The Dual Food-and-Medicine Value of Clams (Wenha / Meretrix)

The clam is a common seafood, scientifically known as Meretrix meretrix (wenha), a bivalve of the family Veneridae. Meretrix is rich in protein; besides its high nutritional value, both its meat and its shell have certain medicinal value.

Meretrix meat, also called hai-ge rou or ge-li rou, is regarded by traditional TCM as moistening dryness and quenching thirst, and softening hardness and dissipating swelling. It is used for wasting-thirst (xiaoke), pulmonary tuberculosis, night sweats due to yin deficiency, goiter and nodules, and scrofulous lymph nodes. The Quanguo Zhongcaoyao Huibian records its effects as follows: "It moistens the five zang, quenches wasting-thirst, softens hardness and disperses swelling; it is a nutrient and also a diuretic. Moreover, by softening hardness it treats goiter and nodules below the neck (including lymphadenopathy and goiter), pulmonary tuberculosis, and night sweats due to yin deficiency; cooked with Chinese chives as a dish and eaten regularly."

Modern pharmacological research shows that Meretrix meat lowers blood sugar and blood lipids and has antitumor effects. It also raises serum hemolysin levels in mice, promotes splenic lymphocyte proliferation, increases the phagocytic percentage and phagocytic index of peritoneal macrophages, increases thymus weight and serum hemolysin antibody, and exerts a bidirectional regulatory effect on hypersensitivity reactions. The clam substance contained in clams inhibits tumor growth. In addition, hydrolyzed Meretrix meat lowers whole-blood viscosity in normal and hyperlipidemic quails and inhibits ADP-induced rabbit platelet aggregation in vitro; intragastric administration of Meretrix meat raises total serum SOD activity in aged mice.

Thus clams are suitable for patients with diabetes, hyperlipidemia, goiter, lymphadenopathy, and pulmonary tuberculosis. Regular consumption of clam meat has a certain dietary-therapy effect for such patients and can relieve their symptoms.

Clam shells and clam powder (powder ground from clam shells) are common Chinese medicinal materials. Clam shells contain calcium carbonate, chitin, calcium phosphate, magnesium silicate, iodine, and bromide salts. TCM considers clam shells salty and slightly cold, entering the lung, stomach, and kidney meridians; they clear the lung, resolve phlegm, soften hardness, promote urination, neutralize acid, and constrain sores. They are used for phlegm-heat cough, goiter, phlegm nodules, hypochondriac pain, damp-heat edema, strangury and leukorrhea, stomach pain with acid regurgitation, and ecthyma and eczema. They may be taken internally, or ground into powder and sprinkled on or mixed and applied to the affected area; clam powder treats eczema and ecthyma by direct sprinkling.

In the Han dynasty, Zhang Zhongjing's Jingui Yaolue contains the formula "Wenha San" (Meretrix Powder): take five liang of Meretrix, grind into a powder, and take a square-inch spoon (about 1-3 g) each time. Wenha San treats "those who are thirsty and want to drink without cease," which is the TCM "shang-xiao" (upper wasting-thirst) pattern, a common symptom of diabetes.

Meretrix is also often used for edema, cough with upward-reversing qi, difficult urination, and inability to sit or lie. The Sheng Hui Fang records: one liang of Meretrix (finely ground), one liang of sweet Tinglizi (descurainia, stir-fried over paper until purple), one liang of Han Fangji (Stephania Tetrandra), one fen of Xingren (Apricot Kernel), and one liang of Sangbaipi (Mulberry Root Bark). Grind the above into powder, pound together with jujube flesh, and make into pills the size of a phoenix-tree seed. Take seven pills before meals with hemp-seed decoction, to treat edema, cough with upward-reversing qi, and inability to sit or lie down; this pattern resembles the symptoms seen in COPD patients with pleural effusion.

Records of Meretrix for goiter and scrofulous nodules are also common. For example, the "Wuhai Yingliu Wan" in the Yanfang Xinbian uses Haidai (kelp), Haizao (seaweed), Kunbu (bladderwrack), Hai-ge-fen (clam shell powder), and Wuzeigu (cuttlefish bone), each 5 qian, decocted in water and taken as a tea substitute to treat "goiter and nodules." Modern practitioners treating various cancers also often add clam powder to formulas, drawing on its function of softening hardness and dispersing nodulation. When clam powder enters a decoction, it must be wrapped in a non-woven bag and decocted, lest the decoction become pasty and hard to swallow.