The Interplay Between Vitamin D and K2

The interplay between vitamin D and K2 is a complex process that maintains health and promotes wellbeing. How these two pair to work synergistically is complex and fascinating. Cultures around the world instinctively knew how to consume food groups together that had vitamin K2 and vitamin D. Much of this ancient wisdom has been lost as “progress” and “convenience” has taken over the food industry. However, there has been a resurgence of interest in getting back to basics and whole food nutrition. While this is a step forward, our soils have been depleted through poor farming practices, requiring supplementation.

Vitamin K1 and K2: The Differences

Vitamin K is a fat-soluble vitamin essential for various physiological processes, including blood coagulation, bone health, and cardiovascular function. It exists in two forms: vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). Both forms play a role in the activation of vitamin K-dependent proteins, yet they differ in their sources, metabolism, and bioavailability.

Vitamin K1 (Phylloquinone)

Found in green leafy vegetables like spinach, kale, and broccoli. It is absorbed in the small intestine with the help of bile salts and is transported to the liver, where it contributes to the synthesis of clotting factors such as prothrombin.

Vitamin K2 (Menaquinones)

Synthesized by bacteria, namely B. subtilis, a soil-based bacteria naturally found in the healthy gastrointestinal tract of humans and in fermented foods (e.g., natto), animal products (e.g., cheese, eggs), and liver. Unlike K1, K2 has multiple subtypes (MK-4 through MK-13), which vary in chain length and bioactivity. Long-chain menaquinones like MK-7 are more bioavailable due to their longer half-life.

The long half-life allows K2 to be distributed beyond the liver to support bone mineralization and inhibit vascular calcification.

The Vitamin K2 and D3 Dance

Taking vitamin D without MK-7 (vitamin K2) can lead to vascular calcification because vitamin D increases calcium absorption. Without sufficient K2, calcium may deposit in soft tissues and blood vessels instead of being properly utilized in bones.

MK-7 activates matrix Gla-protein (MGP), an inhibitor of vascular calcification. Without MK-7, MGP remains inactive, impairing its ability to prevent calcium buildup in arteries, which can contribute to cardiovascular risks and arterial stiffness.

Essentially, MK-7 leads the dance—it tells the calcium where to go.

Whether you get your vitamin D from the sun or supplements, you need adequate K2. Cultures around the world instinctively knew this. In fact, the highest consumption of vitamin D in the world was the Inuit tribe’s traditional diet—cold water, fatty fish, and mammals—before their diet changed to processed foods. They also consumed a variety of fermented foods, leading to MK-7 intake.

Challenges in Getting K2 from Fermented Foods

The problem with consuming fermented foods to get your vitamin K2 is that there is no way to tell how much MK-7 is in the food. The concentration of MK-7 can vary depending on the specific strains of bacteria used and the fermentation conditions.

Sources of Fermented Foods Rich in K2

• Sauerkraut
• Kimchi
• Natto (highest source of MK-7)
• Kefir
• Cheeses
• Yogurt
• Tempeh/Miso/Natto
• Kombucha

Our Vitamin D3 + K2 formula: https://www.twc.health/products/vitamin-d-and-k2 

A rewarding probiotic and prebiotic ferment recipe can be found here: Sauerkraut Recipe

Citations

1. Sato T, Inaba N, Yamashita T. MK-7 and Its Effects on Bone Quality and Strength. Nutrients. 2020 Mar 31;12(4):965. doi: 10.3390/nu12040965.
2. Wang J, Zhou JJ, Robertson GR, Lee VW. Vitamin D in Vascular Calcification: A Double-Edged Sword? Nutrients. 2018 May 22;10(5):652. doi: 10.3390/nu10050652.
3. Wikipedia contributors. (2023). Vitamin K. Retrieved February 27, 2025, from Wikipedia.
4. Chilton SN, Burton JP, Reid G. Inclusion of fermented foods in food guides around the world. Nutrients. 2015 Jan 8;7(1):390-404. doi: 10.3390/nu7010390.
5. Kuhnlein HV. Vitamin D intake by Indigenous Peoples in the Canadian Arctic. Public Health Nutr. 2018 Aug;21(11):1986-1987. doi: 10.1017/S1368980018000411.

Written By Brooke Lounsbury