Vitamin D3 + K2 for People Who Live and Work Indoors
Office hours, long commutes and short winter days all cut your sunlight. Here is how vitamin D3 and K2 work together, how to read the label, and what to check first.
In short
Your skin makes vitamin D from sunlight, which is hard to get if you work indoors or live where winter days are short. Our capsule pairs 125 mcg (5,000 IU) of D3 with 200 mcg of K2. That is a higher-strength dose, so check your total vitamin D intake with your doctor.
Why indoor life makes vitamin D harder to get
Your skin makes vitamin D when it is exposed to UVB light. Office work, commutes in the dark and winter all reduce that exposure. In much of the northern US, winter sunlight is too weak for your skin to make much vitamin D at all. Window glass blocks UVB too, so a sunny desk does not count.
Few foods are rich in vitamin D. The main ones are fatty fish like salmon, egg yolks, and fortified milk and cereals.
What D3 and K2 do
- Vitamin D3 contributes to normal bone health and immune function.* D3 (cholecalciferol) is the form your skin makes.
- Vitamin K2 is involved in calcium metabolism, which is why it is often paired with D3.* Our capsule uses the MK-7 form.
Reading the label: IU, mcg and %DV
US labels list vitamin D in micrograms (mcg), often with international units (IU) in parentheses. 1 mcg equals 40 IU, so our 125 mcg is 5,000 IU.
The Daily Value for vitamin D is 20 mcg (800 IU), so one capsule is 625% of the Daily Value. That is normal for a higher-strength product, but it means this is not a "take as many as you like" vitamin.
Check your total intake
The NIH Office of Dietary Supplements lists 100 mcg (4,000 IU) a day as the upper limit for adults from all sources, unless a doctor advises more. Our capsule is above that on its own. Many people take higher amounts on their doctor’s advice after a blood test, so talk to your doctor, especially if you also get vitamin D from a multivitamin, fortified foods or another supplement. Our Immune+ contains 40 mcg (1,600 IU) of D3, for example.
How to take it
One capsule a day with a meal that contains some fat, since vitamins D and K are fat-soluble. Breakfast with eggs or yogurt, or a lunch with olive oil or avocado, both work.
Talk to your doctor first if
- You take blood thinners such as warfarin: vitamin K affects how they work.
- You take other vitamin D products.
- You are pregnant, nursing, under 18 or have a medical condition.
Shop this guide
- Vitamin D3 + K2: 125 mcg (5,000 IU) D3 with 200 mcg K2 (MK-7)
- Immune+: vitamin C, vitamin D3 and zinc with elderberry and echinacea
*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. This guide is general information, not medical advice. If you are pregnant, nursing, under 18, taking medication or have a medical condition, talk to your doctor or pharmacist before starting a supplement.
