Diets high in protein, unsaturated fats help suppress liver fat

Replacing total dietary carbohydrates with fats does not affect overall liver fat content, while instead replacing it with proteins seems to reduce liver fat, reports a recent meta-analysis.

Accessing the databases of PubMed, Embase, Web of Science, and the Cochrane Library, the researchers retrieved 21 randomized controlled trials that looked at the effect of dietary macronutrient composition (energy percentage of fats, carbohydrates, and proteins) on liver fat content. Overall, 25 comparisons across different macronutrient compositions were analysed.

Pooled analysis of 12 comparisons showed no clear difference between a high-carbohydrate low-fat diet vs a high-fat low-carbohydrate diet (standardized mean difference [SMD], 0.01, 95 percent confidence interval [CI], –0.36 to 0.37). Heterogeneity of evidence for this analysis was substantial.

In contrast, diets rich in unsaturated fats corresponded to significantly lower liver fat than those full of saturated fats (SMD, –0.75, 95 percent CI, –1.11 to –0.39), though only three studies were available for pooling for this comparison.

Similarly, three studies provided information about protein in diet. Pooled analysis revealed that a high-protein, low-carbohydrate diet led to moderate reductions in liver fat as opposed to a high-carbohydrate, low-protein diet (SMD, –0.32, 95 percent CI, –0.58 to –0.05).

“Only a limited number of eligible studies could be included, which supports an essential need for additional experimental studies on dietary macronutrient composition and liver fat content in order to provide optimal prevention and treatment for nonalcoholic fatty liver by dietary interventions,” the researchers said.