Fat: Quality, or Quantity? What Matters Most for the Progression of Metabolic Associated Fatty Liver Disease (MAFLD)

High levels of serum dihomo-γ-linolenic acid are associated with non-alcoholic fatty liver disease in type 2 diabetic patients

An elevated level of saturated fatty acids (SFAs) can cause non-alcoholic fatty liver disease (NAFLD). While n-3 polyunsaturated fatty acids (PUFAs) were shown to improve NAFLD, the effects of n-6 PUFAs in the liver have not been fully elucidated. We examined the association between NAFLD and n-6 PUFAs, particularly dihomo-γ-linolenic acid (DGLA), in patients with type 2 diabetes. A total of 60 patients with type 2 diabetes were included in the study. Patients were categorized into the NAFLD group (n = 35) and non-NAFLD group (n = 25) based on the presence of fatty liver as determined by abdominal ultrasound. We demonstrated that the levels of serum SFAs, specifically palmitic acid and stearic acid, and the levels of n-6 PUFAs, specifically DGLA, and arachidonic acid (AA), were significantly higher in the NAFLD group. The serum palmitic acid, stearic acid, DGLA and AA levels were positively correlated with liver enzyme gamma-glutamyl transpeptidase (GGT). We further demonstrated by multivariate analysis that serum DGLA was a predictor of NAFLD. The serum DGLA level was negatively correlated with blood adiponectin and was positively correlated with blood leptin, high-sensitivity CRP, C-peptide index, and triglyceride-glucose index. Furthermore, delta-5-desaturase (D5D), the AA (product)/DGLA (precursor) ratio calculated from the product-to-precursor ratio of fatty acids, was significantly lower in the NAFLD group. These findings suggest that high serum DGLA levels in NAFLD group may be due to an excessive intake of n-6 PUFAs and changes in desaturase in the human body. High serum DGLA levels may also be associated with insulin resistance and inflammatory factors.

Fat from Hermetia illucens Alters the Cecal Gut Microbiome and Lowers Hepatic Triglyceride Concentration in Comparison to Palm Oil in Obese Zucker Rats

BACKGROUND

Palm oil (PO) is the most widely utilized plant oil for food production. Owing to the great ecologic problems associated with PO production, sustainably produced fats, such as insect fat, might be a suitable alternative.

OBJECTIVES

The hypothesis was tested that fat from Hermetia illucens larvae (HF) compared with PO and soybean oil (SO) has no adverse effects on hepatic lipid metabolism, plasma metabolome, and cecal microbiome in obese Zucker rats.

METHODS

Thirty male obese Zucker rats were randomly assigned to 3 groups (SO, PO, HF; n = 10 rats/group) and fed 3 different semisynthetic diets containing either SO, PO, or HF as the main fat source for 4 wk. The effects were evaluated by measurement of liver and plasma lipid concentrations, liver transcriptomics, targeted plasma metabolomics, and cecal microbiomics.

RESULTS

Supplementation of HF reduced hepatic triglyceride concentration and messenger ribonucleic acid concentrations of selected genes involved in fatty acid and triglyceride synthesis in comparison to PO (P < 0.05). Pairwise comparison of the Simpson index and Jaccard index showed a higher cecal microbial α- and β-diversity in rats fed the HF diet than in rats fed the PO diet (P = 0.015 and P = 0.027), but no difference between rats fed the diets with SO or PO. Taxonomic analysis of the cecal microbial community revealed a lower abundance of Clostridium_sensu_stricto_1 and a higher abundance of Blautia, Mucispirillum, Anaerotruncus, Harryflintia, and Peptococcus in rats supplemented with HF than in rats supplemented with PO (P < 0.05).

CONCLUSIONS

HF, compared with PO, has liver lipid-lowering effects in obese Zucker rats, which may be caused by a shift in the gut microbial community. Thus, HF might serve as a sustainably produced fat alternative to PO for food production.