Fatty liver, or steatosis, can be caused by a variety of conditions, such as alcohol abuse, pregnancy, infectious hepatitis or non-alcoholic fatty liver disease. In all of these conditions, the liver accumulates too much fat, which it stores in the form of triglycerides. A triglyceride is a relatively simple molecule that consists of a short, three-carbon backbone to which three long fatty acids are attached. Most cases of steatosis are asymptomatic. Any symptoms that do occur are usually associated with liver scarring, or cirrhosis, but steatosis usually does not progress to cirrhosis.
Non-Alcoholic Fatty Liver Disease
Non-alcoholic fatty liver disease, or NAFLD, affects approximately 25 percent of American adults. A 2002 review in "The New England Journal of Medicine" reported that NAFLD was the most likely cause of elevated liver enzymes in the U.S. The incidence of NAFLD is increasing due to a rise in obesity, which contributes to this condition. Presumably, the delivery of excess fatty acids to your liver from either dietary sources or adipose tissue overwhelms the liver's metabolic capacity, so it stores the extra fatty acids as triglycerides until they can be processed. Other causes of NAFLD include genetic disorders of lipid metabolism, certain medications, such as steroids or tamoxifen, exposure to toxins and sudden, severe weight loss.
Alcohol Abuse
Alcohol is a known liver toxin that is commonly overused in many countries, and alcoholic steatosis is a common complication of alcohol abuse. According to "The Merck Manual of Diagnosis and Therapy," people who abuse alcohol are often undernourished, so their bodies mobilize fatty acids from adipose tissue to provide needed fuel. However, once these fatty acids reach the liver, they must compete with alcohol for metabolism. Your liver metabolizes alcohol before it burns fatty acids, so those fatty acids that would normally serve as fuel are "backed up" and stored as triglycerides in your liver.
NAFLD and Alcoholic Steatosis
Many people have a combination of alcoholic steatosis and NAFLD. The two are clinically indistinguishable, so diagnosis rests on determining how much alcohol the affected person drinks. According to "American Family Physician," alcoholic steatosis is known to occur when men consume more than 30 gm of alcohol, or two standard drinks, and women drink more than 20 gm, or 1.5 standard drinks, on a daily basis. If you have steatosis and your alcohol consumption falls below these limits, NAFLD is probably the primary reason for your condition.
Pregnancy
Pregnant women can develop fatty liver from the same lifestyle issues that lead to NAFLD and alcoholic steatosis. Excessive weight gain, high-fat diets and, certainly, alcohol consumption should all be avoided during pregnancy. Pregnant women are also at risk for a rare and potentially fatal condition known as "acute fatty liver of pregnancy," or AFLP. Like preeclampsia, another pregnancy-related disorder, AFLP occurs during the third trimester, and its precise cause is unknown. As mentioned in a 2006 "Canadian Journal of Gastroenterology" article, some researchers believe AFLP is related to abnormal fatty acid metabolism in the fetus.
Considerations
Whatever causes steatosis, the presence of excess triglycerides in the liver causes oxidative damage to its cells, which in turn leads to inflammation. If the cause of the fatty liver is not addressed, some people with steatosis develop liver scarring and, eventually, cirrhosis. If you have NAFLD due to a high-fat diet or obesity, you should lose weight and limit fat intake. If you consume too much alcohol, decrease alcohol consumption or stop altogether. If you are pregnant, eat a well-balanced, calorically-appropriate diet, avoid junk foods and alcohol, and see your doctor on schedule to lower your risk for pregnancy-related disorders.
References
- "American Family Physician"; Nonalcoholic Fatty Liver Disease; Bayard M, et al.; 2006
- "Cleveland Clinic Journal of Medicine"; Non-alcoholic fatty liver disease: a manifestation of the metabolic syndrome; Kim C; 2008
- "The New England Journal of Medicine"; Nonalcoholic Fatty Liver Disease; Angulo P; 2002
- "The Merck Manual of Diagnosis and Therapy, 18th Edition: Alcoholic Liver Disease"; Mark H. Beers, M.D., Editor-In-Chief; 2006
- "Canadian Journal of Gastroenterology"; Acute fatty liver of pregnancy; Ho K; 2006
