What dietary factors can cause non-alcoholic fatty liver disease (NAFLD)?

From the Guidelines

Excessive consumption of saturated fatty acids, trans-fats, simple sugars, and animal proteins are the primary dietary factors that can cause non-alcoholic fatty liver disease (NAFLD). The most recent and highest quality study 1 suggests that a healthy diet, such as the Mediterranean diet, which is rich in monounsaturated fats, polyunsaturated omega-3-fats, plant-based proteins, and dietary fibers, can help prevent and potentially reverse early-stage NAFLD. Some key dietary factors that can contribute to NAFLD include:

• High intake of saturated fatty acids, such as those found in red and processed meat
• Consumption of trans-fats, which are commonly found in fried foods, processed meats, and baked goods
• Excessive intake of simple sugars, particularly high-fructose corn syrup found in sodas and processed foods
• High consumption of animal proteins, which can worsen liver fat accumulation On the other hand, a diet rich in:
• Monounsaturated fats, such as those found in olive oil
• Polyunsaturated omega-3-fats, found in fish and nuts
• Plant-based proteins, such as those found in legumes and whole grains
• Dietary fibers, found in fruits, vegetables, and whole grains, can help reduce the risk of NAFLD. It is essential to note that overall excessive calorie intake leading to obesity can also put strain on the liver, as excess calories are stored as fat throughout the body, including the liver 1. The liver becomes overwhelmed when processing these harmful substances, causing fat to accumulate in liver cells, which can progress from simple steatosis to inflammation and eventually fibrosis or cirrhosis if dietary habits aren't improved 1. Therefore, reducing intake of these problematic foods and beverages while increasing consumption of fruits, vegetables, whole grains, lean proteins, and healthy fats can help prevent and potentially reverse early-stage NAFLD.

From the Research

Dietary Factors Contributing to Non-Alcoholic Fatty Liver Disease (NAFLD)

The development of NAFLD is influenced by various dietary factors, including:

• Hypercaloric diets, which promote liver fat accumulation 2
• Macronutrient composition, with different types of fat and carbohydrates having distinct effects on liver fat accumulation 2
• High intake of saturated fats and added sugars, which can increase the risk of NAFLD 2, 3, 4
• Consumption of fructose, which can stimulate de novo lipogenesis and increase liver fat 4, 5
• High-fructose corn syrup and sucrose, which may also contribute to the development of NAFLD, although the evidence is not as robust 6

Specific Dietary Components and Their Effects on NAFLD

• Saturated fats: induce the greatest increase in intrahepatic triglycerides (IHTG), insulin resistance, and harmful ceramides compared to unsaturated fats 2
• Fructose: promotes liver fat accumulation through de novo lipogenesis and may precipitate fat accumulation in the liver due to increased lipogenesis and impaired fat oxidation 4, 5
• Added sugars: may increase the risk of NAFLD, particularly when consumed in excess 3, 4
• Unsaturated fats: may be protective against NAFLD, as they have been found to have beneficial effects on liver fat accumulation 2

Importance of a Balanced Diet

A healthy and balanced diet, along with regular physical activity, is crucial for preventing the development and progression of NAFLD 2. Reducing intake of saturated fats and added sugars, and avoiding excessive energy intake, may help mitigate the risk of NAFLD 2, 3, 4.