Vitamin D3 and K2: What Each Does and How to Read the Label
The Dose AnalysisVitamin D3 helps your body absorb calcium. Vitamin K supports normal blood clotting and bone health. A D3/K2 supplement puts two nutrients in one product, but its name cannot tell you whether you need either one. To compare labels, check each nutrient separately: its form, amount, units and serving size. Then read the warnings. NIH vitamin D guidance and NIH vitamin K guidance explain these different roles.
Key takeaways
- For vitamin D, 25 micrograms (mcg) equals 1,000 IU. These are two ways to state one amount, not two doses to add together.
- A serving may contain more than one capsule. Compare the amounts for the same serving before judging two products.
- Study findings depend on the people, preparation and outcome studied. A combination label does not establish a universal D3-to-K2 ratio.
What do D3, K2 and MK-7 mean?
D3 is cholecalciferol, one form of vitamin D. K2 describes forms of vitamin K called menaquinones; supplement labels may name menaquinone-4 (MK-4) or menaquinone-7 (MK-7). Vitamin K1, also called phylloquinone, is another form. These names identify ingredients, not a rating of a product's effectiveness. Vitamin D forms; vitamin K forms.
Green leafy vegetables provide phylloquinone (K1); menaquinones (K2) are found in fermented foods and foods that come from animals, according to the NIH Office of Dietary Supplements. Read the ingredient description beside the vitamin K amount rather than assuming every product with “K” contains the same form.
How to convert vitamin D from IU to mcg
For vitamin D, 1 mcg equals 40 IU. Multiply mcg by 40 to find IU, or divide IU by 40 to find mcg. The paired amounts in NIH's vitamin D tables use this relationship.
| Vitamin D in mcg | Same amount in IU |
|---|---|
| 10 mcg | 400 IU |
| 25 mcg | 1,000 IU |
| 50 mcg | 2,000 IU |
These are conversion examples, not suggested doses. If a label says “25 mcg (1,000 IU),” it describes one quantity. Do not add 25 and 1,000, compare their numerical size, or apply vitamin D's conversion to the separate vitamin K line.
Read the serving before comparing the numbers
The Supplement Facts panel identifies serving size and amounts per serving. The number on the front of a package should be read alongside that panel. FDA's supplement label explanation describes where this information belongs.
Consider this invented example, which is not the label of any real product, including the formula reviewed on this site:
| Example label item | Amount |
|---|---|
| Serving size | 2 capsules |
| Vitamin D3 per serving | 25 mcg (1,000 IU) |
| Vitamin K2 per serving | 90 mcg |
In this example, one capsule contains half the listed serving: 12.5 mcg (500 IU) of D3 and 45 mcg of K2. That arithmetic explains the label; it is not advice to change the directions. If another product lists amounts for one capsule, first put both products on the same basis.
Keep a short comparison note with four entries: serving size, vitamin D amount, vitamin K amount and vitamin K form. Add the source of each number, such as a current label photograph. If the panel is unreadable or the description and label disagree, leave the amount unresolved and ask the seller for the current label.
What does percent Daily Value tell you?
Percent Daily Value (%DV) shows how a serving compares with a labeling reference. FDA's general reference table lists 20 mcg for vitamin D and 120 mcg for vitamin K. Using those values, the invented serving above supplies 125% DV for D and 75% DV for K. FDA Daily Value guide.
Those percentages do not mean “125% absorbed” or “75% effective.” They also are not personalized prescriptions. NIH distinguishes Daily Values on labels from nutrient recommendations that vary with age and other factors. Consider what you already get from food, fortified drinks and other supplements before deciding whether an additional product fills a gap. NIH multivitamin guidance.
What does research on the combination actually show?
Results differ by the question tested. A 2022 randomized trial assigned 365 men with existing aortic valve calcification to 720 mcg MK-7 plus 25 mcg vitamin D daily or placebo for 24 months. The combination did not significantly slow the primary outcome, progression of aortic valve calcification. Coronary and aortic calcification and the heart ultrasound measures also did not differ significantly from placebo, although one blood marker, dp-ucMGP (dephosphorylated-undercarboxylated matrix Gla-protein), fell significantly in the supplement group. These were study amounts, not general-use directions. Read the trial abstract.
More recently, the August 2026 DANCODE report studied people with severe coronary artery calcification. Its analysis included 398 participants receiving 720 mcg vitamin K2 plus 25 mcg (1,000 IU) vitamin D3 daily, or placebo, for 24 months and found slower progression of calcification in the supplement group. The research team's university report stresses that effects on blood clots and long-term survival remain unknown, and that the results are not a recommendation to start supplementation. Read the researchers' report. Read the DANCODE trial abstract.
Both trials used 720 mcg vitamin K2 with 25 mcg (1,000 IU) vitamin D a day (the 2026 trial specifies D3), and they enrolled different patients and used different primary outcomes (valve calcification versus coronary calcification). The Vitamin K2/D3+ reviewed on this site lists different amounts per one-capsule daily serving: 100 mcg vitamin K2 (MK-7) and 125 mcg (5,000 IU) vitamin D3. That D3 amount is above the 100 mcg (4,000 IU) adult upper limit listed by the NIH Office of Dietary Supplements, so check with your healthcare provider before use. Its label warning also says: “Do not exceed recommended dose. Pregnant or nursing mothers, children under the age of 18, and individuals with a known medical condition should consult a physician before using this or any dietary supplement.” These findings should not be flattened into either “the combination always works” or “it never works.” Neither trial establishes that a particular store formula has the same effects, or that every healthy adult needs a fixed ratio.
Check interactions and overlapping supplements
Warfarin requires particular care. According to the NIH Office of Dietary Supplements, a sudden change in the amount of vitamin K you get can cause dangerous bleeding (if you consume less) or blood clots (if you consume more). Ask the clinician managing your treatment before starting, stopping or changing a K-containing supplement; keep vitamin K intake consistent as directed. NIH vitamin K interaction guidance.
For adults, NIH lists a vitamin D upper intake limit of 100 mcg (4,000 IU) daily from all sources. This is a ceiling, not a goal; clinicians may use different amounts to treat deficiency. Excess vitamin D can be harmful, and thiazide diuretics can increase the risk of high blood calcium when combined with it. NIH vitamin D safety guidance.
Bring the full labels of your multivitamin, D3/K2 product and any other supplements to a pharmacist or clinician. Separate product names can conceal overlapping nutrients. Review medicines, health conditions and pregnancy or nursing before adding a formula, and follow its current warnings.
Frequently asked questions about vitamin D3 and K2 labels
Is 1,000 IU the same as 25 mcg of vitamin D?
Yes. Divide 1,000 by 40 to obtain 25 mcg. A label showing both units is describing the same vitamin D amount twice.
Does MK-7 mean the product contains vitamin D3?
No. MK-7 names a vitamin K2 form. Look for a separate vitamin D entry and its amount. A form name alone does not describe the whole formula.
Is a higher percentage Daily Value always better?
No. The percentage helps you compare a serving with a reference. It does not measure product quality or show what you personally need.
Should I choose a product by its D3-to-K2 ratio?
A ratio leaves out serving size, separate amounts, other intake and medication considerations. The studies discussed above do not supply a universal ratio. Start with the full label and a clear reason for considering supplementation.
Related reading
- Vitamin K2/D3+ review
- Fish Oil Labels: EPA, DHA and Total Omega-3 Explained
- Optional next step: our supplement audit can help you organize your goals; it does not diagnose anything.
Sources
- NIH Office of Dietary Supplements: Vitamin D, Fact Sheet for Consumers, updated November 8, 2022.
- NIH Office of Dietary Supplements: Vitamin K, Fact Sheet for Consumers, updated March 22, 2021.
- U.S. Food and Drug Administration: Questions and Answers on Dietary Supplements, content current as of August 27, 2026.
- U.S. Food and Drug Administration: Daily Value on the Nutrition and Supplement Facts Labels, content current as of March 5, 2024.
- NIH Office of Dietary Supplements: Multivitamin/mineral Supplements, Fact Sheet for Consumers, updated February 15, 2024.
- Diederichsen ACP, Lindholt JS, Möller S, et al. Vitamin K2 and D in patients with aortic valve calcification: a randomized double-blinded clinical trial. Circulation (PubMed 35465686), 2022.
- University of Southern Denmark: Vitamin K and D supplementation may slow the progression of coronary artery calcification (news report on the DANCODE trial), August 31, 2026.
- Hasific S, Øvrehus KA, Mejldal A, et al. Vitamin K2 and D3 supplementation in patients with severe coronary artery calcification: the DANCODE trial. Circulation (PubMed 42661461), 2026.
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If you are pregnant, nursing or trying to conceive, ask your healthcare provider before use.
This article is for education and is not personal medical advice. Individual results vary.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.