The Effects of Dietary Soybean Oil on Liver Fat and Visceral Adipose Tissue in Adults With Nonalcoholic Fatty Liver Disease: Study Protocol for a Randomized Control Trial

Abstract Objectives About 25% of adults in the United States have nonalcoholic fatty liver disease (NAFLD) which often accompanies abdominal obesity. Blood biomarkers of linoleic acid (LA), an essential omega-6 fatty acid, are inversely associated with visceral adipose tissue, liver fat, and the risk of NAFLD. To our knowledge, the effect of increasing dietary LA on ectopic fat in the liver and visceral adipose tissue in adults with NAFLD while maintaining weight has not been investigated. The objective of the Weight, Energy, Lipids and the Liver (WELL) study is to determine the impact of dietary LA-rich soybean oil on ectopic liver fat and visceral adipose tissue in adults with NAFLD. Methods In this 16-week parallel arm randomized control trial, 58 adults with NAFLD will be randomly assigned to consume 3 study foods per day made with either 10g of soybean oil each or 10g of palm oil each (30g of oil per day). Prior to randomization, participants will complete a 2-week run-in period to become acclimated by consuming 3 study foods per day, each delivering 10 g of an oil mixture (safflower oil and shortening in a 3.4:1 ratio). Participants will receive counseling from a registered dietitian to incorporate the study foods into their diets while maintaining their body weight. Self-reported study food consumption will be collected daily. Body weight will be measured every two weeks. Dietary intake and physical activity will be assessed through 24 hour recalls. Fasting blood will be collected every two weeks to measure fatty acids, cholesterol, triglycerides and markers of inflammation and glycemia. Magnetic Resonance Imaging (MRI) will be used to assess liver and visceral fat before and after the 16-week randomized intervention period. Additionally, postprandial cholesterol, triglycerides and markers of inflammation and glycemia will be measured before and after the randomized intervention period. Results We hypothesize that consumption of the study foods made with LA-rich soybean oil (30g/day) will result in a reduction in hepatic ectopic fat and visceral adipose tissue, without altering body weight. Conclusions Reducing liver fat and visceral adipose tissue through consumption of a LA-rich soybean oil may ultimately lead to improved cardiometabolic outcomes for adults with NAFLD. Funding Sources The United Soybean Board.