Hyperthyroidism and hyperthyroid-like symptoms including anxiety and insomnia, and Grave’s disease.
Mechanism of Action
When thyroid-stimulating hormone (TSH) binds to the outer membrane of thyroid cells, it triggers a cAMP response on the inside of the cell via adenylate cyclase enzyme activation. Melissa extracts interfere with the binding of TSH to the TSH receptor by direct electrostatic effects on TSH and by the stimulation of cells because of direct effects on the TSH receptor.1
Melissa contains phenolic acid derivatives such as rosmarinic and the related lithospermic and chlorogenic acids, which may exert an antithyroid effect and reduce excessive thyroxine output in cases of hyperthyroidism.2 Rosmarinic acid slows TSH-driven stimulation of thyroid cells via adenylate cyclase inhibition.2
Rosmarinic acid also forms “adducts” with TSH. Because of particular electromagnetic affinities, rosmarinic acid forms loose bonds with endogenous TSH, thereby reducing its ability to bind and agonize TSH receptors.3 This may reduce thyroxine output in cases of hyperthyroidism.
Melissa inhibits the ability of Grave’s autoantibodies to bind TSH receptors and promote intracellular cAMP responses, thereby reducing adenylate cyclase–driven signal transduction and the resulting increase in thyroid hormone output.1,4
There are currently no published clinical studies on Melissa for thyroid disorders, although there are several studies investigating Melissa for anxiety and sleep disorders.5
One randomized controlled trial using Melissa extract reported the occurrence of “side effects” that included reduced alertness as well as palpitation and thyroid hormone inhibition.6
Safety in Pregnancy and Breastfeeding
There are no published studies on the safety of Melissa during pregnancy or breastfeeding.
Melissa is generally considered to be safe and well tolerated within recommended dosing ranges.7
This herb is generally considered safe at doses of 600 mg and up to doses as high as 1800 mg/day of the crude leaf.
Melissa officinalis goes by the common name lemon balm because of the strong lemon aroma released from the leaves. This low-growing, herbaceous plant has been used traditionally for mood disorders, insomnia, infections, and the symptoms of hyperthyroidism. Melissa contains rosmarinic acid, a phenolic compound derived from caffeic acid and found in several other Melissa family members, all emphasized historically for the symptoms of hyperthyroidism.
2 Endocrinology. 1984;115(2):527–34. Inhibition by certain plant extracts of the binding and adenylate cyclase stimulatory effect of bovine thyrotropin in human thyroid membranes. Auf’mkolk M, Ingbar JC, Amir SM, Winterhoff H, Sourgens H, Hesch RD, Ingbar SH.
3 Endocrinology. 1985;116(5):1677–86. The active principles of plant extracts with antithyrotropic activity: Oxidation products of derivatives of 3,4-dihydroxycinnamic acid. Auf’mkolk M, Amir S, Kubota K, Ingbar S.
4 Endocrinology. 1985;116(5):1687–93. Extracts and auto-oxidized constituents of certain plants inhibit the receptor-binding and the biological activity of Graves' immunoglobulins. Auf'mkolk M, Ingbar JC, Kubota K, Amir SM, Ingbar SH.
5 Med J Nutrition Metab. 2011;4(3):211–8. Pilot trial of Melissa officinalis L. leaf extract in the treatment of volunteers suffering from mild-to-moderate anxiety disorders and sleep disturbances. Cases J, Ibarra A, Feuillère N, Roller M, Sukkar SG.
6 J Herb Pharmacother. 2005;5(4):71–114. Lemon balm (Melissa officinalis L.): an evidence-based systematic review by the Natural Standard Research Collaboration. Ulbricht C, et al.
7 J Ethnopharmacol. 2016;188:204–28. Melissa officinalis L. - A review of its traditional uses, phytochemistry and pharmacology. Shakeri A, Sahebkar A, Javadi B.