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August 19, 2021


Lindsay Delk, RDN
Why Is K2 + D3 Better Than Just D3?

Fact Checked By Lindsay Delk, RDN
 August 19, 2021

Working Together

Do you want to decrease your risk of osteoporosis and cardiovascular disease?

If so, read further to see how taking a vitamin D3 supplement with vitamin K2 can do just that.

Two Types of Vitamin K

Many vitamins and other nutrients don’t work alone in your body and depend on each other.

Calcium, vitamin D, and vitamin K are like that. Calcium can’t get into your body well without vitamin D.

And it can’t get into your bones without vitamin K.

Calcium can make your bones stronger, but it can also make your blood vessels harder if it doesn’t have vitamin K to help.

So, having a good intake of vitamin D and calcium can be dangerous if you don’t also get enough vitamin K.

If you are taking a vitamin D supplement, it is vital that you also include vitamin K.

If you increase your intake of vitamin D without enough vitamin K, you can increase the calcium in your blood without the ability to use it properly.

This calcium can then get deposited into your blood vessels and soft tissues instead of your bones.

Calcium buildup in your blood vessels and soft tissues can lead to heart disease, heart attack, or stroke.

Vitamin K is a nutrient that helps the body deposit calcium into your bones instead of your arteries.

Vitamin D and vitamin K work together as a team to maintain the right calcium levels in your blood.

  • Vitamin D

Vitamin D helps you absorb calcium from your food.

If you eat enough calcium, vitamin D helps to get the calcium into your bones to make them stronger. If you don’t eat enough calcium, vitamin D will pull calcium from your bones, which makes them weaker (1, 2).

Your body must maintain the right level of calcium in your blood even if your bones become weaker.

  • Vitamin K

Vitamin K works with vitamin D to get calcium into the right place – your bones and not your blood vessels and soft tissues.

Osteocalcin is a protein that uses calcium to build your bones (3).

Osteocalcin cannot work without vitamin K. Matrix Gla protein (MGP) is another protein that prevents calcium from building up in your arteries and soft tissues, like organs (4).


Benefits of Teamwork

Vitamin D is strongly linked to bone health, immunity, and mental health, and vitamin K is important for blood clotting, healthy bones, and healthy arteries.

But these vitamins also have important work to do together.

Animal and human studies show that healthy levels of vitamin D and vitamin K are good for bone and cardiovascular health (5).

And evidence suggests that supplementing with vitamin D and K together might be more effective for bone and cardiovascular health than taking either alone.

  • Bone Health

Studies show that healthy levels of both vitamin D and K support bone strength and lower the risk of broken bones (6).

In one study, the combination of low vitamin D and vitamin K levels was linked with a greater risk of a broken hip. There wasn’t a higher risk if the person was only low in one of the vitamins (7).

Another study on postmenopausal women showed that adding vitamin K to a vitamin D and calcium supplement increased bone density compared to the vitamin D and calcium supplement alone (8).

  • Cardiovascular Health

Research shows that calcification of the arteries is linked to high blood pressure and heart disease because it causes the arteries to get stiff and hardened (9).

One study showed that the combination of low vitamin D and low vitamin K was linked with high blood pressure (10).

Although more research is needed, there are indications that supplementation of vitamin D and vitamin K together might benefit cardiovascular health (11).

If there is not a balance between vitamin D levels and vitamin K levels, extra calcium will be deposited in your blood vessels and soft tissue instead of your bone (12).

This makes your bones weak and your blood vessels hard. Over time, this could lead to osteoporosis and cardiovascular disease.

Which Vitamin D and Vitamin K Are Best?

  • Vitamin D3 – Vitamin D has two main forms: D2 (ergocalciferol) and D3 (cholecalciferol). Vitamin D3 is the best choice for a vitamin D supplement because vitamin D3 raises vitamin D levels in the blood higher and keeps them there longer than vitamin D2 (13).
  • Vitamin K2 – Vitamin K2 is the best choice for a vitamin K supplement. Research shows that higher intakes of vitamin K2 are linked with less buildup of calcium in the blood vessels and soft tissues more than vitamin K1 (14).

Another study concluded that a healthy intake of vitamin K2 could help prevent cardiovascular disease (15).

  • MK-7 – MK-7 is the most effective type of vitamin K2 because of its higher bioavailability and longer half-life. Higher bioavailability means that more of the vitamin is absorbed and used by your body. A longer half-life means that the vitamin stays in your body longer (16).

In one study, rats that were given vitamin K2 supplements in the form of MK-7 had less cardiovascular buildup of calcium (17).

Another study found that long-term use of vitamin K2 supplements in the form of MK-7 improved the stiffness of arteries in healthy postmenopausal women (18).

D3 + K2 Supplements

If you and your doctor decide that you need to take a vitamin D supplement, make sure it is vitamin D3.

Also, make sure that it contains vitamin K2 in the form of MK-7.

You could take your vitamin D3 and vitamin K2 supplements separately, but it is obviously more convenient to get your vitamin D and vitamin K in one pill.

Vitamin D and vitamin K are both fat-soluble vitamins.

Fat-soluble vitamins dissolve in fat or oil and are stored in your body tissues.

They are absorbed by your body better when they are eaten with fat.

So, take your supplement with a meal or snack that has some fat. The fat in the food will help your body absorb the vitamins.

Supplements are not regulated by the Food and Drug Administration (FDA), so make sure you are buying high-quality supplements from a reputable source.

Avoid buying supplements made outside of the U.S., which may not be regulated at all.