Combining Vitamin D3 and K2: Effects, Dosage, and What You Should Pay Attention To

Vitamin D3 and K2 – Why They Work Best Together

According to studies, people who regularly take vitamin D supplements benefit from also ensuring they get enough vitamin K2. Vitamin K2 plays a key role in helping the body incorporate calcium into bones and teeth and in reducing unwanted deposits in arteries and soft tissues.

Vitamin D promotes the formation of vitamin K2-dependent proteins that transport calcium in the body. However, vitamin K2 is required for these proteins to perform their function.

Therefore, taking vitamin D3 increases the need for vitamin K2. Both vitamins work synergistically: together, they support bone health and can contribute to normal calcium metabolism.

EFSA-confirmed functions:

• Vitamin D: contributes to normal absorption of calcium and phosphorus and supports normal bone health
• Vitamin K: contributes to normal blood clotting and is important for the maintenance of normal bones

Vitamin K2 – Dosage Information

Since vitamin K is stored in the body only in small amounts, we rely on a regular intake through food or dietary supplements. Evidence suggests that many people in Western populations do not consume enough vitamin K.

According to the scientific literature, people over 50 may have an increased risk of cardiovascular disease and osteoporosis. At the same time, older adults tend to consume less vitamin K through their diet.

Vitamin K2 researcher Prof. Cees Vermeer of Maastricht University has found evidence in several studies that supplementation with vitamin K2 (MK-7) in doses of 100 to 200 µg daily may be beneficial for adults—especially for those over 50.

Why take Vitamin D3 and K2 together?

Vitamin D3 stimulates the production of so-called Gla proteins—particularly osteocalcin and matrix Gla protein (MGP). However, these proteins can only perform their function if sufficient Vitamin K2 is present to activate them.

• Supports calcium absorption from the intestines
• Contributes to the normal function of the immune system
• Promotes bone health

• Activates Gla proteins, which regulate calcium balance
• Supports the incorporation of calcium into bones and teeth
• May help reduce calcium deposits in arteries and soft tissues

Note: The claim that vitamin K2 “prevents” atherosclerosis has not been conclusively proven scientifically. However, studies show associations between vitamin K2 intake and vascular health.

EFSA Reference Values for Vitamin D and Vitamin K

The European Food Safety Authority (EFSA) has developed reference values for adequate nutrient intake. These apply to healthy individuals and are not individual recommendations. Personal needs may vary depending on age, health status, and lifestyle. If in doubt, consult a doctor.

Reference Values for Vitamin K (EFSA, 2023)

Reference Values for Vitamin D (EFSA, 2023)

Source: EFSA DRV Finder (multimedia.efsa.europa.eu/drvs)

How do you combine vitamin D3 with vitamin K2?

We recommend taking vitamin K2 daily in an amount that suits you—regardless of whether you also take vitamin D3 supplements. The dosage of vitamin D3 should ideally be adjusted based on your personal 25(OH)D blood level.

Experts generally recommend keeping blood 25(OH)D levels within the optimal range. Have your levels checked regularly by a doctor to determine the right dosage for you.

How does vitamin K2 work?

Research on vitamin K2 has increased significantly in recent decades. In particular, studies conducted at Maastricht University have helped to better understand the importance of vitamin K2 for calcium metabolism.

Vitamin K2 influences how calcium is distributed and utilized in the body. This occurs via so-called GLA proteins (gamma-carboxyglutamic acid proteins), which can only be activated with the help of vitamin K2.

Important GLA proteins:

• Osteocalcin: This protein plays a role in the incorporation of calcium into the bones. It is produced by vitamin D3 but requires vitamin K2 to be activated.
• Matrix Gla protein (MGP): MGP is involved in regulating calcium in the arterial walls. Studies suggest that an adequate supply of vitamin K2 may be associated with healthy vascular function.

Studies indicate that an insufficient supply of vitamin K2 may be associated with an increased risk of vascular calcification and bone loss. Research in this area is still ongoing.

For this reason, it is recommended to take vitamin D3 together with sufficient vitamin K2 to support the optimal effect of both vitamins on calcium metabolism.

Sources & Further Reading

• EFSA (2017): Dietary Reference Values for Vitamin D. EFSA Journal 2017;15(9):4928.
• EFSA (2017): Dietary Reference Values for Vitamin K. EFSA Journal 2017;15(5):4780.
• Vermeer C. (2012): Vitamin K: the effect on health beyond coagulation – an overview. Food & Nutrition Research, 56.
• Holick MF. (2007): Vitamin D Deficiency. New England Journal of Medicine, 357:266-281.
• EU Health Claims Register: EC Regulation No 1924/2006 – authorized health claims for Vitamins D and K.