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NutrInsight • Do we need dietary polyphenols for health?
Polyphenols
Stimulation of stress-related cell signaling
bZIP
ARE NUCLEUS
PI3K Grb2
Akt PKC ERK1/2
Nrf2 P
Synthesis of antioxidants (GSH)
Nrf2
Figure 10: Indirect antioxidant activity of polyphenols. GSH: Reduced form of glutathione
Source: From F. Visioli
One example is found in the paper by Visioli et al [Visioli et al., 2009] who reported a study in which 98 Chinese Malay subjects ingested an olive preparation which was high in phenolics. After 1h, no difference in plasma antioxidant capacity was observed but a significant increase in total plasma glutathione concentration was measured. The authors postulated that the observed effects of the olive phenols on glutathione levels might be governed by the antioxidant response element (ARE)-mediated increase in phase II enzyme expression.
3.2 Inflammation
Inflammation is involved in the onset and maintenance of several degenerative diseases and, while useful in the short-term to fight infections and promote wound healing, a longer term anti-inflammatory action represents an important target for selected food components. Several enzymes involved in inflammation depend on cellular “peroxide tone”. Polyphenols have been shown to exert anti-inflammatory actions, via multiple mechanisms of actions that include interference with signal transduction and direct inhibition of pro-inflammatory enzymes.
E.g. a prospective study of premenopausal women has shown that whole grain cereal consumption is associated with decreased C-reactive protein and it is believed that the polyphenols in wholegrain may be responsible for this effect [Gaskins et al., 2010]. Recently, bioprocessed whole wheat bread with increased bioavailable polyphenols has shown an anti-inflammatory on ex-vivo LPS-challenged blood. In this trial, the ratios of pro-anti-inflammatory cytokines was improved after 3 days of consumption of the bioprocessed bread compared to control by healthy men [Mateo Anson et al., 2011].
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