Silicon-Enriched Restructured Pork Affects the Lipoprotein Profile, VLDL Oxidation, and LDL Receptor Gene Expression in Aged Rats Fed an Atherogenic Diet.

BACKGROUND

Research has shown that silicon can play an important role in protecting against degenerative diseases. Restructuring pork by partially disassembling meat permits the incorporation of active components with potential functional effects. However, there has been no research to date on the impact that silicon, as a functional ingredient in restructured pork (RP), has on lipoprotein composition, metabolism, and oxidation.

OBJECTIVE

This study was designed to evaluate the effect of silicon-enriched RP on lipemia, lipoprotein profile, and oxidation markers of aged rats fed high-fat, high-energy, cholesterol-enriched diets.

METHODS

RP samples similar to commercial sausages (16% protein and 22% fat, wt:wt) were prepared by mixing lean pork and lard alone or with silicon (1.3 g Si/kg fresh matter) under controlled conditions and then freeze-dried. Saturated fat-rich diets were designed by mixing 78.3% purified diet with 21.7% freeze-dried RP. Three groups composed of 8 aged male Wistar rats (1 y old) were fed for 8 wk a control RP (C) diet, a cholesterol-enriched RP (Chol-C) diet [C diet enriched with 1.26% cholesterol plus 0.25% cholic acid, or a cholesterol and silicon-enriched RP (Chol-Si) diet (same as the Chol-C diet but containing silicon)]. Plasma lipid concentrations, lipoprotein profile, the degree of VLDL oxidation, and LDL receptor gene (Ldlr) expression were tested.

RESULTS

Compared with the C diet, the Chol-C diet did not modify food intake or body weight but significantly increased (P < 0.05) plasma cholesterol (32%) and total lipids (19%), VLDL and intermediate density lipoprotein + LDL cholesterol (both >600%), total lipids and proteins (both >300%), and the degree of VLDL oxidation [conjugated dienes >250%; thiobarbituric acid-reactive substance (TBARS), 900%] and reduced Ldlr expression (64%) and liver arylesterase activity (54%). The Chol-Si diet partially normalized changes induced by the Chol-C diet. Compared with the Chol-C group, Chol-Si rats had lower VLDL compound concentrations (P < 0.001; e.g., 75% less VLDL cholesterol) and VLDL oxidation (65% less conjugated dienes and 85% less TBARS) but greater Ldlr expression (200%).

CONCLUSIONS

Silicon added to RP strongly counterbalanced the negative effect of high-cholesterol-ingestion, functioning as an active hypocholesterolemic, hypolipemic, and antioxidative dietary ingredient in aged rats.