I get asked about Vitamin K1 and Vitamin K2 almost daily. I am amazed at how much mis-information about vitamin K is out there on the interwebby.
Vitamin K Basics
Vitamin K is an essential player in coagulation pathways of our body. It helps to maintain the viscosity or “thinness” of our blood. It is a cofactor required for the activity of several key proteins containing carboxyglutamic acid residues in the clotting pathways.
Despite what the “Keto-Guru’s” tell you, Vitamin K deficiency is rare. The exception is in neonates and patients with predisposing conditions including hepatobiliary (liver) or pancreatic disease.
Vitamin K Structures
Vitamin K1 (phylloquinone) has a phytyl side chain.
Vitamin K2 (menaquinone) has several forms, each with an isoprenoid side chain, designated MK-4 (or menatetrenone) through MK-13 according to the length of the side chain. The most common form of menaquinone has four residues (MK-4).
Using the Vitamin K In Your Diet
Vitamin K is fat soluble. You gotta’ have fat in your diet for it to be absorbed and used correctly. This is where the vegans and the vegetarians of the world may find challenges in using the vitamin K they get through diet.
Vitamin K absorption requires intact pancreatic and biliary function and fat absorptive mechanisms. Dietary vitamin K is protein-bound and is liberated by the proteolytic action of pancreatic enzymes in the small intestine. Bile salts then solubilize vitamin K into mixed micelles (little fat transport busses) for absorption into enterocytes (cells of the gut wall), where it is incorporated into chylomicrons (the largest of the cholesterol transport molecules), thereby facilitating absorption into the intestinal lymphatics and portal circulation for transport to the liver. In the liver it is repackaged into very low-density lipoprotein (VLDL). It circulates in small quantities bound to lipoprotein. Yes, that means your vitamin K is transported in cholesterol molecules with the essential fats your body uses.
Vitamin K’s Functions
Coagulation – It is essential for activation of Factors VII, IX, X and prothrombinActivation of proteins C & S – These proteins require vitamin K’s presence and they facilitate too much thrombin generation
Reversal of coumarin-like anticoagulants – Vitamin K interrupts the reduction of inactive K2,3 epoxide to the active form of the vitamin to stop excessive bleeding from Coumadin (warfarin) or coumarin-like products.
Bone formation – it helps in bone formation and use of calcium in the matrix Gla protein. The combination of vitamin K and D can significantly increase the total bone mineral density and significantly decrease undercarboxylated osteocalcin. A more favorable effect is expected when vitamin K2 is used. This finding has been used to promote the sales of Vitamin K2 among many “diet experts.” Remember, plenty of K2 is found in eggs, liver and meat when these are a part of your diet.
Coronary vascular calcification – matrix Gla protein is dependent on vitamin K-mediated carboxylation for activity. In its active form it is thought to play a role in vascular calcification. Theoretically, vitamin K deficiency leads to increased vascular calcification because of lack of matrix Gla protein activity. Vascular calcification predisposes to coronary artery disease. Few trials have assessed the role of vitamin K in coronary artery disease. Those available are not conclusive, but they suggest that further studies are warranted.
Dietary menaquinones are found in meat (especially liver), cheeses, fermented soybeans, and eggs. This is why ketogenic or carnivores diets are so effective, as they provide the essential vitamins for efficient metabolism.
With this understanding, I explain to all of my patients that anyone peddling vitamin K supplements to those on ketogenic or carnivorous diets are just tryin to make their boat payment.
Symptoms of Vitamin K Deficiency
Clinical signs and symptoms of vitamin K deficiency include easy bruisability, mucosal bleeding, splinter hemorrhages, melena, hematuria, or any other manifestations of impaired coagulation.
Dietary Sources of Vitamin K:Vitamin K1 can be found in green veggies like spinach and broccoli and some oils
Vitamin K2 can be produced from phylloquinone by the body and is the main storage form in animals. The other menaquinones are synthesized by microflora in the gut, providing a portion of the dietary requirement of vitamin K. Daily requirements of Vitamin K are 90 micrograms daily in women and 120 micrograms daily in men.
Not familiar with ketogenic diets? Check out my diet page for the diet I use in my practice with my patients here.
References:
- Food and Nutrition Board of the Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc (2000). National Academies Press, Washington DC, 2000. p. 162-196 http://books.nap.edu/openbook.php?isbn=0309072794
- Furie B, Furie BC. Molecular basis of vitamin K-dependent gamma-carboxylation. Blood 1990; 75:1753.
- Kuang X, Liu C, Guo X, Li K, Deng Q, Li D. The combination effect of vitamin K and vitamin D on human bone quality: a meta-analysis of randomized controlled trials. Food Funct. 2020 Apr 30;11(4):3280-3297. doi: 10.1039/c9fo03063h. PMID: 32219282.
- Shea MK, O’Donnell CJ, Hoffmann U, et al. Vitamin K supplementation and progression of coronary artery calcium in older men and women. Am J Clin Nutr 2009; 89:1799.
