Vitamin K2 Improves Energy & Cardiac Output

A very exciting study was just published showing supplementation with vitamin K2 caused a 12% increase in cardiac output.  How does vitamin K2 improve cardiac output?  Well, vitamin K2 is needed for energy production via what’s known as the electron transport chain.  Let’s discuss what these results mean and if you should consider using vitamin K2.

Dr. R’s Fast Facts

Oral Consumption of Vitamin K2 for 8 Weeks Associated With Increased Maximal Cardiac Output During Exercise.


  • 26 aerobically trained male and female athletes (N = 26)


  • Placebo-Control
  • Participants were randomly assigned either to a control group that received a rice flour placebo or to an intervention group that received vitamin K2
  • For weeks 1 to 4, participants received 300 mg/d; for weeks 5 to 8, they received 150 mg/d


  • Vitamin K2 supplementation was associated with a 12% increase in maximal cardiac output

Why does K2 help?

  • Part of the electron transport chain needed for mitochondrial function
  • Mitochondria are the energy producing aspects of your cells
  • Good mitochondrial function ensures good energy production in the cells via ATP

Foods high in vitamin K2

  • Natto
  • Hard cheese
  • Soft cheese
  • Egg yolk
  • Butter
  • Chicken liver
  • Salami
  • Chicken breast
  • Ground beef

Dr. Mike T Nelson, an expert in health, fitness, and exercise physiology weighs in

  • Would be nice to see a follow up study with better understanding of K2 status prior to study.
  • Segmenting participants would also help us understand more about performance level once participants have reached optimal levels of K2. Does performance increase or remain the same?

Should I take vitamin K2 indefinitely?

  • Little is known about the long-term effects of taking vitamin K2.
  • If you are low in vitamin K2, it’s best to speak with your doctor about the proper dose and duration of supplementation.

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Vitamin K2 Improves Energy & Cardiac Output

Dr. Michael Ruscio: Hi, this is Dr. Ruscio. And let’s discuss the ability of vitamin K2 to help increase cardiac output, or the ability of your heart to circulate blood.

A very exciting study was recently published that essentially showed a 12%, which is very significant, increase in cardiac output after eight weeks on supplemental vitamin K2. And I’ll put the abstract of the study up here on the screen. The study was entitled, “Oral Consumption of Vitamin K2 for Eight Weeks Associated with Increased Maximal Cardiac Output During Exercise.”

So in this study, 26 participants, trained athletes essentially, were divided into either a placebo group, where they were given a placebo, or a control group, where they were given either 300 or I believe it was 150 mg of vitamin K2, 300 mg for about four weeks and then 150 mg for another four weeks.

And they assessed cardiac output before the intervention, so at week one essentially, or at week zero technically, and then again in eight weeks. And they found a 12% increase again in cardiac output, which is very significant. This may increase one’s energy level, certainly could increase one’s endurance performance or exercise performance, and may also help someone if they have shortness of breath or fatigue with exertion. So this is definitely a very significant finding.

Now, it’s one study. It’s a small study. So we can’t infer too much from it. But certainly very exciting.

Now, why might it be that vitamin K2 helps? Well, vitamin K2 is a part of what’s known as the electron transport chain, which is part of the mechanism through which your mitochondria produce energy. Your mitochondria are the energy-producing aspects of your cells. So having good mitochondrial function can ensure that you have good energy production in the cellular level via something known as ATP.

And of course, if your heart muscle has adequate energy, it can output blood. Hence, the connection to cardiac output.

So definitely something to keep in mind if you’re trying to increase your heart health, your cardiac output, or potentially your sports or endurance performance.

Now, the other aspect of this is where can you get vitamin K2 from foods? And unfortunately, and part of the reason why the supplementation with vitamin K2 may have helped is because many people do not eat much in the way of vitamin K2 rich foods.

And I’ll put a list up here on the screen of foods that are rich in vitamin K2. But you have things like many fermented foods and things like liver. And fermented foods and liver are definitely part of a healthy diet and are things that should be incorporated into the diet.

But unfortunately, many people don’t love liver. And not everyone eats much in the way of fermented foods. So part of the reason why this group may have benefited was because they were a bit deficient in vitamin K2 to begin with.

Now, what about the question of, “Well, I want to use vitamin K2 forever now because it seems to have this benefit. Should I be taking it every day? Is there a potential risk of toxicity, of overdose?”

To my knowledge, no. However, I still would not recommend taking a concentrated supplemental dose—300 mg, 150 mg—of vitamin K2 indefinitely, because there may be some unintended negative side effect from that. Again, I don’t know of anything reported in terms of toxicity with vitamin K2. I also have not looked very in depth.

But as a general rule, I think the most proven approach is to use a supplement for a few months, try to get yourself up out of the range of being deficient, and then from there trying to rely on food sources. So looking at some of those fermented foods that we outlined a moment ago.

Now, I sent this study over to my colleague, Dr. Mike Nelson, who is a brilliant exercise physiologist, because I really wanted to get a weigh in from someone who is an expert in health, fitness, and exercise physiology. And I’ll put his comments in the video here.

Dr. Mike Nelson: Hey, what’s going on? This is Dr. Mike T. Nelson here. I’m actually down in South Padre, Texas. You can see the ocean out there. Hence, the funny sunglasses for kite boarding.

But Dr. Ruscio wanted me to comment about the K2 study. And overall I thought it was super interesting. So one, that’s a pretty big increase in pretty trained individuals.

My only quick comment is it’d be really nice to see a follow-up study that, instead of doing just a pure randomized, control trial, which I know is always considered the highest level of evidence. The downside with that is we don’t know what their K2 status was when they enrolled.

So it’d be nice if you took a group of people, and you said, “We’re going to look at your K2 status. And then we’re going to segment you between a group that’s low and a group that maybe is adequate or high.” Run the performance test on both groups and see if there’s a difference between the two groups.

And then what you can do as a follow up is you can take the group that was low, you could supplement them up to an adequate level, run the performance test again, and see if the supplementation in a group that was low helped. Or if you supplement the group that was okay to even a little bit higher level if that would be beneficial.

My guess is that in most studies when you look at different types of vitamins and minerals, once they get to an adequate level, you usually don’t see much of a performance increase at that point.

If you look at some of the research done on zinc. So athletes that are low in zinc and we give them zinc back to an adequate level, they tend to do better. If they were already at the good level and we give them more, they don’t tend to get any better.

Vitamin D is the same way too. If you’re super deficient and we get you back to a good level, you’re going to be better. If you’re already at a good level and we get you higher with vitamin D, it doesn’t seem to confer any other benefits.

So again, I’m Dr. Mike T. Nelson. And those are my thoughts on the study.

DrMR: And so Dr. Nelson makes some great points. I think we’re definitely on the same page in looking at this study in an exciting manner but also being a bit cautious.

And so remember, if you’re trying to improve your cardiac output, or put it in more plain talk—if you’re trying to increase your endurance, then supplementation with vitamin K2 and also incorporating K2 foods into your diet may be very helpful.

Again, this is only one study, so we can’t draw too much from it. It’s certainly exciting when we see just a basic vitamin cause a pretty significant impact in improving sports or endurance performance.

So this is Dr. Ruscio. And I hope this information helps you get healthy and get back to your life. Thanks!

What do you think? I would like to hear your thoughts or experience with this.

Dr. Ruscio is your leading functional and integrative doctor specializing in gut related disorders such as SIBO, leaky gut, Celiac, IBS and in thyroid disorders such as hypothyroid and hyperthyroid. For more information on how to become a patient, please contact our office. Serving the San Francisco bay area and distance patients via phone and Skype.


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