Vitamin K2 & Testostorone

Vitamin K is to vitamins what that guy who isn’t Sammy Davis Jr, Dean Martin or Frank Sinatra was to the Rat Pack in the 50s.

Like that guy though, just because it’s not as well-known as its counterparts, doesn’t mean it’s not extremely useful. For example, it plays a crucial part in helping our blood to clot when we’re injured and is also associated with the formation of healthy bones.

There are in fact thousands of different forms of vitamin K, the most common of these though being K1, or phylloquinone, found in nearly all leafy green vegetables, and K2, also known as menaquinone, present in things like red meat, egg yolks, butter and liver.

Despite only requiring a fairly small dose of vitamin K to get the recommended daily amount it is estimated that up to 80% of us do not get enough.

For a while it was K1 which took the spotlight when discussing vitamin K’s health benefits. This is perhaps because we get roughly 10 times the amount of K1 in in our diets than we do K2 and for a long time it was mistakenly believed, owing to a similar process having been observed in some animals, that our bodies would simply convert K1 into K2 where required.

However we now understand that not only does K2 need to be sourced separately but it also brings significant advantages which K1 does not. A study from the German Cancer Research Centre in Heidelberg, Germany, for instance, reported that vitamin K2 supplementation was able to reduce our risk of prostate cancer by up to 30%, whereas K1 had little or no effect.

Likewise researchers at the Erasmus Medical Centre in The Netherlands were able to demonstrate under clinical conditions that vitamin K2 significantly lowered the risk of cardiovascular disease by aiding the removal of calcium deposits from arteries, while again K1 did nothing in this area.

We are interested in it’s effects on testosterone though, so let’s have a look at that.

Does It Boost Testosterone?

The two forms of K2 are referred to as MK-7 and MK-4. MK-7 is produced in our gastrointestinal system and can be boosted through diet by eating fermented foods. It can also be taken effectively as a supplement because it stays in the bloodstream for up to three days. MK-4 on the other hand is synthesised all over the body but predominantly in the brain and reproductive organs. Our best dietary means of gaining this is by consuming the meat of any grass fed animal. MK-4 is often not considered such a strong candidate for supplementation because it only lasts in the body for approximately 8 hours. Ironically though, it is MK-4 which shows the greatest potential for testosterone boosting.

In a Japanese clinical trial, a group of researchers led by Ito Asagi of Tohoku University gave 75 mg/kg of vitamin K2 (MK-4) to male rats for a period of 5 weeks. For the duration they tested the testosterone levels in their blood plasma and testicles. The results at the end of the study showed a whopping 70% increase in the rats’ plasma testosterone and an even bigger upsurge inside the testicles, nearly 90%.

Notably levels of luteinizing hormone didn’t move an inch indicating that all the vastly improved testosterone production stems almost entirely from the testicles rather than the brain. Another strand of this same work was to study the effects vitamin K2 had when interacting directly with testicular I-10 cells inside a petri dish. Sure enough they found that K2 provoked the cells to produce significantly more testosterone.

This evidence is reinforced by a separate Japanese study which approached the hypothesis from a slightly different angle. The team found that in K2 deficient rats, testosterone levels were markedly lower because the genes in cholesterol which are heavily involved in the biosynthesis of testosterone are disrupted.

Vitamin K2 With D3

Again, like that guy who isn’t Sammy Davis Jr, Dean Martin or Frank Sinatra, vitamin K2 would still be great on its own but does its best work when teamed up with another player with a slightly higher profile.

In this case that partnership is with vitamin D3. You’ve possibly already clicked that these two have considerable common ground; namely ensuring the development and maintenance of strong, healthy bones. The simplest way to distinguish their two respective roles in this process is to say that while D3 aids the effective absorption of calcium, K2 directs it to the places in the body where it will be most beneficial, preventing build ups in unhelpful areas such as the arteries.

A 2013 study by Prof. Michal Nowicki and Ilona Kurnatowska published in Nephrology Dialysis Transplantation found that by giving patients with chronic renal disease a combination of vitamins K2 and D they were able to significantly slow the arterial calcification, which is a usual symptom of the condition, in a way that D alone did not. Not only does this cut down on the chances of cardiovascular problems as previously mentioned, but with less accumulation of calcium in the wrong places the vitamin D in our system is uninhibited and free to stimulate more testosterone.

For evidence of D3 and K2 working together to enhance the durability of a physique we can look to a clinical trial by the Kyorin University School of Medicine in Tokyo. There, researchers there took 168 female Sprague-Dawley rats and divided them into five groups for a period of 16 months. These groups consisted of the control group, which was fed a regular diet, group A was given vitamin K2; group B received vitamin D, while group C took high calcium and group D, a combination of vitamins D and K2 and calcium. The rats reached peak bone mass aged 8 months after which the team monitored the rate of decrease in density. They found that the smallest loss occurred in the rats that were given vitamin D and K2 alongside a healthy intake of calcium. The conclusion they drew being that this combination can supress the age relate decrease in bone mass thus ultimately preventing bone fractures caused by osteoporosis. Basically, this particular dream team keeps us stronger for longer.


So there you go. You may not have heard much about vitamin K2, but apparently it’s true what they say about it always being the quiet ones. We’ve seen clear evidence that vitamin K2 has a an important contribution to make as far as boosting our testosterone goes, not only in its own right, but also in a supporting role for vitamin D3, helping it to stimulate test production more efficiently.

Surprisingly the inclusion of K2 is still relatively rare amongst the combined test boosters on the market, but this merely shows how many out there are missing a trick. You’ll find the supplements that are truly instep with the latest research make room for K2 and it really is worth seeking those out, particularly if they’re clued up enough to combine it with D3.

Like I always say in these reviews, no single ingredient will boost your testosterone to the best it can be alone, but combine K2 with the likes of D3, D-Aspartic Acid, genseng and luteolin and you can expect to see real improvements to your physical performance and overall wellbeing. Joey Bishop! That’s that guy. Bugging me all review, that.

Study 1: Nimptsch et al (2008)

Title: Dietary intake of vitamin K and risk of prostate cancer in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition

Researchers: Katharina Nimptsch, Sabine Rohrmann, and Jakob Linseisen

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Study 2: Geleijnse et al Study (2004)

Title Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study.

Researchers: Geleijnse JM, Vermeer C, Grobbee DE, Schurgers LJ, Knapen MH, van der Meer IM, Hofman A, Witteman JC.

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Study 3: Asagi et al Study (2011)

Title: Menaquinone-4 enhances testosterone production in rats and testis-derived tumor cells.
Researchers: Asagi Ito, Hitoshi Shirakawa, Naofumi Takumi, Yoshihiko Minegishi, Ai Ohashi1, Zakir H Howlader, Yusuke Ohsaki, Toshiro Sato, Tomoko Goto and Michio Komai
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Study 4: Shirakawa et al Study (2006)

Title Vitamin K deficiency reduces testosterone production in the testis through down-regulation of the Cyp11a a cholesterol side chain cleavage enzyme in rats
Researchers: Hitoshi Shirakawaa, Yusuke Ohsakia, Yoshihiko Minegishia, Naofumi Takumia, Kousaku Ohinataa, Yuji Furukawaa, Takeo Mizutanib, Michio Komaia
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Study 5: Nowicki & Kurnatowska Study (2010)

Title: Vitamin K2 and Vessel Calcification in Chronic Kidney Disease Patients (CACSK2)
Researchers Prof. Michal Nowicki & Ilona Kurnatowska
Sponsor: Medical University of Lodz
Read More:

Study 6: Hirano & Ishii Study (2002)

Title: Effects of vitamin K2, vitamin D, and calcium on the bone metabolism of rats in the growth phase.
Researchers: Hirano J & Ishii Y.
Read More:

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Comment List

  • keith 18th September 2017

    great read , but what can you get that has vitamin k2 ,d-3 , d-aspartic acid , genseng and lutealin in it .
    i want to increase my testosterone , am over 50

    • Rob Wright 19th September 2017

      Hi Keith,

      Thanks for the comment. Nice to get this as it’s nice to get an easy one! For sure you should be looking at Prime Male. It’s our current number one for low test (so the over 35s category which you fall into). It has all the ingredients you are looking for in doses which all the research indicates will prove to be effective. And there’s a whole load of other ones in the mix as well, it’s a great product.

      Prime Male Ingredients Page
      Our Prime Male review

      Best of luck with it.