Gut Bacteria and the Importance of Vitamin K2 for Health

Reginold Sivarajan, BSc Microbiology and Immunology
Contributor

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Vitamins are essential micronutrients needed in small quantities to sustain life. We need to take vitamins from food because the human body either does not produce enough of them or none at all. There are currently 13 recognized vitamins which are either fat-soluble (stored in the fatty tissues of the body and the liver) or water-soluble (do not get stored in the body for long - they soon get excreted in urine) (1).

As you might have learned from previous blogs, the human gastrointestinal tract (GIT) is colonized by a vast array of microorganisms known as the gut microbiota. The intestinal microbiota (microbes that harbours our gut) plays a pivotal role in food digestion and energy recovery, while it can also act as an important supplier of vitamins. In humans it has been shown that members of the gut microbiota are able to synthesize vitamin K as well as most of the water-soluble B vitamins (2). 
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• Vitamin K2
  • High amounts of Vitamin K2 (also called menaquinone) can be found in foods such as hard cheese, soft cheese, egg yolk, sauerkraut, butter, chicken liver, salami, chicken breast and ground beef.
  •  Vitamin K2 is important for bone and vascular health, and deficiency has been associated with low bone  mineral density, increased fracture risk, increased risk of cardiovascular diseases (3).
  • Two clinical trials suggested that vitamin K2 reduces recurrence of liver cancer and increases survival times (4,5)
  • K2 helps prevent wrinkles by keeping your skin more elastic.

Some subtypes of Vitamin K2 can only be supplied to the host through bacteria in the gut such as  Ruminococcaceae, Bacteroides, Prevotella, Alistipes, Oscillibacter, Bilophila, Odoribacter and Barnesiella species. Moreover, it seems that the Bacteroides and Prevotella species are the most prevalent in generating different subtypes of vitamin K2 (6).

The current research on Vitamin K2 and health is extremely promising. It could have life saving implications for a lot of people. Unfortunately, the average intake of this important nutrient is incredibly low in the modern diet. 

What can you do?

• ​Eat food rich in Vitamin K2 such as  hard cheese, soft cheese, egg yolk, sauerkraut, butter, chicken liver, salami, chicken breast and ground beef.
• Take Vitamin K2 supplements in combination with Vitamin D since it has been shown that the two vitamins taken together have synergistic effects (produces a combined effect greater than the sum of their separate effects) (7).
• Eat foods that promote growth of specific bacterial species in the gut microbiota (8).
  •  High-fibre diet is commonly associated with an increase in Prevotella species.
  • Bacteroides species abundance is linked to the consumption of diet rich in animal fat and protein. 

References
1. Leblanc, Jean Guy, Christian Milani, Graciela Savoy De Giori, Fernando Sesma, Douwe Van Sinderen, and Marco Ventura. "Bacteria as Vitamin Suppliers to Their Host: A Gut Microbiota Perspective." Current Opinion in Biotechnology 24.2 (2013): 160-68
2. Hill, M. J. "Intestinal Flora and Endogenous Vitamin Synthesis." European Journal of Cancer Prevention 6 (1997): n. pag.
3. Marques, Tatiana Milena, Rebecca Wall, R. Paul Ross, Gerald F. Fitzgerald, C. Anthony Ryan, and Catherine Stanton. "Programming Infant Gut Microbiota: Influence of Dietary and Environmental Factors." Current Opinion in Biotechnology 21.2 (2010): 149-56.
4. Mizuta, Toshihiko, Iwata Ozaki, Yuichiro Eguchi, Tsutomu Yasutake, Seiji Kawazoe, Kazuma Fujimoto, and Kyosuke Yamamoto. "The Effect of Menatetrenone, a Vitamin K2 Analog, on Disease Recurrence and Survival in Patients with Hepatocellular Carcinoma after Curative Treatment." Cancer 106.4 (2006): 867-72.
5. Kubota, K., T. Sawada, J. Kita, M. Shimoda, and M. Kato. "6594 POSTER Effect of Menatetrenone, a Vitamin K2 Analog, on Recurrence of Hepatocellular Carcinoma After Surgical Resection – Final Results of Randomized Controlled Study." European Journal of Cancer 47 (2011): n. pag.
6. Karl, J. P., X. Fu, X. Wang, Y. Zhao, J. Shen, C. Zhang, B. E. Wolfe, E. Saltzman, L. Zhao, and S. L. Booth. "Fecal Menaquinone Profiles of Overweight Adults Are Associated with Gut Microbiota Composition during a Gut Microbiota-targeted Dietary Intervention." American Journal of Clinical Nutrition 102.1 (2015): 84-93.
7. Kidd, P. M. "Vitamins D and K as Pleiotropic Nutrients: Clinical Importance to the Skeletal and Cardiovascular Systems and Preliminary Evidence for Synergy." Alternative Medicine Review : A Journal of Clinical Therapeutic. U.S. National Library of Medicine, Sept. 2010.
8. Filippis, Francesca De, Nicoletta Pellegrini, Luca Laghi, Marco Gobbetti, and Danilo Ercolini. "Unusual Sub-genus Associations of Faecal Prevotella and Bacteroides with Specific Dietary Patterns." Microbiome 4.1 (2016): n. pag.