Full-fat cheeses, eggs and beef liver might not be the types of foods that come to mind when you think about eating a heart-healthy diet, but you’d probably be surprised to know that in recent years, one of the most researched nutrients in the field of cardiovascular health has been vitamin K2, found in these very foods.
What are the benefits of vitamin K2? While vitamin K1 has the important role of preventing blood clots and bleeding disorders, vitamin K2 works differently. Vitamin K2 benefits include helping with nutrient assimilation, growth and development in infants and children, fertility, brain function, and dental health. Unfortunately many people don’t get enough of it from their diets.
Something that makes vitamin K unique (both types: K1 and K2) is that it’s not usually taken in supplement form. Vitamin K2 seems to be much more beneficial when obtained naturally from vitamin K foods. What foods are high in K2? Unlike vitamin K1, which is mostly found in plant foods like leafy green vegetables, you get K2 from animal-derived foods. Some of the healthiest vitamin K2 foods include grass-fed meats, raw/fermented cheeses and eggs. It’s also produced by the beneficial bacteria in your gut microbiome.
What Is Vitamin K2?
While we hear the most about vitamin K1 and K2, there are actually a bunch of different compounds that fall into the vitamin K category. (1) Vitamin K1 is also known as phylloquinone, while vitamin K2 is known as menaquinone.
Compared to many other vitamins, vitamin K2 was only recently discovered. What does vitamin K2 help with? It has many roles in the body, but the most important is helping with calcium metabolism and preventing calcification of the arteries, which can lead to heart disease.
If there’s one thing that we need vitamin K2 for, it’s preventing calcium from building up in the wrong locations, specifically in soft tissues. Low intake of vitamin K2 can contribute to plaque building in the arteries, tartar forming on the teeth, and hardening of tissues that causes arthritis symptoms, bursitis, reduced flexibility, stiffness and pain. Some evidence also suggests that K2 has anti-inflammatory properties and may offer some protection against cancer, as research published in the Journal of Nutrition and Metabolism. (2)
What the difference between vitamin k2 and MK7? Vitamin K2 is a group of menaquinones compounds, which are abbreviated as “MK.” MK7 is one type of menaquinones that is responsible for many of the benefits attributed to vitamin K2. MK4 has been the focus of many vitamin K2 studies, but other types like MK7 and MK8 also have unique abilities.
Vitamin K2 Benefits and Uses
What is vitamin K2 good for? Here are some of the major benefits associated with this vitamin:
- Helps Regulate Use of Calcium
- Protects the Cardiovascular System
- Supports Bone and Dental Health
- Helps with Nutrient Assimilation
- Supports Growth and Development
- Improves Hormonal Balance
- Helps Prevent Kidney Stones
1. Helps Regulate Use of Calcium
One of the most important jobs that vitamin K2 has is controlling where calcium accumulates in the body. Vitamin K2 benefits the skeleton, heart, teeth and nervous system by helping regulate use of calcium, especially in the bones, arteries and teeth.
The “calcium paradox” is a common term for the realization by medical professionals that supplementing with calcium can somewhat reduce the risk of osteoporosis but then increases the risk of heart disease. Why does this happen? Vitamin K2 deficiency!
You see, vitamin D is responsible for transporting calcium from the intestines as it digests into the bloodstream. Unfortunately, vitamin D’s job is done at that point. Next, vitamin K2 must activate one of its dependent proteins, osteocalcin, which then takes calcium out of the bloodstream and deposits it into bones and teeth. (3)
Vitamin K2 is essential for the function of several proteins in addition to osteocalcin, which is why it helps with growth and development. K2 is involved in the maintenance of structures of the arterial walls, osteoarticular system, teeth and the regulation of cell growth. (4)
2. Protects the Cardiovascular System
Vitamin K2 is one of the best vitamins for men because it offers protection against heart-related problems, including atherosclerosis (stiffening of the arteries), which are the leading cause of death in many developed countries. According to the Centers for Disease Control and Prevention, every year more than half of deaths due to heart disease are in men. (5)
A 2015 report published in the Integrative Medicine Clinician’s Journal explains that “Vitamin K2 is associated with the inhibition of arterial calcification and arterial stiffening. An adequate intake of vitamin K2 has been shown to lower the risk of vascular damage because it activates matrix GLA protein (MGP), which inhibits the deposits of calcium on the walls.” (6)
The Rotterdam Study, a very large study done in the Netherlands that followed more than 4,800 adult men, found that the highest intake of vitamin K2 was associated with the lowest chances of suffering from aortic calcification. Men who consumed the most K2 were found to have a 52 percent lower risk of severe aortic calcification and a 41 percent lower risk of coronary heart disease. (7)
Vitamin K2 even seems to have life-saving abilities: The men in the Rotterdam study with the highest K2 intake benefited from a 51 percent lower risk of dying from heart disease and a 26 percent lower risk of dying from any cause (total mortality).
Perhaps even more amazing is that vitamin K2 is the only substance on the planet known to reverse plaque buildup in the arteries, making it a unique weapon in the fight against heart disease. (8)
3. Supports Bone and Dental Health
K2 benefits the skeletal system by taking calcium and helping usher it into bones and teeth to make them solid and strong. A number of studies have investigated whether or not vitamin K2 can be useful for helping prevent or treat fractures, osteoporosis and bone loss. Certain clinical studies have found that K2 slows the rate of bone loss in adults and even helps increase bone mass. (9)
K2 can enhance osteocalcin accumulation in the extracellular matrix of osteoblasts inside bones, meaning it promotes bone mineralization. It can even counteract the bone loss experienced during menopause, according to animal studies. (10)
K2 also helps maintain the structure of the teeth and jaws. Many traditional cultures included vitamin K2 foods in their diets because they believed it could help prevent cavities, tooth decay and plaque formation. This impact was observed in the 1930s by dentist Weston A. Price, who found that the primitive cultures with K2-rich diets had strong, healthy teeth although they’d never been exposed to western dental hygiene. (11)
It turns out that getting plenty of K2 during pregnancy is also important for fetal growth. Price also observed this for the first time, although the reason why wasn’t defined until much later. During fetal development, having limited osteocalcin proteins activated (which require vitamin K2) equates to undergrowth of the lower third of the facial bone and jaw structure. Some experts believe this is the reason so many children in modern society need braces. (3)
4. May Protect From Cancer
Those who have high amounts of K2 in their diet are at lower risks of all cancers and death from cancer. (12) Vitamin K2 may also help to protect specifically from leukemia, prostate, lung, and liver cancers. (13, 14, 15, 16)
5. Defends From Rheumatoid Arthritis Damage
In patients with rheumatoid arthritis, supplementing with vitamin K2 resulted in a slowdown of bone mineral density loss and decreased the amount of RANKL, an inflammatory compound, in the blood of subjects. (17) This suggests that vitamin K2 might be a useful supplement to a rheumatoid arthritis diet.
6. Improves Hormonal Balance
Inside our bones, vitamin K2 can be used to produce osteocalcin hormone, which has positive metabolic and hormonal effects. Fat-soluble vitamins are important for the production of reproductive/sex hormones, including estrogen and testosterone. Because of its hormonal-balancing effects, women with polycystic ovarian syndrome (PCOS) can benefit from getting more vitamin K2 in their diets. (18)
K2 can also helps promote blood sugar balance and insulin sensitivity, which can reduce the risk for metabolic problems like diabetes and obesity. (19) Some research suggests that K2 helps regulate glucose metabolism by modulating osteocalcin and/or proinflammatory pathways.
7. Helps Promote Kidney Health
Vitamin K2 may benefit the kidneys by helping prevent the formation of calcium accumulation in the wrong places, the underlying cause of kidney stones. It may also do the same for other organs too, including the gallbladder. (20)
In addition, a lack of K2 and vitamin D is associated with a higher occurrence of kidney disease. (21)
Vitamin K2 Foods and Sources
Below, I’ve included some of the most popular vitamin K2 foods in order of the amount of K2 per 3.5-ounce serving. The best vitamin K2 foods include: (3)
- Natto: 1103.4 micrograms
- Goose liver pate: 369 micrograms
- Hard cheeses: 76.3 micrograms (Gouda, Pecorino Romano, Gruyere, etc.)
- Soft cheeses: 56.5 micrograms
- Goose leg: 31 micrograms
- Egg yolk: 15.5 micrograms (specifically from grass-fed chickens)
- Grass-fed butter: 15 micrograms
- Chicken liver (raw): 14.1 micrograms
- Chicken liver (pan-fried): 12.6 micrograms
- Cheddar cheese: 10.2 micrograms
Vitamin K2 is a fat-soluble vitamin that’s naturally found in animal foods that also contain fat, specifically saturated fat and cholesterol. For example, butterfat, cheese, offal (organ meats), eggs and meat from animals that consume green grasses are all good sources of vitamin K2.
Animals can make vitamin K2 inside their bodies by converting vitamin K1, which is found in green plant foods. The more vitamin K1 an animal consumes from its diet, the higher the level of K2 that will be stored in the tissues. This is the reason that “grass-fed” and “pastured-raised” animal products are superior to products that come from factory farm raised animals. Going back to the fact that vitamin K2 comes in several forms, MK7 is found in the highest concentration in animal foods, while the other types are found in mostly fermented foods. MK4 is the synthetic form of K2.
For vegans, vitamin K2 can be hard to come by — unless you love natto! This “stinky sock” fermented soy food is an acquired taste and is also the only vegan source of K2. Fortunately, it’s also the richest source (and the food used to make the type of K2 supplement I recommend).
Vitamin K2 vs. Vitamin K1
- A growing body of research now demonstrates that vitamins K1 and K2 are not only different forms of the same vitamin, but basically operate like different vitamins altogether due to how they are used in the body.
- Vitamin K1 is more abundant in foods but less bioactive than the vitamin K2. When we eat foods with K1, vitamin K1 mostly makes it to the liver and then the bloodstream once converted. K2, on the other hand, gets distributed to bones and other tissues more easily. Vitamin K1 is very important for supporting blood clotting but not as good at protecting the bones and teeth as K2.
- There’s some evidence that people tend to get about 10 times more vitamin K1 from their diets than vitamin K2. Vitamin K1 is found in mostly green vegetables, while K2 is found in mostly animal products or fermented foods.
- When it comes to how the human body uses vitamin K, vitamin K and vitamin A have certain things in common. Just like the active form of vitamin A (retinol) has unique benefits and is considered superior than the inactive form of vitamin A (beta-carotene), vitamin K is the same.
- Vitamin K2 from animal foods is more active in humans than the plant form, vitamin K1. This doesn’t mean that foods that provide K1 are unhealthy, like broccoli or spinach, just that they are not the best dietary sources of bioavailable vitamin K2.
- Animals help transform vitamin K1 into K2, while humans do not have the necessary enzyme to do this efficiently. This is why we benefit from getting K2 directly from animal-derived foods — and why sticking to grass-fed animal products provides the most K2.
Vitamin K2 Dosage
How much vitamin K2 should you take in a day? The minimum daily requirement of K2 in adults is between 90–120 micrograms per day. I recommend aiming to get about 150 to 400 micrograms daily, ideally from vitamin K2 foods as opposed to supplements. People with a higher risk of heart disease or bone loss may benefit from getting a dose on the higher end of the spectrum (200 micrograms or more) while those looking to maintain their health can get a bit less.
Is it beneficial to take vitamin K supplements? If you take a supplement that contains vitamin K, the chances are very likely that it’s vitamin K1 but not K2. While some newer vitamin K2 supplements are now available, the type of supplement matters greatly.
MK4, the form of K2 found in many vitamin K supplements, is a synthetic K2 with a short half-life — to get the full benefit of it, you have to take it multiple times throughout the day. Often, an MK4 serving size is thousands of micrograms to counteract the half-life of the compound. However, MK7 derived from natto has a much longer half-life and can be taken in more reasonable doses like those listed above, which is why I recommend looking for an MK7 supplement. (3)
Remember that vitamin K works with other fat-soluble vitamins, like vitamins A and D, so the best way to obtain these nutrients is to eat foods that provide many different vitamins — like eggs and raw, full-fat dairy products. Particularly for those at risk of osteoporosis, calcium should also be a nutrient you aim to eat a lot of while increasing your K2 intake.
Vitamin K2 Deficiency Symptoms and Causes
What happens if you get too little vitamin K? Symptoms of vitamin K2 deficiency can include:
- Heart-related problems like arterial calcification and high blood pressure
- Kidney stones
- Cavities and other dental issues tied to tooth decay
- Symptoms of inflammatory bowel disease, like bloody stool, indigestion and diarrhea
- Poor blood sugar balance and higher risk for blood sugar issues and diabetes
- Metabolic problems
- Higher chance of having morning sickness in pregnant women
- Spider veins/varicose veins
Among adults living in industrialized nations, vitamin K deficiency is considered to be rare. However, newborn babies and infants are much more susceptible to vitamin K2 deficiency due to how their digestive systems lack the ability to produce K2.
Adults are at a greater risk of developing vitamin K2 deficiency if they suffer from any of these health conditions:
- Diseases that affect the digestive tract, including types of inflammatory bowel disease like Crohn’s disease, ulcerative colitis or celiac disease
- Malnutrition, due to calorie restriction or poverty
- Excessive alcohol consumption/alcoholism
- Use of drugs that block vitamin K2 absorption, which can include antacids, blood thinners, antibiotics, aspirin, cancer treatment drugs, seizure medication and high cholesterol drugs — cholesterol-lowering statin drugs and certain osteoporosis drugs inhibit the conversion of K2, which can greatly lower levels
- Prolonged vomiting and/or diarrhea
Vitamin K2 Recipes
In order to naturally add more K2 to your diet, try making some of these vitamin K2 recipes rich in fat-soluble vitamins:
- Eggs Benefit with Asparagus
- Chicken Liver Pate
- Cheesy Dark Meat Chicken and Rice Casserole
- Creamy Baked Mac and Cheese
- Goat Cheese And Artichoke Dip
For decades, vitamin K was known to be important for blood coagulation — but only recently have studies uncovered how vitamin K2 can help treat bone and vascular diseases, too.
In 1928, a researcher named Carl Peter Henrik Dam from the Biochemical Institute of the University of Copenhagen first identified vitamin K. (22) He found that when chickens were fed a cholesterol- and fat-free diet, they developed coagulation disorders that did not improve when vitamins A, C and D were added to the diet.
The chickens only recovered when given green vegetables and liver, leading to the conclusion that these foods contained a special nutrient that helped regulate blood clotting. This new vitamin was named “vitamin K” after “Koagulation,” or coagulation as it’s now spelled. After decades of more work, Dam and another researcher named Doisy were jointly awarded the Nobel Prize for discovering the chemical structure of vitamin K.
Shortly thereafter, research by Weston A. Price (a dentist) was published in 1939 featuring information about “Activator X,” a compound he identified in native diets in cultures not exposed to modern culture. He attributed X to the extremely low disease rates and incredibly healthy, strong teeth. While he published these results nearly 80 years ago, only recently have scientists discovered that Price’s “Activator X” was actually vitamin K2. (3, 11)
It was not until the 1970s that researchers uncovered much more about the precise biochemical properties of vitamin K, including how vitamin K interacts with at least 14 different types of proteins, plus calcium and other minerals.
Today, K2 is mostly being researched for its ability to prevent bone and vascular diseases. It’s now known that certain medications, including antagonists such as phenprocoumon and warfarin, can interfere with vitamin K2’s actions in the body. In the years to come, we should see much more research about how K2 affects blood flow (haemostasis), calcium metabolism, control of cell growth, apoptosis, signal transduction and the matrix of bones.
Vitamin K2 Side Effects and Precautions
Can too much vitamin k2 be toxic? While it’s rare to experience side effects from getting high amounts of K2 from food alone, you might develop symptoms if you take high doses of vitamin K supplements. However, for most people even high doses of vitamin K2, such as 15 milligrams three times a day, have been shown to generally be safe. If you’re someone who takes the drug Coumadin, a potential side effect associated with taking too much vitamin K is increasing your risk for heart-related problems. Too much vitamin K can also contribute to complications in people with blood clotting disorders.
While food is the best way to increase your intake of K2, look for a supplement that specifically lists vitamin K2 (menaquinone) if you plan to supplement. Because vitamin K supplements can interact with many medications, talk to your doctor if you plan to take a vitamin K supplement and are taking any daily medications.
- Vitamin K2 (menaquinone) is a fat-soluble vitamin that helps with calcium metabolism, bone and dental health, heart health, and hormone balance.
- Vitamin K1 is found in mostly green vegetables, while vitamin K2 is found in mostly animal products or fermented foods.
- Benefits of getting more vitamin K2 from your diet include helping to reduce your risk for calcification of the arteries, atherosclerosis, cavities, tooth decay, kidney stones and hormonal imbalances.
- Vitamin K2 seems to be much more beneficial when obtained naturally from vitamin K foods rather than supplements. I recommend consuming raw, fermented cheese and other full-fat dairy products to get vitamin K2. Eggs, liver and dark meats are other good vitamin K2 foods.
Read Next: The Best Vitamins for Men
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