With increasing concern, health experts have been tracking the rise of nonalcoholic fatty liver disease (NAFLD), a disorder characterized by fat buildup in the liver. It’s now the most common liver disorder in the United States and other western industrialized countries. Today, some experts estimate that about 25 percent of adults worldwide have NAFLD. Among people who are obese, which increases the risk, as many as nine in 10 have the condition.
This increase in NAFLD has fueled a steady rise in liver cancer. Between 2000 and 2010, liver cancer associated with NAFLD soared tenfold. The disease is on track to become the leading cause of terminal liver disease—and the most common reason people need liver transplants.
Types of NAFLD
Most people associate fatty liver disease with drinking too much alcohol—alcoholism has long been known to cause fat to accumulate in the liver. But for reasons that aren’t always clear, people who don’t drink to excess can also get fatty liver disease.
NAFLD has two forms:
- Nonalcoholic fatty liver (NAFL), which has few or no symptoms and is thought to be harmless. The liver normally contains some fat, but when the percentage passes the 5 to 10 percent mark, the liver is considered to be fatty (a condition called steatosis). In NAFL, the liver functions normally despite fat accumulation. Most people with NAFLD have this form of the disease and don’t even know they have it. However, NAFL can occasionally progress to a more serious form of NAFLD.
- Nonalcoholic steatohepatitis (NASH), in which the accumulation of fat is accompanied by inflammation. NASH can lead to the development of scar tissue in the liver (cirrhosis), which can prevent liver cells from functioning properly and result in liver failure. NASH can also lead to liver cancer. It’s usually symptomless but might cause fatigue, a general feeling of illness, and vague discomfort in the upper-right abdomen. It affects about 3 to 5 percent of Americans with NAFLD and is most common in adults between ages 40 and 60.
What causes NSFLD?
Researchers don’t fully understand what causes NAFLD or why some people only get NAFL and others develop NASH.
- Severe overweight or obesity
- Insulin resistance
- Abnormally elevated cholesterol or triglyceride levels
- Large waist size
- High blood pressure
- Elevated blood sugar levels
- Type 2 diabetes
- Metabolic syndrome (having three or more of a cluster of risk factors: high blood pressure; excess abdominal fat; high blood sugar; low HDL, or good cholesterol; and high triglycerides)
A healthy lifestyle = protection
Because NAFLD doesn’t typically cause noticeable symptoms, the first sign of trouble usually appears when routine blood tests show abnormal liver function. Additional tests such as magnetic resonanceimaging (MRI) or a liver biopsy can be used to rule out other liver diseases.
No medications specifically treat the disease. Following a healthy lifestyle can go a long way toward managing NAFLD and even reversing fat buildup in your liver. If the advice sounds familiar, it’s because itincludes the same recommendations that have long been made for preventing heart disease. In fact, cardiovascular disease is the most common cause of death in people who have NAFLD.
Lifestyle changes can be powerful. In a study published in 2020 in Alimentary Pharmacology & Therapeutics, researchers compared 4,040 adults with NAFLD and 7,515 healthy controls. They assessed each person on seven metrics—known as Life’s Simple 7—established by the American Heart Association as measures of a heart-healthy lifestyle, including:
- Not smoking
- Maintaining a healthy body mass index (between 18.5 and 25)
- Exercising most days of the week
- Eating a healthy diet with plenty of plant-based foods
- Maintaining healthy cholesterol
- Keeping blood pressure in check
- Maintaining healthy blood sugar levels
The best protection was afforded by following all seven criteria. But several single metrics stood out as being especially important. Failing to control blood pressure, for example, explained 52.8 percentof deaths in people with NAFLD. Uncontrolled blood sugar levels were also associated with significantly increased risk.
If you’ve been diagnosed with NAFLD, try to follow Life’s Simple 7. In addition:
- Consider participating in a formal weight-loss program. A study published in JAMA Internal Medicine in July 2019 suggests that it’s the most effective way for people with NAFLD to lose weight. Weight-loss surgery may be an option for people with NASH who are unable to lose weight with diet and exercise.
- If you drink alcohol, practice moderation or—better yet—don’t drink at all. Excessive alcohol consumption (more than four glasses a day for men and three for women) can damage your liver.
- Talk to your doctor about getting vaccinated against hepatitis A and B. Both of these diseases attack the liver and can lead to serious complications.
This article first appeared in the May 2020 issue of UC Berkeley Health After 50.
Also see Hepatitis ABCs.