You’ve probably heard lots about vitamins A, C, vitamin D3, zinc, magnesium, and iron, but have you heard much about vitamin K?
Not likely.
Although equally as important as the other essential vitamins and minerals, most people forget about K—it’s pretty rare in the Western diet, and health professionals typically don’t educate us on the importance of this fat-soluble nutrient.
But vitamin K is essential for optimal physiological performance and plays a vital role in bones, the cardiovascular system, insulin regulation, and much more.
If you’re unfamiliar with this nutrient, we’re breaking down the ins and outs of vitamin K, also known as “koagulations vitamin.”
We’ll cover what it is, the benefits of vitamin K, vitamin K deficiency signs and symptoms, and how to get enough vitamin K1 and vitamin K2 in your diet to keep your vitamin K levels up to par.
What Is Vitamin K?
We generally think about vitamin K as a single vitamin, but it’s a group of fat-soluble compounds involved in several body functions ranging from bone health and glucose regulation to blood clotting and vascular health 1.
Vitamin K is essential for the proper function of several proteins in the body, some of which include the coagulation factors (II, VII, IX, X, and protein C, and protein S), osteocalcin (a protein involved in bone health), and matrix-Gla protein (MGP) (an anti-calcification protein)2.
The nutrient exists naturally in two primary forms: vitamin K1 (phylloquinone) and vitamin K2 (menaquinone, MK-4 to MK-10) 2, 3. Because several types of vitamin K naturally exist, they’re named based on the length of their side chain.
Vitamin K1 is naturally found in plant foods like leafy green vegetables and olive oil. In contrast, K2 is found in smaller quantities in animal foods, such as organ meats, chicken, butter, cheese, and egg yolks, along with a fermented soybean product called natto.
The primary function of vitamin K1 and K2 is as a cofactor for the γ-glutamyl carboxylation of all vitamin K-dependent proteins. Vitamin K is the rate-limiting factor for these reactions, and insufficient intake can slow or inhibit specific biological processes 4.
But here’s the thing with vitamin K. Most nutrients must come through diet or supplementation because the body can’t produce them—not vitamin K.
Intestinal bacteria can produce small amounts of vitamin K. However, they cannot produce enough to meet intake requirements, which is why we emphasize diet and supplements.
Vitamin K1 vs. Vitamin K2
So, what’s the actual difference between vitamin K1 and vitamin K2? Aside from naturally existing in different foods, they elicit different functions. And in terms of supplementation, one may be more effective than the other.
As we mentioned before, naturally occurring vitamin K compounds inherent to plant foods are called phylloquinone (vitamin K1).
In contrast, vitamin K2 is naturally found in animal-based products and fermented foods—on top of several bacterial-derived menaquinones (MKs) synthesized in the gut 5.
Although the basic structure of all vitamin K compounds is similar, the side chains differentiate them. These side chains dictate how they are metabolized—transport, target tissue uptake, and excretion.
While vitamin K1 only comes in one form, phylloquinone, there are several menaquinones (vitamin K2).
The ones you’ll want to know about are short-chain MK-4 (eggs, meat, liver) and long-chain menaquinones MK-7, MK-8, MK-9, and MK-10 (cheese, curd, sauerkraut, natto) 6.
We’ll cover the benefits of vitamin K in a minute, but as we said, vitamin K1 and vitamin K2 don’t have the same functions. Menaquinones like MK-7 are more heavily involved in the blood coagulation cascade than K1 or MK-4 6.
And compared to K1, MK-7 has a longer half-life, which means it elicits its effects more long-term effect. However, studies also show that K2 is involved in bone health and cardiovascular function.
The Benefits Of Vitamin K
Supports healthy bones
Calcium and vitamin D are the two nutrients that come to mind when you think about bone health.
But don’t shun vitamin K just yet! Vitamin K plays an essential role in bone integrity and strength through its involvement in calcium metabolism—yep, you read that right (it’s not just vitamin D and magnesium that are needed).
Vitamin K2 is required to activate two calcium-binding proteins: matrix GLA protein (MGP) and osteocalcin, which are involved in building and maintaining bone tissue 7, 8.
Many mechanisms drive vitamin K’s action on bone health, but there are two key ones we want to emphasize:
The gamma-carboxylation of osteocalcin, an essential protein involved in bone mineralization, and bone mineral density.
Vitamin K’s effect on calcium homeostasis
On top of these two functions, vitamin K also plays a vital role in regulating genetic transcription of osteoblastic markers9
- Suppressing bone resorption
- Regulating the formation of osteoclasts
- Low levels of vitamin K interfere with the activation of osteocalcin and decrease the activity of osteoblasts (bone-building cells), which increases the risk of osteoporosis and vascular calcification 10.
- Prevents vascular calcification and improves cardiovascular health
Vascular calcification refers to the deposition of minerals in the walls of blood vessels (arteries and veins).
It can take on several forms, but in any case, it’s associated with several chronic diseases, including atherosclerosis, diabetes, certain heredity conditions, and kidney disease 11.
People with vascular calcification have an increased risk of cardiovascular events, which create issues with blood flow to organs and tissues.
While dietary and lifestyle factors can make a big difference in cardiovascular health, so can vitamin K supplementation. Vitamin K, specifically vitamin K2 is required by the enzyme gamma-glutamate carboxylase to convert Matrix Gla protein (MGP) into its active carboxylated form 12.
When activated, MGP inhibits calcification. Although the exact mechanism isn’t clear, several studies support the role of vitamin K in heart health. One study found that expression of under-carboxylated MGP was linked to vascular calcification and a higher risk of cardiovascular mortality.
However, vitamin K2 supplements increased levels of carboxylated MGP, which could prevent vascular calcification and any associated risks or outcomes.
May improve insulin sensitivity
Although you may not link vitamin K to improved glucose regulation, it turns out that it can! Studies point to a beneficial effect of vitamin K on insulin sensitivity, metabolic syndrome, glucose homeostasis, and reducing the risk of diabetes 13.
Vitamin K has also been shown to cytokines and inflammatory markers, which are implicated in the pathology of insulin sensitivity.
The exact mechanisms as to how vitamin K influences insulin sensitivity isn’t clear, but some experts suggest that the vitamin K-dependent bone protein, osteocalcin, mediates the endocrine pathway.
This pathway then influences insulin sensitivity through pancreatic β cells, promoting their proliferation, and increasing insulin secretion.
Promotes blood coagulation
But the most popularized role—and what initially caused the discovery of the fat-soluble vitamin K—is in blood clotting or hemostasis.
It is required to form 13 proteins needed for the coagulation cascade, which is necessary to put the breaks on bleeding.
They can be broken down into four categories based on conditions they’re associated with 14:
- Only with bleeding (FX deficiency)
- Both bleeding and thrombosis (FII, FVII, and FIX)
- Only with thrombosis (protein C and protein S)
- No association with either bleeding or thrombosis (protein Z)
For your body to stop bleeding, it requires all of these proteins. A deficiency of vitamin K is classified as an acute, life-threatening condition due to excessive bleeding.
Vitamin K deficiency + signs and symptoms
Although a vitamin K deficiency is less common than a deficiency of other nutrients, it can happen—and signs aren’t the most obvious.
Here are some of the reasons for a vitamin K deficiency 15:
- Neonatal deficiency
- Hereditary combined with vitamin K-dependent clotting factors deficiency (VKCFD)
- Inadequate vitamin K absorption due to a chronic disorder
- Drug-related
Coumarin, an anticoagulant more commonly known as Warfarin, can lead to decreased production of the proteins involved in blood clotting.
At the same time, some broad-spectrum antibiotics can cause the body to produce less vitamin K or interfere with its efficacy.
A vitamin K deficiency can also occur in people with fat absorption issues, as it's part of the fat-soluble vitamins and requires the presence of fat for absorption.
Some of these disorders include:
- Celiac disease
- Cystic fibrosis
- Intestinal or biliary tract disorders (liver, gallbladder, bile ducts)
- People with a portion of their intestine removed
So, what should you look out for with a vitamin K deficiency?
Excessive bleeding is one of the tell-tale signs of a vitamin K deficiency, but it’s important to remember that bleeding can happen in areas besides a cut or wound site.
This bleeding may also be evident if someone:
- Bruises easily
- Has small blood clots underneath their nails
- Bleeds in mucous membranes that line areas inside the body
- Produces dark black, tar-like stool that contains some blood
Although vitamin K is heavily involved in blood clotting, a deficiency of vitamin K can also lead to issues with bone and heart health, such as lowered bone mineral density, slow blood clotting, an increased risk of cardiovascular disease, weak bones, and more.
How To Get More Vitamin K In Your Diet
Are you concerned about how much vitamin K you're getting? Want to increase your vitamin K intake naturally?
Taking vitamin K supplements is an easy way to ensure you hit the dietary reference intake. While there are plenty of plant food sources that contain vitamin K1,] when it comes to vitamin K2, you have to be a bit more strategic.
Here are your best sources.
- Vitamin K1
- Kale (cooked)
- Mustard greens (cooked)
- Swiss chard (raw)
- Collard greens (cooked)
- Spinach (raw)
- Broccoli (cooked)
- Brussel sprouts (cooked)
- Green beans (cooked)
- Prunes
- Kiwi
- Avocado
- Green peas (cooked)
- Beet greens (cooked)
- Cabbage (cooked)
- Parsley (fresh)
- Vitamin K2
- Natto
- Beef liver
- Pork chops
- Chicken
- Goose liver pate
- Hard cheeses
- Soft cheese
Note that if you're trying to increase your dietary intake of vitamin K1 and vitamin K2, it's important to consume them alongside healthy fats to enhance absorption.
Vitamin K supplements typically contain a fat source to support absorption or at provided in the most bioavailable form - but dietary vitamin K doesn't have this luxury.
The Alternative: Vitamin K Supplements
On the other hand, supplementation can also be a great way to ensure you’re meeting your daily intake of vitamin K.
Because the concentration of vitamin K is relatively low in most foods, especially plant-based foods, you’ll either end up eating a ton of leafy green vegetables or go the supplementation route.
Our advice? Make it easy and cover all your nutritional needs in one go with vitamin K supplementation.
With Performance Lab NutriGenesis Multi, you don’t need to stress about how much vitamin K you're consuming and if you're consuming enough nutrients in general to support human health (and by the way, stress actually depletes nutrients).
Multi supplies 100% RDI of 17+ vitamins and minerals for optimal full-body performance. It uses NutriGenesis technology to provide nature-identical vitamins and minerals naturally complexed with cofactors to enhance absorption and bioactivities.
Why play with fire and run the risk of a deficiency when you can pop back Multi for your daily dose?
Plus, you're also getting vitamin D3 combined with vitamin K2 to provide greater support for heart and bone health. A vitamin K supplement seems like the most logical solution to us!
References
- Booth SL. Roles for vitamin K beyond coagulation. Annu Rev Nutr. 2009;29:89-110.
- DiNicolantonio JJ, Bhutani J, O'Keefe JH. The health benefits of vitamin K. Open Heart. 2015;2(1):e000300.
- Beulens JW, Booth SL, van den Heuvel EG, Stoecklin E, Baka A, Vermeer C. The role of menaquinones (vitamin K₂) in human health. Br J Nutr. 2013;110(8):1357-1368.
- Stafford DW. The vitamin K cycle. J Thromb Haemost. 2005;3(8):1873-1878.
- Shearer MJ, Newman P. Metabolism and cell biology of vitamin K. Thromb Haemost. 2008;100(4):530-547.
- Sato T, Schurgers LJ, Uenishi K. Comparison of menaquinone-4 and menaquinone-7 bioavailability in healthy women. Nutr J. 2012;11:93.
- Shearer MJ, Fu X, Booth SL. Vitamin K nutrition, metabolism, and requirements: current concepts and future research. Adv Nutr. 2012;3(2):182-195.
- Misra D, Booth SL, Tolstykh I, et al. Vitamin K deficiency is associated with incident knee osteoarthritis. Am J Med. 2013;126(3):243-248.
- Rodríguez-Olleros Rodríguez C, Díaz Curiel M. Vitamin K and Bone Health: A Review on the Effects of Vitamin K Deficiency and Supplementation and the Effect of Non-Vitamin K Antagonist Oral Anticoagulants on Different Bone Parameters. J Osteoporos. 2019;2019:2069176.
- Cranenburg EC, Schurgers LJ, Vermeer C. Vitamin K: the coagulation vitamin that became omnipotent. Thromb Haemost. 2007;98(1):120-125
- Wu M, Rementer C, Giachelli CM. Vascular calcification: an update on mechanisms and challenges in treatment. Calcif Tissue Int. 2013;93(4):365-373.
- Westenfeld R, Krueger T, Schlieper G, et al. Effect of vitamin K2 supplementation on functional vitamin K deficiency in hemodialysis patients: a randomized trial. Am J Kidney Dis. 2012;59(2):186-195.
- Suksomboon N, Poolsup N, Darli Ko Ko H. Effect of vitamin K supplementation on insulin sensitivity: a meta-analysis. Diabetes Metab Syndr Obes. 2017;10:169-177.
- Girolami A, Ferrari S, Cosi E, Santarossa C, Randi ML. Vitamin K-Dependent Coagulation Factors That May be Responsible for Both Bleeding and Thrombosis (FII, FVII, and FIX). Clin Appl Thromb Hemost. 2018;24(9_suppl):42S-47S.
- Eden RE, Coviello JM. Vitamin K Deficiency. . In: StatPearls . Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536983/