Fatty Liver Disease
Some fat in the liver is normal. But if fat makes up more than 5%-10% of the weight of your liver, you may have alcoholic or nonalcoholic liver disease. In some cases, these diseases can lead to serious complications.
Alcoholic Liver Disease (ALD)
More than 15 million people in the U.S. abuse or overuse alcohol. Almost all of them -- 90%-100% -- develop fatty livers.
Fatty liver can occur after drinking moderate or large amounts of alcohol. It can even occur after a short period of heavy drinking (acute alcoholic liver disease).
Genetics or heredity (what is passed down from parent to child) plays a role in alcoholic liver disease in two ways: It may influence how much alcohol you consume and your likelihood of developing alcoholism. And, it may also affect levels of liver enzymes involved in the breakdown (metabolism) of alcohol.
Other factors that may influence your chances of developing alcoholic fatty liver disease include:
- Hepatitis C (which can lead to liver inflammation)
- An overload of iron
Nonalcoholic fatty liver disease (NAFLD)
Nonalcoholic fatty liver disease is now the most common cause of chronic liver disease in the U.S. Some people with excess fat in the liver simply have what's called a fatty liver. Although this is not normal, it is not serious if it doesn't lead to inflammation or damage.
Others have what's called nonalcoholic steatohepatisis (NASH). Although it is similar to alcoholic liver disease, people with this type of fatty liver disease drink little or no alcohol. NASH can lead to permanent liver damage. The liver may enlarge and, over time, liver cells may be replaced by scar tissue. This is called cirrhosis. The liver can't work right and you may develop liver failure, liver cancer, and liver-related death. NASH is one of the leading causes of cirrhosis.
Both types of NAFLD are becoming more common. Up to 20% of adults may have either fatty liver or NASH. And more than 6 million children have one of these conditions, which are most common in Asian and Hispanic children. Recent evidence indicates that NAFLD increases the risk of heart disease in children who are overweight or obese.
Causes of Nonalcoholic Fatty Liver Disease (NAFLD)
The cause of nonalcoholic fatty liver disease is not clear. Certain factors tend to increase risk, but in some cases, no risk factors show up. However, NAFLD tends to run in families. It also shows up most often in people who are middle-aged and overweight or obese. These people often have high cholesterol or triglycerides and diabetes or prediabetes (insulin resistance), as well.
Other potential causes of fatty liver disease include:
- Viral hepatitis
- Autoimmune or inherited liver disease
- Rapid weight loss
Recent studies show that an overgrowth of bacteria in the small intestine and other changes in the intestine may be associated with nonalcoholic fatty liver disease. Some researchers now suspect this may play a role in the progression of NAFLD to NASH.