Dietary Soybean vs. Palm Oils Differ in Effects on Liver Fat in Adults With MAFLD : A 16‐Week, Double‐Masked, Randomized Controlled Trial

ABSTRACT Background Dietary linoleic acid (LA)‐rich oils reduce liver fat in healthy adults who are not otherwise undergoing weight loss strategies. Effects on the liver fat in adults with fatty liver disease are unknown. Objective The objective of this randomized double‐masked controlled trial was to compare the effects of a dietary soybean oil (SO) which is high in LA vs. palm oil (PO) which is composed of a mixture of saturated, mono‐ and polyunsaturated fats, on changes of liver fat level in adults with MAFLD. Methods Adults with MAFLD were recruited to complete a double‐masked, randomized controlled trial consisting of a 2‐week run‐in period followed by a 16‐week dietary intervention. Study foods contained either SO or PO to deliver 30 g oils per day. At week 0 and week 16, liver fat and visceral adipose tissue were measured by 1 H‐magnetic resonance spectroscopy imaging and fasting blood was collected for secondary biochemical markers of cardiometabolic disease risk. Results Sixty‐five adults with MAFLD (mean age ~53 y, BMI 36 kg/m 2 ) completed the study. Overall, there was a significant difference in the change of liver fat between SO and PO groups; however, after adjusting for baseline liver fat the diet group differences were no longer significant ( p = 0.14). The direct effect of diet group on the change of liver fat was not mediated by weight change ( p = 0.11). For within group change, liver fat tended to decrease in SO group ( p = 0.11) and tended to increase in PO group ( p = 0.11). Conclusions There was no significant difference for the effect of PO over SO on liver fat change when controlling for baseline liver fat or weight change. Larger trials testing dietary strategies that reduce liver fat in adults with MAFLD in the context of weight change are needed. Trail Registration The WELL study is registered on ClinicalTrials.gov ( NCT05199948 ).