Recent studies clearly demonstrate that vitamin D3 and vitamin K2 are essential to good health. Deficiencies in both these vitamins are extremely common, which is why more and more people are taking vitamins D3 and K2 as a daily dietary supplement.
It's very important to know that if you take vitamin D3 regularly over a long period, you definitely need to take vitamin K2 as well. This raises the question of how these two key vitamins should best be combined in order to promote health and vitality.
Vitamin D3 helps your body absorb calcium from the diet. But without enough vitamin K2, that calcium may not be directed where it’s needed such as your bones and teeth and can instead end up in soft tissues like arteries, potentially leading to calcification and arteriosclerosis.
Vitamin K2 activates specific proteins such as osteocalcin and matrix Gla-protein (MGP) that:
Direct calcium into bones and teeth
Prevent calcium buildup in arteries and soft tissues
In short: Vitamin D3 increases calcium availability, while vitamin K2 ensures it’s used properly.
The Synergistic Relationship
Taking vitamin D increases the body’s production of vitamin K2-dependent proteins. But without enough K2, these proteins remain inactive, and calcium can go to the wrong places. Together, D3 and K2:
Strengthen bones
Support heart and vascular health
Reduce the risk of osteoporosis and arteriosclerosis
EFSA nutrient intake reference values for vitamin D and vitamin K
The European Food Safety Authority (EFSA) has developed recommendations for adequate nutrient intake.
These nutrient intake reference values are intended for healthy people and should not be understood as direct recommendations for individuals. Individual requirements for vitamin D and vitamin K can vary considerably depending on personal circumstances.
If in doubt, consult your doctor or a specialist to find out your individual requirements.
Reference values for vitamin K according to EFSA
Target group
Adequate intake
Adults aged 18 and over, both sexes
70 µg / day
Children aged 15 to 17, both sexes
65 µg / day
Children aged 7 to 10, both sexes
30 µg / day
Children aged 4 to 6 years, both sexes
20 µg / day
Children aged 1 to 3 years, both sexes
12 µg/day
These estimated values indicate the average intake of the nutrient that is considered sufficient based on observations or experimental studies.
Osteocalcin – helps bind calcium to the bone matrix
Matrix Gla Protein (MGP) – prevents calcium from depositing in arteries
Without vitamin K2, calcium can accumulate in the wrong places—even when taking vitamin D3. This imbalance can contribute to:
Arterial calcification
Weakened bones
Higher cardiovascular risk
Conclusion
Vitamin D3 and vitamin K2 are a powerful team that work best when taken together. If you’re supplementing with vitamin D3, don’t overlook K2. The right balance supports your bones, heart, and overall health while avoiding the risks of misplaced calcium.
Frequently Asked Questions About Combine Vitamin D and Vitamin K
There is no “best” product for everyone. It is important that D3 comes from a high-quality source, preferably cholecalciferol. K2 should be in the form of MK-7 all-trans because it is the most stable. Drops are practical because you can dose them precisely, while capsules are more convenient for on the go. Also, make sure that the supplement is dissolved in oil, as D3 is fat-soluble.
Different organizations recommend varying doses of vitamin D. For example, in cases where vitamin D formation through sunlight is deficient, the DGE currently recommends a dose of 400 IU for infants up to 1 year of age and 800 IU for children, adolescents, adults, seniors, and pregnant and nursing women.
According to vitamin D experts this recommendation is too low and only represents the minimum daily intake required to stave off rickets.
The Complete Guide to Vitamin D: Benefits, Deficiency, Dosage and More
Vitamin D ensures healthy bones and is involved in a variety of metabolic processes in the human body. In contrast to all other vitamins, the need can't be met through nutrition alone; and a lack of the vitamin can cause serious illnesses. An adequate supply of vitamin D is therefore important.
You can measure your vitamin D levels by using a blood test to determine if you have enough vitamin D in your body. In fact, not the active form of vitamin D is measured, but the concentration of 25(OH)D (25-hydroxyvitamin D) in the blood.
The 25 (OH)D value is a precursor of vitamin D, in which form is is transported in the blood. If necessary, this form is converted into the active form of vitamin D (calcitriol).
The 25 (OH)D value shows how much vitamin D you got through nutrition or produced during sun exposure. But this value does not tell you anything about your vitamin D levels throughout the year, which will vary depending on the sun exposure and vitamin D uptake from food.
The half-life of 25(OH) Vitamin D is 2 month. This means, that the vitamin D level will fall to half of its value, provided that you no longer get any vitamin D at all.
