Eating "rubbish"? Exploring the herbal secrets of "Laji-He," a traditional herbal rice snack from southern China.

Background: Laji-He is a traditional rice-based snack from the Beibu Gulf region in southern China. In the Beibu Gulf region, "Laji-He" (literally "garbage He") signifies the removal of toxins from the body, making it a truly "green" food. Laji-He holds essential cultural and medicinal value, incorporating various medicinal plants into its preparation. Despite its local importance, there is limited scientific documentation on the ethnobotanical properties and cultural relevance of the plants used. This study aims to analyze the medicinal plant used in Laji-He and its implication in human medicine.

Methods: Ethnobotanical surveys and interviews were conducted in the Beibu Gulf region, covering local markets and communities. Voucher specimens were collected and identified for each plant collected, using botanical references, while the relative frequency of citation index was used to assess the cultural importance of each plant. Additionally, the medicinal properties of these plants were categorized based on traditional Chinese medicinal theory and modern pharmacological literature. A detailed review of historical texts and local chronicles was also performed to trace the historical development and cultural changes of Laji-He.

Results: A total of 63 medicinal plants from 36 families and 53 genera were documented, with Rubiaceae, Fabaceae, and Lamiaceae being the most frequently represented families. The most commonly used plants, such as Paederia foetida, Piper sarmentosum, Houttuynia cordata, Centella asiatica, and Morus alba, were primarily utilized for their heat-clearing, detoxifying, and wind-dampness expelling properties. Laji-He serves as a symbol of cultural identity and community cohesion, particularly during traditional festivals and family gatherings, reinforcing collective memory and local heritage.

Conclusions: Laji-He is a traditional functional snack, with the plants used in its preparation serving as both food and medicine. Preserving and promoting the culture of Laji-He can contribute to enhancing food security and sovereignty at both the local and national levels.