Lime-treated corn husks lower plasma LDL cholesterol in guinea pigs by altering hepatic cholesterol metabolism

doi:10.1016/S0955-2863(97)00062-4

The Journal of Nutritional Biochemistry

Volume 8, Issue 8, August 1997, Pages 479-486

https://doi.org/10.1016/S0955-2863(97)00062-4 Get rights and content

Abstract

Lime-treated corn husks (LTCH) containing 69% of fiber (5.0% as soluble fiber) were evaluated on their hypolipidemic properties in guinea pigs. Animals were fed two doses of corn husks replacing dietary fiber: 7,5% and 10% (w/w) and LTCH effects on hepatic cholesterol metabolism and lipoprotein levels were compared to a control diet containing cellulose. LTCH significantly lowered plasma LDL cholesterol by 25% (P < 0.01) and VLDL cholesterol by 37% (P < 0.05), although a dose effect was not observed in this parameter. Plasma triacylglycerol (TAG) concentrations and HDL cholesterol levels were not affected by LTCH intake. The number of cholesteryl ester, TAG and phospholipid molecules were lower in VLDL from animals fed LTCH diets compared to control (P < 0.01) indicating modifications on VLDL size that were confirmed by the smaller calculated VLDL diameter of guinea pigs treated with LTCH. In addition, LTCH intake resulted in a smaller, cholesteryl ester depleted LDL particle compared with LDL derived from control animals. Hepatic cholesterol and TAG were not affected by LTCH, however, microsomal-free cholesterol was lower in animals fed LTCH compared with control. In agreement with the observed reductions on microsomal cholesterol, HMG-CoA reductase activity was upregulated 87% and 100%, ACAT downregulated 54% and 65% and cholesterol 7α-hydroxylase activity upregulated 120% and 180% by LTCH diets in a dose dependent manner (P < 0.01). In addition, LDL binding to hepatic membranes (B_max) was higher in animals fed LTCH diets. These results indicate that the lower plasma VLDL and LDL cholesterol concentrations induced by LTCH intake are associated with decreases in microsomal cholesterol that alter the regulatory enzymes of cholesterol homeostasis and upregulate LDL receptors.

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The aims of this study were to compare the cholesterol-lowering properties of corn fiber oil (CFO) to corn oil (CO), whether the addition of soy stanols or soy sterols to CO at similar levels in CFO would increase CO’s cholesterol-lowering properties, and the mechanism(s) of action of these dietary ingredients. Fifty male Golden Syrian hamsters were divided into 5 groups of 10 hamsters each, based on similar plasma total cholesterol (TC) levels. The first group of hamsters was fed a chow-based hypercholesterolemic diet containing either 5% coconut oil + 0.24% cholesterol (coconut oil), 5% CO, 5% CFO, 5% CO + 0.6% soy sterols (sterol), or 5% CO + 0.6% soy stanols (stanol) in place of the coconut oil for 4 weeks. The stanol diet significantly inhibited the elevation of plasma TC compared to all other dietary treatments. Also, the CFO and sterol diets significantly inhibited the elevation of plasma TC compared to the CO and coconut oil diets. The CFO, sterol, and stanol diets significantly inhibited the elevation of plasma non-high density lipoprotein cholesterol compared to the CO and coconut oil diets. The stanol diet significantly inhibited the elevation of plasma high density lipoprotein cholesterol (HDL-C) compared to all other dietary treatments. The sterol diet significantly inhibited the elevation of plasma HDL-C compared to the CO and coconut oil diets, whereas the CFO diet significantly inhibited the elevation of plasma HDL-C compared to the coconut oil diet only. No differences were observed between the CFO and CO for plasma HDL-C. There were no differences observed between groups for plasma triglycerides. The CO and CFO diets had significantly less hepatic TC compared to the coconut oil, sterol, and stanol diets. The CO and CFO diets had significantly less hepatic free cholesterol compared to the sterol and stanol diets but not compared to the coconut oil diet; whereas the coconut oil and sterol diets had significantly less hepatic free cholesterol compared to the stanol diet. The CFO, sterol, and stanol diets excreted significantly more fecal cholesterol compared to the coconut oil and CO diets. In summary, CFO reduces plasma and hepatic cholesterol concentrations and increases fecal cholesterol excretion greater than CO through some other mechanism(s) in addition to increase dietary sterols and stanols—possibly oryzanols.
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Research communicationLime-treated corn husks lower plasma LDL cholesterol in guinea pigs by altering hepatic cholesterol metabolism

Abstract

Ad. Food Nutr. Res.

Am. J. Clin. Nutr.

J. Lipid Res.

J. Lipid Res.

Am. J. Clin. Nutr.

J. Lipid Res.

Atherosclerosis

Gastroenterology

Clin. Biochem.

Anal. Biochem.

J. Biol. Chem.

Anal. Biochem.

Clin. Chim. Acta

J. Biol. Chem.

Methods Enzymol.

J. Steroid Biochem.

Am. J. Clin. Nutr.

Am. J. Clin. Nutr.

Am. J. Clin. Nutr.

Am. J. Clin. Nutr.

J. Lipid Res.

J. Lipid Res.

Research communication
Lime-treated corn husks lower plasma LDL cholesterol in guinea pigs by altering hepatic cholesterol metabolism