Intake of unsaturated fat, protein provides benefits on liver fat, metabolism in adults

Adherence to a diet rich in protein and unsaturated fatty acids (UFAs) helps improve liver fat and lipid metabolism in people at risk of unhealthy ageing, a recent study has shown.

Adults aged 50‒80 years, with at least one risk factor for unhealthy ageing, were included in this 36-month randomized controlled trial. Eligible participants were randomly assigned to either a high intake of mono-/poly-UFAs (15‒20 percent/10‒15 percent of total energy [%E], respectively), plant protein (15‒25 percent %E), and fibre (≥30 g/d; intervention group), or usual care (dietary recommendations of the German Nutrition Society: fat 30%E/carbohydrates 55 %E/ protein 15 %E; control group).

The investigators stratified participants based on the following: sex, known cardiovascular disease, heart failure, arterial hypertension, type 2 diabetes, and cognitive or physical impairment. They then carried out nutritional counseling and supplementation of foods that mirror the intended dietary pattern in the intervention group. Finally, they assessed the diet-induced effects on intrahepatic lipids (IHLs) using magnetic resonance spectroscopy, as well as on lipid and glucose metabolism.

Overall, 346 participants without significant alcohol consumption had their IHL content analysed at baseline and 258 after 12 months.

After adjusting for age, sex, and weight loss, the intervention and control groups showed similar reductions in IHLs (‒33.3 percent, 95 percent confidence interval [CI], ‒49.1 to ‒12.3; n=128 vs ‒21.8 percent, 95 percent CI, ‒39.7 to 1.5; n=130; p=0.179). This effect achieved significance when comparing adherent participants (‒42.1 percent, 95 percent CI, ‒58.1 to ‒20.1; n=88 vs ‒22.2 percent, 95 percent CI, ‒40.7 to 2.0; n=121; p=0.013).

However, participants in the intervention group exhibited a more robust decrease in low-density lipoprotein (p=0.019) and total cholesterol (p=0.010) than did those in the control group. Notably, triglycerides (p=0.799) and insulin resistance (p=0.124) decreased in both groups.

“Diets enriched with protein and UFAs have beneficial long-term effects on liver fat and lipid metabolism in adherent older [adults],” the investigators said.