Vitamin D3 & K2 Interactions in the Body

01/02/2024 | 6 min. read

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Many people have heard of the restorative effects of vitamin D3 supplements, in fact it has been estimated that up to 33% of adults use vitamin D3 supplements. However, it seems that many people have not yet heard of vitamin K2.

Vitamin K2 also has many restorative effects in the body and plays an integral role in many of the same mechanisms that vitamin D3 is involved in. Medical science has established an important interaction between vitamin D3 and vitamin K2 that has potential for significant health benefits.

Let’s explore these two vitamins and their interactions a little bit deeper.

Vitamin D

There are many different types of vitamin D, but only two of these forms are relevant to the human body: vitamin D2 and vitamin D3.

Vitamin D2 is typically produced by exposing fungus or yeast to UV light and has been used to treat severe vitamin D deficiency.

Vitamin D3 is made by the human body through exposure to the sun and has numerous benefits over vitamin D2, including:

  • Better absorption rate
  • Better storage rate
  • Faster conversion to active form

Vitamin D Production and Absorption

All forms of Vitamin D are fat soluble, meaning that they are better ingested and absorbed when taken with fatty foods such as fish, eggs and dairy.

While ingestion of food and supplements is one way to get more vitamin D, the activation of 7-dehydrocholesterol into vitamin D3 through exposure to UV light from the sun is the main way that your body synthesizes this vitamin.

The sun’s UV rays can give electrons a little extra energy moving them up an energy level, placing them in a new orbital location. This excited electron can make the molecule unstable and so the whole molecule will undergo a chemical change to a new form that will restore stability.

In this case, previtamin D forms from 7-dehydrocholesterol after it has been exposed to UV light through the skin. Then, chemical equilibrium ensures that previtamin D gradually changes to vitamin D3 as the body needs it.

Vitamin D3 and the Body

Vitamin D3 is an important precursor to several communication molecules such as calcifediol or “Vitamin D, 25-OH” as you might see it on your annual blood testing results.

The hormones that vitamin D3 becomes when activated by the liver then kidney are responsible for regulating blood calcium levels, and vitamin D3 has a profound impact on many other body functions including:

  • Healthy parathyroid function
  • Glycemic control
  • Healthy triglyceride levels
  • Bone health
  • Mood
  • Immune function
  • Muscle recovery after exercise in men
  • Muscle strength

Vitamin K

Like Vitamin D, Vitamin K is also a fat soluble vitamin that is better absorbed in hydrophobic, non-aqueous, environments. Vitamin K is found in two forms in the body: K1 and K2.

Vitamin K1 can be found primarily in leafy vegetables and is used by the liver to produce collagulating factors, which are important for blood clotting and scab formation. On the other hand, Vitamin K2 is found primarily in fermented foods and works in bones and cardiovascular tissue to ensure their proper function.

Some multivitamins contain vitamin K1 but leave out vitamin K2. Vitamin K deficiency is more rare in adults, but common amongst certain populations, including alcoholics and malnourished individuals.

Interactions of Vitamins D and K

The study of interactions between vitamin D and vitamin K has been interesting, due to their many similarities in both use and characteristics:

  • Both vitamins are fat soluble
  • Both vitamins are essential vitamins
  • Both vitamins are involved in calcium regulation
  • Both vitamins are associated with bone formation

The interactions between these molecules have been evidenced in multiple health areas including bone health and cardiovascular health.

Bone Health

The regulatory effects on blood calcium by the hormone products of vitamins D and K are integral to bone health. Bones are the body’s calcium storage system, and bones rely on having substantial calcium stores to ensure they can bear the weight of the rest of the body.

The interactions between vitamin D3 and vitamin K2 have been shown to use completely different pathways for bone maintenance than when vitamin K is present by itself. These mechanisms have synergistic effects on bone construction particularly by:

  • Supporting vitamin K dependent bone protein formation
  • Supporting gene expression of osteoblasts - bone forming cells
  • Supporting calcium regulation through reabsorption

Enabling the body to have healthy bone formation is an integral part of bone health and maintenance. The combination effect of vitamins D3 and K2 upregulates this process and promotes better bone health.

However, vitamin K2 pathways have been shown to not be affected by particular blood thinning medications, such as Warfarin, and may have negative health outcomes when blood thinning medications are necessary for blood clot maintenance, such as following a surgery.

Be sure to talk to your doctor before supplementation if you are currently prescribed one of these medications.

Metabolic and Cardiovascular Health

As with bones, calcium plays an important role in cardiovascular health. Calcium is the main electrical signaling molecule for cardiac tissue, making it a crucial nutrient to keep your heart beating.

However, calcium can also have a negative effect on your heart and vascular system. Calcium deposits in cardiovascular tissue such as heart valves and major arteries are one of the biggest contributors to chronic heart issues for the general population.

The mechanism behind arterial calcium build-up has been shown to be closely linked to poor dietary habits.

Vitamin D and vitamin K are deeply involved in cardiac issues that arise separately from the metabolic pathways, as well. Proper vitamin D and K levels in synergy enable the body to properly engage its calcium regulatory mechanisms, vitamin D can have beneficial coronary health benefits. Vitamin K supports healthy blood flow in women.

Other synergistic effects of vitamin D and vitamin K are still being researched with particular interest in how they may directly influence various areas of cardiovascular and metabolic health.

Too Much of a Good Thing

Each vitamin is an important essential nutrient for the human body. However, as important as each of these nutrients is for the body, having too much of a single vitamin can actually have some detrimental effects.

For instance, promoting proper calcium regulation with a D3 supplement can become an interference to renal and cardiovascular function when done in excess. The resulting symptomatology is called “metastatic calcium” and is combated by proper calcium uptake.

Vitamin K2 facilitates calcium uptake by providing pathways for integration of calcium into the bones, effectively removing calcium from the bloodstream. This, along with all the other aforementioned research on the interactions between the two vitamins, is why the best supplement for vitamin D should have vitamin K2 as well.

So, what are the proper doses of vitamin D and vitamin K to take?

Well, it depends on your diet and other factors, you may not even have a deficiency. The body is meant to maintain clinical ranges of 25-hydroxyvitamin D above 30 ng/ml or preferably between 40-60 ng/ml.

The Endocrine Society recommends a daily intake between 1500 and 2000 IU of vitamin D for all adults. For vitamin K, the National Academy of Science Food and Nutrition Board states that an adequate intake is 120 and 90 ug/day for men and women, respectively.

In Conclusion

In conclusion, more and more people are realizing the importance of achieving an optimal balance for micronutrients such as vitamin D. Although these micronutrients are needed in small quantities most people seem to be deficient and are missing out on the extraordinary cardiovascular, metabolic, and bone health benefits.

If you want to see these benefits for yourself, consider picking up a great supplement that incorporates the most up-to-date science to keep your body going strong for many more years to come.

Healthy Directions Staff Editor