Vitamin K2: What is it and What Does it Do?

Vitamin K2 is one of the less well known essential vitamins, but the body needs it in order to function properly. Vitamin K2 is one form of vitamin K, which is a fat-soluble vitamin that we receive primarily from dietary sources.

Although researchers once did not understand what a critical role vitamin K2 plays in the body, recent research has shown that the vitamin may offer a variety of different benefits. Unfortunately, most people do not consume much vitamin K2 from their diets, which makes it difficult to obtain these benefits. Taking a multivitamin that contains vitamin K2 is often your best bet to meet your daily recommended intake of the nutrient. So, what is vitamin K2 and what does it do?

What is vitamin K?

Vitamin K is a fat-soluble vitamin that exists in two primary forms: vitamin K1 and vitamin K2. Vitamin K1, also called phylloquinone, is naturally found in dark leafy green vegetables and is the body’s main source of vitamin K. Vitamin K2, or menaquinone, is commonly found in organ meats and fermented foods, and it can also be produced by the gut bacteria in small amounts. Fat-soluble vitamins like vitamin K require a fat source in order to dissolve. That means that they should be taken with food, including a fat source such as oil or saturated fat, in order to be properly absorbed by the body. Unlike water-soluble vitamins, which dissolve in water and cannot be stored when consumed in excess, vitamin K can build up in the liver if the body receives more than it needs.  Vitamin K is used by the body to produce prothrombin, which is a protein that is critical for allowing the blood to clot, promoting bone metabolism, and healing wounds. Vitamin K is also needed for the production of energy by the mitochondria found in the cells. 

What does vitamin K2 do?

Vitamin K2 is essential for the body’s ability to clot the blood and heal wounds, but it also has a number of other health benefits. Some of the numerous health benefits of vitamin K2 are discussed below. 

Promotes heart health

Researchers have been studying the role of vitamin K2 in promoting heart health and have found that the vitamin may reduce the risk of cardiovascular damage and increase overall heart health.  It is believed that vitamin K2 contributes to heart health by preventing calcium deposits from building up in the walls of the blood vessels. Intake of vitamin K2 activates a protein that helps prevent the buildup of these deposits, which corresponds to a lower risk of experiencing coronary heart disease. Diets rich in vitamin K2 are associated with a lower risk of heart disease, and one study that followed participants for seven to ten years found that people with the highest intake of vitamin K2 had a 57 percent lower risk of dying from heart disease and were 52 percent less likely to develop arterial calcification. Another study of more than 16,000 women found that for every ten mcg of vitamin K2 that the subjects consumed each day, their risk of heart disease lowered by nine percent.

Promotes healthy bone density

Vitamin K2 plays an important role in promoting bone mineral density because it is responsible for carboxylating a protein called osteocalcin that binds calcium to the bones, which strengthens them. Osteoporosis is very common in Western countries and most commonly affects postmenopausal women, who are more likely to experience fractures as a result of the condition. One study of postmenopausal women, conducted over three years, found that study participants that took vitamin K2 supplements lost bone mineral density more slowly than participants who did not take the supplement. Long term studies conducted in Japan found that vitamin K2 supplementation reduced the incidence of non-spinal fractures by 81 percent, hip fractures by 77 percent, and spinal fractures by 60 percent; as a result, Japan officially recommends supplementing with vitamin K2 to prevent and treat osteoporosis.

Promote dental health

In addition to promoting strong bone mineral density, vitamin K2 may also be helpful in promoting dental health. Bone mineral density and dental health are strongly linked, as one of the most important regulating proteins in dental health is osteocalcin. As noted above, osteocalcin is activated by vitamin K2 and is critical to bone metabolism. In the mouth, Osteocalcin is responsible for helping to stimulate the growth of the calcified tissue under the tooth enamel, which is called dentin. Without an adequate amount of vitamin K2, the body may not be able to produce new dentin and dental health may suffer as a result.

Reduce the symptoms of depression and anxiety

Depression and anxiety have many causes, but one surprising factor that has been linked to the two conditions is high blood glucose levels. People with high blood glucose levels are more likely to develop depression and anxiety than those with normal blood glucose levels, and treatment with vitamin K2 may help. A study conducted in 2016 treated rats with metabolic syndrome, high blood glucose levels, and symptoms of anxiety and depression with vitamin K2. Ten weeks later, the rats treated with vitamin K2 had brought their blood glucose levels down to normal and had reduced symptoms of anxiety and depression.

Protect against cancer

Cancer is one of the leading causes of death in many Western countries, but studies have shown that vitamin K2 may be able to help protect against cancer. Vitamin K2 boasts antioxidant properties that reduce inflammation in the body and may suppress the growth of tumors. A study conducted in 2018 found that modified vitamin K2 significantly lowered tumor growth in mouse cells, while other clinical studies found that vitamin K2 can reduce the recurrence of liver cancer and improve survival times in current patients. Vitamin K2 may also be tied to a lower risk of experiencing advanced prostate cancer; an observational study of 11,000 men found that high intake of vitamin K2 lowered the risk of advanced prostate cancer by 63 percent.

What are some natural sources of vitamin K2?

Unlike vitamin K1, which is commonly found in a variety of vegetables, including dark leafy greens, vitamin K2 is less common and is harder to acquire in large quantities. Fortunately, the body can use vitamin K1 and partly convert it into vitamin K2, which is helpful because we receive about ten times as much vitamin K1 in our diets as compared to vitamin K2. However, the conversion process is inefficient and people are better off making a concerted effort to consume more vitamin K2. Vitamin K2 is primarily found in certain animal products, including organ meats, and fermented foods. Because many people, including those following a plant-based diet, such as vegans and vegetarians, do not eat large quantities of these foods, supplementing your diet with a multivitamin that contains vitamin K2 may be helpful.

Dietary sources of vitamin K-2 include:

  • natto, a traditional Japanese dish of fermented soybeans
  • sauerkraut
  • pork
  • egg yolks
  • dairy products, especially hard cheeses
  • liver and other organ meats
  • beef
  • chicken
  • fatty fish, such as salmon

What are the symptoms of vitamin K deficiency?

Although many people do not receive enough vitamin K2, vitamin K deficiency overall is relatively uncommon. The people most likely to experience vitamin K deficiency are newborns and people with certain gastrointestinal disorders, including ulcerative colitis and celiac disease, but overall, few adults in the United States suffer from a vitamin K deficiency. The levels of vitamin K in the body can be impacted by certain medications, including the use of long term antibiotics. The body is able to produce some vitamin K from the gut bacteria, and antibiotics can kill these bacteria and prevent them from producing vitamin K. Medications that are taken to lower the cholesterol can also interfere with the body’s ability to absorb vitamin K, which can cause a deficiency over time.

Those individuals who do experience a vitamin K deficiency will have symptoms that include an increased risk of bruising, bleeding, and hemorrhage due to the blood taking longer to clot. Because of the importance for vitamin K in supporting bone health, people who experience a vitamin K2 deficiency are also more likely to experience osteoporosis and osteopenia. 

People taking certain blood thinners, such as warfarin, need to watch their consumption of vitamin K in order to prevent dangerous interactions between the medication and the vitamin. It is important to consume the same amount of dietary vitamin K every day as recommended by your doctor if taking these medications, and do not make any dietary changes or start taking supplements containing vitamin K without first speaking to your doctor.