Does Caffeine Affect Vitamin B1?

May affect absorption or how you feel

The short answer

Coffee tannins can bind thiamine (B1) in the GI tract, and caffeine's diuretic effect increases B1 urinary loss.

How to arrange timing

Take vitamin B1 at least 1 hour apart from coffee.

Reference

Reference noted for this food and supplement combination: NIH ODS 2024; Vimokesiri et al. 1982

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.