Vitamin K2 refers to a group of menaquinones (MK-n) - fat-soluble vitamers distinguished by the length of their isoprenoid side chains. Among the bulk Vitamin K2 MK-7 forms, menaquinone-7 (MK-7) has drawn significant scientific attention due to its superior bioavailability and longer circulatory half-life compared with other menaquinones and phylloquinone (Vitamin K1). Unlike Vitamin K1, which is abundant in green leafy vegetables and primarily involved in hepatic blood-clotting pathways, MK-7 functions extensively in extra-hepatic tissues - most notably in bone metabolism and cardiovascular health through modulation of vitamin K-dependent proteins such as osteocalcin and matrix Gla protein (MGP). So, What Are the Best Natural Sources of bulk Vitamin K2 MK-7?
What Are the Best Natural Sources of Vitamin K2 (MK-7)?
The "Best" Natural Source of MK-7: Natto
1. What Is Natto?
Among all known dietary sources of vitamin K2, natto is widely recognized as the most concentrated and effective natural source of menaquinone-7 (MK-7). Natto is a traditional Japanese food produced by fermenting cooked soybeans with a specific bacterial strain, Bacillus subtilis natto. During the fermentation process, this microorganism actively synthesizes large amounts of MK-7 as part of its metabolic activity. As a result, natto contains significantly higher MK-7 levels than any other commonly consumed food, making it unique in the human diet.
2. Quantitative and Qualitative Evidence
Multiple biochemical analyses have shown that natto contains unparalleled levels of MK-7 compared with other dietary sources, primarily due to the metabolic activity of B. subtilis during fermentation. It produces long-chain menaquinones, particularly MK-7, rather than the shorter molecules, such as MK-4.
In human nutritional studies, habitual consumption of natto has been shown to significantly elevate serum levels of MK-7, enhance gamma-carboxylation of osteocalcin (an indicator of active bone formation), and is associated with higher bone mineral density compared with lower or non-consumers.
A controlled dietary intervention feeding fermented soybeans to volunteers demonstrated significant increases in circulating bulk Vitamin K2 MK-7 concentrations and improved osteocalcin carboxylation, showing that dietary natto can directly influence systemic vitamin K2 status.
3. Why Natto Is the Best Natural Food Source?
• Highest Concentration of MK-7:
Natto is widely recognized as the richest natural dietary source of bulk Vitamin K2 MK-7. The unique fermentation process using Bacillus subtilis natto enables the bacteria to synthesize large quantities of MK-7 that are rarely found in other foods. Compared with fermented dairy products, meats, or vegetables, natto delivers a significantly higher MK-7 content per serving, making it unmatched in terms of natural concentration. This high level allows natto to make a meaningful contribution to daily MK-7 intake, even in relatively small portions, which is difficult to achieve with other commonly consumed foods.
• Bioavailability:
Another key advantage of bulk Vitamin K2 MK-7 from natto lies in its molecular structure. MK-7 contains a long isoprenoid side chain, which enhances its absorption in the digestive tract and allows it to remain in the bloodstream for a longer period compared with shorter-chain menaquinones (such as MK-4) or vitamin K1. This extended half-life results in more stable serum vitamin K levels, supporting consistent activation of vitamin K–dependent proteins in extra-hepatic tissues such as bone and blood vessels.
• Functional Outcomes:
Higher circulating MK-7 levels are strongly associated with improved activation of osteocalcin and matrix Gla protein, two key vitamin K–dependent proteins involved in bone mineralization and vascular health. These effects are particularly relevant for aging populations, as they support bone strength and may help maintain normal calcium metabolism in blood vessels, contributing to long-term skeletal and cardiovascular integrity.
Despite its remarkable bulk Vitamin K2 MK-7 content, natto's strong flavor and unique texture limit its acceptance in many diets outside Japan, which is one reason many people turn to targeted supplements to ensure adequate intake.
Other Natural Sources of Vitamin K2 and Limitations
• Fermented Dairy Products
Certain cheeses and fermented milk products (e.g., hard cheeses like Gouda or Edam) contain menaquinones, including minor amounts of bulk Vitamin K2 MK-7 as well as other menaquinones such as MK-8 and MK-9.
However, while these foods contribute to total vitamin K2 intake, their MK-7 content is lower and more variable than natto. To achieve comparable MK-7 levels from cheese alone, dietary consumption would have to be exceptionally high, which is impractical for many people.
• Other Fermented Foods
Sauerkraut, kefir, and other fermented vegetables contain small quantities of MK-7, but their levels are significantly lower compared with natto and fermented dairy products.
• Animal-Based Foods
Animal products like egg yolks, butter, and organ meats contain bulk Vitamin K2 MK-7, but predominantly in the MK-4 form rather than MK-7, and at much lower concentrations of MK-7. While MK-4 has biological activity, its shorter half-life in circulation may reduce its utility for long-term nutrient status compared with MK-7.
Why Is Vitamin K2 MK-7 Supplementation Necessary?
Limited Dietary Availability in Modern Diets
Although bulk Vitamin K2 MK-7 plays a critical role in human health, natural dietary sources of MK-7 are extremely limited. Natto is the richest food source, but it is rarely consumed outside of Japan due to its strong taste and unfamiliar texture. Other foods, such as fermented dairy products or meats, contain much lower and inconsistent levels of vitamin K2, often in forms other than MK-7. As a result, most people consuming Western-style or modern diets do not achieve sufficient MK-7 intake through food alone, making supplementation a practical solution to address this nutritional gap.
Superior Bioavailability and Longer Half-Life of MK-7
Bulk Vitamin K2 MK-7 has a unique molecular structure with a long isoprenoid side chain, allowing it to remain active in the bloodstream for an extended period compared with vitamin K1 or MK-4. This longer half-life leads to more stable serum levels and more efficient utilization by the body. Supplementation ensures a consistent and predictable supply of MK-7, which is especially important for activating vitamin K–dependent proteins in bones and blood vessels that require continuous vitamin K availability.
Support for Bone and Cardiovascular Health
MK-7 is essential for activating osteocalcin and matrix Gla protein, which regulate calcium distribution in the body. Without adequate MK-7, calcium may not be efficiently incorporated into bone tissue and may instead accumulate in soft tissues. Supplementation helps support normal bone mineralization, maintain bone strength, and promote healthy vascular function. These benefits are particularly relevant for older adults, postmenopausal individuals, and those concerned about long-term skeletal and cardiovascular health.
Reduced Endogenous Production with Age and Lifestyle Factors
While intestinal bacteria can synthesize certain forms of bulk Vitamin K2 MK-7, this contribution is often insufficient to meet physiological needs, especially as gut microbiota diversity declines with age, antibiotic use, or digestive disorders. Supplementing with MK-7 helps compensate for reduced endogenous production and ensures adequate vitamin K status throughout different life stages, supporting long-term metabolic and structural health.
Conclusion:
Natto stands as the richest and most bioavailable natural source of Vitamin K2 MK-7, backed by evidence showing its capacity to elevate serum MK-7 and support markers of bone health. While fermented foods provide valuable dietary MK-7, supplementation with high-quality Vitamin K2 MK-7 ingredients offers a practical and standardized way to ensure adequate intake, especially where fermented food consumption is minimal. Guanjie Biotech's bulk Vitamin K2 MK-7 powder/oil is a relevant ingredient for health product manufacturers seeking to capitalize on MK-7's extensive research and applications. Welcome to enquire with us at info@gybiotech.com.
References
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[5] Knapen, M. H. J., Drummen, N. E., Smit, E., Vermeer, C., & Theuwissen, E. (2013). Three-year low-dose menaquinone-7 supplementation helps decrease bone loss in healthy postmenopausal women. Osteoporosis International, 24(9), 2499–2507.
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[7] Tsukamoto, Y., Ichise, H., Kakuda, H., & Yamaguchi, M. (2000). Intake of fermented soybean (natto) increases circulating vitamin K2 (menaquinone-7) and γ-carboxylated osteocalcin concentration in normal individuals. Journal of Bone and Mineral Metabolism, 18(4), 216–222.
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