Fructooligosaccharide supplementation ameliorates gut associated metabolic dysregulation in estrogen-deprived rats via targeting oxidative stress, inflammation, apoptosis, and gut microbiome
A 28-day preclinical study published in Scientific Reports tested FOS (fructooligosaccharide) as a non-hormonal option for the gut/metabolic disruption caused by estrogen deficiency. Female rats were bilaterally ovariectomized (OVX), a standard surgical method for recreating postmenopausal conditions, then given oral FOS at 25, 50, or 100 mg/kg daily, estrogen replacement therapy (17βE2 at 10μg/kg), or a saline placebo. A group of intact control rats served as a reference. Researchers tracked body weight, abdominal fat, liver function, and lipid markers, along with markers of oxidative damage, inflammation, and cell death in the colon and liver. They also measured gut barrier integrity (e.g. mucus layer, tight junctions) and gut microbiome composition across 10 specific bacterial groups.
OVX rats showed broad metabolic dysfunction by day 28, with body weight rising by ~31%, abdominal fat increasing by ~80%, and BMI elevating by ~90% above control values. Liver inflammation followed. TNF-α levels rose ~84%, CRP by ~79%, and a key protein that drives inflammatory gene activity (NF-kB/p65) rose by ~86% (all p<0.001). Oxidative damage in the liver, measured by lipid peroxidation, increased by ~85%, with drops in antioxidant enzymes (SOD, CAT, and GSH). The colon showed the same picture. Gut barrier genes deteriorated, with MUC-2 (the mucus layer protein) falling to 0.47-fold of control, claudin (a tight junction protein) to 0.62-fold, and TLR-4 (a receptor that triggers inflammatory responses) rising 2-fold. The microbiome shifted toward dysbiosis, showing Akkermansia fell below normal levels, while Firmicutes rose 3.4-fold and Enterobacteriaceae rose 3.5-fold.
FOS at 50 and 100 mg/kg reversed essentially all of these changes (p<0.001), matching estrogen replacement on most gut and metabolic markers. FOS had no effect on estrogen receptor activity (ER-α or ER-β), uterine weight, or circulating E2 levels, Showing the mechanism was through the gut, not hormonal pathways. FOS at 25 mg/kg produced no measurable effect on any endpoint.
The study makes the case that FOS can restore gut-metabolic function in estrogen deficiency without the hormonal risks tied to HRT. The likely mechanism runs through microbiome rebalancing and gut barrier repair, driven by short-chain fatty acid production. Importantly, SCFA levels were not measured in this study, which the authors flag as the main gap. The microbiome analysis covered only 10 pre-selected bacterial groups rather than comprehensive sequencing, and the study used a single animal model. Translating these findings to menopausal women requires more work, including SCFA quantification, broader microbiome analysis, and human trials.
