in various beneficial microbes, including some that produce vitamin K2.
• Certain Cheeses: Aged and hard cheeses like Gouda and some varieties of cheddar contain menaquinone-producing bacteria. The specific strains and aging process determine the final vitamin K2 content.
• Sauerkraut: Made from fermented cabbage, unpasteurized sauerkraut contains lactic acid bacteria that contribute to vitamin K synthesis.

How Dietary Choices Impact Vitamin K Production

Dietary habits play a crucial role in supporting the growth of vitamin K-producing bacteria in the gut. Just as a diverse intake of fermentable fibers feeds beneficial gut microbes, specific foods can enhance the production of menaquinones.

Comparison of Common Vitamin K-Producing Probiotics

Probiotic Strain	Primary Fermented Food Source	Major Menaquinone Produced	Key Benefit(s)
Bacillus subtilis natto	Natto (fermented soybeans)	MK-7	Highest known food source of K2
Lactococcus lactis	Cheeses, fermented dairy	MK-8, MK-9	Contributes significantly to K2 levels in dairy
Bifidobacterium longum	Intestinal flora, some supplements	Various long-chain MKs	Important for gut health and immune function
Lactobacillus plantarum	Sauerkraut, kimchi	Various long-chain MKs	Aids digestion and produces K2 in fermented veggies
Escherichia coli	Intestinal flora	MK-8	Primary endogenous source of K2 in the large intestine

Limitations of Relying Solely on Gut Production

While the bacteria in your gut synthesize a significant amount of menaquinones, relying solely on this endogenous production may not be sufficient for optimal health. The absorption of vitamin K2 from the colon is not fully efficient, and dietary intake remains the most reliable way to obtain this nutrient. Factors like antibiotic use, which disrupts gut flora, and other digestive conditions can also impact the availability of bacterially-produced K2.

Conclusion

Understanding which probiotics produce vitamin K can empower you to make informed dietary choices that benefit your overall health. From the potent MK-7 found in natto produced by Bacillus subtilis to the menaquinones synthesized by Lactococcus lactis in cheese, many fermented foods offer a delicious way to support your body's vitamin K levels. While your gut microbiota, including species like Bifidobacterium and E. coli, contribute to K2 production, dietary sources remain critical for optimal absorption and function. Incorporating a variety of vitamin K-rich foods and probiotic sources is a great strategy to ensure you meet your nutritional needs for bone, heart, and clotting health.

Optional Outbound Link: For more technical information on vitamin K2 synthesis by engineered microorganisms, refer to the NCBI Bookshelf on normal gut flora and vitamin production.

How to get vitamin K-producing probiotics into your diet

Integrating foods like natto, kefir, and certain cheeses and fermented vegetables into your weekly meals can boost your intake of these beneficial microbes and the vitamin K2 they produce.

Note: This article is for informational purposes only and is not a substitute for professional medical advice. Always consult a healthcare provider before making significant dietary changes or starting new supplements.

Frequently Asked Questions

What is the difference between vitamin K1 and vitamin K2?

Vitamin K1 (phylloquinone) is found in leafy green plants, while vitamin K2 (menaquinone) is primarily synthesized by bacteria. K2 has a longer half-life and is absorbed more readily by the body than K1.

What is the best food source of vitamin K-producing probiotics?

Natto, a traditional Japanese fermented soybean dish, is the single best food source. It contains extremely high levels of vitamin K2 (MK-7) produced by Bacillus subtilis natto during fermentation.

Can I get enough vitamin K from my gut bacteria alone?

No, it is not recommended to rely solely on endogenous production. Although gut bacteria produce menaquinones, the absorption from the large intestine is often limited and inefficient. A balanced diet with dietary sources is crucial.

Does all yogurt contain vitamin K-producing probiotics?

No, not all yogurt contains live and active probiotic cultures that produce vitamin K. Processing methods like pasteurization can kill beneficial bacteria. Look for labels that specify 'live and active cultures'.

Are all strains of *Lactobacillus* and *Bifidobacterium* equally effective at producing vitamin K2?

No, the vitamin K2 producing capacity can vary significantly between different species and even specific strains of Lactobacillus and Bifidobacterium. Research has identified particular strains with notable production capabilities.

How do antibiotics affect vitamin K-producing probiotics?

Antibiotics can disrupt the balance of gut microbiota, potentially killing off beneficial bacteria, including those that produce vitamin K2. This can temporarily impact the body's endogenous production of the vitamin.

Is it safe to get vitamin K from *E. coli* in my gut?

Yes, many non-pathogenic strains of E. coli are normal, healthy residents of the lower intestine and are significant producers of menaquinone. This is a natural process within a healthy gut microbiome.