An Overview of Alcoholic Liver Disease
Alcoholic liver disease (ALD) refers to liver damage and a series of lesions caused by long-term excessive drinking. According to severity, it can be divided into five types: mild alcoholic liver injury, alcoholic fatty liver, alcoholic hepatitis, alcoholic hepatic fibrosis, and alcoholic cirrhosis. If a patient also has other liver diseases such as hepatitis B, liver cancer, or metastatic liver cancer together with alcoholic liver disease, the condition is more severe. Long-term heavy drinkers have a higher risk of alcoholic liver disease; severe alcohol abuse can even induce widespread hepatocyte necrosis leading to liver failure.
Why does alcohol cause such great harm to the liver? This begins with the metabolic process of alcohol in the human body. After alcohol enters the body, more than 90% is metabolized in the liver. Alcohol is oxidized to acetaldehyde under the catalysis of alcohol dehydrogenase (ADH). Acetaldehyde is then converted to acetic acid under the catalysis of aldehyde dehydrogenase (ALDH). The acetic acid then undergoes chemical reactions, ultimately turning into carbon dioxide and water, which are excreted from the body.
Acetaldehyde is a highly toxic metabolite that can directly damage hepatocytes. Acetaldehyde binds to proteins and DNA, interfering with cellular function and damaging mitochondria, leading to energy metabolism disorders. Acetaldehyde can also inhibit the liver's ability to repair itself and promote hepatic inflammation and fibrosis. Hepatic fibrosis is a precursor to cirrhosis. If hepatic fibrosis continues to progress, it develops into cirrhosis and then into liver cancer.
Long-term drinking leads to elevated activity of cytochrome P450 2E1 (CYP2E1), producing large amounts of ROS that attack liver cell membranes, proteins, and DNA. The liver's antioxidants (glutathione, etc.) are excessively consumed and cannot neutralize free radicals, which leads to hepatocyte injury and death. Acetaldehyde can also inhibit fatty acid oxidation and promote fat synthesis, causing triglycerides to accumulate in hepatocytes and forming alcoholic fatty liver. The basic progression of alcoholic liver disease is: alcoholic fatty liver → hepatitis → fibrosis → cirrhosis → liver cancer (HCC). Once it progresses to cirrhosis, this process is no longer reversible.
Abstaining from alcohol is the best way to prevent alcoholic liver disease. If abstinence is impossible, the amount of drinking should be limited to ≤40 g of alcohol per day for men and ≤20 g per day for women. Those who must drink long-term for work should supplement with antioxidants such as vitamin C, vitamin E, and glutathione precursors (e.g., N-acetylcysteine). They should also maintain a balanced diet, choosing a high-protein, low-fat diet rich in B vitamins and folic acid. Regular physical check-ups should be performed, including liver ultrasound as well as liver function tests and alpha-fetoprotein.
Ancient Chinese physicians discovered the harm of alcohol to the human body very early. The "Shang Gu Tian Zhen Lun" chapter of the Huangdi Neijing (Yellow Emperor's Inner Canon) specifically pointed out that "taking wine as a fluid" (meaning excessive drinking) is an important cause of human disease. Zhang Zhongjing, author of the Shanghan Lun (Treatise on Cold Damage), noted in the clause on Guizhi Tang (Cinnamon Twig Decoction) that "a wine drinker's illness should not be treated with Guizhi Tang." Zhang Zhongjing also specifically mentioned "wine jaundice" (jiu dan)-jaundice caused by drinking. It can be seen that as early as the Han dynasty and even the Spring and Autumn and Warring States periods before it, Chinese physicians had discovered that the constitution of long-term drinkers differed from that of normal people and that they were prone to jaundice-type diseases.
Chen Yan of the Song dynasty further pointed out in his San Yin Ji Yi Bing Zheng Fang Lun (Treatise on the Three Causes and Patterns of Diseases and Formulas) that "among the five types of jaundice, only wine jaundice has the most variable manifestations," meaning that wine jaundice has a complex course and a poor prognosis. Li Shizhen further elaborated on the poor prognosis of excessive drinking in the Bencao Gangmu (Compendium of Materia Medica), saying: "Excessive and unrestrained drinking kills in an instant."
Ancient Chinese physicians also discovered the relationship between drinking and ascites. For example, the Zhangshi Yi Tong (Comprehensive Medicine of the Zhang Family) mentions: "In a person addicted to wine, the abdomen becomes distended like a vat; this disease is formed when damp-heat damages the spleen." The Jingyue Quanshu (Complete Works of Jingyue) also states: "Indulging in wine without restraint in youth often leads to water drum." Here, "abdomen distended like a vat" and "water drum" are both symptoms of cirrhotic ascites, which is a typical sign of advanced alcoholic liver disease.
There is no specific therapy for this disease; one can only follow the principle of symptomatic treatment to improve the patient's quality of life and prolong survival. If the patient can stop drinking, the progression of liver lesions can be slowed. But alcoholics often have other problems (such as post-traumatic stress disorder, bipolar disorder, or borderline personality disorder) that have led to substance dependence, so abstinence is very difficult and the prognosis is poor.