Lack of effect of spearmint on lower oesophageal sphincter function and acid reflux in healthy volunteers.
BACKGROUND
Spearmint is commonly used as an antispasmodic and as a flavouring in several medications including antacids. It can produce heartburn, presumably by lowering lower oesophageal sphincter (LES) tone, but the mechanism has not previously been objectively examined.


OBJECTIVE
To study the effect of spearmint on LES function, acid reflux and symptoms.


METHODS
In healthy volunteers, a Dent Sleeve and a pH electrode were placed in the distal oesophagus. They were then given spearmint either in a flavouring (0.5 mg), or a high (500 mg) dose, or a placebo, using a double-blind randomized crossover design. LES pressure, oesophageal pH and symptoms were recorded for 30 min before and after administration.


RESULTS
LES pressure was not affected by spearmint, either high dose (19.6 vs. 16.0 mmHg), flavouring dose (20.2 vs. 19.8 mmHg) or placebo (20.5 vs. 19.2 mmHg, all N.S.). There were no differences in reflux occurrence following high dose (mean = 0.65 vs. 0.85 episodes), low dose (0.4 vs. 0.5 episodes) or placebo (0.7 vs. 1.10 episodes, all N.S.). There was a significant increase in mean symptom scores following high-dose spearmint (0 vs. 0.35, P = 0.03), but not low dose (0 vs. 0.2) or placebo (0 vs. 0.5, both N.S.). One subject reported symptoms with placebo, one with low dose, and six with high dose; all without increased reflux episodes or decreased sphincter pressure.


CONCLUSIONS
Spearmint has no effect on LES pressure or acid reflux. Flavouring doses of spearmint do not produce more symptoms than placebo while high doses can be associated with symptoms, presumably from direct mucosal irritation but not reflux.
Bulat
R
R
Division of Gastroenterology and Digestive Diseases Research Program, McMaster University Medical Centre, Hamilton, Ontario, Canada.
Fachnie
E
E
Chauhan
U
U
Chen
Y
Y
Tougas
G
G
D000293:Adolescent; D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004943:Esophagogastric Junction / Q000187:drug effects* / Q000502:physiology; D005421:Flavoring Agents / Q000009:adverse effects*; D005764:Gastroesophageal Reflux / Q000139:chemically induced*; D006801:Humans; D009822:Oils, Volatile / Q000009:adverse effects*
D005421:Flavoring Agents; D009822:Oils, Volatile