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

Summary.

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 (T0), 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_2α, 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_2α in urine was also significantly lower (–53%, P < 0.05 compared with T0) 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.