Have you ever heard of vitamin K2?
If the answer is no, you are not alone.
Most people don’t even know vitamin K2 exists. This vitamin is a rare sight in our diet, and because of it, mainstream media hasn’t given it a lot of attention.
However, this doesn’t mean this nutrient is useless. Quite the opposite, actually. Vitamin K2 plays a key role in numerous functions for your health.
Vitamin K2 is one of the silent heroes in boosting your overall health and testosterone.
That’s why we’ve decided to shine some light on it – using scientific research to back up our findings.
What is Vitamin K
Vitamin K is a fat-soluble vitamin. It was first discovered back in 1929. It was quickly recognized as a nutrient important for blood coagulation, aka, clotting.
The symbol “K” actually comes from the word Koagulationsvitamin – this is how vitamin K was first called. 
Believe it or not, but vitamin K was also discovered by a dentist. His name was Weston Price.
Weston realized that there was some unknown nutrient in many non-industrial foods which protected against chronic diseases and tooth decay. He initially called this nutrient “activator X.” While in fact, it’s now known as vitamin K2. 
History aside, how many types of vitamin K are there?
There are actually two main forms of this vitamin, and they are vitamin K1 and K2.
However, vitamin K2 is further divided into different subtypes. The best-known forms of vitamin K2 are MK-4 and MK-7.
You’ll find vitamin K1 mostly in plant foods. Vitamin K2, on the other hand, is found in fermented foods and animal products. 
To sum it up:
Vitamin K was first discovered in 1929 as an essential nutrient for blood coagulation. There are two types of vitamin K: K1 and K2. Vitamin K2 has two subtypes: MK-4 and MK-7. You’ll find vitamin K1 in plants. And vitamin K2 in fermented foods and animal products.
How Does Vitamin K Work?
Before going any further, let me make it clear that when I say vitamin K, I’m referring to both Vitamin K1 and K2. Although there is some evidence that K2 is more effective, both generally have the same effects.
Okay, so what does vitamin K do in your body?
For starters, it activates proteins that regulate cardiovascular health, calcium metabolism, and blood coagulation.
One of vitamin K’s most important functions is that it regulates where calcium is stored in your body.
This is important because calcium needs to go primarily to your bones. Without enough vitamin K, calcium gets stored in your arteries and kidneys. As you can imagine, this isn’t good news for your heart. [3, 4]
There is some emerging science showing that vitamin K1 and K2 have different effects when it comes to calcium metabolism. Some even argue that they should be classified as different nutrients.
Certain animal studies show that vitamin K2 (specifically MK-4 subtype) is far more effective at reducing artery calcification than vitamin K1. 
Studies in people also suggest that vitamin K2 supplementation yields better benefits on heart and bone health as opposed to vitamin K1. 
However, these are just two studies, so it’s smart to take them with a grain of salt.
Until more evidence comes out, it’s safe to say that both vitamin K1 and K2 play an important role in our health.
To sum it up:
Vitamin K activates a protein which plays a key role in heart health, bone health, and blood coagulation (clotting). Some evidence suggests that vitamin K2 might be more effective at this than K1, but we need more research to fully understand the differences between them.
Differences Between Vitamin K1 and K2
While both vitamin K1 and K2 are important for heart and bone health, they have some slight differences.
First and foremost, you’ll find vitamin K1 in plants, while vitamin K2 usually comes from animal products.
Generally, vitamin K1 has a poor absorption rate in the body. One study suggested that only 10% of K1 that you consume through plants actually gets utilized in the system. 
As for vitamin K2’s absorption, there’s not much research behind it. Some experts suggest that since vitamin K2 is a part of fatty foods, it could lead to better absorption than K1. 
That’s because vitamin K is a fat-soluble nutrient. Meaning it dissolves in fat.
On top of this, the long side chain of vitamin K2 enables it to stay in your blood longer than vitamin K1.
For example, K1 might stay in your body for only several hours, whereas K2 can keep circulating in your blood for days. 
Some experts suggest that vitamin K2’s ability to circulate longer than K1 enables it to be better utilized in various tissues in the body. 
To sum it up:
Only 10% of consumed vitamin K1 gets absorbed. Vitamin K2 absorbtion rate is still unknown. However, it’s thought that vitamin K2 is more efficient because it stays circulating in your blood for longer – allowing tissues in the body to use it more efficiently.
Foods Rich in K1
You’ll find vitamin K1 mostly in plants. It’s actually the dominant vitamin in our diet.
Here we have a list of foods rich in vitamin K1. Each value shows how much vitamin K1 you’ll find in one cup of cooked vegetables. 
- Kale: 1,062 mcg
- Collard greens: 1,059 mcg
- Spinach: 889 mcg
- Broccoli: 220 mcg
- Brussels sprouts: 218 mcg
Foods Rich in K2
Different subtypes of vitamin K2 come from different foods.
For example, animal products are rich in the MK-4 subtype. These include egg yolks, butter, and chicken.
Vitamin K2, subtypes MK-5 through MK-15 are found in fermented foods. It is bacteria that produce them.
The best source of MK-7 is a Japanese delicacy called Natto. It’s a dish made from fermented soybeans.
Some pork products also contain hefty amounts of vitamin K2. 
- Natto: 1,062 mcg
- Pork sausage: 383 mcg
- Hard and soft cheeses: 50-76 mcg
- Chicken legs and thighs: 60 mcg
- Egg yolk: 32 mcg
Effects of Vitamin K2 on Testosterone
It’s one thing to increase your testosterone levels, and other to keep them increased. Vitamin K2 is particularly good at the latter. 
As I said, you’ll find vitamin K2 in fatty foods. Such as eggs, cheeses, chicken, pork, and butter.
However, the problem with these foods is that they contain a bunch of fats. And not all of them are healthy. This might not tie in with your diet if you’re looking to stay lean.
That’s where supplementation comes it. Recent research suggests that vitamin K2 supplementation helps maintain elevated testosterone production by stimulating your testes.
And again, when you combine it with vitamin D3, it further enhances the sunshine vitamin’s benefits on your male hormone. On top of that, it also supports healthy and strong bones. 
To sum it up:
Vitamin K2 is shown to prevent testsoterone loss by stimulating testes to spurt out testosterone when necessary. In addition, it also boosts the effects of vitamin D3 on the male hormone. It’s not exactly a testosterone booster, but a testosterone maintainer if you will.
Other Benefits of Vitamin K2
Maintains Healthy Teeth
Studies have shown that vitamin K2 appears to affect dental health.
One of the proteins which play a key role in maintaining healthy teeth is called osteocalcin. This is the same protein that is regulated by vitamin K2. 
It’s worth mentioning that vitamins A and D also play an important role here. Because they work synergistically with vitamin K2.
Reduces Cancer Risk
Cancer is no joke. It’s one of the most common causes of death in Western civilization.
While modern research has found ways to mitigate and treat it, there’s still a lot unknown about this malign illness. So finding effective and natural remedies for it is extremely important.
There are more studies needed to prove this, but so far vitamin K2 looks like a promising agent for fighting specific types of cancer.
Supplementing With Vitamin K2
As we’ve discussed, there are different forms of vitamin K. The main ones are vitamin K1 and K2.
The minimum dosage for vitamin K1 is 50 micrograms daily. The upper limit is 1,000 micrograms per day.
As for vitamin K2, the minimum dosage for the MK-4 subtype is 1,500 micrograms. However, this is only to satisfy the basic needs.
If you want to reap its full benefits for heart, testosterone, and bone health, then you want to take between 2,000-3,000mcg of K2.
However, doses up to 45,000 micrograms are safe to use as a part of a super loading regimen – according to the studies.
The minimum daily dosage for MK-7, MK-8, and MK-9 forms of vitamin K2 is 90mcg. The optimal dosage is around 360mg.
The upper limit for the MK-7 subtype is still unknown. However, experts suggest there’s no reason to worry since it’s an extremely safe form of the vitamin – no side effects were reported from taking normal doses.
With or Without Food?
Whether you’re taking vitamin K1 or K2, remember to take it alongside food.
Even if you’re eating vitamin K from a plant source, make sure to accompany it with some fat. This will improve its absorption drastically, because it’s a fat-soluble vitamin.
Vitamin K2 is a fat-soluble nutrient and is one of the K vitamins, the other one being K1.
While vitamin K1 benefits blood clotting, vitamin K2 promotes heart, bone, and testosterone health. Looking at the studies, it’s clear that we need both vitamin K1 and K2 to maintain optimal health.
Food sources of vitamin K1 include plants such as leafy greens. Vitamin K2, on the other hand, is mostly found in fatty foods and fermented products.
Depending on your goals, you might want to supplement with vitamin K2 for additional benefits. Such as improved cardiovascular health, elevated testosterone levels, and such.
Vitamin K is fairly safe to supplement with, even at high doses. There are no reported negative side effects from optimal dosages of this vitamin.
However, it’s always smart to consult with your doctor if you’re on any kind of medication before taking vitamin K. This especially applies to those who are taking a blood clotting or heart drugs.
References[showhide type=”links” more_text=”Show References” less_text=”Hide References”]
 Vitamin K Metabolism - link.springer.com  Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7.  Osteocalcin: the vitamin K-dependent Ca2+-binding protein of bone matrix; Hauschka PV.  The role of vitamin K in soft-tissue calcification; Theuwissen, Smit E, Vermeer C. - NCBI.  Tissue-specific utilization of menaquinone-4 results in the prevention of arterial calcification in warfarin-treated rats; Spronk HM1, Soute BA, Schurgers LJ, Thijssen HH, De Mey JG, Vermeer C.  Vitamins K1 and K2: The Emerging Group of Vitamins Required for Human Health Gerry Kurt Schwalfenberg.  Effect of food composition on vitamin K absorption in human volunteers. Gijsbers BL1, Jie KS, Vermeer C.  The role of menaquinones (vitamin K₂) in human health. Beulens JW1, Booth SL, van den Heuvel EG, Stoecklin E, Baka A, Vermeer C.  Vitamin K-containing dietary supplements: comparison of synthetic vitamin K1 and natto-derived menaquinone-7. Schurgers LJ1, Teunissen KJ, Hamulyák K, Knapen MH, Vik H, Vermeer C.  Vitamin K: the effect on health beyond coagulation - an overview. Vermeer C1.  United States Department of Agriculture, Agricultural Research Service. USDA Food Composition Databases.  Measurement of Multiple Vitamin K Forms in Processed and Fresh-Cut Pork Products in the U.S. Food Supply. Fu X1, Shen X1, Finnan EG1, Haytowitz DB2, Booth SL1.  Determination of phylloquinone and menaquinones in animal products with fluorescence detection after postcolumn reduction with metallic zinc. Koivu-Tikkanen TJ1, Ollilainen V, Piironen VI.  Determination of phylloquinone and menaquinones in food. Effect of food matrix on circulating vitamin K concentrations. Schurgers LJ1, Vermeer C.  The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review. Adriana J. van Ballegooijen, Stefan Pilz, Andreas Tomaschitz, Martin R. Grübler, and Nicolas Verheyen.  Menaquinone-4 enhances testosterone production in rats and testis-derived tumor cells. Ito A1, Shirakawa H, Takumi N, Minegishi Y, Ohashi A, Howlader ZH, Ohsaki Y, Sato T, Goto T, Komai M.  Effect of continuous combined therapy with vitamin K(2) and vitamin D(3) on bone mineral density and coagulofibrinolysis function in postmenopausal women. Ushiroyama T1, Ikeda A, Ueki M.  Dietary vitamin K alleviates the reduction in testosterone production induced by lipopolysaccharide administration in rat testis. Takumi N1, Shirakawa H, Ohsaki Y, Ito A, Watanabe T, Giriwono PE, Sato T, Komai M.  The health benefits of vitamin K: Review. James J DiNicolantonio, Jaikrit Bhutani, and James H O'Keefe. NCBI article.  Vitamin K2 enhances osteocalcin accumulation in the extracellular matrix of human osteoblasts in vitro. Koshihara Y1, Hoshi K. NCBI.  Formation of odontoblast-like cells from cultured human dental pulp cells on dentin in vitro. Huang GT1, Shagramanova K, Chan SW.  Induction of type I collagen and osteocalcin in human dental pulp cells by retinoic acid. Thaweboon S1, Thaweboon B, Choonharuangdej S, Chunhabundit P, Suppakpatana P.  Effect of menatetrenone, a vitamin k2 analog, on recurrence of hepatocellular carcinoma after surgical resection: a prospective randomized controlled trial. Ishizuka M1, Kubota K, Shimoda M, Kita J, Kato M, Park KH, Shiraki T.  The effect of menatetrenone, a vitamin K2 analog, on disease recurrence and survival in patients with hepatocellular carcinoma after curative treatment: a pilot study. Mizuta T1, Ozaki I, Eguchi Y, Yasutake T, Kawazoe S, Fujimoto K, Yamamoto K.  Dietary intake of vitamin K and risk of prostate cancer in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition (EPIC-Heidelberg). Nimptsch K1, Rohrmann S, Linseisen J.[/showhide]