In a double-masked trial, 65 adults with MAFLD (mean age about 53, BMI 36) ate foods delivering 30 g per day of either linoleic acid-rich soybean oil or mixed-fat palm oil for 16 weeks. Liver fat, measured by 1H-MR spectroscopy, differed between groups in the unadjusted analysis, but the gap vanished after adjusting for baseline liver fat (p = 0.14). Weight change did not mediate the effect. Within groups, liver fat drifted down on soybean oil and up on palm oil, both at p = 0.11.
The headline result is a null, and the unadjusted difference most likely reflects regression to the mean, since participants with higher starting liver fat tend to fall more regardless of diet. The directional pattern is intriguing and fits earlier work in non-MAFLD adults linking linoleic acid to reduced liver fat, as well as evidence that saturated fat promotes hepatic fat accumulation. But the within-group trends were not significant, and a trial of this size is probably underpowered to detect modest effects on a variable as noisy as liver fat. The gold-standard imaging is a real strength, as is the masking. Limitations include the single comparator, short duration, and the lack of a weight-loss context, which remains the proven lever for MAFLD. For now, no one should add soybean oil as a liver treatment. This is a confirmatory, inconclusive study that mainly argues for larger, longer trials.