Bird's nest, specifically edible bird's nest (EBN) made from the saliva of swiftlets, has been traditionally used in Chinese medicine for centuries, primarily to nourish the lungs and improve respiratory health. Historical texts such as the Bencao Gangmu (Compendium of Materia Medica) mention bird's nest as a remedy for chronic coughs, phlegm, and to "moisten" the lungs. It is believed to be particularly useful for individuals with weak constitutions or those recovering from illness, attributed to its supposed ability to "replenish qi" and promote overall vitality.

Scientific evidence supporting these claims is limited. Some in vitro and animal studies have identified that EBN contains glycoproteins, sialic acid, and epidermal growth factor-like substances, which may have anti-inflammatory, immunomodulatory, or tissue-reparative effects. However, these studies are preliminary and do not directly demonstrate efficacy in treating or supporting human lung function. There are no robust clinical trials in humans validating bird's nest for respiratory health or lung support. Thus, its use for the lungs is primarily based on traditional practice and anecdotal reports rather than strong scientific validation.

In summary, while the use of bird's nest for lung support is deeply rooted in traditional medicine, current scientific evidence supporting this use is weak and not definitive.