NASH is a severe and aggressive type of nonalcoholic fatty liver disease (NAFLD) characterized by inflammation (hepatitis) and damage to the liver caused by excessive fat accumulation. NASH is associated with an increased risk of cirrhosis, liver cancer, liver failure, cardiovascular disease, and mortality.^[1]

The majority of people with NASH exhibit no signs or symptoms. As NASH progresses and becomes more severe, people may experience vague symptoms, such as fatigue, weakness, or right upper quadrant abdominal pain. Blood tests may reveal elevated liver enzymes, but this isn’t found in all people with NASH.^[2]

The gold standard for diagnosing NASH is through a liver biopsy, but this procedure is reserved for people at risk of advanced liver fibrosis. There’s no standard screening for NAFLD, so It’s more common for NASH to be diagnosed incidentally when being assessed for other health conditions. Imaging — specifically, an ultrasound, computed tomography (CT) scans, or certain types of magnetic resonance imaging (MRI) techniques — may be also used to look for signs of fat accumulation in the liver.^[2][3]

The main approach to managing NASH is weight loss, usually achieved via diet and exercise. Although no standard medications or treatments are approved for NASH, medications are prescribed to manage overall cardiometabolic risk from other comorbid conditions such as diabetes, hyperlipidemia or cardiovascular disease. In severe cases, liver transplantation may be needed if NASH has progressed to end stage liver disease.^[2][4]

Hepatitis A and Hepatitis B vaccinations in unvaccinated individuals would reduce the risk of additional liver damage.

Many supplements have been studied for the treatment of NASH, including vitamin E, L-carnitine, betaine, and melatonin. Other supplements studied for NASH include silymarin^[5][6], which is found in milk thistle, and also various probiotic combinations.^[7]

Weight loss through a hypocaloric diet and lifestyle changes is recommended to manage other factors that contribute to the disease (e.g., obesity) and to prevent further complications (e.g., cirrhosis). Losing 5% or more of body weight can help reduce liver fat, losing 7% or more of body weight can lead to the resolution of NASH, and losing 10% or more of body weight can stabilize or regress fibrosis. It is also recommended that people with NASH reduce their consumption of saturated fat (particularly from processed red meat), commercially produced fructose, and alcohol consumption.^[8]

Although there are fewer data on other dietary strategies for treating NASH, such as a low-carbohydrate/high-protein diet or intermittent fasting, these dietary strategies may be helpful if people find them easier to follow while still maintaining a caloric deficit.

Coffee consumption has been associated with a reduced risk of progression to cirrhosis in patients with NASH.^[9]

Regular physical activity and exercise are recommended for people with NASH, to promote weight loss, reduce liver fat and improve overall health. When diet and exercise are insufficient to manage obesity in persons with NASH, then obesity pharmacotherapy and bariatric surgery might be considered.^[4]

NASH results from excessive fat buildup in the liver which surpasses its capacity for secretion or metabolism, leading to liver damage and inflammation. This excess fat accumulation, also known as steatosis, is caused by an imbalance between energy intake and expenditure, with more energy consumed than expended.^[10] People with obesity, metabolic syndrome, and type 2 diabetes are at the highest risk of developing NAFLD, which can then progress to NASH.^[4]