What does this research mean for the field?

Dietary supplementation with full-fat rice bran ameliorates insulin resistance, reduces visceral fat, and improves muscle strength in high-fat diet-fed ovariectomized mice, potentially through modulation of the gut microbiota and short-chain fatty acids. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

The study aimed to assess the effects of varying doses of full-fat rice bran on insulin resistance and muscle-related parameters in high-fat diet-fed ovariectomized mice.

June 3, 2026Open Access

Full-Fat Rice Bran Ameliorates Insulin Resistance and Modulates Muscle-Related Parameters in High-Fat Diet-Fed Ovariectomized Mice with Potential Involvement of the Gut–Muscle Axis

Key Points

The study aimed to assess the effects of varying doses of full-fat rice bran on insulin resistance and muscle-related parameters in high-fat diet-fed ovariectomized mice.
Thirty-six female ICR mice were assigned to six groups, including OVX mice fed high-fat diet with or without 5%, 10%, or 20% full-fat rice bran.
The primary outcome measured was insulin resistance assessed by HOMA-IR, along with muscle strength and gut microbiota composition.
20% FFRB reduced body weight gain by 43% and decreased visceral fat mass, with HOMA-IR decreased by 65%, Ptrend = 0.001.
FFRB improved grip strength with forelimb Ptrend = 0.013 and four-limb Ptrend < 0.001, while upregulating muscle protein synthesis genes and downregulating atrophy markers.
FFRB increased fecal acetate levels, upregulated colonic tight junction genes, and revealed a greater abundance of g_Muribaculum with SCFAs positively associated with muscle strength.

Abstract

Objectives: The study aimed to evaluate the effects of full-fat rice bran (FFRB; Tainung No. 81, Taiwan) at various doses on insulin resistance, muscle atrophy, and gut microbiota composition in middle-aged ovariectomized (OVX) mice fed a high-fat diet (HFD), using young sham-operated mice as a life-stage reference group. Methods: Thirty-six female ICR mice were assigned to six groups, including OVX mice fed HFD with or without 5%, 10%, or 20% FFRB. Results: Compared with HFD-fed OVX controls, 20% FFRB reduced body weight gain by 43%, decreased visceral fat mass, and improved insulin resistance (homeostasis model assessment of insulin resistance, HOMA-IR reduced by 65%, Ptrend = 0. 001). FFRB attenuated the decline in relative grip strength (forelimb, Ptrend = 0. 013; four-limb, Ptrend < 0. 001), and upregulated muscle protein synthesis genes, including insulin receptor substrate 1 (IRS-1), mammalian target of rapamycin (mTOR), eukaryotic translation initiation factor 4E binding protein 1 (eIF-4EBP1), while downregulating forkhead box protein O1 (FOXO1), muscle RING-finger protein-1 (MuRF-1), and interleukin (IL) -6. FFRB was also associated with higher fecal acetate levels (Ptrend < 0. 001), upregulated colonic tight junction genes (occludin and zonula occludens (ZO) -1), and greater relative abundance of gMuribaculum. Correlation analyses revealed positive associations between short-chain fatty acids (SCFAs) and muscle strength, muscle anabolic markers, genus LachnospiraceaeUCG₀01, and Muribaculum. Conclusions: Dietary inclusion of FFRB was associated with favorable metabolic and muscle-related parameters in HFD-fed middle-aged OVX mice, with potential involvement of gut microbiota and SCFA alterations.

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