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Mechanisms and Biomarkers (WG 4) page 51
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No literature reports any change in TRAP levels in response to daily consumption of tomato
products providing different quantities of lycopene (Steinberg and Chait, 1998; Böhm and
Bitsch, 1999; Pellegrini et al., 2000). However, trials by Rock et al. (1992), using subjects on
self-selected tomato sauce-rich diets assessed uptake, bioavailability and half-life of blood
carotenoids and yielded some useful, indirect evidence that lycopene may function as a
plasma antioxidant. Lycopene repletion following a diet rich in pasta sauce stabilized at
approximately 1 µM. After 7 days on a tomato/carotenoid free diet the lycopene levels had
declined to around 100nM . Over the same period the levels of β-carotene and lutein had
fallen from 200nM to 150nM. These interesting observations indicate that lycopene may
possibly have a role as a sacrificial antioxidant by virtue of its increased sensitivity to oxygen
and ROS/RNS as compared to the other carotenoids, thus sparing them to mediate their
known antioxidant and other protective functions. Other results exist suggesting a role of
lycopene from the diet in saving other antioxidant compounds and preventing tissue damage
in vivo. Ribaya-Mercado et al. (1995) hypothesized that lycopene may protect other
carotenoids and antioxidant substances as, in a human study, up to 46 % reduction in skin
lycopene was observed after a single exposure to a dose of solar simulated light. This seems
to suggest a role of this carotenoid in mitigating oxidative damage in tissues. Furthermore the
exposure of human plasma to the gas phase of cigarette smoke produced the disappearance of
most of the lipophilic compounds and firstly lycopene (Handelman et al., 1996). At this
regard Clinton et al. (1996) and Rao et al. (1999) hypothesized a role of lycopene in prostate
tissue, however more research is needed to clarify this action.
POTENTIAL CONTRIBUTION OF OTHER COMPOUNDS PRESENT IN TOMATO
Present research on the effect of tomato products against oxidative stress is focusing on the
possible interaction among all the antioxidant compounds present in this food. It is argued
that antioxidants such as β-carotene, vitamin C, vitamin E might work in synergy with
lycopene and this would better explain the healthy effect of tomato consumption. These
compounds are present in little and variable amount depending on the cultivar and/or the
processing of tomato, however it is not excluded that tomato products may contribute
significantly to their intake and, consequently, to the antioxidant protection.
Vitamin C, E and β-carotene have been all suggested as protective compounds in relation to
lipid peroxidation and DNA damage. Many in vitro and in vivo studies have been conducted