Metabolic dysfunction-associated steatotic liver disease (MASLD) occurs in subjects with obesity and metabolic syndrome. MASLD may progress from simple steatosis (i.e., hepatic steatosis) to steatohepatitis, characterized by inflammatory changes and liver cell damage, substantially increasing mortality. Lifestyle measures associated with weight loss and/or appropriate diet help reduce liver fat accumulation, thereby potentially limiting progression to steatohepatitis. As for diet, both total energy and macronutrient composition significantly influence the liver's fat content. For example, the type of dietary fatty acids can affect the metabolism of lipids and hence their tissue accumulation, with saturated fatty acids having a greater ability to promote fat storage in the liver than polyunsaturated ones. In particular, polyunsaturated fatty acids of n-3 series (omega-3), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have been intensively studied for their antisteatotic effects, both in preclinical animal models of obesity and hepatic steatosis and in overweight/obese patients. Their effects may depend not only on the dose and duration of administration of omega-3, or DHA/EPA ratio, but also on the lipid class used for their supplementation. This review summarizes the available evidence from recent comparative studies using omega-3 supplementation via different lipid classes. Albeit the evidence is mainly limited to preclinical studies, it suggests that phospholipids and possibly wax esters could provide greater efficacy against MASLD compared to traditional chemical forms of omega-3 supplementation (i.e., triacylglycerols, ethyl esters). This cannot be attributed solely to improved EPA and/or DHA bioavailability, but other mechanisms may be involved. Keywords: MASLD • Metabolic dysfunction-associated steatotic liver disease • NAFLD • Non-alcoholic fatty liver disease • n-3 polyunsaturated fatty acids.

• MeSH
• Liver * metabolism   drug effects   pathology   MeSH
• Humans MeSH
• Lipid Metabolism drug effects   MeSH
• Non-alcoholic Fatty Liver Disease metabolism   drug therapy   diet therapy   pathology   MeSH
• Obesity metabolism   drug therapy   diet therapy   pathology   MeSH
• Fatty Acids, Omega-3 * administration & dosage   metabolism   therapeutic use   MeSH
• Dietary Supplements * MeSH
• Fatty Liver metabolism   drug therapy   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Fatty Acids, Omega-3 * MeSH

Preclinical evidence suggests that n-3 fatty acids EPA and DHA (Omega-3) supplemented as phospholipids (PLs) may be more effective than triacylglycerols (TAGs) in reducing hepatic steatosis. To further test the ability of Omega-3 PLs to alleviate liver steatosis, we used a model of exacerbated non-alcoholic fatty liver disease based on high-fat feeding at thermoneutral temperature. Male C57BL/6N mice were fed for 24 weeks a lard-based diet given either alone (LHF) or supplemented with Omega-3 (30 mg/g diet) as PLs (krill oil; ω3PL) or TAGs (Epax 3000TG concentrate; ω3TG), which had a similar total content of EPA and DHA and their ratio. Substantial levels of TAG accumulation (~250 mg/g) but relatively low inflammation/fibrosis levels were achieved in the livers of control LHF mice. Liver steatosis was reduced by >40% in the ω3PL but not ω3TG group, and plasma ALT levels were markedly reduced (by 68%) in ω3PL mice as well. Krill oil administration also improved hepatic insulin sensitivity, and its effects were associated with high plasma adiponectin levels (150% of LHF mice) along with superior bioavailability of EPA, increased content of alkaloids stachydrine and trigonelline, suppression of lipogenic gene expression, and decreased diacylglycerol levels in the liver. This study reveals that in addition to Omega-3 PLs, other constituents of krill oil, such as alkaloids, may contribute to its strong antisteatotic effects in the liver.

• Keywords
• C57BL/6N mice, NAFLD, high-fat diet, krill oil, obesity, omega-3, phospholipids, thermoneutral temperature,
• MeSH
• Housing, Animal MeSH
• Diet, High-Fat adverse effects   MeSH
• Euphausiacea MeSH
• Phospholipids pharmacology   MeSH
• Animal Nutritional Physiological Phenomena MeSH
• Insulin Resistance MeSH
• Liver metabolism   MeSH
• Disease Models, Animal MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Non-alcoholic Fatty Liver Disease etiology   therapy   MeSH
• Obesity etiology   therapy   MeSH
• Dietary Supplements * MeSH
• Fish Oils pharmacology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Phospholipids MeSH
• Fish Oils MeSH

Long-chain n-3 polyunsaturated fatty acids (Omega-3) and anti-diabetic drugs thiazolidinediones (TZDs) exhibit additive effects in counteraction of dietary obesity and associated metabolic dysfunctions in mice. The underlying mechanisms need to be clarified. Here, we aimed to learn whether the futile cycle based on the hydrolysis of triacylglycerol and re-esterification of fatty acids (TAG/FA cycling) in white adipose tissue (WAT) could be involved. We compared Omega-3 (30 mg/g diet) and two different TZDs-pioglitazone (50 mg/g diet) and a second-generation TZD, MSDC-0602K (330 mg/g diet)-regarding their effects in C57BL/6N mice fed an obesogenic high-fat (HF) diet for 8 weeks. The diet was supplemented or not by the tested compound alone or with the two TZDs combined individually with Omega-3. Activity of TAG/FA cycle in WAT was suppressed by the obesogenic HF diet. Additive effects in partial rescue of TAG/FA cycling in WAT were observed with both combined interventions, with a stronger effect of Omega-3 and MSDC-0602K. Our results (i) supported the role of TAG/FA cycling in WAT in the beneficial additive effects of Omega-3 and TZDs on metabolism of diet-induced obese mice, and (ii) showed differential modulation of WAT gene expression and metabolism by the two TZDs, depending also on Omega-3.

• Keywords
• adipocytes, glucose homeostasis, insulin, lipogenesis, obesity,
• MeSH
• Adipose Tissue, White metabolism   MeSH
• Diet, High-Fat MeSH
• Hypoglycemic Agents pharmacology   MeSH
• Lipogenesis drug effects   MeSH
• Fatty Acids metabolism   MeSH
• Lipid Metabolism drug effects   MeSH
• Mice, Inbred C57BL MeSH
• Mice, Obese MeSH
• Mice MeSH
• Obesity drug therapy   metabolism   MeSH
• Fatty Acids, Omega-3 administration & dosage   pharmacology   MeSH
• Pioglitazone pharmacology   MeSH
• Thiazolidinediones administration & dosage   pharmacology   MeSH
• Triglycerides metabolism   MeSH
• Adipocytes drug effects   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Hypoglycemic Agents MeSH
• Fatty Acids MeSH
• Fatty Acids, Omega-3 MeSH
• Pioglitazone MeSH
• Thiazolidinediones MeSH
• Triglycerides MeSH

Antisteatotic effects of omega-3 fatty acids (Omega-3) in obese rodents seem to vary depending on the lipid form of their administration. Whether these effects could reflect changes in intestinal metabolism is unknown. Here, we compare Omega-3-containing phospholipids (krill oil; ω3PL-H) and triacylglycerols (ω3TG) in terms of their effects on morphology, gene expression and fatty acid (FA) oxidation in the small intestine. Male C57BL/6N mice were fed for 8 weeks with a high-fat diet (HFD) alone or supplemented with 30 mg/g diet of ω3TG or ω3PL-H. Omega-3 index, reflecting the bioavailability of Omega-3, reached 12.5% and 7.5% in the ω3PL-H and ω3TG groups, respectively. Compared to HFD mice, ω3PL-H but not ω3TG animals had lower body weight gain (-40%), mesenteric adipose tissue (-43%), and hepatic lipid content (-64%). The highest number and expression level of regulated intestinal genes was observed in ω3PL-H mice. The expression of FA ω-oxidation genes was enhanced in both Omega-3-supplemented groups, but gene expression within the FA β-oxidation pathway and functional palmitate oxidation in the proximal ileum was significantly increased only in ω3PL-H mice. In conclusion, enhanced intestinal FA oxidation could contribute to the strong antisteatotic effects of Omega-3 when administered as phospholipids to dietary obese mice.

• Keywords
• Omega-3 index, Omega-3 phospholipids, high-fat diet, krill oil, small intestine,
• MeSH
• Diet, High-Fat * MeSH
• Erythrocyte Membrane metabolism   MeSH
• Euphausiacea MeSH
• Phospholipids administration & dosage   MeSH
• Blood Glucose analysis   MeSH
• Fatty Acids metabolism   MeSH
• Lipid Metabolism drug effects   MeSH
• Mice, Obese MeSH
• Oils MeSH
• Fatty Acids, Omega-3 administration & dosage   MeSH
• Oxidation-Reduction MeSH
• Intestines anatomy & histology   MeSH
• Intestinal Mucosa metabolism   MeSH
• Body Weight MeSH
• Triglycerides administration & dosage   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Phospholipids MeSH
• Blood Glucose MeSH
• Fatty Acids MeSH
• Oils MeSH
• Fatty Acids, Omega-3 MeSH
• Triglycerides MeSH

We found previously that white adipose tissue (WAT) hyperplasia in obese mice was limited by dietary omega-3 polyunsaturated fatty acids (omega-3 PUFA). Here we aimed to characterize the underlying mechanism. C57BL/6N mice were fed a high-fat diet supplemented or not with omega-3 PUFA for one week or eight weeks; mice fed a standard chow diet were also used. In epididymal WAT (eWAT), DNA content was quantified, immunohistochemical analysis was used to reveal the size of adipocytes and macrophage content, and lipidomic analysis and a gene expression screen were performed to assess inflammatory status. The stromal-vascular fraction of eWAT, which contained most of the eWAT cells, except for adipocytes, was characterized using flow cytometry. Omega-3 PUFA supplementation limited the high-fat diet-induced increase in eWAT weight, cell number (DNA content), inflammation, and adipocyte growth. eWAT hyperplasia was compromised due to the limited increase in the number of preadipocytes and a decrease in the number of endothelial cells. The number of leukocytes and macrophages was unaffected, but a shift in macrophage polarization towards a less inflammatory phenotype was observed. Our results document that the counteraction of eWAT hyperplasia by omega-3 PUFA in dietary-obese mice reflects an effect on the number of adipose lineage and endothelial cells.

• Keywords
• adipocyte, cellularity, fat, nutrition, obesity, proliferation, white adipose tissue,
• MeSH
• Adipose Tissue, White drug effects   MeSH
• Diet, High-Fat MeSH
• Endothelial Cells drug effects   MeSH
• Macrophages drug effects   pathology   MeSH
• Mice, Inbred C57BL MeSH
• Mice MeSH
• Fatty Acids, Omega-3 administration & dosage   MeSH
• Cell Proliferation drug effects   MeSH
• Adipocytes cytology   drug effects   MeSH
• Inflammation pathology   MeSH
• Animals MeSH
• Check Tag
• Male MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Fatty Acids, Omega-3 MeSH