Ashwagandha, Hashimoto’s Disease, and Subclinical Hypothyroidism

Ashwagandha is one of my favorite supplements for Hashimoto’s disease and hypothyroidism and we have some excellent studies to support using it for these conditions.

The main study I’ll cover in this research review is entitled, “Efficacy and Safety of Ashwagandha Root Extract in Subclinical Hypothyroid Patients: A Double-Blind, Randomized Placebo-Controlled Trial” published in The Journal of Alternative and Complementary Medicine. We’re already off to a good start just by reading the title which indicates that it is a double-blind, randomized placebo-controlled study so we know it is of the highest standard.

The authors begin by discussing subclinical hypothyroidism which is usually caused by Hashimoto’s thyroiditis. Subclinical hypothyroidism is characterized by a TSH of 4.5-10 with or without the symptoms of hypothyroidism as well as positive thyroid peroxidase (TPO) and antithyroglobulin antibodies. Subclinical hypothyroidism is connected to type 2 diabetes, abnormal cholesterol, atherosclerosis, aortic calcification, impaired vascular function, as well as abnormal heart, muscle, and nerve function.

Interestingly, a full review was done which found that treating patients with prescription thyroid hormone who have a TSH between 4.5 and 10 did not yield any improvements in any of the above risks.
What is Ashwagandha?
Ashwagandha or Withania somnifera is an adaptogen which stabilizes biochemical processes in the body. Scientific studies have found Ashwagandha beneficial for adrenal stress, fatigue, depression, anxiety, inflammation, and it helps to regulate the immune system, improve low blood pressure, and it works as an antioxidant. It has been shown in previous studies to improve T4 and T3 levels in animals. And in a human study on those with bipolar disorder, Ashwagandha improved TSH, T4, and T3 levels. Ashwagandha was even able to reverse hypothyroidism caused by the drug Metformin.
How was this study done on Ashwagandha and Subclinical Hypothyroidism?
This was an 8-week study including 25 subjects taking Ashwagandha at 300mg twice a day and 25 taking the placebo pill. They all had an elevated TSH between 4.5 and 10 but T4 and T3 levels were within the normal range. TSH, T4, and T3 levels were tested at the beginning of the study, at 4 weeks, and at 8 weeks.
What were the study results?
2 subjects from each group dropped out of the study so we finished with 23 people in each group.

T3 levels increased by 18.6% at 4 weeks and 41.5% at 8 weeks.
T4 levels increased by 9.3% at 4 weeks and 19.6% at 8 weeks.
TSH levels decreased (which means they improved) by -12.5% at 4 weeks and -17.4% at 8 weeks.

Only 1 person in the Ashwagandha group experienced side-effects including fever, cough, headache, and weakness but these were reported as mild and temporary.
Author conclusions:
The author’s do state that Ashwagandha normalized thyroid function in subclinical hypothyroid subjects to a significant degree and treatment was safe and tolerable. They do point out the limitations of this study including small sample size and the low duration of the study of only 8 weeks. A better study would include hundreds of subjects monitored for a much longer period of time.
Dr. Hedberg’s Comments
I was impressed to see a discussion in the paper on how stress inhibits thyroid function. When the hypothalamic-pituitary-adrenal axis, or HPA axis, is upregulated, it suppresses the hypothalamic-pituitary-thyroid axis, or HPT axis which inhibits thyroid function. We also know that cortisol inhibits T4 and T3 production so Ashwagandha can help lower excess cortisol levels which will allow thyroid hormone levels to improve. Inflammation will also upregulate the HPA axis and Ashwagandha is an excellent anti-inflammatory agent.

Since this was a double-blind, randomized placebo controlled trial, I don’t have much criticism for the study other than what the author’s already pointed out including the small sample si...