Hashimoto’s thyroiditis is an autoimmune disease and the most common cause of hypothyroidism. Its prevalence is growing, particularly in women, who have 5-10 times greater incidence than men.^1,2 Autoantibodies against thyroid peroxidase (anti-TPO) and thyroglobulin antibodies are diagnostic biomarkers, and testing typically shows reduced serum triiodothyronine (T3) and thyroxine (T4) concentrations, and elevated thyroid-stimulating hormone (TSH).²

Hashimoto’s thyroiditis is characterised by weight gain, irregular menstrual periods, cold intolerance, constipation, hair loss, dry skin, muscle and joint pain, depression, and bradycardia. It is also one of the leading causes of high blood pressure, cardiovascular disease, and dyslipidaemia.²

As demonstrated in this research review, Nigella sativa (Nigella) has potent effects in improving thyroid status, body composition, and metabolic health in patients with Hashimoto’s thyroiditis.^1,3

Investigating Nigella for Hashimoto’s thyroiditis

A double-blinded, placebo-controlled trial investigated the effects of Nigella on thyroid function and body composition in patients with Hashimoto’s thyroiditis.¹ Forty participants (aged 22 to 50 years) were randomly assigned to receive either powdered Nigella seeds (2 g/day) or placebo for 8 weeks, in addition to levothyroxine (started 6 weeks prior until study completion).

Fasting blood samples were taken at baseline and following treatment to assess thyroid status (TSH, T3, T4, anti-TPO), and serum concentrations of VEGF (vascular endothelial growth factor, an important regulator of benign and malignant disease processes in the thyroid)⁴ and Nesfatin-1 (a regulator of energy homeostasis). Body weight, height, waist and hip circumference, body mass index (BMI), waist to hip ratio and dietary intakes were also assessed.

Nigella improves thyroid function and body composition

Following treatment, Nigella had favourable effects on thyroid function in Hashimoto’s patients, decreasing serum concentrations of TSH and anti-TPO antibodies and increasing T3 levels (P<0.05). Those taking Nigella had significantly reduced body weight, BMI, and waist and hip circumference (P<0.05); while no significant changes were seen in the placebo group. Serum VEGF reduced significantly with Nigella supplementation (p=0.02), however changes in Nesfatin-1 concentrations were not significant.¹

Herbal support for metabolic health

As well as improving body composition, a later study on the same treatment group highlighted Nigella’s lipid-lowering effects in Hashimoto’s patients.³ Following eight weeks of Nigella treatment (2 g/day), serum low-density lipoprotein cholesterol (LDL) and triglycerides were decreased, and high-density lipoprotein cholesterol (HDL) significantly increased (p<0.05). This research supports the clinical use of Nigella to address both thyroid dysfunction and concomitant metabolic abnormalities seen in patients with Hashimoto’s thyroiditis.

Understanding Nigella’s influence on thyroid function and body weight

Known as black cumin, Nigella’s aromatic seeds have a long history of use in Middle/Far Eastern folk medicine for treating infections, obesity, hypertension, and gastrointestinal conditions. Thymoquinone is an important constituent with demonstrated antioxidant, anti-inflammatory and immune modulating properties.¹

The mechanisms by which Nigella and thymoquinone influence thyroid function and body weight are explored in the Figure 1 below.¹

Figure 1: Mechanisms of action of Nigella sativa on thyroid status and body weight.¹

Nigella’s anti-obesity and metabolic effects may be due to the herb improving satiety and fullness, thereby influencing food intake. Other possible mechanisms include increased energy expenditure, and decreased lipogenesis and increased lipolysis.^1,3

Antioxidant and immunomodulatory effects protect the thyroid

Oxidative stress plays an important role in the pathogenesis of Hashimoto’s.⁵ In a 2020 study, Nigella treatment significantly improved markers of oxidative stress in Hashimoto’s thyroiditis patients, increasing serum total antioxidant capacity (TAC), superoxide dismutase (SOD) and reducing malondialdehyde (MDA) concentrations (p<0.05).⁵

Animal studies suggest Nigella may protect against hyperplastic changes of thyroid parenchyma in hypothyroidism and may potentially repair the thyroid gland via antioxidant defence mechanisms.^1,6,7

Nigella’s immunomodulatory actions may be responsible for the reduction in thyroid antibodies. Possible processes include reduced autoantibody synthesis as well as reductions in transforming growth factor (TGF)-β and interleukin (IL)-23, an inflammatory cytokine involved in amplifying and stabilizing Th17 cells.²

Summary

Research demonstrates a potent beneficial effect of Nigella seed in improving thyroid status, reducing body weight, and improving metabolic health in patients with Hashimoto’s thyroiditis.

References

1. Farhangi MA, Dehghan P, Tajmiri S, Abbasi MM. The effects of Nigella sativa on thyroid function, serum Vascular Endothelial Growth Factor (VEGF) - 1, Nesfatin-1 and anthropometric features in patients with Hashimoto's thyroiditis: a randomized controlled trial. BMC Complement Altern Med. 2016 Nov 16;16(1):471. doi: 10.1186/s12906-016-1432-

2. Tajmiri S, Farhangi MA, Dehghan P. Nigella Sativa treatment and serum concentrations of thyroid hormones, transforming growth factor β (TGF-β) and interleukin 23 (IL-23) in patients with Hashimoto’s Thyroiditis. Eur J Integr Med. 2016;8:576–580.

3. Farhangi MA, Dehghan P, Tajmiri S. Powdered black cumin seeds strongly improves serum lipids, atherogenic index of plasma and modulates anthropometric features in patients with Hashimoto’s thyroiditis. Lipids in Health and Disease. 2018;17(1):59.

4. Klein M, Catargi B. VEGF in physiological process and thyroid disease. Ann Endocrinol (Paris). 2007 Dec;68(6):438-48. doi: 10.1016/j.ando.2007.09.004.

5. Farhangi MA, Tajmiri S. The effects of powdered black cumin seeds on markers of oxidative stress, intracellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 in patients with Hashimoto's thyroiditis. Clin Nutr ESPEN. 2020 Jun;37:207-212. doi: 10.1016/j.clnesp.2020.02.015.

6. Khalawi AA, Al-Robai AA, Khoja SM, Shaker AS. Can Nigella Sativa oil (NSO) reverse hypothyroid status induced by PTU in rat biochemical and histological studies. Life Sci J. 2013;10(2):1–5.

7. Ismail M, Zabid Y, Hanefi O, Ramazan U. Effect of Nigella sativa L. on serum concentration of thyroid hormone, thyroid stimulating hormone and glucose in alloxan-induced diabetic rabbits. Ir Vet J. 2003;59(9):462–4.