At least one study, however, has investigated the association of intake of phylloquinone and menaquinone with coronary calcification. The intake of both forms of the vitamin was estimated using a food-frequency questionnaire. It was found that K2 had an effect on coronary calcification, but K1 did not.
According to the study:
"This study shows that high dietary menaquinone [Ks] intake, but probably not phylloquinone [K1], is associated with reduced coronary calcification. Adequate menaquinone intakes could therefore be important to prevent cardiovascular disease."
Vitamin K is an extremely important vitamin to have in your diet; it may very well be the next vitamin D in terms of the numerous health benefits it may provide. But, according to Dr. Cees Vermeer, one of the world's top researchers in the field of vitamin K, nearly everyone is deficient in vitamin K -- just like most are deficient in vitamin D.
Most people get enough vitamin K from their diets to maintain adequate blood clotting, but NOT enough to offer protection against health problems like arterial calcification and cardiovascular disease. Yet, as the study above showed, adequate amounts of the right type of vitamin K may offer immense benefits to your heart health, including reducing coronary calcification and thereby decreasing your risk of heart disease.
Which Type of Vitamin K May be Best for Your Heart?
Vitamin K comes in two forms -- K1 or K2 -- and it is important to understand the differences between them.
- Vitamin K1 (phylloquinone): Found in green vegetables, K1 goes directly to your liver and helps you maintain a healthy blood clotting system. (This is the kind of vitamin K that infants are often given at birth to help prevent a serious bleeding disorder.) It is also vitamin K1 that keeps your own blood vessels from calcifying, and helps your bones retain calcium and develop the right crystalline structure.
- Vitamin K2 (menaquinone, MK): Bacteria produce this type of vitamin K. It is present in high quantities in your gut, but unfortunately is not absorbed from there and passes out in your stool. K2 goes straight to vessel walls, bones, and tissues other than your liver. It is present in fermented foods, particularly cheese and the Japanese food natto, which is by far the richest source of K2.
Vitamin K3, or menadione, is a third form that is synthetic and manmade, which I do not recommend. Each type of vitamin K has different roles in your body, and emerging research is showing that vitamin K2, not K1, may be especially important. For instance, research published in Atherosclerosis found that high dietary intake of vitamin K2 is associated with reduced coronary calcification (hardening of the arteries), a result that should also lessen your risk of heart disease.
What made this study unique was that it compared dietary intakes of both vitamin K1 and K2, and only K2 showed a benefit. Vitamin K1 was NOT associated with reduced coronary calcification. This is consistent with separate research also showing superior health benefits from vitamin K2, including:
- The Rotterdam Study, the first study demonstrating the beneficial effect of vitamin K2, showed that people who consume 45 mcg of K2 daily live seven years longer than people getting 12 mcg per day.
- The Prospect Study, in which 16,000 people were followed for 10 years. Researchers found that each additional 10 mcg of K2 in the diet results in 9 percent fewer cardiac events, whereas vitamin K1 did not offer a significant heart benefit.
Why Might Vitamin K2 be so Beneficial for Your Heart?
Vitamin K engages in a delicate dance with vitamin D; whereas vitamin D provides improved bone development by helping you absorb calcium, there is new evidence that vitamin K2 directs the calcium to your skeleton, while preventing it from being deposited where you don't want it -- i.e., your organs, joint spaces, and arteries. A large part of arterial plaque consists of calcium deposits (atherosclerosis), hence the term "hardening of the arteries."
Vitamin K2 activates a protein hormone called osteocalcin, produced by osteoblasts, which is needed to bind calcium into the matrix of your bone. Osteocalcin also appears to help prevent calcium from depositing into your arteries. In other words, without the help of vitamin K2, the calcium that your vitamin D so effectively lets in might be working AGAINST you -- by building up your coronary arteries rather than your bones.
This is why if you take calcium and vitamin D but are deficient in vitamin K, you could be worse off than if you were not taking those supplements at all, as demonstrated by a recent meta-analysis linking calcium supplements to heart attacks.
This meta-analysis looked at studies involving people taking calcium in isolation, without complementary nutrients like magnesium, vitamin D and vitamin K, which help keep your body in balance. In the absence of those other important cofactors, calcium CAN have adverse effects, such as building up in coronary arteries and causing heart attacks, which is really what this analysis detected. So if you are going to take calcium, you need to be sure you have balanced it out with vitamin D and vitamin K.
Vitamin K2 Helps Produce Heart-Protective Protein MGP
Another route by which vitamin K offers heart-protective benefits is through the Matrix GLA Protein (or MGP), the protein responsible for protecting your blood vessels from calcification. When your body's soft tissues are damaged, they respond with an inflammatory process that can result in the deposition of calcium into the damaged tissue. When this occurs in your blood vessels, you have the underlying mechanism of coronary artery disease -- the buildup of plaque -- that can lead you down the path to a heart attack.
Vitamin K and vitamin D again work together to increase MGP, which, in healthy arteries, congregates around the elastic fibers of your tunica media (arterial lining), guarding them against calcium crystal formation.
According to Professor Cees Vermeer:
"The only mechanism for arteries to protect themselves from calcification is via the vitamin K-dependent protein MGP. MPG is the most powerful inhibitor of soft tissue calcification presently known, but non-supplemented healthy adults are insufficient in vitamin K to a level that 30 percent of their MGP is synthesized in an inactive form. So, protection against cardiovascular calcification is only 70 percent in the young, healthy population, and this figure decreases at increasing age."
Four More Reasons to Make Sure Your Diet Includes Vitamin K2
Vitamin K not only helps to prevent hardening of your arteries, which is a common factor in coronary artery disease and heart failure, it also offers several other important benefits to your health.
Fight Cancer …
Vitamin K has been found beneficial in the fight against non-Hodgkin lymphoma, liver, colon, stomach, prostate, nasopharynx, and oral cancers, and some studies have even suggested vitamin K may be used therapeutically in the treatment of patients with lung cancer, liver cancer, and leukemia.
Improve Bone Density …
Vitamin K is one of the most important nutritional interventions for improving bone density. It serves as the biological "glue" that helps plug the calcium into your bone matrix.
Studies have shown vitamin K to be equivalent to Fosamax-type osteoporosis drugs, with far fewer side effects.
Stave off Varicose Veins …
Inadequate levels of vitamin K may reduce the activity of the matrix GLA protein (MGP), which in turn has been identified as a key player in the development of varicosis, or varicose veins.
Lower Your Risk of Diabetes …
People with the highest intakes of vitamin K from their diet had a 20 percent lower risk of diabetes compared with those with the lowest intakes, according to the latest research from University Medical Center Utrecht in the Netherlands. Past studies have also shown vitamin K to help reduce the progression of insulin resistance.
How Much Vitamin K2 do You Need?
How many people have adequate vitamin K2? Just about zero, according to Dr. Vermeer and other experts in the field. But at this time there is really no commercial test that can give you an accurate measure of your levels. Vitamin K measurements in blood plasma can be done accurately, but the results are really not helpful because they mainly reflect "what you ate yesterday," according to Dr. Vermeer.
Dr. Vermeer and his team have developed and patented a very promising laboratory test to assess vitamin K levels indirectly by measuring circulating MGP. Their studies have indicated this to be a very reliable method to assess the risk for arterial calcification -- hence cardiac risk. They are hoping to have this test available to the public within one to two years for a reasonable price, and several labs are already interested. They are also working on developing a home test that would be available at your neighborhood drug store.
In the meantime, since nearly 100 percent of people don't get sufficient amounts of vitamin K2 from their diet to reap its health benefits, you can assume you need to bump up your vitamin K2 levels by modifying your diet or taking a high-quality supplement.
As for dietary sources, eating lots of green vegetables, especially kale, spinach, collard greens, broccoli, and Brussels sprouts, will increase your vitamin K1 levels naturally. For vitamin K2, cheese and especially cheese curd is an excellent source. The starter ferment for both regular cheese and curd cheese contains bacteria -- lactococci and proprionic acids bacteria -- which both produce K2.
You can also obtain all the K2 you'll need (about 200 micrograms) by eating 15 grams of natto daily, which is half an ounce. It's a small amount and very inexpensive, but many Westerners do not enjoy the taste and texture.
If you don't care for the taste of natto, the next best thing is a high-quality K2 supplement. Remember you must always take your vitamin K supplement with fat since it is fat-soluble and won't be absorbed without it.
Although the exact dosing is yet to be determined, Dr. Vermeer recommends between 45 mcg and 185 mcg daily for adults. You must use caution on the higher doses if you take anticoagulants, but if you are generally healthy and not on these types of medications, I suggest 150 mcg daily.