Vitamin K2

Organic substances involved in various biological processes and essential for the human body include menaquinone or fat-soluble vitamin K2, which is a structural variant of vitamin K.

What does the body need vitamin K2 for?

Like vitamin K (phylloquinone), vitamin K2 (produced by intestinal probiotic bacteria menaquinone) is a member of a cluster of organic phenolic compounds widely distributed in nature - quinones, acting as cofactors (coenzymes) in the processes of respiration of cells of various tissues of our body and accumulation of energy in their mitochondria in the form of adenosine triphosphoric acid (ATP), which is necessary for all intracellular biochemical processes.

Of course, the role of vitamin K2 in the synthesis of clotting factors (prothrombin, proconvertin, Christmas and Stuart-Prower factors) is very important, but this vitamin also contributes to normal bone mineral density. It is involved in the production of carboxylase, an enzyme necessary for the synthesis by osteoblasts (young bone tissue cells) of the gamma-carboxylated bone matrix protein osteocalcin, which holds calcium in the bones by synthesizing the major bone mineral component, hydroxyapatite.

Some experts believe that the main effect of vitamin K2 on bone quality is to improve calcium transport from the bloodstream to bone. Although it is known that parathyroid hormone (PTH), calcitonin released by thyroid C-cells, and vitamin D3 (cholecalciferol), which mediates calcium absorption by the active transport system of the duodenum, play a major role in calcium homeostasis. [1], [2]

Menaquinone may also reduce osteolysis (bone destruction) by blocking the increased production of osteoclasts, cells that not only initiate normal bone remodeling but also destroy bone and mediate bone mass loss in pathological conditions. [3]

However, this is not the only reason why our body needs vitamin K2. It is involved in the biosynthesis of pyrimidines (which are part of nucleotides and nucleic acids) and porphyrins (present in hemoglobin molecules).

In addition, vitamin K2 is required for the synthesis of sphingolipids, components of cell membranes that ensure their structural integrity and transmembrane signaling in cells, and are involved in the regulation of cell proliferation, senescence (aging), and apoptosis.

The cardiovascular benefits of vitamin K-2 have also been established. Menaquinone activates matrix GLA-protein (MGP), which is an inhibitor of calcification of atherosclerotic plaques or calcinosis of blood vessels, that is, it prevents calcium deposition on vascular walls. [4]

Vitamin K2 for women is primarily needed to increase bone strength and reduce the risk of bone fracture in postmenopausal osteoporosis.

Also read - How does vitamin K affect the body?

Incidentally, nine isoforms of vitamin K2 are known; the most important of these are MK-4 and MK-7. [5] Menatetrenone or MK-4 is produced in the body by transformation of vitamin K1 (phytomenadione), which has the same molecular structure and is distributed throughout all tissues and organs with a relatively higher content in the liver, heart and pancreas. And K-2 is found in high concentrations in the brain and kidneys. Studies have found that vitamin K2 in the MK-4 form reduces the proliferation of rheumatoid synovial cells in rheumatoid arthritis.

To date, the norm of vitamin K2 has not been established; the Food Supplement Administration of the National Institutes of Health (USA) recommends only the norm of daily intake of vitamin K (for men - 120 mcg, for women - 90 mcg). In supplements with vitamin K2, its single dosage is about 100 mcg. Dietary supplements are not medicines, and they are not legally registered, and the composition and quantity of any given ingredient does not require authorization documents from the U.S. FDA (Food and Drug Administration).

Indications Vitamin K2

The attending physician may recommend taking dietary supplements (BAAs) with vitamin K2 when:

• osteoporosis and osteopenia (decreased bone mineral density) with increased susceptibility to fractures;
• bone mass loss in various pathologic conditions;
• violation of calcium-phosphorus metabolism in the body due to increased levels of parathyroid hormone (hyperparathyroidism);
• Osteochondropathies;
• sphingolipidosis;
• malabsorption syndrome - intestinal absorption failure syndrome.

Release form

Dietary supplements containing vitamin K2 are available in the following forms:

• Vitamin K2 capsules: Natural Vitamin K2, Solgar (USA); Vitamin K2 MK-7, Carlson Labs (USA); Vitamin D-3 + K-2, Super Nutrition (USA); Vitamin D-3 + K-2, Elixir (Ukraine); D-Vitum K2 Forte, Oleofarm (Poland) and others;
• tablets: Vitamin D3+K2, OstroVit (Poland); K2+D3 Mason Natural (USA); lingual micro tablets D-3 K-2 (KAL, USA);
• chewable tablets vitamin K2 menaquinone - Zahler, Junior D3 K2 (USA);
• drops for oral administration: Vitamin D3 2000me + K2 50 mcg drops (20 ml), Dr. Jacob's Medical GmbH (Germany); Vitamin D3 + K2, Seeking Health (USA).

Pharmacodynamics

The mechanism of biologically active action of vitamin K2 is due to its participation in the previously mentioned biochemical processes.

The combination of menaquinone with cholecalciferol (vitamin D3) is due to their synergistic (joint) effects, which help maintain bone strength and cardiovascular health.

Pharmacokinetics

The transformation of exogenous menaquinone ingested by dietary supplements containing menaquinone is under investigation and their clinical pharmacokinetics are not provided in the accompanying instructions.

Dosing and administration

The vitamin is taken orally, 45-100 mcg per day, with meals, for one month.

Vitamin K2 supplements are not used in children.

Use Vitamin K2 during pregnancy

Menaquinone supplements are not intended for pregnant and breastfeeding women.

Contraindications

Biologically active food supplements with vitamin K2 are contraindicated in thrombophilia (increased blood clotting) and predisposition to thrombosis.

Side effects Vitamin K2

Possible side effects of vitamin K2 include heartburn, nausea and vomiting, stomach pain, and diarrhea.

Overdose

Prolonged excessive intake of capsules or tablets of the vitamin can lead to increased blood clotting, vascular thrombosis, and cardiovascular disorders.

Interactions with other drugs

Vitamin K2 should not be combined with taking indirect anticoagulants (Warfirin, etc.) and antibiotics of the cephalosporin group, which reduce the absorption of menaquinone.

Storage conditions

The vitamin in any form should be stored out of direct sunlight at temperatures up to +25°C.

Shelf life

Information regarding the expiration date is placed by the manufacturer on the package.

What foods contain vitamin K2

Although intestinal microflora (Bacteroides fragilis, Escherichia coli) produce a certain amount of menaquinone, its bioavailability is limited and consumed foods are an important source of functionally available vitamin K2. [6]

Vitamin K2 contains such foods as fatty meat (beef and pork), liver and other offal, dairy products (primarily hard cheese), egg yolks, fatty fish (sardines, mackerel, salmon). [7]

Since MK-4 (one of the most active variants of menaquinone) can be produced in the body from vitamin K1, keep in mind that dark green leafy vegetables (including spinach and lettuce), broccoli, grapes, blueberries, and vegetable oils are considered good sources of it.