Vitamin D3 and K2 supplement
Julie Hambleton
Julie Hambleton
November 7, 2023 ·  5 min read

Is Taking Vitamin D Without Vitamin K Harmful to Your Health?

Vitamin D has been gaining popularity recently as a sort of “super” vitamin. Also known as the sunshine vitamin, research shows that it is for so much more than just bone health. With more people turning to vitamin D supplements, it is important we understand supplementation and its pros and cons. Some research shows that taking vitamin D without another vitamin – vitamin K – could possibly be harmful to our health. This is what the research says.

Taking Vitamin D Without Vitamin K: Harmful to Your Health?

Vitamin D and vitamin K are essential nutrients that play distinct but complementary roles in maintaining optimal health and well-being. Both vitamins are crucial for many bodily functions, including bone health, cardiovascular health, immune system support, and blood clotting. While taking a vitamin D supplement is generally considered a good idea, especially in winter months, it is important to understand the relationship between vitamin D and vitamin K and how they work together for optimal health. (1)

The Role of Vitamin D

Vitamin D is a fat-soluble vitamin that acts as a hormone in the body. Its primary role is to regulate the absorption and utilization of calcium and phosphorus, which are vital for healthy bones and teeth. In addition to its function in bone health, vitamin D also supports immune function, reduces inflammation, and plays a role in cell growth and differentiation.

Our bodies can produce vitamin D naturally when exposed to sunlight. However, many people have insufficient sun exposure, particularly those living in regions with limited sunshine or those who spend most of their time indoors. This is where vitamin D supplements come into play, providing a convenient and effective way to ensure adequate levels of this crucial nutrient.

The Role of Vitamin K

Vitamin K is a group of fat-soluble vitamins, with vitamin K1 (phylloquinone) and vitamin K2 (menaquinone) being the most common forms. While vitamin K is primarily known for its role in blood clotting, it serves several other key functions in the body. It is essential for proper bone metabolism and plays a critical role in ensuring calcium is properly utilized and deposited in the bones. (2)

In addition to bone health, vitamin K also contributes to heart health by preventing the calcification of arteries, reducing the risk of cardiovascular diseases. Vitamin K has also been linked to a lower risk of certain cancers and the regulation of cell growth.

Read: Vitamin D May Help Prevent Heart Attacks, New Evidence Shows

The Synergistic Relationship between Vitamin D and Vitamin K

Vitamin D and vitamin K interact synergistically within the body. Vitamin D aids in calcium absorption from the digestive system, while vitamin K helps to ensure that this calcium is properly utilized and directed towards bone tissues. Without sufficient vitamin K, calcium may not be adequately directed towards the bones, possibly leading to the accumulation of calcium in soft tissues, such as arteries and kidneys. This can increase the risk of arterial calcification and kidney stones.

Furthermore, vitamin K supports the regulation of proteins involved in blood clotting, helping to prevent excessive bleeding. Vitamin D promotes the synthesis of these proteins, and vitamin K activates them. Therefore, adequate levels of both vitamins are necessary for optimal blood clotting function.

Not A One-Way Ticket To Arterial Health

Despite this play between the two vitamins, recent research has not shown that vitamin K supplementation calcium buildup in the heart valves of older men (65+). This was a two year-long randomized controlled trial that examined the effect of vitamin K and vitamin D supplementation on the progression of aortic valve calcification (AVC) among 365 men (mean age of 71) with existing aortic stenosis. The research team randomly assigned the participants to take both vitamin K2 MK7 (720 µg) and vitamin D (1,000 IU), or a placebo, daily. The baseline AVC score, assessed using a noncontrast CT scan. Unfortunately, the vitamin K supplement had no effect. (3)

The Importance of Balancing Vitamin D and Vitamin K Supplementation

While taking supplements can be very beneficial for your health, you must always do so with caution and under the consultation of a medical professional. Taking large doses of vitamin D without adequate vitamin K intake may increase the risk of calcium being deposited in soft tissues, potentially leading to arterial calcification and other health concerns. That being said, taking vitamin K may or may not help this issue, so it is always advisable to speak to your healthcare provider first.

Before starting any supplementation regimen, it is essential to consult with a healthcare professional who can assess your nutritional needs and provide personalized advice. They can help determine the appropriate dosage and guide you on how to achieve a balanced intake of vitamin D and vitamin K.

The Bottom Line

Taking a vitamin D supplement is generally a wise choice to address deficiencies caused by inadequate sunlight exposure. However, it is crucial to understand the interplay between vitamin D and vitamin K to ensure optimal health benefits. Vitamin K may play a role in directing calcium to the bones and preventing its deposition in soft tissues, making it vital to maintain a balance between the two vitamins.

If you choose to take a vitamin D supplement, consider opting for one that also contains vitamin K or speak with a healthcare professional to determine the appropriate dosage and balance. A holistic approach to supplementation, focusing on the interactions between various nutrients, will help support overall wellbeing and ensure you achieve the best results for your health.

Keep Reading: Massive Study Shows Vitamin D Supplements May Help Fend Off Dementia


  1. Is Vitamin D Harmful Without Vitamin K?.” Healthline. Atli Arnarson BSc, PhD. March 4, 2017.
  2. Vitamin K.” LPI
  3. The effects of vitamin K2 and vitamin D on aortic valve calcification.” Examine

    Disclaimer: This information is not intended to be a substitute for professional medical advice, diagnosis or treatment and is for information only. Always seek the advice of your physician or another qualified health provider with any questions about your medical condition and/or current medication. Do not disregard professional medical advice or delay seeking advice or treatment because of something you have read here.