Vitamin K is a fat-soluble vitamin that is well-known for its role in blood clotting. However, there are two different kinds of vitamin K, each providing its own set of health benefits. Vitamin K1 is primarily responsible for blood clotting. Vitamin K2 works with calcium, magnesium and vitamin D providing various health benefits.
The 2010 European Prospective Investigation into Cancer and Nutrition (EPIC) study found that high intake of vitamin K2 — not K1 — leads to reduced cancer risk, as well as a 30% lower risk of dying from cancer. Higher Vitamin K2 intake has also been associated with improved heart health.
A deficiency in Vitamin K2 produces symptoms associated with vitamin D toxicity, which includes inappropriate calcification of soft tissues that can lead to atherosclerosis (hardening of arteries). A double-blind, placebo-controlled study published in 2015 found the treatment group had a 5.8% lower stiffness index beta (a parameter of arterial stiffness) and a 3.6% lower carotid-femoral pulse wave velocity (a test that measures arterial stiffness). The placebo group, on the other hand, saw a 1.3 and 0.22% increase in these measurements respectively. While previous studies have only shown an association, this is the first studying confirming long-term use of vitamin K2 in the form of MK-7 improves cardiovascular health.
When supplementing your diet for Vitamin K, it’s important to supplement with fermented foods. While the K1 in vegetables is poorly absorbed, virtually all of K2 in fermented foods is readily available to your body. Vitamin K2 is further broken down by your body into:
1. MK-4 (menaquinone-4), a short-chain form of vitamin K2 is found in animal-based foods such as grass-fed butter (only grass-fed butter has higher levels of K2), butter oil and pastured egg yolks. As supplements containing MK-4 are synthetic obtained from a tobacco plant and has a short biological half-life, it’s best to avoid this in supplement form.
2. MK-7 (menaquinone-7), longer-chain forms of vitamin K2 are found in fermented foods. This is the one you’ll want to look for in supplements, as this form is extracted from real food. When buying or making fermented foods, look to make sure you begin with a special starter culture designed with bacterial strains that produce vitamin K2.
How Much Vitamin K2 Do You Need?
If you are taking an oral vitamin D3 supplement, you may also need more vitamin K2, in order to maintain a healthy ratio which is suggested as 100 mcg of vitamin K2 for every 1,000 IUs of vitamin D3 you take. If you opt for a vitamin K2 supplement, make sure it’s MK-7. Also remember to take it with fat since it’s fat-soluble and won’t be absorbed otherwise. You don’t need to worry about too much K2, as it appears to be completely nontoxic. People have been given a thousand-fold “overdose” over the course of three years, showed no adverse reactions.
Vitamin K2 taken every day is a simple way to ensure your blood vessels don’t calcify and lead to heart disease. However, if you have experienced stroke, cardiac arrest, or are prone to blood clotting, do not begin taking vitamin K2 supplements without consulting your health care provider.
While nontoxic, people who are taking vitamin K antagonists (i.e., drugs that reduce blood clotting by reducing the action of vitamin K), are advised to avoid Vitamin K supplements. Also, if you are pregnant or nursing, avoid vitamin K2 supplementation higher than the RDA (65 mcg) unless specifically recommended and monitored by your health care provider.