The Bacterial Origin of K2 MK7
Unlike Vitamin K1, which is found in leafy green vegetables, Vitamin K2 MK7 is fundamentally a product of bacterial activity. Menaquinones, the family of compounds that constitutes Vitamin K2, are synthesized by a wide range of bacteria. Among these, the bacterium Bacillus subtilis natto is the most notable producer of the MK7 subtype. This bacterium is responsible for the high concentration of MK7 found in natto, a traditional Japanese food made from fermented soybeans. The discovery that this fermented food was an exceptionally potent source of MK7 revealed the microbial genesis of this essential nutrient. While other fermented foods, like certain cheeses and sauerkraut, also contain smaller amounts of MK7, natto remains the richest dietary source.
The Fermentation Process
In both traditional and modern production, the creation of K2 MK7 relies on a controlled fermentation process. The process for making natto involves soaking, steaming, and then fermenting soybeans with the Bacillus subtilis natto culture. As the bacteria grow and multiply, they produce MK7 as a byproduct of their metabolic processes. This solid-state fermentation process is now adapted for industrial production of MK7 supplements. While the exact MK7 content can vary based on factors like fermentation time, temperature, and ingredients, the bacterial action is the central driver of production.
Can the Gut Produce Enough MK7?
Some people believe their intestinal bacteria produce sufficient Vitamin K2, but research suggests this is not the case for most. While the microflora in the gut, including species like Bacteroides, can synthesize menaquinones (primarily longer-chain versions like MK-10 and MK-11), the bioavailability is poor. This means that even if intestinal bacteria produce significant quantities, the body's ability to absorb it is limited, particularly compared to dietary intake of MK7. This is why diet and supplementation are the primary strategies for ensuring adequate MK7 levels.
Natural vs. Synthetic K2 MK7 Production
Not all K2 MK7 on the market is created equal. The source of the supplement, whether natural fermentation or chemical synthesis, can significantly impact its quality and bioavailability. The key difference lies in the molecular structure of the final product, specifically the presence of cis and trans isomers. The bioactive form of MK7 is the all-trans isomer, while cis isomers are less effective.
Comparison Table: Natural vs. Synthetic K2 MK7
| Feature | Natural Fermentation MK7 | Synthetic MK7 |
|---|---|---|
| Production Method | Bacterial fermentation using strains like Bacillus subtilis natto. | Chemical processes using organic solvents and catalysts. |
| Source | Traditional foods like natto; derived from natural biological processes. | Lab-created, non-biological synthesis. |
| Isomer Purity | High percentage of the bioactive all-trans isomer (often >99%). | Higher proportion of less-effective cis isomers can be present. |
| Biocompatibility | Considered very safe, derived from generally recognized as safe (GRAS) bacteria. | Requires careful removal of chemical byproducts; presence of toxic substances is a potential risk. |
| Market Perception | Often favored by consumers seeking 'natural' health products. | Concerns exist over purity and safety due to chemical processes. |
Modern Enhancements to MK7 Fermentation
While traditional methods established the foundation for producing MK7, modern biotechnology has sought to enhance and optimize the process for large-scale industrial use. Researchers utilize genetic engineering and bioprocess optimization to increase MK7 yields from bacterial cultures. These advancements focus on engineering more efficient microbial “factories” that can produce higher concentrations of all-trans MK7. Techniques include modifying fermentation media and conditions, utilizing advanced reactor systems, and manipulating genetic pathways within the bacteria to boost production. This allows for a more consistent and cost-effective supply of high-purity MK7 for supplements.
Sources of K2 MK7 in Diet and Supplements
Food Sources Rich in K2 MK7
- Natto: The most concentrated dietary source, a Japanese dish of fermented soybeans.
- Certain Cheeses: Aged and hard cheeses like Gouda and Edam, and some soft cheeses, contain moderate levels due to bacterial fermentation.
- Sauerkraut: Fermented cabbage can contain modest amounts of MK7.
- Fermented Dairy: Products like kefir and some types of yogurt can contain K2 from lactic acid bacteria, though amounts are generally lower than natto.
- Meat & Eggs: Some animal products, particularly from grass-fed animals, contain K2. However, this is more likely to be the MK4 subtype rather than MK7, and the amount can vary greatly.
Supplementation as a Practical Solution
Given the low levels of MK7 in most Western diets and the specialized nature of natto, supplementation has become a practical way to ensure adequate intake. High-quality supplements derived from natural fermentation are widely available and can provide the active all-trans MK7 isomer in a concentrated form. This ensures consistent dosing, which is difficult to achieve through diet alone, especially for those who dislike natto or have dietary restrictions. The development of standardized fermentation processes has also allowed manufacturers to produce reliable and pure MK7 products for the global market. For those interested in the science behind dietary recommendations, the National Institutes of Health (NIH) provides extensive research on vitamin K and its functions.
Conclusion
In summary, K2 MK7 is not sourced from common plants or animals like other vitamins, but rather from the specific metabolic processes of certain bacteria. The most famous and potent source is the Japanese food natto, which is made by fermenting soybeans with Bacillus subtilis. This natural fermentation process is also the basis for producing high-quality, all-trans MK7 supplements. While synthetic versions exist, they may contain less effective isomers. Because the body cannot absorb significant amounts of MK7 produced by its own gut flora, obtaining this nutrient from fermented foods or supplements is crucial for health. Understanding this bacterial origin highlights why a varied diet, particularly one including fermented products, or the use of high-quality supplements, is necessary to maintain sufficient MK7 levels.
