In a recent review published in the Nutrients Journal, researchers reviewed existing data on dietary patterns, foods, and nutrients to ameliorate nonalcoholic fatty liver disease (NAFLD).
Study: Dietary Patterns, Foods, and Nutrients to Ameliorate Non-Alcoholic Fatty Liver Disease: A Scoping Review. Image Credit: sweet marshmallow/Shutterstock.com
Background
Despite being the most frequent cause of chronic liver disease globally, NAFLD lacks pharmaceutical therapy and dietary recommendations to address its severe health consequences.
NASH worsens cirrhosis and hepatocellular carcinoma, resulting in higher medical costs, financial losses, and a worse quality of life.
Dietary adjustments, lifestyle changes, and lifestyle modifications are examples of treatment options. Metabolic syndrome, obesity, cardiovascular disease, hypertension, diabetes, and chronic renal disease have all been associated with NAFLD.
About the review
In this review, researchers have discussed various dietary strategies for managing Non-Alcoholic Fatty Liver Disease (NAFLD). They conducted searches in databases like MEDLINE, Web of Science, Google Scholar, and Scopus from January to July 2023 to find relevant records published in either English or Spanish.
The Mediterranean Diet (MedDiet) is a predominantly plant-based eating pattern rich in monounsaturated fatty acids (MUFAs) and low in red meat consumption. Research suggests that individuals who follow a high-fat Western diet are more prone to developing NAFLD.
MedDiet distinguishes itself from other diets by its low carbohydrate intake, avoidance of refined carbohydrates, and minimal sugar consumption, with a focus on using olive oil as the primary source of added fats. Studies have shown that MedDiet is associated with a reduced risk of NAFLD, as well as a decrease in weight gain, insulin resistance, and the development of NAFLD.
Due to its low carbohydrate content and emphasis on plant-based foods, MedDiet represents a viable alternative to Western diets.
Saturated fats, commonly found in Western diets, can disrupt phospholipid metabolism, leading to mitochondrial dysfunction, increased production of reactive oxygen species (ROS), and cell apoptosis. Furthermore, high consumption of animal protein has been linked to NAFLD in individuals who are obese.
Moreover, diet plays a direct role in de novo lipogenesis, the process by which liver cells convert excess carbohydrates, particularly fructose, into fatty acids. Regular fructose consumption has been associated with an increased risk of fibrosis, primarily due to the use of industrial fructose.
Lastly, diets high in fructose, including sucrose, fructose, and high-fructose corn syrup, have been linked to an elevated risk of developing steatosis and non-alcoholic steatohepatitis (NASH), especially in overweight and obese individuals.
Genetics, foods, and NAFLD amelioration
Diet plays a significant role in the development of NAFLD because it can impact DNA homeostasis and telomere biology. Proper DNA production and repair depend on the presence of essential nutrients like folate, calcium, retinol, vitamin E, and nicotinic acid. Conversely, trans fats have the potential to cause DNA damage.
In NAFLD, there is a noticeable phenomenon of telomere shortening, which can be mitigated by incorporating fiber, omega-3 fatty acids, and vegetables into the diet. Conversely, high-glycemic index carbohydrates, processed meats, and saturated fats tend to accelerate telomere shortening.
PNPLA3 (patatin-like phospholipase domain-containing 3) plays a crucial role in regulating the accumulation of fat in the liver and the development of NAFLD. Diets rich in carbohydrates and fatty acids can lead to the production of specific proteins encoded by this mutant gene. Consequently, diet has the potential to alter how the liver utilizes lipids, affects insulin resistance, influences oxidative stress, and impacts mitochondrial function through epigenetic changes.
Deficiencies in nutrients such as betaine, choline, folate, and vitamin B12 may promote DNA methylation, which, in turn, can boost the production of hepatic triglycerides. Thus, the inclusion of foods like nuts, seeds, seafood, and high-fiber diets can significantly reduce the risk of developing NAFLD. Nuts have been shown to have a positive effect on lipid profiles, liver health, and inflammation, potentially serving as an effective treatment for NAFLD.
Fish can produce omega-3 fatty acids, which can help reduce fat accumulation in the liver and prevent the development of NAFLD, nonalcoholic steatohepatitis (NASH), and fibrosis.
High-fiber diets and whole grains can influence the composition of gut microbiota, potentially affecting the communication between the gut and the liver in NAFLD development. A diet rich in legumes, such as peas, lentils, and beans, is strongly associated with a decreased risk of NAFLD.
While the exact mechanism behind the protective benefits of vegetables and fruits against NAFLD risk is not fully understood, it is thought to be related to their lower energy density after their addition to the diet and the antioxidant properties derived from polyphenols and carotenoids found in these foods.
Dairy products, especially yogurt containing Lactobacillus acidophilus La5 and Bifidobacterium lactis Bb12, have been linked to a reduced risk of NAFLD due to their high whey protein content, which aids in weight reduction and reducing fat mass.
Probiotics, such as strains of Bifidobacterium and Lactobacillus, have been demonstrated to decrease oxidative and inflammatory damage in the liver while reducing hepatic triglycerides (TG) and steatosis.
Prebiotics, exemplified by unsweetened filtered coffee, can influence the composition of gut microbiota, which is implicated in the development of NAFLD. Choline, an essential B vitamin obtained from food intake and produced endogenously, is primarily digested and stored in the liver.
Micronutrients associated with NAFLD include zinc, copper, iron, selenium, magnesium, vitamins A, C, D, and E, as well as carotenoids. These micronutrients are known for their antioxidant, antifibrotic, immunomodulatory, and lipoprotective properties, which are reported as mechanisms of action in mitigating NAFLD.
Conclusion
Based on the findings, the MedDiet, which focuses on lowering oxidative stress and inflammation, can help control NAFLD.
A high-quality diet, frequent exercise, and limiting sugar consumption are important tactics, and enough fiber and coffee consumption can help guard against unwanted gut bacteria associated with NAFLD onset.
Penn State study examines how a person's telomeres are affected by caloric restriction