Polygala, particularly Polygala tenuifolia (commonly known as Yuan Zhi in Traditional Chinese Medicine), has a long history of use in East Asian herbal traditions as a remedy to support mental health, including mood, memory, and emotional balance. Historically, it is believed to "calm the spirit" and "open the orifices," which has led to its use in formulas intended to address symptoms such as anxiety, insomnia, and forgetfulness—conditions thought to involve imbalances in the nervous system. These traditional uses have, in contemporary wellness circles, been extrapolated to suggest possible support for the serotonin system, as serotonin is a key neurotransmitter involved in mood regulation.

Scientifically, there is limited evidence directly linking Polygala to serotonin modulation in humans. Some animal and in vitro studies suggest that extracts or isolated compounds from Polygala may have neuroprotective, antidepressant-like, or anxiolytic effects, potentially involving neurotransmitter systems including serotonin. However, these findings are preliminary, and the exact mechanisms remain unclear. There are no well-controlled human trials demonstrating a clear effect of Polygala on serotonin levels or signaling.

In summary, the use of Polygala to support the "serotonin body system" is rooted mainly in traditional practice, with only weak scientific evidence, mostly preclinical, suggesting a possible connection.