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Mechanisms and Biomarkers (WG 4) page 49
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quickly before the formation of lipid peroxidation products.
Sutherland et al. (1999) found no effect of tomato juice supplementation (2 x 200 mL/day)
for 4 weeks on TBARS, FLOP (fluorescence index of lipid oxidation product) and the
resistance of LDL to oxidation in patients with kidney graft. This, despite a doubling of
plasma lycopene concentration after the treatment.
A significant decrease in lipid oxidation evaluated by TBARS (Rao and Agarwal, 1998b) and
LDL oxidation evaluated by TBARS and conjugated dienes (Agarwal and Rao, 1998) was
seen after the supplementation for 1 week with tomato juice (about 50 mg/day lycopene),
spaghetti sauce (about 39 mg/day lycopene) or tomato oleoresin (about 75 mg/day lycopene).
This decrease was not shown by Steinberg and Chait (1998) who evaluated lipid peroxidation
by breath pentane excretion after tomato juice supplementation. It should be noted that some
of these effects may be due to vitamin E which is present as an additive in the spaghetti
sauces and oleoresin products.
DNA DAMAGE
Several studies support an antioxidant role for lycopene and/or tomato consumption on DNA
protection from oxidative damage. Even if still insufficient to extrapolate conclusive remarks,
a few intervention studies have been conducted with the aim to evaluate both the effect of
lycopene on endogenous and exogenous DNA damage. Thus the potential to protect against
"basal" and/or "induced" oxidative stress is considered.
The supplementation daily for 2 weeks with tomato juice (330 ml, 40 mg lycopene), but also
carrots and spinach, was shown to decrease the levels of endogenous strand breaks in
lymphocyte DNA evaluated with the comet assay, while after the ex vivo oxidative treatment
with H2O2 only the carrot intervention was effective (Pool-Zobel et al., 1997). Subsequently
the same authors suggested that the reduced genetic DNA damage in lymphocytes could be
attributed to the enhancement of cytosolic GSTP1, and DNA repair proteins by tomato and
carrot juices (Pool-Zobel et al., 1998).
Lower endogenous lymphocyte DNA oxidation evaluated by 8-OHdG was also reported by
Rao and Agarwal (1998b) after the daily consumption for 1 week of two types of spaghetti
sauces, a tomato juice and a lycopene rich oleoresin from tomato.
More recently it has been reported that also the consumption of a single serving of tomatoes
was sufficient to decrease the level of the mutagenic oxidized purine base 8-OHG. If these
results were confirmed there would be support for the ability of tomato in modulating
oxidative damage (Rehman et al., 1999).