To many, marshmallows are white, puffy confections that people enjoy eating and roasting over a campfire and melting into s’mores. The origin of these spongy edibles is Althea officinalis, a plant that has been used in alternative medicine for more than 2,000 years.A. officinalis has been used to treat sore throat, cough, skin burns, and gastrointestinal problems.2 A perennial herb that grows up to 120 cm tall on a sturdy single stem, A. officinalis is mostly found in Southern and Western Europe, Western Asia, and the Northeastern region of North America.2


Background


The parts of A. officinalis that are harvested are the root and leaf structures, which are then cleaned and dried. For medicinal use, solvents from water to methanol are used to form extracts of the plant components. The resulting product is a thick, slippery gel (mucilage) that has been shown to be useful for soothing the mucous membranes of the upper respiratory system and the lining of the gastrointestinal system.1

The mechanism of action of A. officinalis is linked to its high polysaccharide content. The herb’s main chemical constituents are pectin, starch, and mucilage.2

Science 


Compounds processed from A. officinalis have been studied for their use as a cough suppressant and expectorant. In a laboratory study using animals, marshmallow reduced episodes of cough by about 50%, compared with the control product of codeine, which reduced cough by 61%.3 However, as an expectorant, marshmallow improved sputum liquidity by 90%, compared with a standard of guaifenesin, which improved sputum liquidity by nearly 97%, and codeine, with its known anticholinergic side effects, at 30%.3

Claims of an antibacterial action of A. officinalis are common in the literature, but human trials are almost nonexistent. In a small in vitro study that used a disk diffusion method, the effects of increasing concentrations of the root extract of A. officinalis on two gram-negative and two gram-positive bacteria were compared with the effects of pharmaceutical-grade antibiotics on these strains.4 Although the results were not statistically significant, the most concentrated strength of the root did show an inhibitory diameter that was more than 50% larger than the control antibiotic agent.4