Does Soy foods Affect Desiccated Thyroid?

Amount or timing may matter

The short answer

Soy protein and isoflavones reduce absorption of thyroid hormones (T3/T4) in desiccated thyroid, potentially causing hypothyroid symptoms.

How to arrange timing

Take desiccated thyroid at least 4 hours before or after soy foods.

Reference

Reference noted for this food and supplement combination: Bell & Grauer, J Am Board Fam Med 2001; NIH ODS 2024

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.