Introduction
One of the most prevalent causes of chronic liver disease globally, nonalcoholic fatty liver disease, has a significant association with morbid obesity. Obesity has become a major public health concern due to its sharp increase in prevalence over the past 20 years on a worldwide scale. The number of nonalcoholic fatty liver disease (NAFLD) cases has increased significantly as a result of the obesity pandemic. Nonalcoholic fatty liver disease is a group of diseases that includes cirrhosis, liver fibrosis, nonalcoholic steatohepatitis (NASH, an advanced form of nonalcoholic fatty liver), nonalcoholic fatty liver (NAFL), and eventually the development of hepatocellular carcinoma (HCC).
What Is Nonalcoholic Fatty Liver Disease?
Global public health is facing a crisis due to obesity and the metabolic disorders associated with it. Nonalcoholic fatty liver disease, which affects around 25 percent of obese adults globally, is one of the most prevalent comorbidities. The term ‘nonalcoholic fatty liver disease’ describes a cluster of disorders in which individuals who consume little to no alcohol have a buildup of extra fat in their liver. Fatty liver is a common ailment that is the most prevalent kind of non-alcoholic fatty liver disease. Fat builds up within the liver cells when an individual has a fatty liver.
Individuals who have diabetes, high blood triglyceride or cholesterol levels, or obesity are at risk for developing fatty liver. They are also usually overweight or obese. It is recommended that such people should undergo liver tests every year. Those with elevated liver test results should be checked for liver fat through imaging modalities like ultrasound. If fat cells are high in the liver, the cause should be determined, whether it is due to alcohol consumption, intake of some types of medication, or obesity. Appropriate treatments should be done to prevent further complications.
What Is Bariatric Surgery?
Since 1953, there have been advancements in weight loss surgery, which have persisted for many years. Several different bariatric surgery procedures have been developed. To avoid severe long-term complications, extreme malabsorptive techniques like the jejunoileal bypass are abandoned. These techniques primarily rely on malabsorption by diverting digestive juices to the very distal part of the ileum (biliopancreatic diversion [BPD], and duodenal switch). Nowadays, sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are the most commonly used procedures worldwide. These two laparoscopic procedures are linked to extremely low rates of death and morbidity.
The mechanisms underlying the complicated consequences of BS include more than just weight loss brought on by restriction or malabsorption; these mechanisms could also impact the liver. Weight reduction has little bearing on how insulin signaling is affected by changes in bile acid levels, inflammation in adipose tissue, or gut hormone signaling. Peptide YY and glucagon-like peptide (GLP-1) are two gut peptides secreted in much higher amounts when gastric emptying in SG and RYGB is accelerated. The entire pool of circulating bile acid is increased by both RYGB and SG, which function as metabolic signaling molecules. Along with changing the endocrine activities of the adipose tissue, such as raising adiponectin and lowering serum leptin levels, bariatric surgery also reverses the inflammation of the adipose tissue. The beneficial effects on the liver may result from any one of these physiological modifications.
How Are NAFLD Patients Benefitted by Bariatric Surgery?
NAFLD is closely linked to metabolic syndrome (a group of conditions that occur together and increase the risk of stroke, heart conditions, and type 2 diabetes) symptoms such as obesity, type 2 diabetes, and others. NAFLD reduction or remission appears to be dependent on all mechanisms involved in treating obesity and T2DM that develop following bariatric surgery. Patients who undergo bariatric surgery and lose weight experience inflammatory changes.
Bariatric surgery reduces the risk of death from cancer and cardiovascular disease, the two most common causes of death for people with nonalcoholic steatohepatitis. It also produces long-term excess weight loss of up to 30 percent and remission of diabetes mellitus. People who have the required criteria for bariatric surgery (body mass index more than 40 kg/m², or any other comorbidities of obesity) may have the features of NAFLD or NASH. Although NAFLD or NASH is particularly common among patients following bariatric surgery, it is not always established as a reliable indicator. In addition, screening for non-invasive markers at the time of surgery or using a liver biopsy to stage hepatic fibrosis (scarring of liver cells) is not frequently done for fatty liver disease.
Another study found that of the patients, 66 percent had resolved steatosis, 50 percent had inflammation, 76 percent had ballooning degeneration (a condition where the liver cells become swollen and rounded), and 40 percent had fibrosis (scarring of the tissue). NASH was found to be resolved within a year after the bariatric surgery. All these pointed to the durability of the response. NASH persistence was linked to limited weight reduction and reduced improvement in insulin resistance after bariatric surgery.
A recent cohort study revealed a significant reduction in adverse effects in liver and heart conditions in patients who have undergone bariatric surgery, compared to their non-surgical counterparts with NASH and obesity. Other than preventing liver fibrosis, the development of NAFLD-related malignancies is another aspect that requires attention.
According to retrospective cohort studies, bariatric surgery individuals had a lower altered cumulative incidence (CI) for malignancy linked to NAFLD, including HCC, than those who did not. Cumulative incidence is the number of new cases that develop within a period. Finally, the advantages of bariatric surgery extend beyond liver disease to include disorders of other organ systems, including the risks associated with stroke, cardiovascular disease, and kidney failure.
Conclusion
Bariatric surgery may be beneficial for obese patients with NASH fibrosis. Clinical research suggests that BS is safe, improves inflammation, fibrosis, and steatosis, and lowers mortality risk from NAFLD-associated hepatocellular carcinoma and cardiovascular disease. Following bariatric surgery, misuse of alcohol and severe malnutrition related to rapid weight loss are two factors that can negatively affect liver functioning. Hence, these should be carefully observed to prevent adverse effects following the surgery.
