When it comes to cardiovascular health, you don't want to just focus just on your heart, but your circulatory system as well.
This complex network of arteries, veins, and capillaries is incredibly extensive. If laid out end to end, it would cover more than 60,000 miles—enough to circle the Earth twice! It is also extremely important, because this is the system that delivers nutrients and oxygen to, and removes wastes from, cells throughout your body.
Unhealthy blood vessels are the underlying cause of several major cardiovascular disorders, including atherosclerosis (hardening of the arteries), aneurysm (ballooning/weakness in an artery or vein), and peripheral artery disease (narrowed blood vessels, usually in the legs).
Blood pressure control, regular exercise, weight management, and a good diet are the usual recommendations for supporting circulatory function, and I heartily endorse them. But you also need to know about an often-overlooked nutrient that plays a critical role in enhancing circulation and overall heart health: vitamin K2.
Two Types of Vitamin K
Vitamin K isn’t a single nutrient, but rather a group of fat-soluble vitamins that are required for the activation of “vitamin K-dependent proteins.” The best known is vitamin K1 (phylloquinone), often referred to as the clotting vitamin because it activates proteins involved in blood coagulation and prevents excessive bleeding. K1 also has positive effects on inflammation.
Vitamin K2, on the other hand, has only gained research attention over the past few decades—but what they’ve discovered is truly remarkable. Vitamin K2 activates two important vitamin K-dependent proteins:
- Matrix Gla protein (MGP): Inhibits the buildup of calcium in the walls of the blood vessels, which protects against vascular calcification and stiffening.
- Osteocalcin: Binds to calcium and promotes bone formation. Osteocalcin also plays a role in insulin secretion/sensitivity, glucose metabolism, brain development, and cognitive function.
So, vitamin K2 helps to keep calcium out of your arteries and in your bones, which is exactly where you want it. Plus, it keeps your arteries flexible and responsive, your circulation robust—and your risk of vascular disease lower. As an added bonus, this vitamin also supports brain health and improves insulin sensitivity and blood sugar metabolism.
Impressive Research on Vitamin K for Heart Health
Vitamin K’s heart benefits were documented in a 2021 study in the Journal of the American Heart Association. This study, which involved more than 53,000 Dutch men and women, examined the relationship between dietary intake of vitamin K and hospitalization for coronary artery disease, stroke, and peripheral artery disease.
The researchers found that the risk of these cardiovascular disorders was inversely associated with diets high in vitamin K1 or K2—the higher the intake of vitamin K, the lower the risk. They concluded that at-risk individuals may benefit from an increased dietary intake and/or vitamin K supplementation.
Although this study revealed protective effects of vitamins K1 and K2, vitamin K2 is particularly important for circulatory health. Earlier research involving postmenopausal women and men or women over age 55 linked higher consumption of vitamin K2—but not K1—with a lower risk of arterial calcification and death from cardiovascular causes.
What’s the Best Way to Get Vitamin K?
The “adequate intake” (AI) of vitamin K, according to the Food and Nutrition Board of the US Institute of Medicine, is 90 mcg for men and 120 mcg for women per day.
It’s pretty easy to get vitamin K1 in your diet. Top sources include kale, spinach, Swiss chard, parsley and other leafy greens, plus cruciferous vegetables like broccoli. A cup of raw spinach (145 mcg), cooked broccoli (220 mcg), or chopped kale (472 mcg) and you’re covered.
Vitamin K2 is trickier—and most Americans don’t get enough of it. Egg yolks, pork, liver and other organ meats, butter, and full-fat dairy provide some vitamin K2, and a small percentage of the vitamin K1 you eat is converted into K2. One of the main subtypes of this vitamin (MK-7, which we will discuss below) is synthesized by bacteria in a fermentation process, so fermented foods like sauerkraut and cheese also contain vitamin K2. Natto, a fermented soy product popular in traditional Japanese cuisine, has the highest K2 concentration of any food—a whopping 250 mcg per ounce.
Cheese Is Another Good Source of Vitamin K2
Cheese runs a distant second to natto, with an average of 7.5–15 mcg of K2 per ounce, but it is a top source of vitamin K2 in the Western diet.
Several years ago, I met with two of the world’s top vitamin K experts, Drs. Cees Vermeer and Leon Schurgers, biochemists at Holland’s Maastricht University who have been researching this nutrient for 30 years. In a study on K2’s effects on arterial calcification, they found that the men and women who consumed the most K2—primarily from cheese—had the least calcification and atherosclerosis and the fewest cardiovascular deaths.
The Dutch are big cheese eaters. Gouda and Edam cheeses are named for the Dutch towns where they originated, and the Netherlands are one of the world’s largest exporters of cheese. Apparently, this tradition serves not only the Dutch economy but the heart health of the Dutch people as well.
Drs. Vermeer and Schurgers also suggest that the French fondness for cheese may be an unsuspected reason for the relatively low level of heart disease in France despite their notoriously high intake of fatty foods. We have long believed that the salvation of French hearts was due to copious consumption of red wine. However, K2 research indicates that there may be more to the story.
In countries such as Holland and France, it looks like there are major heart benefits from all the cheese they eat. Who would have thought.
Why I Recommend Vitamin K2 Supplements
Unless you eat natto or a lot of cheese, your intake of vitamin K2 is likely quite low. That’s why vitamin K2 is one of my top supplement recommendations.
As mentioned earlier, there are several subtypes of vitamin K2, including MK-4 and MK-7. The "M" stands for menaquinone and indicates how many "side chains" are attached to the main vitamin K molecule. The side chains in vitamin MK-7 are longer, making this form more active and bioavailable for promoting healthy circulation. To get the most powerful support for your blood vessels and circulatory system, I recommend supplementing with MK-7.
I have closely followed the developing science on MK-7 and I’m excited about its unique ability to help keep excess calcium out of arterial walls while at the same time encouraging calcium movement into bone tissue and promoting insulin sensitivity and brain health.
I believe that vitamin K2 ranks right up there with CoQ10—and I wouldn’t practice cardiology without CoQ10, which speaks volumes. The recommended dose of vitamin K2 (MK-7) is 180 mcg per day, although as little as 50 mcg per day is also therapeutic, especially when used as part of an advanced nutritional program for supporting circulatory health.
Some studies have looked at daily doses of 360 mcg, and this higher amount has also been shown to be safe and effective. Since I met the two Dutch researchers at a Yale conference more than 12 years ago, I personally have been taking 360 mcg of MK-7 per day, and some of my colleagues take similar doses as well.
Note of caution: If you take any blood-thinning medication, especially Coumadin (warfarin) but also Heparin and Lovenox, don’t use any supplemental form of vitamin K, as it may seriously interfere with the effect of your medications. If you are on a non-vitamin K oral anticoagulant (NOAC) like Eliquis and Pradaxa, talk to your doctor before taking vitamin K2.