Do You Supplement with Vitamin D? Please Remember This…

By Dr. Mercola

Vitamin K is frequently called the “forgotten vitamin” for a good reason — it’s often not fully appreciated, considering its immense value to your health.

One of these oft-overlooked benefits is in relation to your insulin sensitivity, which has implications for a slew of potentially life-threatening chronic diseases.

Vitamin K Enhances Insulin Sensitivity

Research shows that vitamin K can help to regulate your glucose metabolism by converting to a substance called carboxylated osteocalcin in your body, which affects insulin sensitivity.

A recent study found for the first time that vitamin K2 supplementation increased insulin sensitivity in healthy young men, and the effect seemed to be related to increased carboxylated osteocalcin levels, rather than to another factor such as modulation of inflammation.

According to the study in Diabetes Care:

“Although our study could not provide the underlying mechanism, we speculate that [carboxylated osteocalcin] or vitamin K could modulate adipokines or inflammatory pathways other than the IL-6 pathways.

Alternatively, [carboxylated osteocalcin] can directly regulate glucose disposal at skeletal muscle or adipose tissues.”

Past research has also shown that vitamin K slowed the development of insulin resistance in elderly men, adding to the growing evidence that vitamin K has a potentially beneficial role in insulin metabolism.

This is an incredibly important benefit, as enhanced insulin sensitivity means that it is easier for your body to take up sugar from your bloodstream.

Impaired insulin sensitivity, also known as insulin resistance, occurs when your body cannot use insulin properly, allowing your blood sugar levels to get too high. Insulin resistance is a precursor to type 2 diabetes as well as a risk factor in many other chronic diseases.

In fact, controlling insulin levels is one of the most powerful ways to reduce your risk of chronic diseases, including high blood pressure, heart disease, and cancer. The increase in insulin-related diseases we’re now seeing is largely due to lack of exercise combined with the excessive consumption of fructose and carbohydrates in the average American diet, which means healthy sources of vitamin K are often lacking!

Are You Getting Enough Vitamin K to Get These Important Benefits?

According to Dr. Cees Vermeer, one of the world’s top researchers into vitamin K, nearly everyone is deficient in it — just like most people are deficient in vitamin D. Most of you get just enough vitamin K from your diet to maintain adequate blood clotting, but NOT enough to offer protection against the following health problems — and the list continues to grow:

Arterial calcification, cardiovascular disease and varicose veins

Brain health problems, including dementia (the specifics of which are under study)


Tooth decay

Prostate cancer, lung cancer, liver cancer and leukemia

Infectious diseases such as pneumonia

For a comprehensive exploration of all the research and functions of vitamin K, refer to this article on the Weston Price website, but before you head out to buy a supplement or increase your dietary intake, it’s important to understand the differences between the two forms, as they can impact its potential benefit.

What are the Different Types of Vitamin K?

Vitamin K exists in two basic forms, K1 and K2:

  1. Vitamin K1: Found in green vegetables, K1 goes directly to your liver and helps you maintain a healthy blood clotting system. (This is the kind of K that infants need to help prevent a serious bleeding disorder.)
  2. Vitamin K2: 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.

There are several different forms of vitamin K2: MK4, MK7, MK8, and MK9. The form of vitamin K that has the most relevance for health benefits is MK7, a newer and longer acting form with more practical applications. MK7 is extracted from the Japanese fermented soy product called natto. You could actually get loads of MK7 from consuming natto, as it is relatively inexpensive and available in most Asian food markets.

Few people, however, tolerate its smell and slimy texture, so most people who find natto unpalatable prefer to take a supplement. Most vitamin K2 supplements are in the form MK7. You can also get MK7 by eating fermented cheeses.

Do You Take Oral Vitamin D? Why Vitamin K2 is Especially Important for You

There are very compelling reasons to make a concerted effort to get ALL your vitamin D requirements from exposure to sunshine, or by using a safe tanning bed (one with electronic ballasts rather than magnetic ballasts, to avoid unnecessary exposure to EMF fields).

As a quick summary, when you expose your skin to sunshine, your skin synthesizes vitamin D3 sulfate. This form of vitamin D is water soluble, unlike oral vitamin D3 supplements, which is unsulfated. The water soluble form can travel freely in your blood stream, whereas the unsulfated form needs LDL (the so-called “bad” cholesterol) as a vehicle of transport. The suspicion is that the oral non-sulfated form of vitamin D likely will not provide the same benefits as the vitamin D created in your skin from sun exposure, because it cannot be converted to vitamin D sulfate.

For more details, please refer to my recent interview with Dr. Stephanie Seneff.

As a last resort, if neither sun exposure nor safe tanning beds are feasible options, then you may resort to taking an oral vitamin D3 supplement. Getting back to vitamin K, there is evidence that the safety of vitamin D is dependent on vitamin K, and that vitamin D toxicity (although very rare with the D3 form) is actually mitigated by vitamin K2 deficiency. So if you take oral vitamin D, ideally you should take vitamin K2 as well.

There is also a synergistic effect between vitamins D and K, as these two agents work together to increase MGP, or Matrix GLA Protein, which is the protein responsible for protecting your blood vessels from calcification. In healthy arteries, MGP congregates around the elastic fibers of your tunica media (arterial lining), guarding them against calcium crystal formation.

Vitamin K Keeps Calcium Where You Need It, Not Where You Don’t

There is new evidence that it is vitamin K (specifically, vitamin K2) that directs 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. So while increasing calcium is good for your bones, it is not so good for your arteries, which can become calcified. Vitamin K protects your blood vessels from calcifying when in the presence of high calcium levels.

Optimizing Your Vitamin K Intake

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. Because there are no good laboratory assessments, he and his team have developed and patented a very promising laboratory test to assess vitamin K levels indirectly by measuring circulating MGP.

They are hoping to have this test available to the public in the next several years for a reasonable price, and several labs are already interested. Additionally, they are working on developing a home test that would be available at your neighborhood drug store.

At this time, however, there is really no commercial test that would give you meaningful information. But since nearly 100 percent of people don’t get sufficient amounts of vitamin K from their diet to reap its full health benefits, you can assume you need to bump up your vitamin K levels.

Ideally, optimize your vitamin K through a combination of dietary sources (leafy green vegetables, fermented foods like natto, raw milk cheeses, etc.) and a K2 supplement, if needed. Although the exact dosing (for oral supplementation) is yet to be determined, Dr. Vermeer recommends up to 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 150-300 mcg daily.

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