World Liver Day 2022: What Causes Fatty Liver Disease And What Are Its Symptoms?

Non-alcoholic fatty liver disease (NAFLD) is a condition in which fat builds up in the liver, and is an umbrella term for a range of liver conditions affecting people who drink little to no alcohol.

Fatty liver disease is a reversible condition wherein large vacuoles of fat (pale yellow circles) accumulate in liver cells. | Photo: Getty Images

New Delhi: World Liver Day is observed every year on April 19, to spread awareness about liver related diseases. The liver is the largest gland and the second largest organ of the human body. It plays an important role in digestion.

Structure And Functions Of Liver

The liver weighs about 1.2 to 1.5 kilograms in an adult human. Located in the abdominal cavity, just below the diaphragm, the liver has two lobes, known as the right and left lobes. 

The structural and functional units of the liver are known as hepatic lobules. The hepatic lobules can be pentagonal or hexagonal in shape.

They are made up of hepatic cells arranged in the form of cords. Blood filled spaces between the hepatic cords are called sinusoids. The hepatic cords are enlarged capillaries lined with endothelium. 

A portal triad is present at each corner of the lobule. Each portal triad contains a branch of hepatic artery and lymph vessels, hepatic portal vein, and bile ducts. 

Each hepatic lobule is covered by a thin connective tissue sheath called the Glisson's capsule, which is a characteristic feature of the mammalian liver.

Phagocytic cells called Kupffer cells are also present in the mammalian liver. These cells eat worn out white blood cells (WBCs), red blood cells (RBCs) and bacteria. Kupffer cells are the macrophages of the liver. 

The hepatic cells secrete bile, which is transported to the gallbladder through hepatic ducts. Bile is an alkaline and a yellowish green fluid. It is devoid of enzymes, but helps in the emulsification of fats due to the presence of bile salts.

The gallbladder is a thin muscular sac which has a capacity of 30 to 50 millilitre, and where the bile is stored and concentrated. The ducts from the gallbladder, and the hepatic duct from the liver form the common bile duct. 

Bile salts such as sodium taurocholate and sodium glycocholate act on fats and break them into fine droplets, through a process called emulsification. 

The liver performs several complex functions including fighting infections and illnesses, regulating blood sugar, removing toxic substances from the body, controlling cholesterol levels, helping blood to clot, and releasing bile.

Diseases Of The Liver

When people do not maintain a healthy lifestyle or consume excessive amounts of alcohol, the liver may get damaged. Some examples of liver diseases are jaundice, fatty liver, and hepatitis. The five main strains of the hepatitis virus are Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, and Hepatitis E. 

What Is Fatty Liver Disease?

Non-alcoholic fatty liver disease (NAFLD) is a condition in which fat builds up in the liver, and is an umbrella term for a range of liver conditions affecting people who drink little to no alcohol. The main characteristic of NAFLD is that too much fat is stored in the liver cells. 

According to the United States National Institutes of Health (NIH), non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH) are types of NAFLD. If a person suffers from NASH, he or she has inflammation and liver damage, along with fat in the liver. 

According to Dr Bhaskar Nandi, HOD, Liver & Digestive Sciences, Sarvodaya Hospital, Sector 8, Faridabad, Hepatitis B infection was the most common cause of chronic liver disease in India, a few decades back. Hepatitis B leads to liver cirrhosis, liver cancer, and liver failure. "However, fatty liver, a metabolic disorder, now constitutes the largest burden of liver disease today due to changing lifestyle of people. Fatty liver is a warning sign that you have other components of liver disease which may mature and turn into something more serious," he further said.

Dr Nandi also said that liver disease is fast becoming a public health problem for India. In 2015, acute and chronic liver diseases accounted for two million deaths worldwide. Of these, 18 per cent occurred in India.

"In our experience, as many as 80% of people coming for an ultrasound checkup today are found to have fatty liver disease. About one-third of these will progress to chronic liver disease, liver cancer, cirrhosis, or end-stage liver disease. But it is difficult to predict which ones of the 80% will fall in that one-third bracket, so everyone with fatty liver is at risk. Preventive measures should be taken early, including lifestyle restrictions, avoiding alcohol and periodic check-ups," Dr Nandi added.

What Are The Symptoms And Causes Of Fatty Liver Disease?

According to the NIH, non-alcoholic fatty liver disease is a silent disease with few or no symptoms. 

However, when the disease causes symptoms, they may include fatigue, and pain or discomfort in the upper right abdomen, according to Mayo Clinic. 

The possible signs and symptoms of non-alcoholic steatohepatitis and advanced scarring or cirrhosis include abdominal swelling, enlarged blood vessels just beneath the skin's surface, enlarged spleen, red palms, and yellowing of the skin and eyes. 

There is limited understanding of why some fatty lovers develop inflammation that progresses to cirrhosis, and it is not known exactly why some people accumulate fat in the liver.

The causes of fatty liver diseases can be obesity, insulin resistance, in which the cells do not take up sugar in response to the hormone insulin, high blood sugar or hyperglycemia, and high levels of fat, particularly triglycerides, in the blood.

The combined health problems may promote the deposition of fat in the liver. 

The diseases and conditions which can increase the risk of non-alcoholic fatty liver disease include high cholesterol, high levels of triglycerides, metabolic syndrome, obesity, polycystic ovary syndrome, and hypothyroidism.

Hepatitis

Hepatitis is an inflammation of the liver caused by a variety of infectious viruses and non-infectious agents. Sometimes, the health effects can prove to be fatal. 

All these strains cause liver disease. However, they differ in important ways including modes of transmission, severity of the illness, geographical distribution, and prevention methods.

According to the World Health Organization (WHO), Hepatitis B and Hepatitis C lead to chronic disease in hundreds of millions of people and together are the most common cause of liver cirrhosis, liver cancer, and viral hepatitis-related deaths. 

Though hepatitis may occur with limited to no symptoms, it often leads to jaundice, anorexia (poor appetite) and malaise. 

Some forms of hepatitis can be prevented through vaccination. As many as 4.5 million premature deaths could be prevented in low- and middle-income countries by 2030 through vaccination, diagnostic tests, medicines, and education camps, according to the WHO.

According to Dr Nandi, every year, more than 115,000 people die in India due to Hepatitis B related complications, and about four crore people in the country are carriers of the virus but remain asymptomatic and unaware of the risk they pose to others. He said that Hepatitis B vaccination is commonly given to children for immunisation, but it is not popular among adults. 

"Due to lack of awareness, most people do not get the vaccine, even though it needs to be taken only once for lifetime protection against the virus. So many needless deaths can be saved every year by simply spending a minute at a hospital to take the low-cost vaccine. People should understand that there is no cure for hepatitis B infection. It can only be prevented," he further said.

How Can One Be Warned Of Liver Disease?

According to Dr Nandi, one of the best ways to be warned of liver disease is to donate blood. This is because the donated blood is always tested for Hepatitis B and C. If these infections are found in the blood of donors, they will be informed immediately.

The Union Ministry of Health and Family Welfare launched the National Viral Hepatitis Control Program on July 28, 2018. 

The aim of the program is prevention and control of viral hepatitis in India in order to achieve Sustainable Development Goal 3.3 by 2030, according to the National Health Portal of India.

How To Keep The Liver Healthy?

One can keep the liver healthy by following a healthy lifestyle, and consuming a balanced diet. 

One's diet should include foods such as grains, protein, dairy products, fruits, vegetables, and fibrous foods.

Since alcohol, tobacco, and drugs can damage the liver cells, people should avoid consumption of these harmful substances.