In 1929 Henrik Dam, a Danish scientist, observed that chickens feed a cholesterol-depleted diet developed hemorrhages and started bleeding. When these conditions could not be reversed with the addition of pure cholesterol in the chickens diet, it was surmised that an additional factor must have been extracted with the cholesterol in the first place. The Danish scientist named this newly discovered anti-hemorrhagic factor “Koagulationsvitamin,” which was later renamed vitamin K.

While most of us are familiar with vitamin K’s role in clotting blood and preventing uncontrolled bleeding, there is more to the vitamin K story. We now know that there are two forms of vitamin K, vitamin K1 and vitamin K2, and scientists are becoming more in awe of vitamin K2 and its role in preventing heart disease and osteoporosis!

As nutritionists who specialize in bone health, we constantly hear the media extoll the importance of vitamin D and calcium for strong bones, but often overlook the role of its fat-soluble partners in bone-building: vitamin A, vitamin E, and vitamin K. Read on to learn more about both forms of this vitamin, how you can improve your levels, and what is not only safe, but effective.

What is Vitamin K?

Vitamin K is also known as the molecular family of quinones and includes vitamin K1 (phylloquinone) which are from plants, K2 (menaquinone), which are by bacteria and there is even a K3 (menadione), which is synthetic and not found in nature. These quinones are fat-soluble vitamins (except for K3, which is water soluble) and cofactors for a group of gamma-carboxylase enzymes. Activated by vitamin K, these enzymes modify proteins by adding a carboxyl group to them to prepare them for action. These proteins that depend on vitamin K for activation are called GLa proteins.

Vitamin K1, aka phylloquinone. (and phytomenadione or phytonadione) is the vitamin K of plants and cyanobacteria. About 90% of most human dietary intake of vitamin K is in this form. K1 helps add a carboxyl group to glutamate residues found in GLa protein clotting factors II (prothrombin), VII (proconvertin), IX, and X,[1] which are part of the cascade of reactions that help blood clot. This is the reason why patients taking warfarin, the blood thinner that antagonizes vitamin K must take in relatively stable amounts of vitamin K from day to day to avoid problems.

Vitamin K2, aka menaquinone, is the vitamin K of (intestinal) bacteria. Because ruminating animals use bacteria for the bulk of their green-plant-digestion, their guts are factories for vitamin K2. So is yours, to an extent – your good gut bacteria can convert vitamin K1 to K2, although the debate rages as to whether modern humans can convert an adequate amount of K1 to K2 to support basic functions. However, new research does not support these levels being adequate for heart or bone health- so we will continue to monitor and report new findings as we have them. This is important because K2 helps activate two major proteins that support calcium balance in your body- osteocalcin and matrix GLa protein.

Klear Arteries, Klotting on Kue, and a Strong Skeleton

Vitamin K really is an unsung hero. Here are some of its functions:

  • Blood Clotting (“Koagulation”). The primary role of vitamin K1 is to activate clotting factors such as prothrombin. It is referred to as an anti-hemorrhagic.
  • Bone Building, Breaking, and Re-making. Sufficient vitamin K2 is required to grow bones successfully as we mature, but it also has a role to play in maintaining bone density as an adult! In our successful efforts to reverse Mira’s osteoporosis, we looked in depth at every micronutrient that she needed beneficial amounts of. We found that K2 is absolutely essential in order to activate (or carboxylate) a protein called osteocalcin, which removes calcium from our artieries, where it can form dangerous plaque, and deliver it to our bone where it is needed to maintain our healthy bone density.

The role vitamin D plays in bone building (making calcium available) is balanced by both vitamin A (that helps control the rate at which bone cells are made and broken down) and vitamin K2 (which helps deliver calcium into the bones by activating osteocalcin). Because high calcium running around outside of your bones is dangerous (can make your heart race or become calcified in atherosclerotic plaques), it is best to get adequate vitamin K2 when supplementing vitamin D- otherwise, you risk low bone density at best and a stroke or heart attack at worst.

In Japan, vitamin K2 is the recommended standard of care for osteoporosis, which is telling as this population can k-learly see the bone-health-divide between consumers of natto (a food very rich in K2) in certain areas in Japan versus non-natto-consumers. Currently neither the United States nor Canada recommends the use of K2 for treating osteoporosis. However, if you are suffering from low bone density or are interested in preventing osteopenia or osteoporosis you should be looking for a daily multivitamin that understands your needs and supplies adaquate amounts of both vitamin K1 and K2.

  • Prevents atherosclerosis (hardening of the arteries). Matrix GLa protein (MGP) is found in arterial walls, and just like osteocalcin, it requres vitamin K2 to activate or carboxylate it, allowing your body to mobilize calcium in arterial deposits and remove it from the scene of the inflammation. This now activated MGP directly blocks the formation of calcium crystals inside blood vessels and arteries. Notice how clearly the calcium link is between bone and heart health when you think about the role of vitamin K2! Only focusing on inflammation, protein intake, blood sugar, or other imbalances related to poor bone health isn’t enough. Our internal systems are interconnected and micronutrient deficiency connects them directly.
  • Protection from Oxidative Stress. Vitamin K helps protect cells- particularly nerve cells- from damage. Moreover, vitamin K2 has been shown to turn off certain cancer genes. Both roles reduce cancer risk.
  • Metabolic Health and Exercise Performance. Some research suggests that vitamin K2 improves energy utilization during exercise,[2] insulin production, and insulin sensitivity. All promote a healthy blood sugar and weight.
  • Sexual Healing. Vitamin K1 has been shown to boost testosterone levels in male rats with vitamin K deficiency by healing lipopolysaccharide-induced damage that reduces testosterone synthesis,[3] and has been shown to boost male rat testosterone production directly.[4] More research in humans is needed to support this finding. In females, there is also evidence that vitamin K2 boosts fertility and helps resolve polycystic ovarian syndrome, but only in those with pre-existing vitamin D deficiency, so more research is needed to support this finding as well.[5]
  • Cardiovascular Health. Vitamin K1 clots your blood while vitamin K2 keeps your arteries clear of calcified blockages. As you may note, these roles balance.

Vitamin K1 and K2 Deficiencies Increases Disease Risk

Vitamin K2 is far newer to nutritional researchers than K1, and thus it is a bit too early to make bold claims about vitamin K2 deficiency. Still, there are some obvious drawbacks to insufficient vitamin K2 levels, and there are well documented signs of vitamin K1 deficiency.

  • Particularly in developing children, vitamin K2 deficiency makes it hard to deliver calcium into bone. Anecdotal research indicates that teeth grow in straighter and stronger with adequate vitamin K2- a great alternative to braces or invisalign!
  • Heavy Bleeding. Severe vitamin K1 deficiency can lead to hemorrhage, whether it is an uncontrollable nose bleed, gum bleed, or an abnormally heavy menstrual flow. Those with liver disease cannot appropriately use vitamin K1 to activate clotting factors and often are given supplemental vitamin K to avoid uncontrolled bleeding.
  • Cardiovascular Disease from Atherosclerosis (Hardened Arteries). As noted above, vitamin K2 mobilizes calcium that would otherwise stick in arterial plaques.

Who is likely to be vitamin K deficient?[6]

  • Premature Infants
  • Infants and Young Children in Developing Countries
  • Pregnant and Lactating Women in Developing Countries
  • People with Cystic Fibrosis / Pancreatic insufficiency / Low Lipase Production
  • Vegans, and to a lesser extent Vegetarians (vitamin K2)
  • Low fat Dieters
  • People with Poor Gallbladder Function / Gallbladder Removal
  • People with Liver Disease
  • People with poor probiotic status
  • People with Chron’s disease and/or Celiac disease

Vitamin K – The Right Way

So what’s a nutrition-minded k-onsumer to do? Read on to learn about how to improve your vitamin K1 and K2 status from food, lifestyle adjustments, and supplementation.

STEP ONE – FOOD: Choose whole food sources of vitamin K1 from plants and vitamin K2 from animal and fermented foods.

  • Choose (mostly green) vegetables to boost your vitamin K1. Dark, leafy green vegetables (such as most salad greens, spinach, kale), green vegetables (such as broccoli, asparagus, brussel sprouts, green peas), tomatoes, and cauliflower deliver high amounts of vitamin K1. Furthermore, foods increase vitamin K concentration with less water (so tomato paste is higher than tomatoes) and the outer leaves of green leafy vegetables are more nutrient-rich in vitamin K than the inner leaves. When fruits or vegetables are commercially processed into juice, vitamin K is depleted.
  • Choose pasture-raised animal products and certain fermented foods to boost your vitamin K2. Vitamin K2 that you can buy as a supplement comes in two forms- MK-4, which has a shorter half-life, and MK-7, which has a longer half life. To get MK-4 (and appreciable amounts of MK9, MK10, and MK11), focus on animal products. Choose lard and dairy from 100% grass-fed cows, such as milk, butter or ghee, cream, and cheeses, to ensure you are getting meaningful amounts of vitamin K2. Cows fed grain cannot produce K2 in the same amounts because they are consuming grain feed rather than vitamin K1-rich grasses. Most soft, fermented cheeses have appreciable amounts of vitamin K2. Gouda cheese is the highest with 75 mcg per 3.5 oz serving. Brie, blue cheese, jarlsberg, and edam also contain beneficial amounts of K2, while hard cheeses such as parmesan, colby, swiss, and cheddar have less. Fresh cheeses and yogurt are lower in K2.[7] In addition, grass-fed meats such as meat and liver from beef and bison, egg yolks from pasture-raised chickens, and goose liver serve up vitamin K2. Bacteria in your digestive tract can also manufacture MK-4[8] from K1 in the plants you consume, but it is harder to digest and absorb than we initially thought- best to consume preformed K2 to be on the safe side. Fermented foods, including the hard and soft cheeses mentioned above, also supply appreciable amounts of vitamin K2 as MK-7. Natto, a traditional Japanese food, is the winner, serving up over 1000 micrograms of K2 for a 3.5 oz serving, but tastes horrible. Sauerkraut and other fermented vegetables are delicious sources of MK-7.
  • Choose high quality proteins that deliver high quality fats. We cannot understate the importance of grass-fed sources for your K2 containing meats, lard, and dairy. Without vitamin K1-rich grass as the initial foodstuff for the ruminant whole meat or milk, all K2 bets are off.
  • Avoid Antinutrients. Foods containing trypsin inhibitors, a plant’s natural insect repellent, can wreak havoc on your digestion because trypsin is an important digestive enzyme. Trypsin inhibitors can prevent you from absorbing not only fat soluble vitamins (A, D, E, and K), but also vitamin B12 and amino acids. Excessive trypsin inhibitors can even damage your pancreas. Be wary of consuming excessive quantities in beans, grains, nuts, seeds, and nightshade vegetables (such as potatoes, peppers, tomatoes, goji berries, and eggplant). Sprouting, soaking or fermenting your grains, nuts, seeds and vegetables can reduce this effect.[9]
  • Make Room for Microbes. Fermented foods such as natto and sauerkraut may be a great source of pre-formed vitamin K2, but all fermented foods have the potential to help seed your gut with beneficial bactiera than can convert K1-to-K2.

STEP TWO – LIFESTYLE: Consider your digestive health, medications, and overall health to support your vitamin K status.

  • Living a vegan or vegetarian lifestyle can easily increase the risk of deficiency. Even if you consume a lot of dark leafy green vegetables, you cannot assume your gut bacteria will make enough vitamin K2 for you and that you will absorb it from your lower gut. This is why we recommend that vegans and most vegetarians supplement at least 80 micrograms per day of vitamin K2 because vitamin K1 by itself has not been shown to be sufficient to reduce heart disease or osteoporosis risk. A study published in the Journal of Nutrition found that taking vitamin K2 reduced heart disease risk while intake of K1 did not show a beneficial effect.[10] Researchers in the Netherlands report that vitamin K2 is three times as capable as vitamin K1 at activating osteocalcin, the protein that helps put calcium into bones.[11] Furthermore, components of the vegan diet such as trypsin inhibitors (see above) may be excessive for proper vitamin K1 absorption as well, be it by preventing absorption or simply disturbing the lining of your gut.
  • Mind your Medications.
    • Because vitamin K makes blood clot, it is important for those on blood thinners (such as Warfarin) to be consitant with their vitamin K intake from both food and supplemets. Despite the common medical advice to avoid green vegetables when taking a blood thinner, it is not generally considered unsafe to get vitamin K from food or supplements as long as you are getting the same amount each day. That way your dose of blood thinner can be adjusted to your daily intake of vitamin K and you don’t have to miss out on all the benefits of vitamin K that can make or break your metabolism- and bones!
    • The use of antibiotics for longer than 10 days has been documented to stifle vitamin K2 production in the gut from your good gut bacteria. This is not unique to vitamin K– antibiotics can stifle their production of butyrate and B vitamins as well.[12]
    • Furthermore, it is somewhat ironic that cholesterol-lowering statin drugs, bile acid sequestrants (e.g. cholestyramine, colesevelam), lipase inhibitors (such as Xenical or Orlistat), and certain osteoporosis drugs (yes, really) inhibit the conversion of vitamin K1 to K2.[13] This means that it is up to you if you take these drugs to decide whether you are focused on micronutrient sufficiency or medications to deal with heart disease or osteoporosis. We stand squarely with micronutrient sufficiency as our wellness mission and are here to help you balance your medications with the proper supplementation to succeed on your journey to extraordinary health.
  • Munch Mindfully. Giving your body time to eat makes a huge difference in the production of digestive juices (acid, enzymes, and bile) that can do the hard work of digesting food and helping you to absorb this fat-soluble vitamin and others. Take your time.


  • Mix and Match. If you choose to supplement, get a blend of K1 with both the short and long forms of K2 (MK-4 and MK-7) as an insurance policy. Remember, there are two forms of vitamin K2 currently supplemented in the United States: MK-4 and MK-7. MK-4 is taken up more rapidly in your body after you consume it and may be less effective than MK-7 at reaching liver and bone, but more effective at reaching other tissues, such as sex organs. Meanwhile, vitamin K2 as MK-7 has a longer half life so it does not need to be taken multiple times per day and may be more effective at reaching liver and bone. As common sense dictates, we recommend you choose a multivitamin that delivers both vitamin K2 forms in quantities large enough to do the necessary maintenance. In fact, MK-7’s longer half life in the liver makes it even more effective than vitamin K1 at supporting blood clotting. Moreover, the MK-7 K2 Delta form we use in our multivitamin, nutreince has been shown to be the most effective (more on this in a future blog).

The RDA for vitamin K regardless of form is 120 mcg per day and to the time of this post no toxicity level has been set for vitamin K. To ensure you have your bone and blood bases covered, our nutreince multivitamin delivers all three forms of non-GMO vitamin K: 40 micrograms of vitamin K1, 40 micrograms of MK-4 and 40 micrograms of MK-7 in the superior K2Delta form so you get get calcium out of your arteries and into your bones.

  • Bone up on K2, if needed. If you are trying to increase your bone density, we suggest taking a liquid vitamin K2 MK-7 supplement at around 120-240 mcg daily (beyond the levels in your current multivitamin). If your K2 supplement delivers MK-4 rather than MK-7, you will have to take larger quantities (15 mg, 3 times per day) because it breaks down sooner in your body.[14]
  • Supplement Vitamins D and K separately. This is important, because vitamins K and D comptete with one another for absorption.[15] An optimal multivitamin or vitamin K supplement, for instance, will not contain both vitamins D and K in the same dose- that’s why we separate them into AM and a PM doses in our nutreince multivitamin.
  • Ensure Adequate Vitamin E. Remember from our previous blog that vitamin E helps your body utilize vitamin K. Moreover, both vitamins reduce your risk of a heart attack or stroke by keeping arteries k-lear: vitamin E reduces lipid peroxidation and damage to LDL-cholesterol particles so they are less likely to become part of plaque in your arterial walls, while vitamin K2 helps you keep calcium out of your arteries.
  • Power up with Probiotics. Your good gut bacteria do a great job of manufacturing vitamin K2 as MK-4 when you consume vitamin K1-rich vegetables. While we wish the human body converted more MK-4 from K1 than it does, we do not recommend- for several health reasons- that you neglect your good gut generators of several vitamins and beneficial compounds.

In k-onclusion, many of us are simultaneously concerned about heart and bone health- but that’s not all that vitamin K2 does for us. While a lot is known about the health benefits and functions of vitamin K1, we continue to learn more about the wonders of the elusive “factor X” now known as K2. We will keep the research-based recommendations k-oming for your wellness in the short term- and for your long-term health.

Moreover, the role of good gut bacteria in grazing animals boosts K2 levels, so the value of pasture-raised eggs, grass-fed meats, well-aged cheeses, and several fermented foods that support health in myriad way cannot be understated. Vitamin K2 really is the elusive “X factor” that Dr. Weston A. Price said was present in many healthy cultural diets around the world- cultures with straight teeth, strong bones, and good longevity.









[9] Micronutrient Miracle