Animal studies have shown that both polyphenol-rich pomegranate extract (PomX) and the polysaccharide inulin help alleviate metabolic alterations caused by a high-fat diet, but the impact they have when combined has not been discovered.
Therefore, researchers conducted a study to determine the effect of PomX and inulin on cholesterol and lipid metabolism in mice, both individually and together.
They divided six- to seven-week old male mice into four groups, all placed on a high-fat, high-sucrose diet: the first (control group) was fed the diet with no supplementation, the second was supplemented with PomX, the third with inulin, and the last with both PomX and inulin.
After four weeks, the researchers observed that supplementation with both PomX and inulin lowered hepatic and serum total cholesterol, more so than supplementation with either the extract or the polysaccharide individually.
Individually, PomX increased the gene expression of two key regulators of bile acid synthesis pathways and lowered liver triglyceride levels, while inulin had no significant impact on either liver or serum triglyceride levels.
Instead, inulin on its own decreased the gene expression of key regulators of cholesterol de novo synthesis and increased faecal elimination of total bile acids and neutral sterols.
Only the mice supplemented with the PomX-inulin combination saw their liver and lipid weight lowered.
In addition, the researchers wrote: “When inulin and PomX were combined, PomX-induced stimulation of main bile acid synthesis pathway remained, inulin-induced inhibition of cholesterol synthesis (was) reduced, but the faecal neutral sterol excretion further increased compared to (in supplementation with) inulin alone.”
Involving the gut
The researchers wrote that this was the first study to investigate and report in detail on the enhanced cholesterol-lowering effects of PomX and inulin supplementation combined.
They concluded: “Individually, PomX lowered cholesterol by increasing bile acid synthesis and slightly increasing faecal cholesterol and bile acid excretion, while inulin mainly targeted hepatic cholesterol de novo synthesis, and faecal cholesterol and bile acid excretion involving changes in the metabolism of the intestinal microbiome.
“Detailed analysis cholesterol reabsorption and intestinal cholesterol synthesis, as well as the gut microbiota in future studies, will increase our knowledge of how PomX and inulin regulate whole-body cholesterol homeostasis”.
Source: Journal of Nutritional Biochemistry
“Cholesterol-lowering effects of dietary pomegranate extract and inulin in mice fed an obesogenic diet”
Authors: Jieping Yang, et al.