Vitamin D3 and K2: what they are and why they often come together

Vitamins D3 and K2 appear together in many supplements. Here's what each one is and how to read their label.

Vitamin D3

D3 (cholecalciferol) is the form of vitamin D the body also makes from sunlight. Labels express it in micrograms (mcg) or international units (IU): 25 mcg equals 1,000 IU.

Vitamin K2

K2 is a group of forms of vitamin K. MK-7 is one of the most used in supplements. Many manufacturers combine it with D3 in a single capsule.

How to take them

• They're fat-soluble vitamins: take them with a meal that contains some fat.
• Stick to the serving on the label.
• If you take blood thinners or other medication, check with your health professional first.