Discovered in the 1920s, vitamin K is similar to vitamin B in that it is more a family of nutrients than a single compound. Vitamin K1, for example, is a nutrient found naturally in leafy green vegetables, while vitamin K2—a fat-soluble micronutrient—is most often found in meats, cheeses, eggs, fermented dairy products and other fermented foods like natto. K-2 (also known as menaquinone) is the lesser known K vitamin, but it’s catching the attention of researchers and supplement users for its wide range of potential applications.
Vitamin K as a family plays a critical role in blood coagulation, which is how the nutrient got its name. The German scientists who first reported on its discovery called it Koagulations-vitamin, or vitamin K for short. Though blood clotting remains vitamin K’s most well-known function, K2 in particular plays a very specific role in bone health... and, in a related manner, it may also impact cardiovascular health. But first, let’s take a closer look at the different types of vitamin K2.
Types of Vitamin K2
Just like there are several forms of vitamin K, there are also a few different forms of vitamin K2. The two main forms in supplement form are menaquinone-4 (MK-4) and menaquinone-7 (MK-7); however, MK-4 is rare as a supplement because it has such a short viable life span. Thus, your body has a limited window to make use of the nutrient, and you end up having to take several doses per day to make it worth it. As such, if you’re buying a K2 supplement, chances are high you’re buying menaquinone-7, so we’ll focus the rest of the discussion on MK-7.
Supplemental MK-7 is most often derived from a bacterial fermentation process, offering a number of potential health benefits. The nutrient is extracted from a fermented soy product called natto. As a fat-soluble nutrient, it’s important to take vitamin K2 supplements with some form of fat to ensure absorption. For those who prefer diet over supplements, eating just a teaspoon of natto per day is roughly equivalent to a common dosage of supplemental MK-7.
How Vitamin K2 Impacts Heart & Bone Health
Let’s get back to the basics for a bit. The main role vitamin K plays in your body is promoting blood coagulation and clotting. It does this by activating the natural calcium-binding properties of various proteins (blood clotting). While vitamin K1 is mostly involved in this coagulation process, vitamin K2 actually influences where that calcium ultimately ends up in your body.
Interestingly, it’s this influence over calcium that connects vitamin K2 to both cardiovascular and bone health. Calcium is a mineral most often associated with bone health, as it is a primary component of your bone structure. But calcium is also found arteries and blood vessels, where it can have negative health effects at high quantities.
Vitamin K plays a role in supporting proper calcium levels throughout the body. Without adequate levels of K2, this process is inefficient and can lead to concerns. This has led many health professionals to recommend vitamin K2 supplements to those who are already taking bone health products like vitamin D, calcium and magnesium to help further support adequate calcium levels throughout your body.
Natural Food Sources of Vitamin K2
Getting enough vitamin K2 from your diet can be tough. Its only vegetarian source is natto due to the specific bacteria used during the fermentation process. Certain animal-derived foods contain K2 thanks to the way in which the animals digest grass. They can actually make their own K2 from the K1 found naturally in the grass, so grass-fed beef products in particular can provide dietary K2. Liver, meat, eggs and high fat dairy are your best bets if you’re not keen on natto.
Some good news: your body can convert, though inefficiently, some vitamin K1 into K2. If you’re set on eating your daily vitamin K2 versus supplementing, here’s a list of foods with healthy quantities of K1 you can add to your grass-fed beef products:
|Most leafy greens|
How do you get vitamin K2 in your diet?