The bark of the white willow tree is a source of salicin and other salicylates – compounds which are similar in structure to aspirin (acetyl salicylic acid). \n\nnative americans are thought to have used ground willow bark and bark steeped for tea as a medicinal remedy for everything from pain relief to fevers. today, white willow bark is often used as a natural alternative to aspirin - one of the most common uses in dietary supplements is as an adjunct for weight loss. action:\n\n1) it has has the same effect on the body as aspirin without.