For the past 2 decades, there has been increasing evidence supporting a very high prevalence of non-alcoholic liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH) in the general population. The main characteristic of NAFLD is too much fat stored in liver cells. NAFLD is a distinct hepatic condition and one of the most common causes of chronic liver disease globally. About 20% of people with NAFLD have NASH. The inflammation and liver cell damage that happen with NASH can cause serious problems such as fibrosis and cirrhosis which may lead to liver cancer and fatal liver failure. The prevalence of NASH in the general population is estimated to be between 1.5% and 6.45%.

Most Common Causes of Fatty Liver Disease

The most common cause of fatty liver disease is obesity. Besides obesity, nutritional causes of fatty liver disease are starvation and protein malnutrition. Certain conditions which contribute to fatty liver disease are type 2 diabetes, insulin resistance, an increase in lipid/cholesterol in the blood, high blood pressure, genetic factors, and some drugs and chemicals.

The high prevalence rates for NAFLD and NASH are mainly due to the global epidemic of diabetes and obesity. Considering the continuing increase in diabetes and obesity, the future burden of NAFLD in the United States is estimated to increase substantially. Prevalence of the fatty liver disease is estimated to be around 9-32% in the general Indian population, with a higher incidence rate amongst obese and diabetic patients.

In addition to these metabolic risk factors, age, sex, and ethnicity can also have a major influence on the risk of NAFLD. In fact, NAFLD prevalence is higher in older patients, and this prevalence rate increases with age, male sex, and Hispanic ethnicity.

Also Read: Top 11 Myths and Facts Associated With Fatty Liver Disease That You Should Know

Type 2 diabetes and fatty liver 

Type 2 diabetes mellitus (T2DM) is an important risk factor for NAFLD. Additionally, T2DM seems to accelerate the progression of liver disease in NAFLD. The prevalence of NAFLD in patients with type 2 diabetes mellitus is more than 2-fold higher than in the general population. The overall prevalence of NAFLD among patients with type 2 diabetes mellitus is 55.5%. The global prevalence of non-alcoholic steatohepatitis among patients with type 2 diabetes is 37.3%. Of the patients with NAFLD and type 2 diabetes mellitus who undergo a liver biopsy, 17% have advanced fibrosis.  

Despite the high prevalence and serious clinical implications of NAFLD in patients with T2DM, it is usually overlooked in clinical practice. In this context, increasing awareness about the importance of NAFLD in patients with T2DM among all important stakeholders (primary care physicians, specialists, and health policy makers) must be prioritized.

Obesity and fatty liver

Healthcare providers don’t know the exact cause of fatty liver disease. But they think that obesity is the most common cause. Obesity in the U.S. has doubled in the last decade, and healthcare providers are seeing a steady rise in fatty liver disease. 

It tends to develop in people who are overweight or obese, particularly if they have a lot of fat around the middle of their body (waist). It can also develop in a person whose body weight is in the healthy weight range, but who typically eats a lot of sugary and fatty foods and who has extra fat around the waist.

Although children and young adults can also get fatty liver disease, it is most common in middle age. Fatty liver disease is now becoming evident in children, due in large part to an alarming increase in childhood obesity.

Metabolic syndrome and fatty liver

NAFLD has been shown to be strongly associated with metabolic syndrome—a health disorder characterized by a group of risk factors (large waist circumference, high blood pressure, high blood sugar levels, high cholesterol, and abnormal amounts of lipids in the blood) that greatly increase the risk of many chronic illnesses.

With the worldwide increase in obesity and type 2 diabetes, in recent years, NAFLD has shown novel epidemics in both developed and developing countries. Understanding temporal trends in NAFLD prevalence is vital to better understanding its disease burden and preventing additional cases of NAFLD.

References

1. Zobair MY, Golabi P, de Avila L, Burns L, Afendy A, Nader R (2019). The global epidemiology of NAFLD and NASH in patients with type 2 diabetes: A systematic review and meta-analysis. J Hepatology. 71 (4): 793-801.

2. MY Zobair, M Giulio, PC Helena, P Salvatore (2019).  Epidemiology of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: Implications for Liver Transplantation. Transplantation. Volume 103: 22-27.