Is Ashwagandha safe?
Many online resources suggest that those with thyroid disease should avoid Ashwagandha. Some warn of hyperthyroidism as a possible side effect.
There are two main reasons for these concerns.
First were some worrisome animal studies.
In the 1980s, several studies showed that rats given extremely high doses of Ashwagandha developed a higher rate of conversion of T4 into T3. Later studies showed that the same effect did not occur in humans when used at usual dosages.
Second was a case report.
In 2022, there was a case of a person who developed hyperthyroid symptoms in a possible connection to Ashwagandha ingestion, including paroxysmal ventricular tachycardia (dangerous heart rate elevation).
The final analysis found that some Ashwagandha products were contaminated with synthetic T3 and T4. Thyroid hormones do not naturally occur in Ashwagandha. These were deliberately added to plain Ashwagandha and Ashwagandha in the context of thyroid supplements.
The consensus is that using non-contaminated Ashwagandha is safe within normal dosages.