What Is vitamin K2 (aka Menaquinone)?
Discovered in the 1920s, vitamin K is similar to vitamin B in that it is more of a family of nutrients versus one 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. K2 (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.1 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, may also impact cardiovascular health. But first, let’s take a closer look at the different types of vitamin K2.
Different 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 that are available in supplement form are menaquinone-4 (MK-4) and menaquinone-7 (MK-7),2 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 natural 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 menaquinone-7.
Benefits of Vitamin K2 for Heart Health and Bone Health
Let’s get back to basics for a bit. The main role vitamin K plays in your body is promoting blood coagulation and blood clotting. Is does this by way of activating the natural calcium binding properties of various proteins (blood clotting). While vitamin K1 is 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 heart health and bone health.3 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 K2 has been shown to help with the removal of calcium from the lining of your blood vessels, as well as the redistribution of that calcium back to your bones. Without adequate levels of K2, this process is inefficient and can lead to bone and cardiovascular health issues. This connection has led many health professionals to recommend vitamin K2 supplements to those who are already taking bone health supplements like vitamin D, calcium and magnesium to ensure the calcium gets to where it’s supposed to go — your bones.
When it comes to bone health, research strongly suggests vitamin K2 is helpful in preserving bone strength and structure. Studies examining menaquinone 7, or MK-7, from natto show increased intake may be linked directly with increased bone-matrix formation and bone mineral density… the results are backed up by a 3-year study of more than 900 women aged 20 to 79.3
Which Foods are High in Vitamin K2?
Unfortunately, getting enough vitamin K2 from your diet can be tough. It’s only vegetarian source is natto, due to the specific bacteria used during the fermentation process. Certain animal-derived foods contain K2 due to the way in which the animals digest grass. Cows, for example, can make their own K2 from the K1 found naturally in the grass. Thus, grass-fed beef products are one of the natural foods sources of vitamin K2. Liver, meat, eggs and high-fat dairy are your best bets if you’re not keen on natto.
Further complicating the matter is the fact that our bodies, in general, just aren’t that good at absorbing vitamin K from food. For example, you only absorb about 10 percent as much vitamin K from spinach as you would from a tablet (approximately 80 percent).2 Your body can convert, though inefficiently, some vitamin K1 into K2. So, 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, which contain some natural K2.
|Most leafy greens|
If you’re looking for more information about essentials vitamins, read Say Hello to the Sunshine Vitamin: Top Foods High in Vitamin D.
1Vitamin K2: Everything You Need to Know: Healthline. https://www.healthline.com/nutrition/vitamin-k2 (Accessed 11/29-/017)
2Vitamin K: National Institutes of Health. https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/ (Accessed 11-/29/2017)
3Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health: US National Library of Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4566462/ (Accessed 11/29/2017)
(updated 12/27/2017, original publish date 3/6/2017)