Ethnobotanical Survey on Bitter Tea in Taiwan

Abstract

Ethnopharmacological evidence: In Taiwan, herbal tea is considered a traditional medicine and has been consumed for hundreds of years. In contrast to regular tea, herbal teas are prepared using plants other than the regular tea plant, Camellia sinensis (L.) Kuntze. Bitter tea (kǔ-chá), a series of herbal teas prepared in response to common diseases in Taiwan, is often made from local Taiwanese plants. However, the raw materials and formulations have been kept secret and verbally passed down by store owners across generations without a fixed recipe, and the constituent plant materials have not been disclosed. Aim of the study: The aim was to determine the herbal composition of bitter tea sold in Taiwan, which can facilitate further studies on pharmacological applications and conserve cultural resources. Materials and methods: Interviews were conducted through a semi-structured questionnaire. The surveyed respondents were traditional sellers of traditional herbal tea. The relevant literature was collated for a systematic analysis of the composition, characteristics, and traditional and modern applications of the plant materials used in bitter tea. We also conducted an association analysis of the composition of Taiwanese bitter tea with green herb tea (qing-cao-cha tea), another commonly consumed herbal tea in Taiwan, as well as herbal teas in neighboring areas outside Taiwan. Results: After visiting a total of 59 stores, we identified 32 bitter tea formulations and 73 plant materials. Asteraceae was the most commonly used family, and most stores used whole plants. According to a network analysis of nine plant materials used in high frequency as drug pairs, Tithonia diversifolia and Ajuga nipponensis were found to be the core plant materials used in Taiwanese bitter tea. Conclusion: Plant materials used in Taiwanese bitter tea were distinct, with multiple therapeutic functions. Further research is required to clarify their efficacy and mechanisms.

Keywords: Taiwanese bitter tea; Taiwanese traditional medicine; ethnobotany; field survey; health geography.

FIGURE 1

Geographical distribution of 32 stores with available bitter tea formulations. Red dots indicate that the store provided bitter tea formulation but did not receive interviews (seven stores), and green dots indicate that the store provided complete bitter tea formulation and accepted interviews (25 stores).

FIGURE 2

Origin analysis of 73 plant materials used in bitter tea. (A) Families; (B) plant parts; (C) the number of shared plant materials in areas of Taiwan.

FIGURE 3

Traditional and modern pharmacological analysis of plant materials used in Taiwanese bitter tea. (A) Nature; (B) flavor; (C) comprehensive analysis of nature and flavor (%); (D) ethnomedicinal effects; (E) modern pharmacological applications of plant materials with a frequency greater than nine.

FIGURE 4

Comparisons between Taiwanese bitter tea and green herb tea. (A) Venn diagram of the top 15 most commonly used plant materials in bitter tea and green herb tea. (B) Comparison of the nature and flavor of the plant materials. (C) Use values of the top five most commonly used plant materials (1–5 indicate the top five commonly used plant materials). The horizontal dotted line indicates the highest UV of BT. (D) Modern pharmacological applications of the top 15 most commonly used plant materials. QCC, qing-cao-cha (green herb tea); BT, bitter tea.

FIGURE 5

Venn diagram showing the number of shared plant materials in herbal tea from different regions.

FIGURE 6

Network analysis of the high frequency drug pairs found in Taiwanese bitter tea. The number is the UV of the plant material, and the length of the connecting line indicates co-occurrence frequency. The circle sizes represent the relative ratio of UV. AN, Ajuga nipponensis Makino; IC, Ixeris chinensis (Thunb.) Nakai; IA, Ilex asprella (Hook. & Arn.) Champ.; TD, Tithonia diversifolia (Hemsl.) A. Gray; MR, Mallotus repandus (Willd.) Müll. Arg.; BM, Bombax malabarica DC.; SI, Solanum incanum L.; AP, Andrographis paniculata (Burm. f.) Nees.