DEAR MAYO CLINIC: Is nonalcoholic fatty liver disease treatable?

ANSWER: Nonalcoholic fatty liver disease (NAFLD) — a condition in which excess fat accumulates in the liver of people who drink little or no alcohol — has become one of the most common liver diseases in the U.S. It’s estimated that the disorder affects up to 20 percent of American adults. Researchers believe this is associated with rising rates of obesity. While some studies have shown a benefit from vitamin E and the prescription medication pioglitazone, the focus is generally on treating the risk factors.

The liver performs many tasks, including processing what you eat and drink into energy and nutrients and filtering harmful substances from your blood. With NAFLD, fat builds up in liver tissue. Some people may experience nonspecific symptoms; however, most individuals with NAFLD experience no symptoms at all.

The buildup of fat in the liver can result in inflammation and scarring (fibrosis). This more serious form of NAFLD — called nonalcoholic steatohepatitis, or NASH — can cause severe liver damage and eventually lead to liver failure or liver cancer in a small percentage of people. Although rare, the scarring can also harden the liver and impair its ability to function properly — a condition known as cirrhosis.

NAFLD may not be discovered until blood tests show an elevation in certain liver enzymes. Additional blood tests may be ordered to rule out other causes of liver disease. To confirm the presence of fat in your liver, doctors often perform an imaging procedure — such as ultrasound, computerized tomography (CT) or magnetic resonance imaging (MRI) — and may also recommend a liver biopsy to examine a sample of tissue for signs of inflammation and scarring.

A number of diseases and conditions can increase the risk of fatty liver disease. These include obesity, high blood cholesterol, and type 2 diabetes. Other risk factors include malnutrition and rapid weight loss. Certain medications, such as corticosteroids, and exposure to some toxins and chemicals also may contribute to fatty liver disease.

Although no specific treatment exists, weight loss can improve and possibly even reverse fatty liver disease to some degree. Shedding excess pounds through diet and exercise or with the help of weight-loss (bariatric) surgery can prevent additional liver damage when inflammation and scarring is already present. However, any weight loss should be gradual — no more than a few pounds a week — because losing weight too quickly can actually worsen fatty liver disease.

Eating a diet rich in fruits, vegetables and whole grains, and limiting the consumption of cholesterol and saturated fats also can help. Cutting out fast food may be particularly helpful, because research has found that the high level of cholesterol, saturated fat and fructose in fast food is associated with progressive inflammation and scarring in people with NAFLD and NASH.

A recent study of adults with NAFLD suggests that vigorous physical activity may also help reduce damage from fatty liver disease. Government guidelines advise that healthy adults get at least 150 minutes per week of moderate physical activity, such as walking, or 75 minutes of vigorous physical activity, such as running on a treadmill. Increasing that time to 300 minutes of moderate physical activity or 150 minutes of vigorous physical activity each week can yield even greater benefits, such as weight loss. But if you don’t already exercise regularly, talk with your doctor first about the best way to start.

It’s also important that people with fatty liver disease avoid excessive alcohol and unnecessary use of medications, which can put stress on the liver. Carefully follow medication instructions and warnings. For instance, acetaminophen — a pain reliever found in many prescription and nonprescription drugs — can cause liver damage if more than the recommended amount is taken. The risk of liver injury primarily occurs when people exceed the current maximum dose of 4,000 mg within a 24-hour period.

Finally, people who have diabetes, high blood cholesterol or medical problems that may be contributing to fatty liver disease should work with their doctor to keep these conditions well managed, which in turn will help manage NAFLD. — Vijay Shah, M.D., Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minn.

Medical Edge from Mayo Clinic is an educational resource and doesn’t replace regular medical care. Email a question to medicaledge@mayo.edu. For more information, visit www.mayoclinic.org.