Vitamin K2: The Surprising Health Benefits

Let’s face it: vitamin K is probably not on your “must-have” list of supplements. Most of us don’t realize that “vitamin K” is a generic term for several structurally related compounds – or that the lesser-known K2 has far more benefits for our health than we ever imagined.

The research is showing that K2 should make it onto your stack of daily supplements, especially if you’re older or have a chronic health condition.

The current RDA (recommended daily allowance) is all about K1, with no mention of K2. Some researchers say this should change (1).

What is vitamin K2?

Vitamin K is a class of fat-soluble vitamins. K1 is the name for a molecule called phylloquinone, whilst K2 refers to a group of molecules called menaquinones. Their chemical structures differ only slightly – by the length of the side chains. This is important because a longer chain remains in the blood longer and is better absorbed. 

The two most widely available forms of vitamin K2 are menaquinone-4 (MK-4) and menaquinone-7 (MK-7). MK-7’s longer side chain makes it a better choice for supplementation.

How do we obtain vitamin K1 and K2 from our diet?

Dietary sources of K1 are found mostly in plants such as dark leafy green vegetables (broccoli, kale, spinach, brussels sprouts, cabbage, lettuces) and algae.

Vitamin K2 is microbial; the highest amounts are found in fermented foods such as natto (a traditional Japanese food made from fermented soybeans). K2 can also be found in some cheeses (mostly hard), some meats (liver and organ), sauerkraut, and some fish (including salmon). 

A small amount of K2 can be found in the colon, where it is synthesized by the intestinal bacteria.

Why is K2 important for health?

K1 primarily helps make proteins that enable blood clotting (also known as coagulation). One of K2’s most important functions is to support vitamin K-dependent proteins (VKDPs), which play a role in various biological functions. 

Osteocalcin (bone Gla protein) and matrix Gla protein (MGP) are two important VKDPs. Without enough K2, these VKDP’s cannot convert from their inactive form to an active one. The result is a higher risk for osteoporosis, cardiovascular disease (due to calcification of cardiovascular arteries) and other chronic conditions. (2)

What are the signs of vitamin K2 deficiency?

There is no blood test to measure vitamin K2 directly. Instead, the labs can measure the level of activation of VKDPs such as osteocalcin to get a rough idea of your K2 status.

There are, however, some signs that you may have a deficiency:

1. Bruising or bleeding easily

If you have a vitamin K1 deficiency, there’s a good chance you’re low on K2 as well. That’s because K2 also comes from the conversion of K1 in the body.

2. Osteoporosis or weak bones

K2 supports bone density. A deficiency increases the risk of osteoporosis and bone fractures. 

3. Cardiovascular disease

A K2 deficiency may lead to calcification of the cardiovascular arteries, a condition that’s not easily recognized. A coronary calcium scan, which uses computerized tomography (CT) imaging to take pictures of the arteries, can measure the amount of calcified plaque. 

4. Medications

Certain medications affect vitamin K levels in the body. Antibiotics can kill the gut bacteria that produce it, and blood thinners like warfarin can interact with it.

Some studies suggest that there is an association between statins and vitamin K2. There is evidence that statins may increase vascular calcification, and this may also be linked to a K2 deficiency. (3)

5. Existing conditions

People with gastrointestinal disorders (for example inflammatory bowel disease or colitis), or who have kidney disease may be at higher risk.

Growing Evidence for K2 in Other Chronic Health Conditions

K2 may be useful for more than bone and cardiovascular health. There’s growing interest in the role it may play in diabetes, some cancers, peripheral neuropathy, Alzheimer’s disease and other forms of dementia, chronic kidney disease, and other chronic health conditions (2,4,5).

1. Type 2 Diabetes

Research indicates that, through the involvement of osteocalcin, K2 may improve insulin sensitivity. It may also help reduce inflammation and lower lipid levels. (4)

2. Cancer

Jadhav and colleagues indicate that vitamin K2 may exert anti-cancer effects on leukemia, hepatocellular carcinoma (HCC), lung cancer, ovarian cancer, pancreatic cancer, and colorectal cancer (4).

Scientists believe it may help suppress cancerous cell growth by (1) stopping the cells from dividing and transforming into cancerous cells, (2) assisting in the removal of damaged parts of the cells, and (3) eliminating cancerous cells via apoptosis (programmed cell death). (6)

Combining K2 with some chemotherapy drugs may also lead to better results with fewer side-effects. (6)

3. Peripheral Neuropathy

Peripheral neuropathy occurs when the nerves outside of the brain and spinal cord – especially in the hands, feet, and arms – are damaged. Some of the symptoms include weakness, numbness, and pain. One of the causes of peripheral neuropathy is damage to the myelin sheath, the protective covering that surrounds nerve fibers. (4)

Studies suggest that vitamin K2 may facilitate the repair of the myelin sheath and may alleviate some of the symptoms (including pain, weakness, and fatigue). (2)

4. Alzheimer’s disease and other forms of dementia

There’s a growing number of studies linking vitamin K2 to the slowing and possible prevention of Alzheimer’s disease.

Vitamin K2 as MK-7 is unique because it impacts arterial calcification, and aortic stiffness may increase the risk of dementia in older adults. (2)

K2 is also involved in the synthesis of sphingolipids, an important class of lipids present in high concentrations in brain cell membranes. (7) Sphingolipids play crucial roles in the brain by regulating the rate of growth, differentiation, and death of central nervous system (CNS) cells. Studies have linked alterations in sphingolipid metabolism to age-related cognitive decline and neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. (8)

5. Chronic kidney disease

Chronic kidney disease (CKD) is commonly associated with vitamin K deficiency and is often accompanied by both cardiovascular disease (calcification of the arteries) and poor bone health (impaired bone metabolism). (5)

Poor vitamin K status seems to play a key role in the progression of CKD as well as in the onset and advance of both bone and cardiovascular complications. Evidence suggests that supplementing with vitamin K2 could help to prevent some of the complications associated with CKD. However, more studies are needed.

How much vitamin K2 is required for good health?

Current daily recommendations for K vitamins are based on vitamin K1 and the requirement for proper blood clotting. The current Recommended Daily Intake (RDI) is 120 micrograms (mcg) daily for adult men and 90 mcg for adult women.

When it comes to vitamin K2, these guidelines are yet to be established. Typical K2 supplements range between 100 mcg and 120 mcg, but some researchers suggest that higher intakes may be required when there’s a deficiency. Hopefully as more studies are done, safe amounts will become clearer.

Should we add vitamin K2 to our daily supplement stack?

If you’re older, you don’t get enough K2 in your diet, you’re taking certain medications, or you have a chronic condition like cardiovascular disease or osteoporosis, there’s a good chance you have a K2 deficiency.

There’s a growing body of research demonstrating that K2 may play an essential role in many debilitating and devastating chronic health conditions and that supplementation may both prevent and help alleviate many symptoms associated with these conditions.

Unfortunately, more studies are still needed – but until then, there’s good reason to consider adding K2 to your daily supplements. Just remember that it’s always a good idea to speak to your health professional before taking K2, especially when you’re on medications such as warfarin. 

References

1. Aggarwal S, Gupta S, Sehgal S, Srivastava P, Sen A, Gulyani G, Jain A. Vitamin K2: An emerging essential nutraceutical and its market potential. J Appl Biol Biotech 2022; 10(02): olla173–184

2. Maresz K. Growing Evidence of a Proven Mechanism Shows Vitamin K2 Can Impact Health Conditions Beyond Bone and Cardiovascular. Integr Med (Encinitas). 2021 Aug;20(4):34-38. PMID: 34602875; PMCID: PMC8483258.

3. Zhelyazkova-Savova, M.D.; Yotov, Y.T.; Nikolova, M.N.; Nazifova-Tasinova, N.F.; Vankova, D.G.; Atanasov, A.A.; Galunska, B.T. Statins, vascular calcification, and vitamin K-dependent proteins: Is there a relation? Kaohsiung J. Med. Sci. 2021, 37, 624–631.

4. Jadhav N, Ajgaonkar S, Saha P, Gurav P, Pandey A, Basudkar V, Gada Y, Panda S, Jadhav S, Mehta D and Nair S (2022) Molecular Pathways and Roles for Vitamin K2-7 as a Health-Beneficial Nutraceutical: Challenges and Opportunities. Front. Pharmacol. 13:896920. doi: 10.3389/fphar.2022.896920

5. Bellone F, Cinquegrani M, Nicotera R, Carullo N, Casarella A, Presta P, Andreucci M, Squadrito G, Mandraffino G, Prunestì M, Vocca C, De Sarro G, Bolignano D, Coppolino G. Role of Vitamin K in Chronic Kidney Disease: A Focus on Bone and Cardiovascular Health. Int J Mol Sci. 2022 May 9;23(9):5282. doi: 10.3390/ijms23095282. PMID: 35563672; PMCID: PMC9099759.

6. Xv F, Chen J, Duan L, Li S. Research progress on the anticancer effects of vitamin K2. Oncol Lett. 2018 Jun;15(6):8926-8934. doi: 10.3892/ol.2018.8502. Epub 2018 Apr 16. PMID: 29805627; PMCID: PMC5958717.

7. Popescu A, German M. Vitamin K2 Holds Promise for Alzheimer’s Prevention and Treatment. Nutrients. 2021 Jun 27;13(7):2206. doi: 10.3390/nu13072206. PMID: 34199021; PMCID: PMC8308377.

8. Alessenko AV and Albi E (2020) Exploring Sphingolipid Implications in Neurodegeneration. Front. Neurol. 11:437. doi: 10.3389/fneur.2020.00437