Vitamin K2 benefits: The nutrient in butter you didn't know you needed

• Vitamin K2 is a form of vitamin K that you can get from butter, egg yolks, and fermented foods. 
• The vitamin has benefits for bone health and may help with treating osteoporosis.
• Vitamin K2 may also help improve rheumatoid arthritis and reduce the risk of diabetes.

While major vitamins like C and D get most of the hype, many other vitamins are responsible for keeping your body healthy, including vitamin K. But despite its name, vitamin K is not a single vitamin. 

Rather vitamin K refers to a group of compounds that share a similar chemical structure. The two forms most important for your health are K1 (phylloquinone) and K2 (menaquinones). 

While vitamin K — specifically, vitamin K2 — may be lesser-known, this nutrient plays a key role in important factors like bone and heart health. 

Here's what you need to know about vitamin K2, where you can get it, and its potential health benefits. 

What is vitamin K2?

While vitamin K1 is typically the main dietary source of vitamin K and exists primarily in leafy greens, vitamin K2 is still an important part of a balanced diet and mostly comes in animal-based and fermented foods. 

Something worth noting here is that vitamin K2 (menaquinones) has its own sub-branch of various types depending on chemical make-up. 

Of the menaquinones, MK-4 and MK-7 are the most well-studied, says Erika Zoellner, senior registered dietitian at Baylor College of Medicine. They are most commonly linked with bone health and cardiovascular health, however, more research is needed to fully understand the benefits and mechanisms of these menaquinones.

Matthew Black, registered dietitian at The Ohio State University Wexner Medical Center says sources of vitamin K2 in the form of MK-4 are:

• Butter
• Egg yolks
• Various animal products if the animals' feed was supplemented with vitamin K2

For vitamin K2 in the form of MK-7, Black recommends:

• Natto (a type of fermented soy)
• Certain cheeses (such as camembert, gorgonzola, and munster)
• Sauerkraut 
• Kefir (fermented milk)

If you're looking for vitamin K2 supplements, you will typically find them in MK-4 or MK-7 form, says Black. 

However, when possible, it's generally considered to be better to get your nutrients from food rather than supplements, says Zoellner. This helps ensure that you consume a variety of necessary nutrients, and can help with absorption, since vitamin K is fat-soluble. This means that it is important to pair Vitamin K rich foods with fats including olive oil, nuts, trail mix, nut butters or avocado.

The benefits of vitamin K2

While researchers are still working to fully understand vitamin K2 and its uses, current research is promising. Four possible benefits of K2 are: 

1. May promote bone health

"Research involving the use of vitamin K2 in the treatment of osteoporosis and the prevention of new bone fractures has shown promising results," Black says. This may be due to the fact that there may be proteins in bone that are dependent on K2. 

A 2013 study following postmenopausal women for three years found that those who took an MK-7 vitamin K2 supplement for three years had stronger, denser bones than a placebo group. 

While results are promising for menopausal women, the researchers note that more studies are needed to determine if this holds true for other groups of people, as well. 

2. May lower risk of coronary artery disease

Your heart health may be improved with a higher intake of vitamin K2. 

One early sign of coronary artery disease is calcification of the arteries. A protein called MGP can prevent calcification, but it is dependent on vitamin K to work best, Zoellner says. Therefore, vitamin K2 supplementation may help support MGP in preventing the build up of calcium deposits in the arteries. 

A 2021 review found a link between vitamin K deficiency and arterial stiffness, calcification, and subsequent heart failure. The review also found that coronary artery disease risk can be decreased by increasing your K2 intake, which may slow the progression of calcification.

However, the reviewers say more research is needed to determine how effective vitamin K2 is for this purpose. 

3. May reduce diabetes risk 

Black says there's some promising research that vitamin K2 may reduce the risk of developing diabetes. 

A 2018 review, for example, found that vitamin K2 supplementation is associated with a lower risk of developing type 2 diabetes, which may be due to the improved insulin sensitivity researchers observed across multiple studies. Vitamin K2 specifically was found to have this benefit over vitamin K1. 

Furthermore, in people who already have type 2 diabetes, K2 may be able to help reduce high blood sugar. A 2020 study found that supplementation of vitamin K2 and D3 was beneficial in lowering glucose levels. 

4. May improve rheumatoid arthritis

C-reactive protein (CRP) is a type of protein naturally found in your body. CRP levels rise in association with inflammation. If you have a chronic inflammatory condition like rheumatoid arthritis, your CRP levels may be consistently high. 

"There is evidence that vitamin K2 supplementation could reduce inflammation in rheumatoid arthritis by reducing C-reactive protein levels," says Black. 

A 2013 study found that rheumatoid arthritis patients who took vitamin K2 supplements experienced lower C-reactive protein (CRP) levels, which is linked to less inflammation. 

Furthermore, a 2020 review found that the effect that K2 has on the immune system may play a role in preventing and treating rheumatoid arthritis.

Insider's takeaway

Vitamin K2 can be found naturally in a variety of foods including fermented products or certain animal products. It is also available as a supplement, typically in the form of MK-4 or MK-7. 

While more research is needed for definite answers, vitamin K2 shows promise for treating and preventing certain chronic diseases.