Nonalcoholic Steatohepatitis (NASH)

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is nonalcoholic steatohepatitis?

Nonalcoholic steatohepatitis (NASH) is a form of fatty liver disease. Fatty liver disease is an excessive accumulation of fats in the liver—the largest internal organ. The liver has many jobs, including aiding digestion; storing energy; removing toxins; and breaking down fats, carbohydrates, proteins and drugs. A healthy liver stores a small amount of fat in its cells (hepatocytes). Fatty liver disease develops when stored fat is greater than 5 to 10% of the liver’s weight. Steatosis is the medical name for it.

There are two types of fatty liver disease: alcoholic and nonalcoholic liver disease (NAFLD). The alcoholic form is the result of heavy alcohol use. Nonalcoholic fatty liver disease (NAFLD) looks the same as the alcoholic version, but alcohol does not play a role in its development. NASH is the advanced stage of NAFLD. It occurs when fat buildup causes inflammation and damage to the liver. The medical term for liver inflammation is hepatitis. So, steatohepatitis is liver inflammation as a result of fat buildup.

NAFLD is the most common kind of chronic liver disease in the United States. About 25% of American adults may suffer from NAFLD. NASH likely affects about 20% of this group—or about 5% of American adults. NASH can also occur in children, with obesity being the strongest association in both adults and children. Other risk factors include having type 2 diabetes, high blood pressure, and high cholesterol. However, the exact cause of NAFLD and NASH is unclear.

Unfortunately, neither NAFLD nor NASH typically cause symptoms. So, it is possible to have the disease and not know it. Doctors often find it when routine blood tests or blood tests for another condition show elevated liver enzymes. Doctors may also feel an enlarged liver on a physical exam or see it on an imaging exam for another reason.

The main treatment for NAFLD and NASH is weight loss. It can help reduce fat in the liver, which can decrease inflammation. Treating underlying conditions, such as diabetes, is also important. Left untreated, NASH can lead to fibrosis, or scarring, which can progress to cirrhosis. Cirrhosis is severe scarring and permanent damage.

Regular medical care can help doctors identify people at risk of NAFLD and NASH. See your doctor between your usual appointments if you have symptoms that cause concern.

What are the symptoms of nonalcoholic steatohepatitis?

Like NAFLD, NASH is most often a silent disease. It develops without symptoms or with mild and vague symptoms. This includes fatigue and pain, fullness, or discomfort in the upper right abdomen.

Common symptoms of NASH

Symptoms tend to develop after NASH progresses to cirrhosis. Symptoms can include:

  • Itching and jaundice, which is yellowing of the skin and eyes
  • Red palms
  • Swelling of the abdomen (ascites) and legs (edema)
  • Visible spider-like blood vessels under the skin

Because the disease is usually asymptomatic, doctors often find NASH during testing for other reasons. This may include routine blood tests or imaging exams that reveal liver problems. Seeing your doctor on a regular basis can help uncover potential liver problems early, before irreversible damage occurs.

What causes nonalcoholic steatohepatitis?

Experts do not fully understand what causes NAFLD or NASH. There is a link to other conditions, including obesity, type 2 diabetes, metabolic syndrome, and high blood triglycerides and cholesterol. However, the reason NAFLD develops and progresses to NASH remains unclear. Theories suggest a role for free radicals (toxic metabolic products) and substances called cytokines. Researchers also believe genetics and environmental factors are part of the explanation.

What are the risk factors for nonalcoholic steatohepatitis?

The most consistent risk factor for NASH is obesity. Most people who have NASH, including children, are either very overweight or obese. And they tend to carry the extra weight around the waist and in the abdomen. However, not everyone who is overweight will develop NASH, or even NAFLD. Doctors can’t predict who will and who will not have a problem.

Other factors that increase the risk of developing NASH include:

  • Hispanic or Asian race
  • Older age, although it can also develop in children
  • Other medical conditions, including type 2 diabetes, metabolic syndrome, high blood lipids, high blood pressure, and obstructive sleep apnea
  • Postmenopausal status in women

Reducing your risk of NASH

It’s not always possible to prevent disease. However, when there are modifiable risk factors, you may be able to lower your risk. For NASH, this includes:

  • Eating a healthy diet with plenty of fresh fruits and vegetables, whole grains, and healthy fats (like nuts, fatty fish, and avocado)
  • Exercising regularly most days of the week
  • Maintaining a healthy body weight
  • Treating and controlling chronic medical conditions

If you have risk factors for NAFLD or NASH, have a discussion with your primary care doctor. Ask about specific ways you can reduce your risk. Focus on individual exercise and weight loss goals that are safe for you. Reaching those goals can be challenging. So, also ask about working with a dietitian, physical therapist, or athletic trainer.

What are some conditions related to nonalcoholic steatohepatitis?

Both NAFLD and alcoholic fatty liver disease are related to NASH. They are all forms of fatty liver disease. NASH progresses from NAFLD, but alcoholic fatty liver disease can also progress to hepatitis, fibrosis and cirrhosis. The changes doctors see on a liver biopsy are similar with both conditions. So, physicians rely on your medical and lifestyle history to differentiate them. And while the two look the same, their treatment takes a different focus. For alcoholic fatty liver disease, treatment means stopping all alcohol use. Avoiding alcohol is also important to protect the liver in NASH. But the focus is on losing weight and treating contributing medical conditions.

How do doctors diagnose nonalcoholic steatohepatitis?

NASH almost always occurs without symptoms in the beginning. Doctors most often find it on routine testing or testing for another medical problem. If your doctor suspects there could be a problem with your liver, fatty liver disease, or NASH, a full diagnostic workup is necessary.

To diagnose your condition, your doctor may ask you several questions including:

  • Do you use alcohol? If so, how much and how often do you drink?
  • What other medical conditions do you have?
  • What medications do you take?
  • How would you describe your diet and activity level?
  • Do you have a personal or family history of liver disease, including hepatitis?

Your doctor will also perform a physical exam. It will include feeling your abdomen for signs of an enlarged liver or spleen; calculating your BMI (body mass index); and looking for signs of liver disease, such as jaundice, edema or ascites.

Afterwards, your doctor may recommend testing including:

  • Blood tests to check liver function tests, lipid levels, and fibrosis assessment
  • Imaging exams to look at the size of your liver and measure the stiffness of your liver, a marker of fibrosis
  • Liver biopsy, which is the only definitive way to know if fatty liver disease is present and if it has progressed to NASH

It can be very difficult to tell the difference between NASH and fatty liver disease related to alcohol. If your doctor diagnoses fatty liver disease, he or she will need to make sure alcohol use is not playing a role. It’s important to rule out alcohol-related causes because the treatment focuses on the underlying risk factors.

What are the treatments for nonalcoholic steatohepatitis?

Nonalcoholic steatohepatitis treatment focuses on eliminating or controlling the underlying risk factors. The goal is to reduce fat levels in the liver, relieve inflammation, and prevent progression to fibrosis and cirrhosis.

Since obesity plays a role in most cases, weight loss is the main way to accomplish these goals. Losing 7 to 10% of your body weight over the course of one year is a typical recommendation. Losing weight at a faster pace is not safe because it can make NASH worse. As an added bonus, losing weight often benefits related conditions, such as diabetes, high blood pressure, and high cholesterol. The other main approach to treating NASH is to treat these related conditions, which often involves medications.

When NASH progresses to cirrhosis, liver transplantation may be an option.

Currently, there is no approved drug therapy for NASH. However, research is ongoing in this area and there are several emerging therapies.

Alternative treatments for NASH

Alternative treatments can’t cure NASH, but researchers have been studying vitamin E for NAFLD and NASH. Some evidence suggests people with NASH who take vitamin E have less liver fat and inflammation. This may be due to vitamin E’s antioxidant effects. The supplement is not right for everyone, so talk with your doctor if you want to try vitamin E.

Coffee is another potential alternative treatment. In studies, people with NAFLD who drank at least two cups of coffee per day had less liver damage than people who didn’t. If you already drink coffee, it may be beneficial to continue.

What are the diet and lifestyle tips for nonalcoholic steatohepatitis?

Diet and lifestyle changes are essential to managing NASH. This includes:

  • Avoiding alcohol and other stresses to your liver, including certain drugs and herbal supplements
  • Eating a healthy diet that is low in fat and replaces saturated and trans fats with unsaturated fats and omega-3 fatty acids
  • Exercising for at least 30 minutes or more per day on most days of the week and finding other ways to get more activity, such as parking far away
  • Including plenty of whole grains and fresh fruits and vegetables in your diet
  • Losing weight and maintaining it through calorie reduction and limiting simple sugars and high-glycemic index foods

Ask your doctor for guidance before making significant changes to your diet or exercise habits. If you have tried to lose weight in the past without lasting success, talk with your doctor. You may be a candidate for a medically supervised weight loss program or even bariatric surgery.

What are the potential complications of nonalcoholic steatohepatitis?

The main complication of NASH is cirrhosis. The process starts with fibrosis, which is scarring of the liver with fibrotic tissue. Left untreated, fibrosis will progress to cirrhosis. Cirrhosis is advanced scarring where enough scar tissue has replaced healthy tissue that the liver doesn’t work right and eventually fails. These changes are irreversible. About 20% of people with NASH will eventually develop cirrhosis. Unfortunately, cirrhosis is often the first sign of NASH because it develops silently.

Cirrhosis can lead to life-threatening complications including:

  • Hepatic encephalopathy, a buildup of toxins that affects the brain, which can lead to coma and death
  • Portal hypertension, high blood pressure in a large abdominal vein, which can lead to an enlarged spleen, esophageal varices, and other problems

Alcohol accelerates the progress to NASH and to fibrosis and cirrhosis once NASH develops. Avoiding alcohol is an important part of preventing complications from NASH.

Aside from liver complications, people with NASH are more likely to develop heart disease or vascular disease and type 2 diabetes if they don’t already have it. In fact, most people with NASH end up dying of cardiovascular disease.

Does nonalcoholic steatohepatitis shorten life expectancy?

It is hard for doctors to predict prognosis with NASH. The degree of fibrosis is the only factor that correlates with the need for liver transplantation and liver-related death. Still, not everyone with fibrosis will progress to cirrhosis. The two most important things you can do to decrease the risk of progression is to avoid alcohol and get to and maintain a healthy weight.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Apr 21
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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