Does Caffeine Affect Vitamin C?

May affect absorption or how you feel

The short answer

Caffeine's diuretic effect increases urinary excretion of water-soluble vitamin C, reducing its effective dose.

How to arrange timing

Separate vitamin C from caffeinated beverages by 1 hour to maximize absorption.

Reference

Reference noted for this food and supplement combination: NIH ODS 2024; Massey & Whiting 1993

Important context

The effect can also change with food amount, supplement 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.