Do you need vitamin K when taking vitamin D?

The Question: When supplementing with Vitamin D, do you also need to take Vitamin K?

We've been getting more and more questions on this subject, so let's address this increasingly common question.

The short answer: No, it is not required to take vitamin K when taking vitamin D. Vitamin D supplements will still raise your blood levels of this important nutrient and provide critical support to your health. However, without adequate vitamin K, you may be cutting vitamin D's full potential short and there's a small chance you're risking harm to your cardiovascular system. Supplementing with vitamin K can help ensure you maximize vitamin D's benefits and further protect your cardiovascular, bone and many other aspects of health. Additionally, research continues to shed light on the importance of K2 for many aspects of our health and many Americans are likely not getting enough.

Worth noting, while our bodies can store vitamin D, vitamin K2 is rapidly metabolized and excreted. So while we can hold on to vitamin D for weeks or longer, vitamin K2 usually only lasts about 72 hours in our body. This suggests we need to replenish this important nutrient frequently, via our diet or supplements.

The Full Story

Vitamin D and K are both fat soluble nutrients, often cited as being helpful to bone and cardiovascular health. A common example of these vitamin's overlapping roles is calcium metabolism.

Vitamin D is known to support the absorption of calcium (and other minerals) from our digestive system into our blood stream. Vitamin K activates special proteins that shuttle calcium from our blood to our bones.

This is thought to have a dual benefit of strengthening our bones, while protecting our soft and flexible blood vessels from becoming hardened with excess calcium. K helps move the calcium to our bones where we want it and in doing so, keeps the calcium from ending up where we don't want it.

The logic behind the concern is if you're taking vitamin D, you're increasing your calcium absorption from your gut to your blood. If your vitamin K levels aren't adequate, this increase of blood calcium may end up depositing in the soft tissues of your blood vessels and joints, instead of your bones. 

While the above is the most common example, vitamin D and K's relationship goes much deeper. Vitamin D helps increase production of of two important proteins, osteocalcin and matrix Gla-protein. These proteins are big reasons why we talk about these vitamins for bone and cardio benefits. However, both of these special proteins need vitamin K to be fully functional.

This is what we mean by realizing the full potential of vitamin D. Part of vitamin D's benefits come from increasing the production of these proteins. If you're not able to activate the proteins due to low vitamin K levels, you're missing out on significant health benefits of of both essential vitamins!

It's also worth acknowledging that we are still selling these nutrients short on bone health! Both of these essential nutrients not only help with bone health by getting calcium to the bone, but also work within the bone to further support bone health. Specifically, supporting the activity of osteoblasts and osteoclast cells, which support the formation, growth and overall maintenance of our bones.

Revisiting our original premise of adding vitamin K, we've offered several reasons why this may be beneficial. A fair question then would be, are their any downsides to adding vitamin K?

Vitamin K has a fantastic safety record, with no upper limit set on daily intake. This means no toxicity has been found even in high dose clinical trials. One potential exception is for those on blood thinners, as some blood thinning medications can interact with vitamin K. In addition to vitamin K having no known upper limit, research continues to support greater benefits from higher levels. Similar to vitamin D in recent years, modern research is reexamining old recommended levels and finding good cause to increase your daily intake of vitamin K, especially K2.

Some of you have been taking the next logical step and wondering about the ideal dosage when combing vitamin D and K. We're hearing feedback from our customers ranging from their M.D. to their favorite Youtube channel. As it stands now, we are not aware of a well proven equation for exactly how much K to pair with your vitamin D. The most common one we hear is 10mcg of K2 for every 1000iu/25mcg of vitamin D. However, that would mean for people taking less than 10,000iu/250mcg of vitamin D (which is quite high), they would be recommended to get less K than the current minimum daily intake ...so that doesn't sound quite right to us.

At HealthWay, our approach is a bit different. Our suggestion is to focus on meeting your daily recommended amount of vitamin K (approx. 100mcg), and consider higher dosages when facing health issues that vitamin K may help or when taking high dose vitamin D. As mentioned, vitamin K has a good safety record and a little extra is much more likely to help rather than hurt.

In the future, we hope more research will help clear up this "ideal ratio" question, but we've likely got a long ways to go. While you can get blood tests to determine your vitamin D levels, and thus determine your ideal dosage range, no such tests are in place for vitamin K. As it stands now, Vitamin K levels are tested by measuring how long it takes your blood to clot, as vitamin K is required for clotting. This is not measuring vitamin K directly, and is reminiscent of early views on vitamin D and rickets. The original recommendations on vitamin D levels were the minimum to prevent rickets. A century later when we began to better appreciate vitamin D's role in immune, inflammatory and metabolic health, we revised the recommended levels. Vitamin K seems to be on a similar path and certainly has many benefits beyond blood clotting, so hopefully more research can provide clarity in the future.

Vitamin D and vitamin K work together to support optimal health. While one does not require the other to be beneficial, they are natural partners in our health and work best together. We encourage you to consider your vitamin K levels, especially if you're using high dose vitamin D regularly.

Always remember to talk to your doctor before adding something new to your regimen. If you'd like to learn more about vitamin K, including making sense of terms like "K2" and "MK-7", check out our other blogs on K2!