Protective activity of tomato products on in vivo markers of lipid oxidation

Background It has been suggested that regular consumption of tomato products improves antioxidant defenses due to their endogenous antioxidant compounds, notably lycopene. Aim of the study We evaluated the effects of tomato consumption on parameters of lipid oxidation in healthy human volunteers. Methods Twelve females (enrolled at T-7), after a one-week of carotenoid-poor diet (TO), were instructed to supplement the same diet with different tomato products (raw, sauce, and paste), thereby providing approximately eight mg lycopene/day for three weeks (T21). Blood samples were periodically collected in order to evaluate plasma carotenoid concentrations, plasma antioxidant capacity, and susceptibility of LDL to metal ion-induced oxidation. Furthermore, 8-iso-PGF(2alpha), a marker of in vivo oxidative stress, was analyzed in the 24-hour urine. Results Carotenoid concentrations decreased significantly during the carotenoid-poor diet (P < 0.05), while lycopene concentrations increased significantly after tomato consumption (P < 0.001). The antioxidant capacity of plasma did not vary during the study. Conversely, LDL oxidizability decreased after tomato consumption, as demonstrated by a shortening of the lag phase (P < 0.001). This parameter was significantly correlated with lycopene concentration (r = 0.36, P < 0.05). The excretion of 8-iso-PGF(2alpha) in urine was also significantly lower (-53 %, P < 0.05 compared with TO) after tomato supplementation. Conclusions These results further support a role for tomato products in the prevention of lipid peroxidation, a risk factor of atherosclerosis and cardiovascular disease.