Should You Take Vitamin D and Vitamin K Together?

Although they’re not very close together in the alphabet, and they don’t look much alike, the letters D and K actually have a lot in common — at least when you’re talking about vitamin D and vitamin K.

But there are differences between these nutrients, too. Here, we’ll explore what each vitamin does for the body and also look at how taking them together might unlock other health benefits.

For starters, both vitamin D and vitamin K are fat-soluble vitamins, meaning they do not dissolve in water and are best absorbed when eaten with a bit of fat. Both play a role in helping your body use calcium effectively. And the human body is actually capable of making a form of each vitamin: We can make vitamin D3 when our skin is exposed to sunlight, and bacteria in our gut are capable of synthesizing vitamin K2.

Vitamin D is an important nutrient for muscle development and recovery. It’s also critical for the proper health and functioning of your nervous system and immune system. It’s useful in helping your body deal with infections and inflammation. Some research shows that vitamin D may also help inhibit the growth of certain types of cancer cells. It may also be useful in lowering your risk of depression.

But perhaps vitamin D’s most important role is its ability to help the body absorb calcium — something we simply couldn’t do without it. And of course, we need calcium, not just for the health of the systems mentioned above, but especially for the development and maintenance of strong teeth and bones.

In addition to producing it naturally through sunlight exposure (which is why it’s known as “the sunshine vitamin”), we can also get vitamin D from certain types of mushrooms, fatty and oily fish (like salmon or sardines) egg yolks, red meat and liver, and foods fortified with the vitamin, such as dairy products, cereals, and orange juice. Of course, vitamin D is also available in supplement form for those who may be deficient.

Vitamin K, meanwhile, is actually a group of vitamins that provide the body with many benefits as well. It’s known in some circles as “the clotting vitamin.” That may not be the most appealing nickname, but it sure is an accurate one: Vitamin K is indeed important in helping blood to clot and thus avoid continuous bleeding that would otherwise make it difficult for wounds to heal.

Vitamin K also helps promote heart health. What’s more, it works to reduce calcium levels in your blood and activates certain proteins that are essential for the production of healthy teeth and bone tissue.

Although our gut bacteria create vitamin K, we can also get it from such food sources as broccoli, asparagus, kale, spinach, and other leafy green vegetables. Vitamin K2 is the kind that our bodies produce, and you can also find it in eggs, meats, and cheese. It’s also available in supplement form, although not many people really need a vitamin K supplement unless they’re taking certain medications or have specific health conditions.

Read More: 15 Benefits of Vitamin D

Nutritional research has determined that the two vitamins can have a synergistic relationship, which is to say that they work well together and could provide certain health benefits more effectively working in tandem than either one might provide on its own. In particular, vitamin D appears to promote the production of specific proteins that are important for bone and heart health, but those proteins need vitamin K in order for their benefits to be activated.

Research on both vitamins suggests that taking vitamin D and vitamin K together can optimize your body’s ability to metabolize calcium. The two can be more effective and provide more skeletal and cardiovascular benefits than taking either one separately. Also, if someone is taking very high doses of vitamin D for health reasons (as directed by their doctor), taking vitamin K may help reduce certain risks associated with vitamin D toxicity, such as the buildup of calcium in the bloodstream, also known as hypercalcemia. This condition can cause painful kidney stones or possibly interfere with healthy bone development, as well as heart and brain functions.

While vitamin D and vitamin K are important nutrients — important enough that the human body produces forms of each vitamin by itself, don’t forget — that doesn’t mean that supplementing these vitamins is a good idea for everyone.

In particular, most people should be cautious of taking excessive amounts of vitamin D. The National Institutes of Health’s Office of Dietary Supplements warns that no one should exceed these vitamin D dosages (in micrograms or International Units) without the explicit guidance of a doctor:

• Children under 6 months: 25 mcg or 1,000 IU

• Children 7-12 months: 38 mcg or 1,500 IU

• Children 1-3: 63 mcg or 2,500 IU

• Children 4-8: 75 mcg or 3,000 IU

• Children/Adults 9 and older: 100 mcg or 4,000 IU

• For people who are pregnant or breastfeeding, the recommendation is not to exceed 100 mcg or 4,000 IU without a doctor’s diagnosis or recommendation.

Meanwhile, your body is capable of processing vitamin K fairly quickly, so it’s not likely you can overdose on it. That said, there are certain medications that interfere with the action of this vitamin. As a result, people who are regularly taking antibiotics, blood thinners (including aspirin), or other heart medications (such as cholesterol drugs) should not supplement their vitamin K intake without talking to a doctor. Pregnant people should also be careful of their vitamin K dosage, as research has indicated a link between vitamin K and problems for newborns, such as jaundice.

Read More: What Is the Correct Dosage of Vitamin D for Adults?

Excessive dosing of vitamin D in any form can lead to health problems ranging from nausea and vomiting to muscle weakness or difficulty walking. In extreme cases, taking too much vitamin D can trigger potentially fatal health conditions, such as kidney or heart failure.

As for vitamin K: Again, because the human body is capable of breaking down vitamin K quickly, the risks of taking large doses of this nutrient are generally thought to be less severe compared to vitamin D. Some people taking supplementary vitamin K have reported minor symptoms such as upset stomach or diarrhea. As benign as this vitamin’s safety profile seems to be, no one should be taking supplementary vitamin K without consulting their physician.

Read More: Strange Side Effects From Supplements and What You Need to Know

That said, if you still choose to take supplements of either vitamin, it’s probably best to take supplements that contain vitamin D3 and vitamin K2 — these are the two forms of each vitamin that our own bodies are capable of making, and some research suggests that these forms are more readily absorbed by our systems than others.

Although some nutrition gurus recommend spacing your intake of D and K by a few hours, there’s no conclusive research to suggest that separating your doses of these two vitamins has any real benefit in terms of how well you absorb them. Meanwhile, the supplement aisle at your local pharmacy is chock-full of pills and liquids that combine both D and K in one convenient dose. Try whichever method your doctor recommends.

Read More: Here’s Why You May Want To Take Vitamin D and Magnesium Together

Our writers at Discovermagazine.com use peer-reviewed studies and high quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:

• Frontiers in Endocrinology: Vitamin D Toxicity — A Clinical Perspective

• Harvard T.H. Chan School of Public Health: The Nutrition Source: Vitamin D

• Harvard T.H. Chan School of Public Health: The Nutrition Source: Vitamin K

• Mayo Clinic: Diseases & Conditions: Hypercalcemia

• Mayo Clinic: Drugs and Supplements: Vitamin K

• Mayo Clinic: Nutrition and Healthy Eating: What Is Vitamin D Toxicity

• National Institutes of Health: Office of Dietary Supplements: Vitamin K

• National Library of Medicine: National Center for Biotechnology Information: Depression and Anxiety: The effect of vitamin D supplement on negative emotions: A systematic review and meta-analysis

• Integrative medicine (Encinitas, Calif.). Proper Calcium Use: Vitamin K2 as a Promoter of Bone and Cardiovascular Health

• International journal of endocrinology. The Synergistic Interplay between Vitamins D and K for Bone and Cardiovascular Health: A Narrative Review

This article is not offering medical advice and should be used for informational purposes only.