Liver disease is on the rise globally and in the United States. The most common type of liver disease is nonalcoholic fatty liver disease (NAFLD).1
NAFLD has 2 severities:1,2
- Nonalcoholic fatty liver (NAFL) – Buildup of fat in the liver with little or no inflammation or liver damage
- Nonalcoholic steatohepatitis (NASH) – Buildup of fat in the liver, leading to inflammation and liver damage such as scarring (fibrosis). NASH is the more severe form of NAFLD.
The impact of NASH is significant and growing. Often coined as a “silent liver disease,” NASH quietly affects millions of people worldwide. NASH can lead to serious health complications if left untreated.2
Prevalence of NAFLD and NASH
Cases of NAFLD are increasing worldwide. They mirror the increase in obesity and metabolic syndrome cases. In the United States, about one-fourth of the population is estimated to have NAFLD. Most people who have NAFLD have NAFL.1,2
NASH is the more advanced, severe form of NAFLD, and it is more rare. Experts estimate that of those with NAFLD, about 1 in 5 people have NASH. That equals about 2 to 5 percent – or 6.5 to 16.3 million – of US adults.1,2
Who is affected by NAFLD and NASH?
NAFLD and NASH can affect anyone. While it is more common in adults, it can affect children, too. In fact, about 10 percent of US children between ages 2 and 19 have NAFLD.1
NAFLD and NASH occur in people of all races and ethnicities as well. But certain groups are more at risk, including:1
- Hispanic people
- Non-Hispanic white people
- Asian American people, specifically those from East Asia and South Asia
NAFLD is less common among non-Hispanic Black people. Interestingly, Asian Americans diagnosed with NAFLD typically have a lower body mass index (BMI) compared to non-Hispanic white people who have NAFLD.1
What are the risk factors for NAFLD and NASH?
NAFLD and NASH do not happen on their own. Often, there are pre-existing health conditions that lead to them. Certain risk factors increase the likelihood of NAFLD and NASH.1
Two health conditions in particular put a person at higher risk of developing liver disease: obesity and type 2 diabetes. Research suggests that:1
- Between 33 and 66 percent of people with type 2 diabetes also have NAFLD
- Up to 75 percent of people who are overweight have NAFLD
- More than 90 percent of people who have severe obesity have NAFLD
Other risk factors include:1
- Being over age 50
- Having high cholesterol or high triglycerides (hyperlipidemia)
- Having high blood pressure (hypertension)
- Having a family history of NAFLD
- Living a sedentary lifestyle (sitting or lying down most of the time)
Complications of NASH
When a person’s NAFLD has advanced to NASH, it can lead to:1-3
- Liver cirrhosis – Scarring of the liver becomes permanent. About 1 in 4 people with NASH have cirrhosis.
- Liver failure – The liver begins to fail and cannot function properly.
- Liver cancer – Cancerous cells are found in the liver.
NASH can also lead to a host of other health problems, including:1-3
- Cardiovascular diseases like heart attack and stroke
- Type 2 diabetes
- Chronic kidney disease
One of NASH’s biggest challenges to the medical community is its silent progression. In the early stages, the disease often has no symptoms. Many people with NASH may be unaware of the damage occurring in their liver until it becomes advanced. Experts predict that by 2030 NASH will be the primary reason for liver transplants.2
Taking action against NASH
If NAFLD and NASH are caught early enough, they can be managed and treated. Lifestyle changes like eating a healthy diet, regular exercise, and weight loss play a crucial role in managing liver disease and preventing long-term liver damage or liver failure.1,2
For those with underlying health conditions such as type 2 diabetes or high cholesterol, it is important to manage them to prevent NAFLD and NASH from progressing.1,2