Vitamin D3 and K2: why they are paired, how to read IU vs. mcg, and who should check first
By Melt Daily ·
Vitamin D3 and K2 are one of the most popular nutrient pairings. Our BASE strip combines them in one raspberry strip. Here is what each does, how to read the units on the label, and the one medication question everyone should know about.
What vitamin D does
Vitamin D helps the body absorb calcium, which is essential for building and keeping strong bones. It also plays roles in normal muscle function and the immune system. The skin makes vitamin D when exposed to sunlight, which is why it is nicknamed the sunshine vitamin. People who spend most of their time indoors, live in northern climates, cover most of their skin outdoors, or have darker skin may make less of it from the sun.
D3 vs. D2
Supplements use two forms. Vitamin D2 (ergocalciferol) comes from plant and fungal sources. Vitamin D3 (cholecalciferol) is the form the skin makes from sunlight. BASE and GLOW both use vitamin D3.
IU vs. mcg: converting the numbers
Vitamin D is listed in either international units (IU) or micrograms (mcg). The conversion is simple: 1 mcg equals 40 IU. So the 2000 IU of vitamin D3 in BASE is 50 mcg, and the 20 mcg of vitamin D3 in GLOW is 800 IU.
| mcg | IU | % Daily Value (20 mcg) |
|---|---|---|
| 10 mcg | 400 IU | 50% |
| 20 mcg | 800 IU | 100% |
| 50 mcg | 2000 IU | 250% |
| 100 mcg | 4000 IU | 500%, the adult upper limit |
Daily Value and upper limit from FDA and the NIH Office of Dietary Supplements.
Staying under the upper limit
The NIH upper limit for vitamin D for adults is 4000 IU (100 mcg) a day from all sources. Taking BASE and GLOW together comes to 2800 IU, under that limit. If you also take a multivitamin or another vitamin D product, add those in too. Vitamin D is fat-soluble, so the body stores it, and too much over time can be harmful.
What vitamin K2 does
Vitamin K is best known for its role in normal blood clotting, and it also helps the body use calcium for bone. There are two main forms: K1 (phylloquinone), found in leafy greens, and K2 (menaquinones), found in fermented foods like natto and in some animal foods. BASE contains 120 mcg of vitamin K2, which is 100% of the Daily Value.
Why D3 and K2 are paired
Both nutrients are involved in how the body handles calcium: vitamin D helps you absorb it, and vitamin K is involved in proteins that help direct it in bone. That shared role is why they so often share a label.
The medication question: blood thinners
Because vitamin K plays a role in blood clotting, it can interact with blood thinners like warfarin (Coumadin). Changing how much vitamin K you take can change how those medicines work. If you take a blood thinner, talk with your doctor before taking BASE or any vitamin K supplement.
When to take it
Vitamins D and K are fat-soluble, so some people like to take them around a meal. Many fold BASE into the morning, alongside breakfast. One strip a day.
If you are pregnant, nursing, taking any medication or managing a health condition, check with your doctor or pharmacist before adding a supplement.
*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
