Plants Used for Treating Hypertension Among Ethnic Groups in Northern Thailand

The incidence of hypertension (HT) is rapidly increasing globally, and it is considered to be a critical public health problem. Due to the demand for medication and because various side effects of anti-hypertensive drugs have been reported, complementary and alternative therapies, including Thai Indigenous medicine (TIM), should be explored for treating HT. Medicinal plants traditionally used by multiple cultures over long time periods in HT treatment are more likely to be pharmacologically active and might provide useful data, leading to anti-hypertensive drug discovery. Ethnomedicinal field observations were undertaken with 41 key informants in eleven villages in Chiang Mai province from December 2022 to November 2023. In addition, we gathered data on traditional plants used for treating HT among 12 ethnic groups from 41 original references published between 1987 and 2023, covering nine provinces in northern Thailand. Important species among plants used for treating hypertension were identified by calculating their relative frequency of citation (RFC). In total, we found 237 plant species that were used for treating HT. Of these, 173 species had already been reported in the literature, and 96 species were documented in our fieldwork. There were 30 plant species from our field survey that overlapped with species accounted for in the literature. Fabaceae was the plant family with the most species (23 sp, 10%) used for treating HT. The most commonly used species was <i>Blumea balsamifera</i> (L.) DC. (Asteraceae), and it had the highest recorded RFC value of 0.1979. There were 64 plant species that were reported for the first time for HT treatment among ethnic groups in northern Thailand. Of the recorded species, 24 were particularly promising in the treatment of HT, and their efficacy was confirmed by comparing our results to previous studies of plants with anti-hypertensive properties.