From: Doug Skrecky (oberon@vcn.bc.ca)
Date: Fri Jun 25 1999 - 07:28:05 MDT
Authors
Fremont L. Gozzelino MT. Franchi MP. Linard A.
Institution
Laboratoire de Nutrition et Securite Alimentaire, INRA-CRJ, 78352
Jouy-en-Josas, Cedex, France.
Title
Dietary flavonoids reduce
lipid peroxidation in rats fed polyunsaturated or
monounsaturated fat diets.
Source
Journal of Nutrition. 128(9):1495-502, 1998 Sep.
Abstract
We investigated the influence of dietary
flavonoids on alpha-tocopherol status and LDL peroxidation
in rats fed diets enriched in either polyunsaturated fatty acids (PUFA) or
monounsaturated fatty acids (MUFA). Diets equalized for alpha-tocopherol
concentrations were or were not supplemented with 8 g/kg diet of
flavonoids (quercetin + catechin, 2:1). After 4 wk of
feeding, plasma lipid concentrations were lower in rats fed
PUFA than in those fed MUFA with a significant correlation between plasma
alpha-tocopherol and cholesterol concentrations, r = 0.94, P < 0. 0001).
Dietary lipids influenced the fatty acid
composition of VLDL + LDL more than that of HDL or microsomes. The resistance
of VLDL + LDL to copper-induced oxidation was higher in rats fed MUFA than in
those fed PUFA as assessed by the lower production of conjugated dienes and
thiobarbituric acid reactive substances (TBARS) and by the >100% longer lag
time for dienes production. (P < 0.0001). Dietary
flavonoids significantly reduced by 22% the
amounts of dienes produced during 12 h of oxidation in rats fed diets rich in
PUFA and lengthened lag time 43% in those fed MUFA. Microsomes of rats fed
MUFA produced approximately 50% less TBARS than those of rats fed PUFA (P <
0.0001) and they contained more alpha-tocopherol in rats fed MUFA than in
those fed PUFA with higher values (P < 0. 0001) in both groups supplemented
with flavonoids (P < 0.0001). Our findings suggest that the
intake of dietary flavonoids is beneficial
not only when diets are rich in PUFA but also when they are rich in MUFA. It
seems likely that these substances contribute to the antioxidant defense and
reduce the consumption of alpha-tocopherol in both
lipoproteins and membranes.
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