NO - Besoin d'assistance

Mechanisms and Biomarkers (WG 4) page 57
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resulted correlated with VLDL+LDL α-tocopherol (r=0.72) and β-carotene (r=0.80)
concentration. The authors concluded that the supplementation with antioxidant vitamins and
selenium increases the oxidation resistance of atherogenic lipoproteins in human plasma, and
suggested that when α-tocopherol and β-carotene concentrations in plasma and lipoproteins
are elevated to higher levels than usually achievable by diets, the plasma and lipoprotein
status of the major dietary antioxidants almost entirely determines the oxidation resistance of
VLDL and LDL.
Parfitt et al. (1994) found that plasma lipid peroxidation (conjugated dienes and lipid
peroxides) was significantly lower in a group of healthy young persons from Naples with
respect to a group from Bristol and this was related to a higher consumption of fresh
tomatoes, olive oil and vitamin E.
Recently Steinberg and Chait (1998) investigated the effect on smokers of daily consumption
of a tomato-based juice supplemented with vitamin C (600 mg), vitamin E (400 mg) and β-
carotene (30 mg) on various indexes of lipid peroxidation (breath pentane excretion and
susceptibility of LDL to copper-mediated oxidation). Compared with the results obtained with
the placebo juice, the vitamin-supplemented juice resulted in an increased protection against
lipid peroxidation. Furthermore, the increased concentration of plasma vitamin C, β-carotene
and lycopene correlated significantly with the conjugated diene lag phase. These results
suggest the importance of the concomitant presence of these antioxidants supporting the
hypothesis of a mutual interaction.
DNA Damage
The antioxidant activity of compounds such as vitamin C, E and β-carotene in relation to
DNA damage has been studied more than that of lycopene. Beyond the evaluation of the
oxidized base 8-OHdG and the single strand breaks by the comet assay, DNA damage has
been also investigated by means of bleomycin-induced chromosomal damage assay, nucleoid
sedimentation, post-labelling , micronucleus assay and sister chromatid exchange.
Vitamin E - The association of dietary or plasma vitamin E concentrations and mutagen
sensitivity in healthy populations has not been demonstrated.
High intake of vitamin E has been associated with reduced risk for cancer (Bostik et al.,
1993; Salonen et al., 1985), however it is not known whether it can exert its effect directly by
inhibiting the initiating and/or later stage of cancer or by enhancing the immune response