|Image 1: Who would have thought that this piece of goose liver pate contains a natural test-booster? Unfortunately even this SuperFood won't give you your 1g /day.|
Suttie. 2011). This ability to produce MK-4 from dietary substrates and the high MK-4 content in human brains and reproductive organs speaks for the importance of this hitherto largely overlooked "vitamin" (in the strict sense it is no vitamin if your body can produce it on its own).The Japanese scientists treated a group of Male Wistar rats on a standard diet with 75mg/kg body weight of vitamin K2 (menaquinone-4; human equivalent 12mg/kg, 972mg for an 80kg adult) for 5 weeks and measured their plasma and testes levels of testosterone... and the results, were "sexy", as you can see in figure 1 ;-)
|Figure 1: Serum testosterone levels (in ng/dl) in male Wistar rats in the course of five weeks on 75mg/kg MK4 vs. control (data adapted from Asagi. 2011)|
|Figure 2: MK4 levels (pmol/g tissue) in liver and testes of rats after 5 weeks on 75mg/kg supplemental menaquinone-4 (data adapted from Asagi. 2011)|
From the rat model to the petri-dish: Exploring the underlying mechanism
In in-vitro studies, the scientists also found that vitamin K1 was without effect on testicular I-10 cells, and that Warfarine, a pharmacological anticoagulant did not suppress the dose-depend (cf. figure 3) testosterone boosting effects of MK4 on a cellular level.
|Figure 3: Relative increase in testosterone production of testicular I-10 cells after 24h of incubation with different amounts of MK4 (data calculated based on Asagi. 2011)|
treatment of I-10 cells with MK-4 in the presence of db-cAMP was found to significantly enhance testosterone secretion into the cul-ture medium, and the maximum enhancement of secretion was observed when 30μM MK-4 was present in the medium.That being said, I bet your next question is "where can I get that stuff"? Well, the most obvious answer would be: At the supplement vendor of your choice, which is basically where the scientists got their MK-4 (Nisshin Pharma Inc.), as well.
|Figure 4: MK4-content (µg/100g) of the only significant (~10µg/100g or more) dietary sources of MK4 (data based on Schurgers. 2000)|