The liver is responsible for many important functions. It converts sugars to glycogen and stores it until the body needs it. The liver also produces certain chemicals needed to break down food and alcohol, remove harmful toxins from the blood, and it produces proteins that help the blood clot properly.

Non-alcoholic fatty liver disease (NAFLD) affects about 25% of people in the world. It is the most common chronic liver disorder in Canada and occurs when people who drink little or no alcohol develop certain liver-related conditions. It tends to appear in overweight individuals who have diabetes, high cholesterol, and high triglyceride levels.

NAFLD may begin as simple fatty liver, a mild condition also known as steatosis. With simple fatty liver, fat builds up within the liver, normally without causing any damage to the liver cells. Another more serious form of non-alcoholic fatty liver disease is called non-alcoholic steatohepatitis (NASH). NASH is a more serious condition because inflammation and growth of tissue within the liver may lead to cirrhosis, liver scarring, liver cancer, or the need for a liver transplant.

Several risk factors increase the likelihood of a person developing NAFLD. These risk factors include:

• diabetes
• excess weight and obesity
• high levels of fat in the blood (also known as hyperlipidemia)

It appears that people with metabolic syndrome are more likely to develop some form of NAFLD. Metabolic syndrome is a condition that can include high blood pressure, high cholesterol or blood fat levels, obesity, or an inability to regulate sugar (insulin resistance).

However, people without metabolic syndrome or any of its risk factors can also develop NAFLD. Taking certain medications such as corticosteroids, antiretrovirals, immune-suppressing medications, and some cancer medications may also increase the chance of developing NAFLD.

NAFLD is usually not associated with any symptoms and is discovered with routine blood tests.
If the mild form of the condition develops into NASH or cirrhosis, a person may notice other symptoms including loss of appetite, discomfort in the upper right abdomen, weight loss, jaundice (yellow skin or eyes), dark urine, swollen legs, swollen feet, easy bruising, and mental problems (e.g., memory loss).

Several different tests may be needed to identify NAFLD, including blood tests, ultrasound, biopsy, CT scan, or MRI scan:

• blood tests: Liver inflammation or damage leads to increased liver enzyme levels that may be detected with a simple blood test. Other blood tests can also help rule out other causes of liver disease.
• ultrasound: Using a sound probe, a technician takes pictures of the liver. A doctor uses this image to look for any damage to the liver or increased size, which may indicate swelling or inflammation.
• biopsy: Used alone or in combination with one of the other tests, a biopsy is the best way to confirm NAFLD but it is not used routinely. This technique requires making an incision in order to reach the liver and remove a small sample of liver tissue. Analysis of the tissue shows whether or not the cells are normal.
• CT scan: This type of scan uses X-rays to see the liver. The image is a cross-section of the liver.
• MRI: This type of scan uses radio waves to produce a 3D image of the liver.

Your doctor may also ask you questions relating to your medical history, diet, and alcohol consumption. Ruling out conditions such as hepatitis B and C (which also damage the liver) is important before making the diagnosis of NAFLD.

Since NAFLD is associated with other risk factors such as obesity, diabetes, and high cholesterol levels, getting some or all of these conditions under control can help manage the disease.

Treatment for a person with NAFLD may include:

• regular physical activity
• gradual weight loss (0.5 kg to 1 kg per week)
• reducing toxic substances in your diet (e.g., alcohol)
• stop taking certain medications that might be the cause of NAFLD
• controlling high cholesterol
• controlling diabetes

Preventing this condition requires looking after your health every day. Reaching and maintaining a healthy weight by making healthy food choices and exercising regularly are important. Getting vaccinations for hepatitis A and B, the flu, and pneumococcal disease can help prevent the disease from progressing to liver failure.

Keeping conditions such as diabetes and high cholesterol in control may also reduce your risk of NAFLD.

For information about nutrition and exercise, refer to these publications:

• Canada's Food Guide
• Canada's Physical Activity Guide to Healthy Active Living