Cassia Cinnamon (Cinnamomum cassia) has a long history of use in traditional medicine systems, particularly in Traditional Chinese Medicine (TCM) and Ayurveda. In TCM, Cassia Cinnamon (known as "Rou Gui") is used to warm the body, particularly the "middle burner," which includes the stomach and small intestine. It is believed to support digestive health by dispelling cold, alleviating abdominal pain, and promoting the movement of Qi (vital energy) within the digestive tract. In Ayurveda, cinnamon is similarly used to stimulate digestion, reduce bloating, and help balance digestive fire ("Agni").

However, the use of Cassia Cinnamon specifically for small intestine health is primarily based on these traditional practices. Scientific evidence directly linking Cassia Cinnamon to specific benefits for the small intestine is limited. Most modern research on cinnamon focuses on its potential to regulate blood sugar, its antioxidant properties, and its effects on inflammation or the gut microbiome in general, rather than the small intestine specifically. Some in vitro and animal studies suggest cinnamon may have antimicrobial effects that could influence gut health, but these are not specific to the small intestine nor validated in human trials for this purpose.

In summary, the use of Cassia Cinnamon to support the small intestine is grounded in traditional medicine principles, with minimal direct scientific validation.