Build A Stronger Brain With Vitamin K
By: Dave Asprey
It’s not often you find a supplement that can benefit nearly everyone.
But there’s a lesser known, and frankly, underappreciated nutrient that can boost cognitive function, support bone health, reduce inflammation, and increase blood flow. It’s vitamin K, and you would probably benefit from adding it to your supplements.
Here’s a complete guide to vitamin K: how it works, what it does, and where you can get more of it, both in your diet and in pill form.
How vitamin K works
Vitamin K is a fat-soluble vitamin originally named because it plays a part in blood clot formation: “K” comes from the German word “koagulation.”
Its main function is the activation of a dozen or so different proteins that perform essential functions in the body. This means that these proteins are in their inactive forms until K2 comes along and activates them for use.
There are two types of vitamin K: K1 (phylloquinone) and K2 (menaquinones).
- K1 is the less active form, its main role being blood coagulation. Green leafy vegetables and certain plant oils are packed with K1. It hangs out and functions mainly in your liver.
- K2 is the more active form – the one that does most of the good stuff outlined below. You’ll find it in animal liver, fermented foods, and grass-fed butter. Like K1, K2 also goes to your liver, but it’s quickly sent out to different parts of your body to carry out various functions. So, if you’re deficient in K1, your liver will hold on to K2 to satisfy its needs for this nutrient, preventing K2 from doing its job in the body.
The little known nutrient that packs a big punch
Most studies focus on vitamin K2, which supports everything from bone density to memory. In fact, K2 is found in some of its highest concentrations in the brain, making this a vital nutrient for overall cognitive function. [2,3]
K2 includes a family of 13 molecules called menaquinones (MKs), and of these, MK-4 and MK-7 are the most significant. In other words, look for those two when deciding on a quality supplement.
MK-7 is the more biologically active form of K2, with a half-life of three days, making it easier to build consistent blood levels.
MK-4 has a half-life of about an hour and you can only find it in foods (organ meats, muscle meat, and grass-fed butter) or as a synthetic supplement (we don’t yet know how to isolate MK-4 from natural food sources). You can find both MK-4 and MK-7 in most quality vitamin K supplements.
5 major benefits of vitamin K2
Even if you’re using lots of vitamin K-rich grass-fed butter in your Bulletproof Coffee, you might consider supplementation, as most people are deficient. Benefits of getting enough K include:
- Stronger bones. K2 promotes bone density. Your bone-building protein osteocalcin depends on vitamin K to bind calcium for transport into your bones. This boosts mineralization and keeps bones strong.
- A more powerful cardiovascular system. Without vitamin K transporting calcium to your bones, calcium plaque can build in your arteries, paving the path for heart disease. One meta-analysis of 30 studies associates arterial calcification with a 300-400 percent increase in cardiovascular events. K2 keeps your blood flowing and your arteries pliable.
- Resilience. Vitamin K2, specifically as MK-4, fights inflammation, and strengthens your immune cells, allowing you to fight off pathogens better.
- Cancer. Studies show vitamin K provides cancer protection, including gastric cancer, colon cancer, leukemia, and bladder cancer. [9, 10, 11]
- Memory. Eating more vitamin K-rich foods sharpened memory and staved off dementia in older adults. 
Why most of us are low in K (and what to do about it)
Humans used to get hefty amounts of vitamin K from certain fermented foods and organ meats, but as diet has changed, most people don’t eat either anymore, especially not regularly.
Even though it’s a fat-soluble nutrient, which is usually more likely to get stored in the body, you actually only store small amounts of vitamin K, and the store depletes quickly if you don’t get vitamin K in your diet regularly.
Sure, you get some K2 from your daily grass-fed butter habit, but most of us simply don’t consume enough vitamin K-containing foods to keep up consistent levels. For optimal levels, which hover around 150-320 mcg daily, you can either build a grass-fed liver habit or start supplementing.
Severe vitamin K deficiencies are rare. That said, most people’s cells could benefit from more K and would put it to good use. Deficiencies are more common if you’re taking vitamin K antagonists, if you have significant liver damage or liver disease, or if you have a fat malabsorption disorder like inflammatory bowel disease or cystic fibrosis.
Signs you may be deficient in vitamin K include:
- Problems with blood clotting
- Easy bruising and bleeding
- Bleeding gums
- Blood in your urine or stool
- Black stools
- Heavy menstrual bleeding
How to supplement vitamin K
Like many nutrients, vitamin K works best when you take it with other fat-soluble vitamins and other cofactors.
Vitamin K works most closely with vitamin D for bone health, arterial health, and a stronger immune system. In fact, increasing vitamin D intake without vitamin K can actually be harmful. When you increase vitamin D without sufficient vitamin K, you potentially increase calcium accumulation in your arteries and soft tissue. This impacts artery elasticity and can lead to arterial calcification, aka potential for heart disease .
On the other hand, vitamin K activates matrix Gla–protein (MGP) to maintain healthy calcium metabolism in vascular tissues and optimize vascular elasticity. Studies show vitamin D also helps activate MGP, making both vitamins crucial for strengthening your circulation and heart .
Emerging research shows the synergistic effects of all four fat-soluble vitamins: A, D, E, and K. Problems can occur when you don’t get one or more in sufficient amounts. Supplementing with therapeutic doses of vitamin D demands supportive levels of vitamins A, E, and K or you risk deficiencies in one or more of these fat-soluble vitamins. 
One example is a study in which researchers gave rats high amounts of vitamin A. Serum levels of vitamins E and D immediately dropped. Even higher vitamin A doses lowered serum levels of vitamin K, to the point where some rats experienced hemorrhaging. 
So stack A, D, E, and K, or get them all from your diet. Grass-fed organ meats like liver and kidney are probably the simplest option for getting A, D, E, and K. Don’t despair – you can make organ meats quite tasty.
Otherwise, read up on K supplementation below, and check out this guide to supplementing A, D, and E.
Choosing a supplement
To get the most out of your vitamin K supplement, considering the following 5 points:
- Choose the right K: Look for vitamin K supplements that include K1 and K2 with both MK-4 and MK-7 on the label. If you can’t find one with MK-4, go for a supplement with MK-7 and increase your consumption of grass-fed butter and liver.
- Build a stack: Magnesium, zinc, and boron may help with vitamin D and K absorption and use. You can find some D supplements with these cofactors already included.
- Consider medication you’re on: If you take blood thinners like Coumadin (warfarin), talk with your doctor before supplementing with vitamin K.
- Eat your fat: For maximum absorbability, always take vitamin K and other fat-soluble vitamins with a fat source.
- The dose: You’ll want 2000 mcg/day, at least 100 of which is MK-7. The rest should be MK-4. You can find good sources for vitamin K and other key vitamins and minerals in this article.
Thoughts on vitamin K supplementation? I’d love to hear about them in the comments below or on my Facebook page. Thanks for reading and stay Bulletproof!