X-Message-Number: 24542
Date: Sat, 21 Aug 2004 11:14:43 -0700 (PDT)
From: Doug Skrecky <>
Subject: flax may lower vitamin E levels

[Soy has been associated with increased risk of dementia. With similar
phyto-oestrogenic actions, and now apparently an anti-vitamin E effect I
suspect flax may also increase the risk of dementia. However this
hypothesis has not yet been directly tested.]

---------- Forwarded message ----------
Br J Nutr. 2004 Jul;92(1):169-76
Dietary secoisolariciresinol diglucoside and its oligomers with
3-hydroxy-3-methyl glutaric acid decrease vitamin E levels in rats.
  Secoisolariciresinol diglucoside (SDG) is an important dietary lignan
that is found at very high levels in flaxseed (1-4 %, w/w). Flaxseed
lignans have received much research interest in recent years because of
reported phyto-oestrogenic, anticarcinogenic, and anti-atherogenic
effects. Previously, flaxseed feeding has been shown to decrease vitamin E
concentrations in rats despite the antioxidant potential of SDG in vitro.
Sesamin, a sesame lignan, on the other hand has been shown to increase
vitamin E concentrations in rats. The aim of the present study was to
investigate the effect of dietary SDG and its oligomers on vitamin E and
cholesterol concentrations in rats. SDG was extracted from defatted
flaxseed flour with a dioxane-ethanol mixture and purified by silica
column chromatography. The major oligomers with 3-hydroxy-3-methyl
glutaric acid, containing a high ratio of SDG to p-coumaric and ferulic
acid glucosides, were purified from the extracts by reversed-phase liquid
chromatography. When fed to rats at 0.1 % in the diet for 27 d, both SDG
and its oligomers had no effect on animal performance but caused an
increase in liver cholesterol and a 2-fold reduction in the
levels of alpha- and gamma-tocopherols in rat plasma and liver. It is
notable that a phenolic antioxidant, such as SDG, causes a vitamin
E-lowering effect in rats. This cannot be explained at present, but
warrants further investigations with respect to the magnitude, mechanism,
and significance of the observed effect for human nutrition.

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