American Wintergreen, also known as eastern teaberry, or Gaultheria procumbens is a shrub of the Ericaceae family. It is found in the forests of North America, Canada and China. In traditional medicine, wintergreen essential oil obtained from the leaves is highly valued for its pain-relieving and anti-inflammatory properties.
It is used to relieve arthritis, rheumatism, tendonitis, cramps, muscle contractures, various spasms and osteoarthritis in particular. It frequently enters into the constituents of massage oils intended for athletes to reduce aches, cramps and pain after exercise. Its heating effect is very appreciated. It is also recommended to fight against hypertension, headaches or liver fatigue. It is generally used locally. Its oral use must be monitored by a specialist. The main aromatic compound of this plant is methyl salicylate (MS), a molecule close to the acetylsalicylic acid found in Aspirin®.
A topical treatment consisting of essential oil from wintergreen and peppermint as used in the United States has been shown to be effective in relieving lower back pain. Wintergreen essential oil has analgesic power and the two oils act in synergy to amplify this effect (HEBERT & al., 2014).
In a 2020 study, the analgesic effect of a patch containing 10% MS, 6% menthol and 3.1% camphor, an organic component from the camphor tree, was evaluated. Based on the “Brief Pain Inventory”, a medical pain assessment form given to participants, the treated group was shown to have a 49% decrease in pain severity and a 58.1% decrease in the interference score. The interference score takes up the different consequences of pain on quality of life, activity, mood, work, relationships, sleep, etc. The control group meanwhile, recorded decreases of only 12.3% and 14.8%. In addition, 60.5% of treated individuals reported using significantly less oral pain medication and 90.8% were extremely satisfied with the treatment (GUNDIN & al., 2020).
A topical treatment containing MS has been tested on patients with rheumatoid arthritis in the shoulder or knee. Based on the visual analog scale that quantifies pain, a significant reduction in pain was demonstrated between the 1st and 14th day of treatment compared to the placebo group (JURCA & al., 2021).
MS exerts part of its activity by acting on TRPV1 receptors. These receptors are present on cell membranes and involved in nociception. It acts in a way comparable to capsaicin, a molecule naturally present in peppers, causing first an activation and then a desensitization of the receptors (OHTA & al., 2009).
The MS shows a free radical uptake of 50% during the DPPH test (JURCA & al., 2021). In addition, the polyphenols present in Wintergreen are able to capture oxygen-derived free radicals In vitro with as much efficiency as ascorbic acid (OLSZEWSKA & al., 2021).
The synovial capsule of people with rheumatoid arthritis is thicker. This thickness increase decreases significantly following the use of MS (JURCA & al., 2021).
Wintergreen contains numerous polyphenols which inhibit the In vitro production of COX-2 and the release of IL-1β and TNF-α. It is the MS that is the most effective of all. Its median inhibitory concentration is between that of indomethacin and that of dexamethasone (OLSZEWSKA & al., 2021).
From now on, Wintergreen, which gives such a characteristic scent to sports locker rooms, no longer holds any secrets for you!
