Vitamin K2 and Testosterone: Menaquinone & Androgens

Medical Review by Dr. Vlad Belghiru, MD

There’s one vitamin that really deserves a whole lot more attention than what it’s getting now, and that’s the vitamin K2 (menaquinone). Heck, most people don’t even know that it exists, nor that it reduces cardiovascular disease risk, and greatly enhances bone formation.

Actually, there are thousands of different forms of vitamin K, but the ones that we associate with the term are the K1 (phylloquinone), and K2 (menaquinone).

For some odd reason, the K1 form, which is present in almost all leafy green vegetables is getting all of the attention in media. While nobody seems to talk about the K2 form, which can be found in foods such as cheese, egg yolks, butter, fermented foods, and liver.

Our diets contain roughly 10 times more K1 than K2. And a common misconception is that we wouldn’t need K2 since the human body would convert K1 into K2. But even though the occurrence is seen on animals, the human body doesn’t seem to do it as effectively. In fact, recent studies suggest that we need to consume the actual K2 form in order to get the benefits (study, study).

The benefits you ask? Well, aside from K2 being awesome for our cardiovascular health and bone density, especially when taken in a stack with vitamin D, there’s a bunch of other great effects associated with vitamin K2 supplementation…

…And one of them is the link between vitamin K2 and testosterone:

Vitamin K2 and Testosterone Synthesis

vitamin k2 testosteroneThe importance of vitamin K2 is quite a new thing, even to most researchers. And that’s because, for a long time, it was believed that the K1 form was all that we need and that both of the vitamins (K1 and K2) would of have had similar effects.

However, a few recent studies have proved this to be not true at all.

The forms of vitamin K2 that we’re most deficient in are the MK-7 and MK-4.

  • MK-7 is produced inside our gastrointestinal system, we can get it from fermented foods. MK-7 is also considered to be very effective in terms of supplementation, as it lasts for roughly three days in the bloodstream.
  • MK-4 is synthesized all over the body from enzymes (being exceptionally high in the brain and reproductive organs). We can get it through diet by consuming grass-fed animal meats (grain-fed doesn’t contain it). You can also supplement with MK-4, but it only lasts for roughly 8 hours in the bloodstream, and therefore is considered to be worse for supplementation than MK-7.

Still, there’s one major reason why I consider the MK-4 form to be superior to the more long-lasting MK-7. And that’s because it has a mechanism to increase testosterone production:

a) In this Japanese study, Asagi et al. fed 75 mg/kg of vitamin K2 (MK-4) to male Wistar rats for 5 weeks, while simultaneously measuring the testosterone content from their blood plasma and testicles. The results after the fifth week showed a nice, more than 70% increase in plasma testosterone levels, and an even bigger increase was seen inside the testes (nearly 90%). And as you can see from the pictures below, luteinizing hormone (LH) levels didn’t budge, which probably means that the K2 works by stimulating testosterone production directly inside the ballsack, and not via the brain.

vitamin k2 and male testosterone levels
b) In the same study which is presented above, the scientists tested vitamin K2 (MK-4) incubation directly on the testicular I-10 cells inside a petri dish, and found out that the more MK-4 they exposed to the cells, the more testosterone was produced.

testosterone and vitamin K2
c) Another Japanese study from different researchers found out rather similar results. They saw that in male rats, vitamin K2 deficiency reduces testosterone levels significantly, as it messes up with the genes involved in the biosynthesis of testosterone from cholesterol. When these rats were given vitamin K2 (MK-4), their testosterone levels increased rapidly. Similar results were seen in this study.


The studies above are somewhat solid proof of the fact that vitamin K2 (MK-4) has a mechanism of increasing testosterone levels, but so far the mechanism has only been tested on rodents and isolated testicular cells. And the dosages used in the rat studies are abnormally high.

The human equivalent of the dosage in the first study is 12mg/kg. That’s a huge dose. Given that 45 mg’s is considered to be the upper safe limit for humans.

I doubt that you’d ever need to take that high dose of vitamin K2 to actually see the benefits, but when there are no human studies on its hormonal effects, you can’t really tell…

There will be a time when K2 supplementation is tested similarly in humans, but before it happens, I have no problem supplementing with 30-45 mg’s of potent vitamin K2 (affiliate link) once every few days, just to maintain heart and bone health. And if there’s a bonus testosterone boost happening in the background, I wouldn’t mind at all.

Ali Kuoppala

Ali Kuoppala is the founder of Anabolic Men. He has authored and co-authored multiple men's health books and focuses on uncovering the methods of optimizing hormonal health. To date, his articles on various websites have been read more than 15-million times. To read more about Ali, visit his Medium article.