Willow Bark
Uses
To reduce fever
Willow bark is thought to act in a similar way as aspirin, but clinical trials have not been performed.
To treat pain, including muscle and joint pain
Clinical trials have shown that willow bark extract is effective in treating low back pain. Other study results are mixed for its ability to relieve osteoarthritis pain.
To aid in weight loss
There are no studies to indicate that willow bark can aid in weight loss. A case of allergic reaction was reported following use of a weight-loss product that contained willow bark.
Per Sloan-Kettering:
Clinical Summary
Willow is a deciduous tree native to Europe, Asia and some parts of North America. Its bark has been used for thousands of years in China and Europe as a remedy for fevers and pain. Aspirin is derived from salicin, an active compound in willow bark. Willow bark extracts demonstrated anti-inflammatory , antiproliferative and skin-protective effects in vitro. Clinical studies indicate that willow bark may help manage back pain , although studies of osteoarthritis are mixed , with negative findings for rheumatoid arthritis . Topical application of salicin may help reduce skin aging.
Preclinical studies have shown that salicin has antiangiogenic , anticancer and chemopreventive effects . It was also found to modulate neurite growth in human neuroblastoma cells . Aspirin has been studied for the prevention of cardiovascular diseases as well as cancer . However, willow bark should not be used as a substitute for aspirin because of the variation in its potency. Children should not be given willow bark because of the potential for developing Reye syndrome, a serious condition associated with the use of aspirin.
Mechanism of Action
Mechanisms involved in the anti-inflammatory effect of a standardized willow bark extract
Although anti-inflammatory activity is mostly attributed to salicin , the main bioactive compound in willow bark, catechol and flavonoid compounds have also been found to be responsible . Willow bark inhibits pro-inflammatory cytokines (tumor necrosis factor [TNF]-alpha), cyclo-oxygenase (COX)-2, and nuclear translocation of the transcription factor NF-κB . It was also found to significantly raise low glutathione (GSH) levels, thereby limiting lipid peroxidation .
Antiproliferative effects in human colon and lung cancer cells are due to growth-inhibition and apoptotic induction . In vitro and animal models suggest that salicin can inhibit reactive oxygen species (ROS) and extracellular signal-regulated kinase (ERK) signaling pathways to produce antiangiogenic effects.