Instant Dark Tea Alleviates Hyperlipidaemia in High-Fat Diet-Fed Rat: From Molecular Evidence to Redox Balance and Beyond.

Instant dark tea (IDT) is a new product gaining increasing attention because it is convenient and can endow significant health benefit to consumers, which is partially attributed to its high concentration of functional ingredients. However, the molecular mechanism underlying its regulatory effect on hyperlipidaemia is rarely studied. In this study, we performed omics and molecular verification in high-fat diet (HFD)-fed rat, aiming to reveal the mechanism and provide molecular evidence. The results showed that the major bioactive components in IDT were 237.9 mg/g total polysaccharides, 336.6 mg/g total polyphenols, and 46.9 mg/g EGCG. Rats fed with IDT (0.27-0.54 g/kg for 12 weeks) significantly reduced the body weight and TC, TG, LDL-C, blood glucose, and MDA and induced the level of serum HDL-C and also the levels of liver SOD, CAT, GSH-Px, and Nrf2, compared to HFD group. For molecular mechanism study, HIDT feeding had significant impact on the gene expressions of biomarkers in lipogenesis (, and ), lipid oxidation (γ), and glucose glycolysis ( and ) in liver tissue. Moreover, gut microbiome study found that rats fed with IDT dramatically modified the gut microbial species at the family level, such as suppressing the increase abundance of Proteobacteria and Firmicutes induced by HFD. HIDT significantly boosted the relative composition of beneficial bacterium and and decreased the relative abundance of the harmful bacterium and , compared to HFD ( < 0.01). Correlation analysis between microbiome and animal indicators found that seven genera including , and were found as potential biomarkers that were strongly correlated with oxidative stress and metabolism genes. For instance, was significantly correlated with body weight, TG, HDL-C, Nfr2, , and . Collectively, the above data obtained in this study had provided the primary molecular evidence for the molecular mechanism and brought in novel insights based on omics for the regulatory effect of IDT on hyperlipidaemia.