Tea consumption affects the absorption of levothyroxine

Area of Science:

• Endocrinology
• Pharmacology
• Gastroenterology

Background:

• Levothyroxine (LT4) is a standard treatment for hypothyroidism.
• Coffee is known to interfere with LT4 absorption.
• The effect of tea consumption on LT4 absorption remains unclear.

Purpose of the Study:

• To investigate whether tea intake interferes with levothyroxine (LT4) absorption in hypothyroidism patients.
• To compare the impact of tea, coffee, and combined tea-coffee consumption on LT4 absorption.

Main Methods:

• Thirty-seven hypothyroidism patients were divided into three groups based on beverage consumption: only tea, tea and coffee, or only coffee.
• Thyroid hormone levels (TSH, T3, T4) were measured before and after a 3-month period of adjusted beverage intake.
• Changes in TSH levels (Δln-TSH) were analyzed to assess LT4 absorption.

Main Results:

• All patient groups showed a significant reduction in TSH levels after 3 months (p < 0.001 or p < 0.05).
• The degree of TSH reduction indicated that both tea and coffee consumption interfered with LT4 absorption.
• Calculated Δln-TSH values were comparable across groups, suggesting similar malabsorption effects.

Conclusions:

• Long-term consumption of tea, similar to coffee, interferes with levothyroxine absorption.
• Patients taking LT4 medication should consider avoiding tea to prevent potential malabsorption and improve treatment efficacy.