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Vitamin D3 & K2 Benefits: Why They Work Better Together

By Ethan Boldt

October 7, 2026

When we think of vitamins, we often refer to them only by their main letter, such as vitamin C or D. But many vitamins come in various forms, and vitamins D3 (as cholecalciferol) and K2 (as MK-7) are two prime examples that many argue are not only the superior form of each respective vitamin but also happen to work together in some pretty important ways. 

The combination of vitamins D3 and K2 can support bone health, immune system health, cardiovascular health and more. In fact, there is some evidence that taking the two nutrients together is better than taking either alone, as they work complementary to support proper calcium placement in the body. 

While most people know how important the “sunshine vitamin” (D3) is, less is known about vitamin K2 and the role it plays in the body, such as how it regulates calcium. 

Therefore, with vitamin D a common nutrient shortfall for women and men, along with bone health being of utmost importance to women and men as they age, the vitamin D3–K2 combination has become a popular one in supplement circles. Learn more about the benefits and supplement choices when it comes to this powerful vitamin duo. 

What is vitamin D3?

While D2 and D3 are the two most common forms of vitamin D, vitamin D3 is generally more effective at increasing vitamin D levels in the body compared to vitamin D2 because it’s the more “active” and beneficial form. Therefore, ideally you want a vitamin D supplement that contains vitamin D3, also known as cholecalciferol.

Vitamin D3 is found primarily in animal-derived foods, while vitamin D2 is found in fortified foods and mushrooms. These two types of vitamin D are also metabolized differently in the body.

What is vitamin K2?

Vitamin K is a fat-soluble vitamin that occurs primarily in two forms: vitamin K1 (phylloquinone) and vitamin K2 (menaquinone). Vitamin K1 is found mainly in leafy green vegetables such as kale, spinach and collard greens and is especially important for normal blood clotting. 

Vitamin K2 encompasses several menaquinones (fat-soluble vitamin compounds), including MK-4 and MK-7, and is found in certain animal-derived and fermented foods. Natto is an especially rich source of MK-7, while some cheeses, egg yolks and animal foods provide varying amounts of K2.

Vitamin K2 is becoming better known due to its connection to bone health and calcium metabolism. 

Why take vitamins D3 and K2 together? 

The No. 1 reason why vitamins D3 and K2 are often paired in supplement form is because they play complementary roles in calcium support. 

To simplify the biological process, vitamin D3 helps your body absorb calcium while vitamin K2 helps place calcium where it needs to be in the body. They work together to not just assist with calcium absorption but also utilization. 

When calcium, such as through calcium-rich foods, enters the bloodstream, vitamin D3 works to help with absorption in the gut. Vitamin K2 then helps direct that calcium towards your bones and teeth while helping to keep it from reaching your arteries and soft tissues. 

According to an International Journal of Endocrinology review, combining vitamin D and vitamin K may be more effective in supporting bone and heart health compared to when taken alone. 

Benefits of vitamins D3 and K2

1. Supports healthy bones 

As you’ve already seen, vitamins D3 helps increase calcium absorption while vitamin K2 activates certain proteins (like osteocalcin) that help bind that calcium to where it’s needed, such as the bones and teeth. Otherwise, that calcium can end up in the arteries or soft tissues. 

In a randomized study of postmenopausal women, combined supplementation with vitamins K2 and D3 resulted in supporting bone health and healthy vitamin D levels. 

2. Immune system health

Vitamin D is important for supporting a healthy immune system. It supports key inflammatory biomarkers and a healthy inflammatory response. 

Therefore, maintaining adequate vitamin D levels is important for healthy immune system support, particularly for people who get limited sun exposure or have low vitamin D status.

3. Supports healthy vitamin D levels

Because vitamin D is found in very few food sources — such as some dairy products, egg yolks, liver, fish and mushrooms— it is often challenging for many to meet one’s needs through your diet alone. Not only that, but many are also considered to be at a higher risk of coming up short on vitamin D, including older adults, overweight individuals and those living in northern latitudes, due to poor absorption and low sunshine exposure.

Taking a vitamin D supplement is one of the easiest and most effective ways to help maintain optimal vitamin D levels. Unfortunately, vitamin D shortfalls or even some deficiencies are thought to be incredibly common, especially among older adults, those with darker skin and those with limited sun exposure.

Vitamin D plays a key role in immune system function and is one of the most well-studied nutrients for supporting vitamin D status. 

4. Supports key inflammatory biomarkers 

Vitamins D3 and K2 support key inflammatory biomarkers and a healthy inflammatory response. In particular, D3 supports normal immune system and inflammatory responses, while emerging research suggests K2 may provide complementary support for pathways involved in promoting a healthy inflammatory response. 

5. Supports cardiovascular health

Vitamin D3 and vitamin K2 may provide complementary support for cardiovascular health, largely through their roles in calcium metabolism and vascular function. Vitamin D receptors are present in cardiovascular tissues, and adequate vitamin D is involved in normal cardiovascular function and healthy inflammatory responses. 

Vitamin K2 helps support healthy osteocalcin and matrix Gla protein (MGP) activity. MGP is a vitamin K-dependent protein involved in regulating calcium deposition in blood vessels, as well as osteocalcin, which participates in bone mineralization. 

How to supplement with vitamins D3 and K2

How much vitamin D and vitamin K2 should you take each day? The recommended dietary allowance (RDA) for vitamins D and K varies based on age, but you should always consult your healthcare practitioner before beginning any dietary or supplement regimen.

Overall, adult women and men should aim for at least 600 IU of vitamin D and 90 mcg of vitamin K per day. It’s important to find supplement formulas that combine vitamin D3 (cholecalciferol) with vitamin K2 (as MK-7), as these are the most beneficial forms.

Ancient Nutrition offers two vitamins D3 and K2 combination supplements: 

1. Liposomal Vitamin D3 + K2 Gel Packs (pineapple flavor) 

This ready-to-use gel pack provides 4,000 IU (100 mcg) of vitamin D3 and 180 mcg of vitamin K2. With zero-prep convenience and a great-tasting flavor, it makes getting daily vitamin D support easier than ever. 

It’s designed to help maintain healthy vitamin D levels while supporting bone health, healthy calcium utilization, immune system function, muscle health biomarkers, and a healthy inflammatory and stress response. It also promotes a balance in cortisol levels as well as cardiovascular health and exercise performance after just 14 days.

Ancient Nutrition’s Liposomal Vitamin D3 + K2 Gel Packs also support physical fitness/function and performance, including supporting exercise tolerance, lower-body muscle performance and muscle recovery. It reduces perceived exertion and helps one feel more fit and less fatigued during exercise

2. Ancient Nutrients Vitamin D3 + K2 Capsules

It contains 5,000 IU (125 mcg) of organic, probiotic-fermented vitamin D3 and 95 mcg of vitamin K ( (as MK-7) per serving. It features multi-kingdom ingredients inspired by TCM (Traditional Chinese Method), such as bone broth and liver powder.

Frequently asked questions

Why should I take vitamin D3 and K2 together?

Vitamin D3 helps the body absorb calcium, while vitamin K2 helps activate proteins involved in calcium metabolism and bone mineralization, making them complementary nutrients for supporting bone health.

Should I take K2 and D3 in the morning or at night with fatty food?

Both vitamin D and vitamin K2 are fat-soluble vitamins, so it’s a good idea to take these vitamins with a meal that contains a source of fat to optimize absorption. A few slices of avocado, a handful of nuts or a square of dark chocolate can all help boost absorption.

Regarding morning or night, it doesn’t matter too much, but many people prefer to take with either their breakfast or dinner to help absorption. Some people report that vitamin D may interfere with their sleep, but this isn’t common. 

Why do some vitamin K2 supplements use MK-7?

Menaquinone-7 (MK-7) is a well-studied form of vitamin K2 commonly used in supplements. It’s associated with support for bone and vascular health markers through its role in activating vitamin K-dependent proteins.

What are liposomal vitamins?

“Liposomal” means the vitamins are delivered with the help of tiny fat-like particles called “liposomes.” This is especially helpful for fat-soluble vitamins D3 and K2.