Also known as: Mentha piperita, Menthol, Enteric-coated peppermint, Peppermint essential oil
BotanicalGood evidence
Solid evidence for digestive comfort when enteric-coated, plus a smaller and stranger body of research on inhaled peppermint and exercise performance. The coating is what makes it work.
Typical dose
180.0–600.0 mg per day
Between meals for digestion; before the session for exercise use
What it is
Peppermint oil is distilled from Mentha piperita, a hybrid of watermint and spearmint. Menthol is the principal active compound, typically 30 to 55 per cent of the oil.
For digestive use the enteric coating is essential. Uncoated peppermint oil releases in the stomach, where it relaxes the valve at the top of the stomach and commonly causes reflux and a burning sensation.
An enteric coating carries it past the stomach so it releases in the intestine, which is where the effect is wanted. Uncoated capsules are the usual reason people report that it made things worse.
How it works
Menthol blocks calcium channels in intestinal smooth muscle, relaxing it. That antispasmodic action reduces cramping and the discomfort associated with excessive gut contractions.
It also acts on receptors that sense cold, producing the characteristic cooling sensation, and has mild effects on gas and on the gut microbiota.
The exercise research proposes something different again: inhaled menthol may relax airway smooth muscle and reduce the perception of effort by triggering those same cold receptors in the airways.
What the evidence shows
Digestive comfort is the well-supported use, with multiple controlled trials and meta-analyses reporting reduced cramping, bloating and abdominal discomfort using enteric-coated preparations.
That evidence is among the better bodies of work for any botanical in this index, though almost all of it uses the coated form.
The exercise research is smaller and more curious. Some trials report improved running and cycling performance and reduced perceived exertion following peppermint ingestion or inhalation. Those findings are preliminary and worth treating as interesting rather than established.
Dosing
Digestive trials have used 180 to 225 mg of enteric-coated oil, two or three times daily, taken between meals rather than with food.
Buy enteric-coated capsules and nothing else for this purpose. This single detail determines whether it helps or causes reflux.
Taking it between meals matters too, since food can compromise the coating. For the exercise angle, trials have used small amounts of oil in water or inhaled peppermint before the session, and the effect on perceived effort is the part people notice.
Between meals for digestion; before the session for exercise use
Competition status
Permitted — not on the WADA Prohibited List
Category
Botanical
Safety and side effects
Enteric-coated peppermint oil is well tolerated. Reflux and a burning sensation are the main reported effects and are far more common with uncoated preparations.
Anyone prone to reflux should be cautious even with coated products, since peppermint relaxes the valve at the top of the stomach.
Never give peppermint oil or menthol products to infants or young children, and keep concentrated essential oil out of reach. Speak to your doctor before use if you take regular medication.
Who should avoid it
Take care if you are prone to reflux, since peppermint relaxes the valve at the top of the stomach. Never give peppermint oil or menthol preparations to infants or young children. Keep concentrated essential oil out of reach. Speak to your doctor before use if you take regular medication or have been told there is a problem with your bile ducts.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
