A significant proportion of overweight people have excessive fat accumulation in the liver. According to several recent studies, this non-alcoholic hepatic steatosis represents an important risk factor for the occurrence of certain types of cancer.
We are all familiar with the aspects of overweight and obesity, easily visualized by excessive fat accumulation in adipose tissue. What is less known, however, is that there is also an invisible form of obesity in which certain internal organs such as the liver can become overloaded with fat.
This accumulation of excess fat in the liver, which in medical terms is called non-alcoholic fatty liver disease (to distinguish it from liver damage caused by excess alcohol), is directly linked to a diet too rich in sugar and fat. This “fatty liver” is very dangerous, because the excess liver fat causes a strong inflammatory reaction that triggers the production of fibrous tissue to seal the damage, which creates scars (fibrosis) that disrupt the circulation of blood in the organ and can lead to cirrhosis over time. Arrived at this stage, the function of the liver is irremediably compromised and only a transplant of the organ can save the life of the affected person. It is estimated that fatty liver disease caused by excessive food consumption will become the main cause of liver transplantation in the coming years.
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Overweight: 32% increased risk of being affected by cancer
Two recent studies suggest that fatty liver also has a major influence on the risk of certain types of cancer. In the first, carried out with a cohort of 25,947 people, a team of South Korean scientists observed that people affected by steatosis had a 32% greater risk of being affected by cancer in general compared to those who did not have excess fat in the liver.
This increase is particularly pronounced for the most common form of liver cancer (hepatocellular carcinoma) with a 17-fold increase in risk, but is also observed for colon cancer in men and breast cancer in women (increases twice in both cases).
The authors observed a strong correlation between these increases in the risk of cancer and the presence of fibrosis in the liver, which suggests that the strong hepatic inflammatory reaction in response to excess fat could contribute to tumor development.
Lifestyle can change everything
Another mechanism involved in the progression of hepatic steatosis into hepatocellular carcinoma was recently identified in a study published in the prestigious Cancer Cell. A team of Swiss scientists has shown that liver cells have an enzyme (mTORC2) that induces the production of large amounts of fat essential to the growth of cancer cells, namely sphingolipids (present in the membrane of these cells) and cardiolipins (present in the mitochondria and essential for energy production). This phenomenon most likely plays an important role in tumor progression, since an analysis of biopsies from patients with hepatocellular carcinoma shows an overactivation of the function of the enzyme mTORC2.
These observations show that non-alcoholic fatty liver disease is a very serious condition that should be taken very seriously. Anyone who is significantly overweight should be aware that they are at risk of being affected by this disorder, even if they do not experience any symptoms. Fortunately, like all complications that arise from being overweight and obese, fatty liver disease is closely related to lifestyle and is therefore preventable.
In this sense, avoiding excessive consumption of industrial foods rich in fat and sugar certainly represents an essential prerequisite for reducing the loss of liver function associated with excess fat. Adopting a diet mainly based on plant products is an excellent alternative, especially since recent results suggest that high consumption of red meats and processed meats is also associated with an increased risk of fatty liver disease.
Source
Kim GA et al. Association between non-alcoholic fatty liver disease and cancer incidence rate. J. Hepatol. 2018; 68: 140-146. Guri Y et al. mTORC2 promotes tumorigenesis via lipid synthesis. Cancer Cell 2017; 32: 807-823. Zelber-Sagi S et al. High red and processed meat consumption is associated with non-alcoholic fatty liver disease and insulin resistance. J. Hepatol. 2018; 68: 1239–1246.
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