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August 5, 2021


Lindsay Delk, RDN
Why Do I Need Vitamin K2D3

Fact Checked By Lindsay Delk, RDN
 August 5, 2021


Research estimates that up to 41% of Americans have a vitamin D deficiency and 31% have a vitamin K deficiency. But why does this matter? Let’s take a look (1), (2).

What is Vitamin D?

Vitamin D is a nutrient your body needs for many important functions.

Vitamin D is a fat-soluble vitamin, meaning that it dissolves in fat and can be stored in the body longer than water-soluble vitamins.

It’s found in a few foods naturally, is added to some fortified foods, and can be taken as a supplement.

Vitamin D is known as the sunshine vitamin because it can be synthesized in the skin with UV rays from the sun.

Vitamin D has two main forms: D2 (ergocalciferol) and D3 (cholecalciferol).

While D2 and D3 are both well-absorbed in the gut, vitamin D3 raises vitamin D levels in the blood higher and keeps them there longer than vitamin D2 (3).

Benefits of Vitamin D

Vitamin D plays many roles and provides many benefits in the body.

Ongoing research is continuing to show new benefits of this vital vitamin. Vitamin D is strongly linked to bone health, immunity, and depression.


  • Healthy bones – Vitamin D helps your body absorb calcium, which is one of the main building blocks of bone.

    It helps prevent osteopenia and osteoporosis, diseases that weaken the bones and make them more likely to break.

    Without enough vitamin D, your bones can become thin and brittle.

    Vitamin D deficiency causes rickets in children and osteomalacia in adults (4).

    Rickets is a disease in which the bones become soft, painful, and deformed. Osteomalacia is a disease that causes bone pain and muscle weakness.
  • Healthy Immune System – Vitamin D is needed for a healthy immune system (5).

    Not having enough vitamin D has been linked to lowered immune function and a higher risk for infection.

    However, good levels of vitamin D will help support your body’s ability to fight infections.

    In fact, one study showed that taking a vitamin D supplement helped reduce the risk of respiratory infections (6).
  • Improved Mood – Some studies have found a link between low vitamin D levels and depression. Taking a vitamin D supplement has shown to reduce the severity of depression (7), (8).

Ways to Get Vitamin D

There are three ways to get vitamin D: from the sun, from foods, or from a supplement.

  1. Your body makes vitamin D when your skin is exposed to UV rays from the sun. However, some people may have limited sun exposure, especially in some climates and seasons.

    You have to have direct exposure from the sun's rays, so being in front of a sunny window will not work.

    Plus, too much sun exposure can lead to skin cancer and aging skin. Rightly so, many people use sunscreen to protect their skin, but sunscreen blocks the skin’s ability to produce vitamin D.

  2. Another way to get vitamin D is in your diet. While you should aim to get most of your nutrients from whole foods, it is very difficult to get enough vitamin D from diet alone.

    The few foods that naturally contain vitamin D are fish liver oil, fatty fish, such as trout, salmon, tuna, and mackerel, beef liver, cheese, egg yolks, and mushrooms.

    Most Americans get more vitamin D from fortified foods, such as vitamin D-fortified milk, breakfast cereals, and some orange juice and yogurt.

    Scientific data shows that 92% of men and more than 97% of women in the U.S. do not eat the recommended amounts of vitamin D (9).

  3. If you don’t eat lots of fatty fish, don’t spend a lot of time in the sun, or use sunscreen to protect your skin, you should consider a vitamin D supplement.

    Remember that vitamin D3 is the best choice for a supplement.

    Ask your doctor to test the amount of vitamin D in your blood and if he/she recommends a vitamin D supplement for you.

    The only way to truly know if you have a vitamin D deficiency is to have a blood test that measures your vitamin D level.

What is Vitamin K?

Vitamin K is also a fat-soluble vitamin, and it is important for blood clotting, healthy bones, and healthy arteries.

The vitamin K family includes hydroquinone (vitamin K1) and several menaquinones (vitamin K2). Vitamin K1 is more important for blood clotting, and vitamin K2 is more important for bone health and preventing the calcification of arteries (10), (11).

Calcification of arteries means the buildup of calcium in the walls of the arteries which can lead to heart disease.

Benefits of vitamin K

  • Blood Clotting – Vitamin K is required for blood clotting. You may think that blood clotting is bad, but blood clotting is what causes a wound to stop bleeding and start healing (12).
  • Healthy Arteries – As mentioned earlier, vitamin K2 is more important for preventing the calcification of arteries.

    Calcification of arteries means the buildup of calcium in the walls of the arteries which can lead to the hardening of arteries and heart disease (13).

    Vitamin K2 helps calcium get into the bone instead of your arteries.
  • Healthy Bone Tissue – Vitamin K is required by certain proteins to make bone tissue (14).

    Some studies show that people who eat more vitamin K have stronger bones and are less likely to break a hip (15).

    The European Food Safety Authority even approved a health claim for vitamin K that “a cause and effect relationship has been established between the dietary intake of vitamin K and the maintenance of normal bone.” (16)

Ways to Get Vitamin K

Vitamin K is found naturally in many foods, such as green leafy vegetables (spinach, kale, lettuce), broccoli, blueberries, eggs, meat, cheese, eggs, soybeans, and vegetable oils.

However, up to 31% of adults have insufficient levels of vitamin K, so a vitamin K supplement may be necessary (17).

Vitamin K can interact with the blood thinner, warfarin. If you take warfarin, make sure you get about the same amount of vitamin K every day, whether from foods or a supplement.

Should You Take Vitamins D3 & K2 Together?

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

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

Vitamin K helps get calcium into the bones.

If you are low in vitamin K, the calcium gets into your arteries instead of your bones, which contributes to heart disease. This leads to weak bones and hardened arteries.

If you and your doctor decide that you need to take a vitamin D supplement, make sure it also contains vitamin K2.

Because vitamin D and vitamin K are both fat-soluble, your supplement should be taken with a meal or snack that has some fat.

The fat in the food will help your body absorb the vitamins.