The "Ask Dr. Jiang" column is designed to explore corners of Chinese medicine that may not be easily understood by American practitioners or are underrepresented in American clinical health literature.
Dear Dr. Jiang:
According to Chinese medicine, the sour flavor binds and secures, but herbs that are cooked in vinegar, such as bie jia and da huang, take on a blood stasis dispelling effect. This seems to be just the opposite of what I understand "binding" and "securing" to mean (i.e., preventing substances like sweat or urine from leaving the body). Can you clear up this apparent contradiction?
Insecure About Vinegar
You're right, IAV. It's almost impossible to find references in the ancient or modern literature attributing binding properties to vinegar or herbs cooked in vinegar. That's because in addition to being sour, vinegar is also bitter. In fact, it was known in the Shang Han Lun as ku jiu, or "bitter liquor." Bear in mind that we're talking about the energetic properties of vinegar, and not necessarily its actual flavor. We're also talking about Chinese rice vinegar. I can't say for sure whether the properties outlined below would apply to the vinegars used in this country, which are made from corn, grapes, or apple cider.
According to Chinese medicine, rice vinegar is bitter, sour and warm. The Nei Jing states that when bitter and sour come together, the collective function is to drain. Taken as a whole, therefore, vinegar warms and drains, and this explains most of its functions in Chinese medicine and food therapy. Below is a brief list of the functions and applications of vinegar.
1. Vinegar invigorates blood, dispels blood stasis, and stops pain. Mu xiang, pre-fried in vinegar, can be used to treat abdominal pain, due to blood stasis or qi stagnation; to regulate the liver; and to soften hardness. Da huang, pre-fried in vinegar, breaks up masses and tumors in the abdomen; this process also reduces da huang's purging effects. An ancient formula called cu bie wan used vinegar, bie jia and gan jiang to treat abdominal masses. Derivatives of this formula are used in modern China to treat cirrhosis of the liver and cancer.
Vinegar applied externally can treat external forms of blood stasis. Used alone or formed into a paste with da huang powder, it can help the out-thrusting of early stage boils. This same formula can be used as a salve for first-degree and second-degree burns. Plain vinegar wash can help heal bruises and contusions due to external trauma. As a mouthwash, vinegar can relieve the pain of toothache.
2. Vinegar courses the liver, regulates qi, and moves stagnation. Pre-frying in vinegar can enhance the qi-regulating and pain-reducing properties of herbs such as xiang fu, qing pi and xiao hui xiang. Combined with cooling herbs, the draining properties of vinegar can be used to treat headaches due to liver fire or ascending liver yang. Modern studies in China have found that three-to-five vinegar-soaked peanuts taken daily can help control hypertension.
3. Vinegar relieves toxicity. Egg white boiled in vinegar can be used to treat sore throat due to toxic heat. Vinegar can be used as an external wash to prevent insect bites, or as a treatment after an insect bite has occurred. In some parts of China, vinegar is boiled to clear epidemic toxins from the air and prevent colds and flu. Vinegar is also used in cooking to remove any toxicity that might be present in meat and fish and to prevent food stagnation.
4. Miscellaneous uses: Diluted in water, vinegar can relieve the symptoms of hangovers. Vinegar can be used to expel roundworms, especially if they are lodged in the gall bladder. And of course, vinegar can be used as a form of food therapy: Patients with blood stasis, qi stagnation or liver yang rising should take a little more vinegar in their diet.
Although vinegar is very safe, a little bit of caution is needed because overuse can damage the spleen and stomach. Overall, rice vinegar is an extremely important herb and an important ingredient in cuisines around the world. But don't expect it to bind and secure; its function is to get things moving.
Edited with the assistance of John Pirog, MSOM.