The study, published in Food Science of Animal Resources, used a whey-derived milk polar lipid concentrate containing at least 25 percent total phospholipids, including sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine. Male C57BL/6J mice, a standard strain in metabolic research, were divided into four groups of six animals each. One group received a standard control diet, a second received a high-fat high-sucrose diet deriving 43 percent of its calories from fat and 24 percent from sucrose, a third received that same obesogenic diet modified so that milk fat was replaced with 8 percent of the milk polar lipid concentrate, and a fourth received the obesogenic diet supplemented with 0.01 percent orlistat, the pancreatic lipase inhibitor sold commercially as Xenical, serving as a positive control. The animals were followed for twelve weeks, with body weight and food intake recorded weekly and body composition assessed by dual-energy X-ray absorptiometry shortly before the study’s end.

The results were striking. Mice on the high-fat high-sucrose diet gained substantially more weight than controls, but the animals receiving milk polar lipids ended the study at a final body weight statistically indistinguishable from the normal-diet group. Fat mass, measured by DEXA scanning, was significantly lower in the supplemented animals, and the treatment partially restored lean mass while also improving bone mineral content, an intriguing secondary observation that suggests the lipids may help preserve skeletal status under metabolic stress. Food and calorie intake rose gradually in the unsupplemented high-fat group, but the researchers attributed this to increasing body mass rather than heightened appetite, noting that intake did not differ across groups during the early weeks when body weights were still comparable.

Blood chemistry told a similar story of protection. The obesogenic diet drove up total cholesterol and low-density lipoprotein cholesterol, both well-established indicators of dysregulated lipid metabolism, and elevated alanine aminotransferase and aspartate aminotransferase, the two enzymes clinicians rely on most heavily to detect liver cell damage. Supplementation with the milk lipid concentrate pushed all of these markers back toward normal levels. Serum triglycerides, curiously, were actually higher in the supplemented group than in the unsupplemented high-fat group, but the authors interpret this not as a metabolic failure but as a sign of enhanced lipid mobilization and export from liver and fat stores into circulation, consistent with prior evidence that dietary phospholipids influence very-low-density lipoprotein assembly and hepatic lipid handling. They caution that the relatively short four-hour fast before tissue collection may have introduced postprandial effects and call for future studies measuring free fatty acids and hepatic VLDL secretion rates to clarify the point.

Under the microscope, the differences were unmistakable. Adipocytes in the high-fat group were markedly enlarged, a hallmark of adipose tissue dysfunction that fuels chronic low-grade inflammation and floods peripheral organs with excess free fatty acids. Both the milk lipid and orlistat groups showed significantly smaller adipocytes and reduced weights of inguinal and mesenteric white adipose tissue depots. In the liver itself, hematoxylin and eosin staining and Oil Red O staining revealed heavy fat infiltration in the high-fat group, while the supplemented animals showed dramatically reduced steatosis, lower liver weights, and significantly reduced hepatic triglyceride content. Earlier work had suggested that milk phospholipids partly work by interfering with micellar lipid solubilization in the intestine, reducing absorption and increasing fecal lipid excretion, but the tiny amounts of intact phospholipids recovered in feces in prior studies indicated the supplements themselves are efficiently absorbed, hinting that they must also act systemically after uptake.

That systemic action is where the new study makes its most technically interesting contribution. The researchers probed the hepatic Wnt/β-catenin pathway, an evolutionarily ancient signaling cascade best known for orchestrating embryonic development but increasingly recognized as a metabolic regulator. The obesogenic diet significantly suppressed key components of the pathway, reducing hepatic expression of the co-receptor LRP6 and the ligand Wnt3a. Supplementation with the milk lipids, and to a comparable degree orlistat, restored LRP6 and Wnt3a expression, but only the milk lipid diet significantly upregulated total β-catenin, the pathway’s central transcriptional effector. When Wnt signaling is active, stabilized β-catenin enters the nucleus and suppresses adipogenic transcriptional programs driven by PPARγ and C/EBPα, thereby limiting lipid storage. Consistent with that model, the supplemented animals showed significantly reduced expression of PPARγ and its downstream partners DGAT1 and PLIN2, which govern triglyceride synthesis and lipid droplet formation, along with reduced SREBP1 and the de novo lipogenesis enzymes ACC, SCD1, and FAS.

The authors propose a plausible biophysical explanation for how dietary lipids could touch this membrane-anchored pathway. Polar lipids can alter the composition of cellular membranes, and membrane phosphoinositide metabolism is known to be essential for LRP6 activation, with prior work showing that Wnt3a-mediated formation of phosphatidylinositol 4,5-bisphosphate regulates LRP6 phosphorylation. Milk fat globule membrane supplementation has also been shown in lipidomic studies to enrich membranes in phosphatidylcholine and phosphatidylethanolamine. In other words, the phospholipids consumed in the diet may be incorporated into hepatic membranes in ways that sensitize the Wnt machinery, though the authors are careful to frame this as a plausible mechanism rather than a demonstrated one. Notably, milk-derived sphingomyelin has previously outperformed egg-derived sphingomyelin against hepatic steatosis, suggesting that the source and molecular composition of dietary lipids matter in ways the field is only beginning to map.

The second arm of the mechanism involves the gut microbiome, and here the study employed 16S rRNA gene sequencing of cecal contents processed through the DADA2 and QIIME pipelines. The obesogenic diet significantly reduced microbial alpha diversity, as measured by the Shannon index and phylogenetic diversity, and shifted the community structure into a cluster clearly separated from controls. The milk lipid group formed its own distinct cluster, separate from both the high-fat and orlistat groups, with PERMANOVA confirming significant separation between the supplemented and unsupplemented high-fat animals. Because the orlistat group’s microbiome remained similar to the high-fat group’s, the authors infer that the lipids’ microbial effects extend beyond simple inhibition of fat absorption. At the phylum level, supplementation partially reversed the diet-driven rise in Bacillota and boosted Verrucomicrobiota, the phylum housing Akkermansia muciniphila, a mucin-degrading bacterium celebrated for its associations with gut barrier integrity and metabolic health, and consistently depleted in patients with fatty liver disease and obesity.

Additional taxa shifts reinforced the picture. The high-fat diet enriched bile acid-resistant Lactobacillus and Limosilactobacillus species, a pattern previously linked to altered intestinal bile acid composition in fatty liver models, while the milk lipid diet selectively increased Akkermansia along with Romboutsia and members of the Christensenellaceae family, taxa reported to improve lipid metabolism partly through enhanced short-chain fatty acid production. Prior studies have shown that A. muciniphila supplementation attenuates hepatic steatosis and inflammation, modulates bile acid metabolism through the intestinal FXR-FGF15 axis, and enhances mitochondrial fatty acid oxidation via L-aspartate signaling along the gut-liver axis. The authors are appropriately measured about causality, emphasizing that their microbial findings show association rather than proof and that future work measuring microbial metabolites such as short-chain fatty acids and bile acids will be needed to close the loop.

Taken together, the study sketches a coordinated mechanism in which a single dietary component acts simultaneously on intracellular lipogenic signaling and on the ecology of the gut, offering a template for how food-derived bioactives might be engineered into functional ingredients for metabolic disease. The caveats are real: the work was conducted in mice, the intervention used a concentrated extract at a dose that would be difficult to translate directly to human diets, and the mechanistic links remain partly inferential. But with fatty liver disease affecting hundreds of millions of people and no approved pharmacological therapy for its early stages, the idea that the humble membrane lipids enveloping fat droplets in milk could simultaneously quiet a liver’s fat-building program and cultivate a healthier gut community is precisely the kind of convergent finding that could shape the next generation of nutritional interventions.

Subject of Research: Effects of dietary milk polar lipids on hepatic lipid accumulation, Wnt-PPARγ signaling, and gut microbiota in a mouse model of non-alcoholic fatty liver disease

Article Title: Dietary milk polar lipids ameliorate hepatic lipid accumulation through coordinated regulation of Wnt-PPARγ signaling and remodeling of the gut microbiota

Article References: Kim, H., Park, D., Kwon, Y.-J., & Imm, J.-Y. (2026). Dietary milk polar lipids ameliorate hepatic lipid accumulation through coordinated regulation of Wnt-PPARγ signaling and remodeling of the gut microbiota. Food Science of Animal Resources, 46(1), Article 83. https://doi.org/10.1007/s44463-026-00100-w

Image Credits: AI Generated

DOI: 10.1007/s44463-026-00100-w

Keywords: milk polar lipids, non-alcoholic fatty liver disease, Wnt/beta-catenin signaling, PPARgamma, gut microbiota, Akkermansia muciniphila, sphingomyelin, hepatic steatosis, short-chain fatty acids, gut-liver axis, high-fat high-sucrose diet, milk fat globule membrane