When you take vitamin supplements, they can interfere with the levels of different medications and substances that are absorbed by your body. Increased vitamin D levels appear to be linked with a decrease in the amount of vitamin K in your body, though it is not known if taking vitamin D directly affects vitamin K.
What is Vitamin D?
Vitamin D is a fat-soluble vitamin that can be obtained from your diet or made by your body when your skin is exposed to sunlight. One of the most important roles of vitamin D is in maintaining the strength of your bones. You need vitamin D to absorb calcium, one of the main minerals in your bones. Vitamin D also stimulates some of your bone cells and a lack of vitamin D can make your bones weak.
Vitamin D and Vitamin K
There is some evidence that having more vitamin D in your body can decrease the levels of vitamin K. A study that examined the relationship between vitamin D and vitamin K in Danish girls was published in a 2010 issue of the "British Journal of Nutrition." This study found that girls with elevated vitamin D levels had lower levels of a substance known as undercarboxylated osteocalcin, which is often used as a marker for vitamin K levels, suggesting that high amounts of vitamin D decrease the levels of vitamin K.
What Is Vitamin K?
Vitamin K is another fat-soluble vitamin with multiple roles in the human body. It is best known for its importance in blood clotting; many of the chemical reactions needed to make a blood clot require vitamin K. Vitamin K is also needed to maintain the health of bones and low levels of undercarboxylated osteocalcin is associated with an increased risk of bone fractures. A lack of vitamin K can cause poor blood clotting and impaired bone health.
Considerations
Although there appears to be a link between vitamin D and vitamin K levels, it has not been proven that taking vitamin D supplements will decrease the amount of vitamin K in your body. Talk to your doctor before taking any sort of vitamin supplement, as too much vitamin D can cause a dangerous increase in blood calcium levels and may also weaken your bones.
References
- Office of Dietary Supplements: Vitamin D
- "British Journal of Nutrition"; Vitamin D--vitamin K Interaction: Effect of Vitamin D Supplementation on Serum Percentage Undercarboxylated Osteocalcin, a Sensitive Measure of Vitamin K Status, in Danish Girls; O'Connor et al; 2010
- Linus Pauling Institute; Vitamin K; Jane Higdon; 2004
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