NUTRITION

• Background
• Food content
• Absorbtion
• Efficacy
• Requirement
• Literature

Background

• VITAMIN K
• NUTRITION
• BLOOD COAGULATION
• BONE METABOLISM
• VASCULAR BIOLOGY
• K1 vs K2

The two sources of vitamin K are plants and bacteria. Vitamin K₁ (phylloquinone) is made exclusively by plants, where it is found in the chloroplasts; its function is that of electron carrier during CO2 fixation. Hence green plants are rich sources of vitamin K1. Menaquinones (K2 vitamins) are of bacterial origin, and they are notably produced by Bacillus subtilis natto, Lactobacillus lacti and some colonic bacteria.

Vitamin K1	Vitamin K2

At low concentrations vitamin K is found in a wide variety of food items, but nutritionally relevant amounts of K1 are only found in green vegetables and some plant oils, whereas rich sources of K2 are found in cheese, curd cheese and the Japanese food natto. (click here to see Table as PDF)

Since all K vitamins need bile salts for intestinal absorption, the contribution of vitamin K produced by the intestinal flora is limited: bile salts are absorbed in the small intestine, whereas the production of K2 takes place further downstream in the colon.

Recommended literature:

• Schurgers, L.J., Vermeer, C. Determination of phylloquinone and menaquinones in food. Effect of food matrix on circulating vitamin K concentrations. Haemostasis 2000; 30: 298-307
• Ramotar, K., Conly, J.M., Chubb, H., Louie, T.J. Production of menaquinones by intestinal anaerobes. J. Infect. Dis. 150 (1984) 213-218.
• Groenen-van Dooren, M.M.C.L., Ronden, J.E., Soute, B.A.M., Vermeer, C. (1995). Bioavailability of phylloquinone and menaquinones after oral and colorectal administration in the vitamin K-deficient rat. Biochem. Pharmacol. 50, 797-801.
• Morishita, T., Tamura, N., Makino, T., Kudo, S. Production of menaquinones by lactic acid bacteria. J. Dairy Sci. 82 (1999) 1897-1903.
• Sato, T., Yamada, Y., Ohtani, Y., Mitsui, N., Murasawa, H., Araki, S. Efficient production of menaquinone (vitamin K2) by a menadione-resistant mutant of Bacillus subtilis. J. Industr. Microbiol. Biotechnol. 26 (2001) 115-120.
• Tsukamoto, Y., Ichise, H., Kakuda, H., Yamaguchi, M. Intake of fermented soybean (natto) increases circulating vitamin K2 (menaquinone-7) and gamma-carboxylated osteocalcin concentration in normal individuals. J. Bone Miner. Metab. 18 (2000) 216-222.