The effects of low-fat dairy products on insulin resistance (IR),
hepatic steatosis, and gut microbiota composition in high-fat diet
(HFD)-fed obese mice were examined. C57BL/6 male mice (n = 16/group)
were fed a high-fat diet (HFD, 45% fat) or HFD supplemented with either
fat-free milk (MILK), fat-free yogurt (YOG), or reduced-fat (19% milk
fat) cheddar cheese (CHE) at 10% of the total energy intake for 8 weeks.
Body weight, fat mass, liver lipids, and metabolic enzymes were
evaluated. Compared with HFD, MILK reduced homeostatic assessment of
insulin resistance along with increased hepatic insulin signaling and
decreased hepatic gluconeogenic enzymes. YOG and MILK decreased hepatic
triacylglycerol content and lipid droplet size, while CHE had no effect.
In the liver, MILK and YOG downregulated de novo lipogenesis enzymes.
In MILK, fat oxidation capacity was elevated. Compared with HFD, liver
lipidomic analysis in MILK and YOG revealed unique profiles of decreased
proinflammatory lipid species, including ceramides. Dairy feeding
elicited an increase in beneficial bacteria, such as Streptococcus in YOG and Anaero-tignum
in MILK, as shown by 16S rRNA sequencing of gut microbiota. In
conclusion, the ability of milk and yogurt to reduce hepatic steatosis
in HFD mice may be explained, at least in part, by the regulation of the
gut microbiome and liver lipidome.