Beware of Non-Alcoholic Fatty Liver Disease!

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While “a fatty liver” is a phrase typically heard in association with excessive alcohol consumption or with dry January, even those who don’t consume alcohol can develop a fatty liver. Non-Alcoholic Fatty Liver Disease (NAFLD) is a disease that affects up to 25 percent of the population world-wide.

A healthy liver contains a lipid (fat) concentration of about 5 percent by weight. A person whose liver has a lipid concentration of more than 5 percent is said to have NAFLD. NAFLD encompasses a wide range of conditions, from the slightly above normal accumulation of lipids in the liver and minimal liver damage to Non-Alcoholic Steatohepatitis (NASH), in which the liver is severely damaged due to lipid build up. NAFLD increases chances of developing liver cancer and cardiovascular disease.

One of the main functions of the liver is to perform fat metabolism. The liver converts excess carbohydrates into triglycerides (a type of lipid) and oxidizes lipids to produce energy. Lipids accumulate in the liver when the rate of lipid synthesis in the liver exceeds the rate of lipid oxidation. One of the main causes of excessive lipid synthesis is insulin resistance.

Insulin is a hormone that regulates blood sugar levels by promoting the absorption of glucose in the blood by the liver and muscles. In addition, insulin also simulates lipid synthesis in the liver. Insulin resistance takes place when the liver and the muscles are no longer sensitive to insulin and do not absorb glucose from blood. To prevent blood glucose levels from rising, the body starts to secrete more and more insulin. Insulin resistance, however, doesn’t suppress lipid synthesis in the liver. As a result, lipid synthesis increases as the body secretes higher amounts of insulin, leading to the accumulation of fats in the liver and subsequently, liver damage. Insulin resistance is also a cause of Type 2 diabetes, and 70% of patients with Type 2 diabetes also have NAFLD.

Despite the potentially severe consequences of NAFLD/NASH, there are no symptoms in early stages. As liver damage increases, symptoms including fatigue, unexplained weight loss, and pain in the abdomen may be seen. NAFLD/NASH is not usually directly diagnosed; diagnosis takes place when tests are done to diagnose other health problems.

Some of the risk factors for NAFLD include obesity, high cholesterol, and diabetes. While there are no FDA-approved drugs to treat NAFLD, lifestyle changes including exercising regularly, maintaining a healthy weight, eating a diet low in carbohydrates and fats, and cutting back on alcohol can reduce and even reverse liver damage.

References:
More about the molecular pathogenesis of NASH: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6136489/
More on the evidence linking NAFDL to insulin resistance: https://www.sciencedirect.com/science/article/pii/S0925443914002579