Cassia, which commonly refers to either Cinnamomum cassia (Chinese cinnamon) or Cassia angustifolia (Senna), has a long history of use in traditional medicine systems, such as Traditional Chinese Medicine (TCM) and Ayurveda, to support the Stomach and digestive functions. In TCM, Cinnamomum cassia is known as "Rou Gui" and is believed to warm the interior, dispel cold, and support digestion by harmonizing the stomach and alleviating abdominal discomfort. Similarly, senna, or Cassia angustifolia, is traditionally used as a laxative to address constipation, indirectly supporting digestive health.

The traditional rationale for using Cassia to support the Stomach system is mainly based on centuries of empirical use, rather than modern scientific studies. While there is some preliminary research on the potential effects of cinnamon compounds on gastric motility and microbial balance, robust clinical trials specifically supporting Cassia for stomach health are lacking. Most modern research focuses on other health benefits such as blood sugar regulation and antimicrobial effects, rather than direct stomach support.

In summary, the use of Cassia to support the Stomach system is grounded in traditional, historical practices rather than clear scientific validation. The evidence rating reflects strong traditional but limited scientific support.