Please note that you should never self-prescribe TCM ingredients. A TCM ingredient is almost never eaten on its own but as part of a formula containing several ingredients that act together. Please consult a professional TCM practitioner, they will be best able to guide you.
Preparation: Remove shell and seed, dry them until they aren't sticky anymore.
Dosage: 6 - 15 grams
Main actions according to TCM*: Nourishes the Blood. Calms the spirit. Relieves fatigue, especially mental fatigue.
Contraindications*: Not for conditions of Dampness and Heat.
Common TCM formulas in which longans are used*:
In Traditional Chinese Medicine (TCM), longans are plants that belong to the 'Tonic herbs for Blood Deficiency' category. Tonic herbs are used for patterns of Deficiency, when one lacks one of the 'Four Treasures' (Qi, Blood, Yin and Yang). Blood tonics tend to be bitter-sweet with either a Warm or neutral nature. Because the Liver stores Blood, all Blood tonics enter that Organ meridian.
As suggested by its category longans are plants that are Warm in nature. This means that longans tend to help people who have too much "cold" in their body, although with less effect than a plant that would be Hot in nature. Balance between Yin and Yang is a key health concept in TCM. Those who have too much cold in their body are said to either have a Yin excess (because Yin is Cold in nature) or a Yang deficiency (Yang is Hot in Nature). Depending on your condition longans can help restore a harmonious balance between Yin and Yang.
Longans also taste Sweet. The so-called "five elements" theory in Chinese Medicine states that the taste of TCM ingredients is a key determinant of their action in the body. Sweet ingredients like longans tend to slow down acute reactions and detoxify the body. They also have a tonic effect because they replenish Qi and Blood.
The tastes of ingredients in TCM also determine what organs and meridians they target. As such longans are thought to target the Spleen and the Heart. In TCM the Spleen assists with digestion, blood coagulation and fluid metabolism in the body. In addition to regulating blood flow, the Heart is believed to be the store of the "spirit" which basically refers to someone's vitality.
Longan fruit pericarp has strong antioxidant properties as well as some anticancer properties.1
1. K. Nagendra Prasad, Jing Hao, John Shi, Ting Liu, Jiang Li, Xiaoyi Wei, Shengxiang Qiu, Sophia Xue, Yueming Jiang (2009). Antioxidant and anticancer activities of high pressure-assisted extract of longan (Dimocarpus longan Lour.) fruit pericarp. Innovative Food Science & Emerging Technologies, 10(4): 413-419. DOI: https://doi.org/10.1016/j.ifset.2009.04.003.
Longans are also eaten as food. It is used as an ingredient in dishes such as Longan Cheesecake or Lemon Chicken with Longan.