Vitamin K and vitamin D are incredibly important for human health on their own. However, some nutritionists suggest vitamin D is dangerous to take without K – and you’ll find many supplements which combine both nutrients.

So what’s the reason for the combo? And could missing vit K really be dangerous?

What Are Vitamins D and K?

Firstly, let’s get the run-down on what these vits do for your body. 

Both vitamins D and vitamin K are known as fat-soluble nutrients, meaning they are absorbed best when eaten with high-fat foods.

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Sources of vitamin K, for example, include fatty animal sources like eggs and cheese. The skin produces vitamin D when you’re in the sunshine, but it is also found in oily fish and fortified dairy sources.

Vegan sources of vitamin K include leafy greens like kale and spinach. Getting enough vitamin D in a plant-based diet can be tough, but fortified cereals and milk alternatives are ideal sources.  

Vitamins D and K: Teamwork

Vitamins D and K work as a team in a process known as calcium metabolism.

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The Role of Vitamin D

Among other benefits, vitamin D helps the body absorb calcium. However, if the body lacks adequate levels of calcium from food sources, vitamin D must draw calcium from the bones.

This can lead to scary consequences over time, including osteoporosis and bone loss.

The Role of Vitamin K

However, vitamin D isn’t the only nutrient responsible for making sure calcium is utilised properly. Vitamin K actually has two roles in helping the body use calcium.

Firstly, it activates a protein called osteocalcin which makes sure calcium is built around bones and teeth. 

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Secondly, vitamin K also helps make sure calcium doesn’t accumulate where it shouldn’t be – such as in the walls of your veins and arteries. Known as vascular calcification, this build-up of mineral deposits is associated with atherosclerosiskidney disease and diabetes.

Is Vitamin D Harmful Without Vitamin K?

Evidently, vitamins D and K are both important for regulating calcium’s role in the body. But why do some people warn that high vitamin D levels are dangerous if vitamin K levels are low?

The reason behind this concern involves the calcification of blood vessels, which can lead to heart disease. The theory is that high levels of vitamin D may encourage calcification in those who do not get enough vitamin K.

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To support this hypothesis, symptoms of vitamin D toxicity include very high levels of calcium in the blood (known as hypercalcemia). When exceptionally high levels of calcium are present in the bloodstream, the mineral accumulates and begins to calcify the vessels.

Concerningly, one of the major predictors of heart disease is blood vessel calcification (BVC). 

Moreover, low vitamin K levels is also associated with BVC. Some studies have even shown success in slowing down BVC in older people through the use vitamin K1 supplements. Other studies have suggested those with high levels of vitamin K2 in their diet are less likely to develop BVC and heart disease.

The takeaway

So, very high vitamin D levels may have a negative impact on the body for those without a sufficient vitamin K intake. However, don’t let this discourage you from getting enough vitamin D. It’s important to remember that both have very important roles within the body – particularly in the regulation and use of calcium. 

The recommended daily amount of vitamin D is 10mcg. For vitamin K, the recommended dose is 90mcg for women and 120mcg for men.  

Our new product, Bone and Joint Health Goals, has been specially formulated with vitamins D3 and K2 as well as calcium to help maintain normal bones and joints.