Vitamin K2

Category: Health | Vida Vertical

Summary

Vitamin K2 (menaquinone) is an essential fat-soluble vitamin with a central role in calcium metabolism, bone mineralisation and prevention of cardiovascular calcification. Unlike vitamin K1, found primarily in green leafy vegetables, K2 is produced largely through bacterial fermentation. This article examines the biochemical mechanisms of vitamin K2, its important synergy with vitamin D3 and evidence-based intake recommendations. It concludes by explaining how controlled cultivation of leafy vegetables in hydroponic systems, combined with targeted lactic-acid fermentation, can provide an independent, highly bioavailable supply of vitamins K1 and K2.

1. Introduction: the vitamin K family

Vitamin K is not a single chemical compound, but a group of fat-soluble vitamins structurally characterised by a 2-methyl-1,4-naphthoquinone ring. Two variants are particularly relevant to human physiology: vitamin K1 (phylloquinone), synthesised by plants, and vitamin K2 (menaquinone), produced primarily by bacterial metabolism. While K1 chiefly supports hepatic blood coagulation, K2 performs essential systemic functions in extrahepatic tissues.

2. Physiological functions of vitamin K2

Vitamin K2 acts as a cofactor for gamma-glutamyl carboxylase. This enzyme activates specific proteins through carboxylation, enabling their physiological effects:

• Osteocalcin (bone metabolism): Osteoblasts secrete osteocalcin. Once activated through a K2-dependent process, it binds calcium and incorporates it into bone matrix, supporting bone mineral density and skeletal integrity.
• Matrix Gla protein (MGP; cardiovascular protection): MGP is a potent inhibitor of vascular calcification and helps prevent calcium deposition in arterial walls and soft tissue. Insufficient activated MGP is associated with arterial stiffness and higher cardiovascular risk.
• Blood coagulation: Although K1 has the principal role in hepatic synthesis of coagulation factors II, VII, IX and X, K2 also contributes to haemostatic balance and wound healing.

3. The calcium paradox and synergy with vitamin D3

Vitamin D3 is often supplemented alone to address widespread deficiency in Central Europe. D3 substantially increases intestinal calcium absorption. The article describes a “calcium paradox” in which, without adequate K2, absorbed calcium may not be directed optimally towards bone and may instead contribute to deposition in kidneys or arteries.

Vitamins D3 and K2 act synergistically: D3 increases intestinal calcium absorption and stimulates synthesis of osteocalcin and MGP. K2 then activates these proteins, helping direct calcium towards bone and away from vascular walls.

4. Daily requirements, food sources and bioavailability

The German Nutrition Society (DGE) recommends total vitamin K intake of 60 micrograms daily for women and 80 micrograms for men. Because K1 and K2 have different activity profiles, K2 is increasingly considered separately. Some experts estimate a K2 requirement of about 15–20 micrograms per day, while clinical research often uses higher therapeutic doses when studying prevention of osteoporosis and atherosclerosis.

Food sources:

• Vitamin K1: Green leafy vegetables (spinach, kale, broccoli, parsley and chives).
• Vitamin K2: Fermented foods (natto, sauerkraut, kimchi and certain cheeses) and animal products such as egg yolk, liver and herring, particularly from pasture-raised animals.

Bioavailability: Vitamin K2 occurs with different side-chain lengths (MK-4 to MK-13). Fermentation-derived MK-7, particularly the biologically active all-trans isomer, has high bioavailability and a long plasma half-life and is therefore well suited to systemic supply of extrahepatic tissues.

5. Deficiency

The article describes subclinical K2 deficiency as common in Western populations because traditional fermented foods are consumed infrequently. Potential long-term consequences include reduced bone mineral density, from osteopenia to osteoporosis, and progressive vascular calcification. Severe coagulation disorders usually arise only with substantial overall vitamin K deficiency.

6. Relevance to Vida Vertical: the symbiosis of hydroponics and fermentation

As an aquaponics and hydroponics specialist, I view vitamin K supply not merely as passive food intake but as an active biotechnological process that can be influenced in a home vertical garden.

1. Maximising K1 through controlled indoor cultivation Green leafy vegetables such as kale, spinach and Swiss chard grown in hydroponic systems including NFT or aeroponics provide abundant vitamin K1. Precise control of nutrient solution and light spectrum can optimise the plant’s synthesis of phylloquinone.

2. Targeted K2 synthesis through lactic-acid fermentation Further processing adds value to home cultivation. Cabbage, carrots or radish harvested from a vertical system can be converted into sauerkraut or kimchi by lactic fermentation with salt under anaerobic conditions. Lactic-acid bacteria naturally present on the vegetables or added as a starter may synthesise vitamin K2 during fermentation.

3. Aquaponics as a microbial bridge In aquaponic systems, water not only supplies nutrients to plants but also hosts a complex microbiome. Understanding bacterial metabolic cycles in an aquaponic biofilter helps illuminate analogous fermentation processes used in the kitchen to generate vitamins such as K2 from plant biomass.

4. Optimising absorption with plant lipids Because vitamin K is fat-soluble, absorption in the small intestine requires dietary lipids. Dressing fermented vegetables from a vertical garden with omega-3-rich flaxseed or hemp oil supports absorption while also providing anti-inflammatory fatty acids.

7. Conclusion

Vitamin K2 plays an important regulatory role in human calcium metabolism. In close synergy with vitamin D3, it contributes to protection against vascular calcification and supports bone architecture. Low consumption of traditional fermented foods may contribute to inadequate K2 intake in modern Western diets.

Combining traditional biotechnological preservation with modern urban agriculture offers one approach. Growing leafy vegetables hydroponically and then preserving them through lactic fermentation can provide a fresh, locally controlled source of vitamins K1 and K2. This approach connects an understanding of microbial processes with home food systems.

Note: This article provides general scientific information and does not replace medical diagnosis. People taking anticoagulant medicines such as phenprocoumon (Marcumar) or warfarin must keep vitamin K intake consistent and discuss any dietary change or supplement with their cardiologist or primary-care clinician beforehand.

References:

• German Nutrition Society (DGE): D-A-CH reference values for nutrient intake. Vitamin K. www.dge.de
• Schurgers, L. J., et al. (2007). The synthetic form of vitamin K2 (MK-7) is more bioavailable and has a longer half-life than MK-4 in humans. Blood, 109(8), 3279-3283.
• Knapen, M. H., et al. (2015). Menaquinone-7 supplementation improves arterial stiffness in healthy postmenopausal women. Thrombosis and Haemostasis, 114(5), 1082-1091.
• DiNicolantonio, J. J., et al. (2015). The health benefits of vitamin K. Open Heart, 2(1), e000300.
• Rittenau, N. (2019). Vegan-Klischee ade! Wissenschaftliche Antworten auf kritische Fragen zu veganer Ernährung. Ventil Verlag.

Author: Uwe | Vida Vertical – Health