Can You Take Vitamin C and Vitamin K1 Together?

Dose or timing may matter

The short answer

Very high doses of vitamin C (megadose therapy) may interfere with the vitamin K cycle by altering the redox state of vitamin K epoxide reductase, potentially affecting coagulation factor activation.

How to arrange timing

If taking megadose vitamin C (>2g/day), monitor coagulation parameters if on anticoagulant therapy.

Reference

Reference noted for this combination: Harris JE. Interaction of dietary factors with oral anticoagulants. J Am Diet Assoc. 1995;95(5):580-584

Important context

Whether supplements suit you together also depends on dose, product formulation, health conditions, and medication use. Ask a doctor or pharmacist first if you take medication, are pregnant or breastfeeding, or have a chronic condition.