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There are so many global epidemics that occurred in the last several years including chikungunya, the Ebola virus disease, and more recently, the seasonal influenza virus. Another disorder called the nonalcoholic fatty liver disease has also become a growing concern among health experts. Globally, more than one billion people have been said to be affected by NAFLD and experts believe that the prevalence may increase by up to 50 percent by 2030.
A healthy liver in healthy people has little or no fat build up. But in the nonalcoholic fatty liver, the organ has too much stored fat. In contrast with the alcoholic liver disease, the excess fat in NAFLD is caused by nonalcoholic factors. NAFLD is typically found in people who are overweight or obese. The said liver condition has two separate conditions – the simple fatty liver or the nonalcoholic steatohepatitis or NASH.
1. Simple fatty liver: It is also called nonalcoholic fatty liver or NAFL, in which the liver has excess fat, but does not present any sign of liver cell damage or organ inflammation. Because no abnormalities are occurring regardless of the fat content, the condition does not progress to more serious health complications.
2. Nonalcoholic steatohepatitis: It is a subtype of NAFLD characterized by hepatitis or an inflammation of the liver and liver cell damage. Inflammation of the organ and damage to liver cells can lead to liver fibrosis or an abnormally large scar tissue. Abnormal scar tissues in the liver often result in cirrhosis. NASH can trigger the development of liver cancer.
In the United States, NAFLD is one of the most common causes of liver disease with more than 80 million of Americans affected by it. But most people in the world with NAFLD have a simple fatty liver, while approximately 20 percent of people with the disease have NASH. In the United Kingdom, one out of three people has the early stages of NAFLD and about five percent of the country’s population has NASH. Even if alcohol is out of the equation, there are still several risk factors for a person to develop NAFLD, such as:
- Genetics, specifically the PNPLA 3 gene that triggers the liver condition. A study published in Nature suggested that the gene PNPLA 3 which encodes an enzyme that affects lipid metabolism in liver cells was found to be involved in building scar tissue, making it a contributor in the process of fibrosis. The study noted that NAFLD is more common among Hispanic people and least common among African Americans.
“It’s been reliably and repeatedly shown to be a modifier of fat accumulation in the liver, of inflammation in the liver, of fibrosis in the liver and also of cancer. So it really is an independent modifier of each of those major steps in the pathogenesis of fatty liver disease,” said Dr. Quentin Anstee, a liver specialist at Newcastle University.
- Ethnicity, particularly Asian and Hispanic people. In a 2014 study, researchers concluded that NAFLD and NASH are more prevalent in men and in Hispanics because of the body fat distribution and lipid metabolism, compared to non-Hispanic blacks. An early study in 2013 concluded that Mexican-Americans have the highest rate of NAFLD, followed by non-Hispanic whites, and non-Hispanic blacks with the lowest rate. For Asians, a study in February 2017 found that NALFD risk factors in the continent are very close to that of Western countries. Some Asian countries have a higher prevalence rate of up to 40 percent. But NAFL in Asia is uncommonly associated with cirrhosis and primary liver cancer, possibly because of the lower prevalence of obesity and viral hepatitis in the continent.
- Gender, with women being more prone to NALFD. In a 2013 study, women have been found to be more prone to acute liver failure, autoimmune hepatitis, primary biliary cirrhosis, and benign liver lesions. Women with liver disease usually have a fatty liver that increases the risk of developing cardiovascular complications. But the study revealed that women have a lower risk of malignant liver tumors and viral hepatitis.
- Other health conditions including type 2 diabetes, high blood pressure, and high cholesterol can also increase the risk of developing NALFD.
- Age and unhealthy lifestyle have been attributed to the liver condition. People over 50 years of age are more prone to NAFLD. Smokers are also prone to develop the liver problem.
Reducing the risks associated with nonalcoholic fatty liver disease can help lower the chance of developing complications. The primary changes should be focused on diet, weight management, the gut microbiome, and physical activity. Diet should be balanced with high amounts of fiber from fruits and vegetables, a moderate amount of carbohydrates and protein, and low amounts of fat, sugar, and salt. Weight management can be achieved by combining a healthy diet with a regular exercise regimen. For the gut microbiome, choose specific food sources that contain probiotics or good bacteria. Bananas and leeks are a few known natural sources of probiotics.
[메디컬리포트=Ralph Chen 기자]