Mondo Grass (Ophiopogon japonicus), known as "Mai Men Dong" in traditional Chinese medicine (TCM), has a long history of use for supporting the respiratory system, including the bronchial tract. In TCM, it is traditionally used to "nourish yin," moisten the lungs, and relieve coughs, dry throat, or thick sputum—symptoms often associated with bronchial or lung dryness. Classical texts and modern TCM practitioners frequently include Mondo Grass in herbal formulas designed for chronic dry cough, bronchitis, and other respiratory complaints where dryness and irritation are present.

However, while its historical use is well-documented, scientific studies on Mondo Grass's effects on the bronchial system are limited. Some laboratory and animal studies suggest potential anti-inflammatory, immunomodulatory, and antioxidant properties of its extracts, but direct evidence for efficacy in human respiratory conditions is lacking. There are a few in vitro and animal studies indicating that components of Mondo Grass may reduce airway inflammation or modulate immune responses, but these findings have not yet translated into robust, high-quality clinical trials in humans.

In summary, the use of Mondo Grass for bronchial or respiratory support is justified primarily by traditional medicine practices, with only preliminary scientific evidence available. Its use should be considered traditional and not fully validated by modern clinical research.