Rou Gui, the “flesh cinnamon”

Rou Gui reads “flesh cinnamon”: the name refers to the thick, fleshy bark of mature trees, as opposed to the thin bark of young trees and to the twigs. It is the trunk bark of Cinnamomum cassia, Chinese cinnamon, an evergreen tree of the tropical lowlands of southern China. Its benchmark growing region is Guangxi, around Fangchenggang, Qinzhou and Yulin, as well as Guangdong. It is harvested from August to October, when the bark is richest in essential oil, after ten years or more for the great thick grades. A good bark is thick, heavy and oily to the touch, with an intense, warm and sweet fragrance; chewed, it leaves a strong, lasting warmth. The Shen Nong Ben Cao Jing already called it “the envoy that goes before all other herbs”.

Rekindling the fire of the Kidney

In traditional Chinese medicine, Chinese cinnamon is hot, pungent and sweet in flavour. The pungent and the hot warm and disperse Cold; the sweet tonifies. It is associated with the Kidney, the Spleen, the Heart and the Liver, and its movement goes downwards and inwards. According to tradition, the Kidney houses the Gate of Life, the source of all warmth; Rou Gui rekindles this fire, gently and lastingly rather than abruptly. Its singularity is to lead the Fire back to its source: when the Yang floats upwards, it guides it back to the Kidney, where it belongs.

Warming the interior: the bark, not the twig

Cold, tradition says, contracts and congeals; its hot nature penetrates deeply to warm the interior and restore the circulation of the Blood. Its sweetness also nourishes the Spleen. Added in small proportion to tonifying formulas such as Shi Quan Da Bu Tang, it acts like a spark that relaunches the production of Qi and Blood. The same tree gives the twig, Gui Zhi: light, it rises towards the surface, whereas the bark, with its dense Qi, descends to warm the interior. Modern research is taking a particular interest in cinnamaldehyde, its main compound.