Overeating Saturated Fat Promotes Fatty Liver and Ceramides Compared With Polyunsaturated Fat: A Randomized Trial.
Level 2 - randomized trial
Individual double-blind randomized controlled trial
PubMed 31369090 · doi:10.1210/jc.2019-00160
What was done
In a double-blind randomized trial (LIPOGAIN-2), 61 overweight or obese men and women were assigned to overeat muffins enriched with either palm oil (saturated fatty acids, SFA) or sunflower oil (polyunsaturated fatty acids, PUFA) added to their habitual diet for 8 weeks, followed by 4 weeks of caloric restriction. Changes in liver fat, ectopic fat depots (visceral and pancreatic fat), liver enzymes, atherogenic lipids, and circulating ceramides were assessed.
What was found
Body weight gain did not significantly differ between groups (SFA: 2.31 ± 1.38 kg vs PUFA: 2.01 ± 1.90 kg, P = 0.50). SFA overfeeding caused a 50% relative increase in liver fat content along with increases in liver enzymes and atherogenic lipids. PUFA overfeeding did not increase liver fat, liver enzymes, or adverse blood lipids. There were no differential effects between groups on visceral, pancreas, or total body fat accumulation. SFA increased and PUFA decreased circulating ceramides, which correlated with liver fat changes. Calorie restriction reversed the adverse metabolic effects of SFA.
Why it matters
This study demonstrates that the quality of dietary fat directly dictates hepatic fat storage and ceramide accumulation independently of total body weight gain during positive energy balance.
Limits
The study sample was modest (n = 61) and limited to overweight or obese individuals over an 8-week intervention, precluding conclusions about long-term clinical endpoints or effects in normal-weight individuals. Primary outcome data for lean tissue mass were not reported in the abstract.
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