Summary

Background: Fat tissue mediates the production of inflammatory cytokines and oxidative products, which are key steps in the development of type 2 diabetes and atherosclerosis. Antioxidant-rich diets protect against chronic diseases, but antioxidants may interfere with pro-inflammatory signals.

Objectives: To investigate the effect of the potent tomato-derived antioxidant carotenoid, lycopene, on plasma antioxidants (carotenoids and vitamin E), inflammatory markers (C-reactive protein, interleukin-6, tumor necrosis factor-alpha), and oxidation products (conjugated dienes).

Methods: Eight obese patients (body mass index 37.5 ± 2.5 kg/m²) were compared with a control group of eight lean, age and gender-matched subjects (BMI[1] 21.6 ±  0.6 kg/m²), before and after 4 weeks of lycopene supplementation (tomato-derived Lyc-O-Mato) (30 mg daily).

Results: Plasma carotenoids were significantly reduced in the obese compared to control subjects (0.54 ± 0.06 vs. 0.87 ± 0.08 mg/ml, P < 0.01). CRP[2] levels were significantly higher (6.5 vs. 1.1 mg/L, P = 0.04) in obese vs. controls, as were IL-6[3] and conjugated dienes (3.6 and 7.9-fold, respectively). CRP, IL-6 and conjugated dienes correlated with BMI, while IL-6 and conjugated dienes correlated inversely with carotenoids (P < 0.05). Following lycopene treatment, a significant elevation of plasma carotenoids (1.79 vs. 0.54 ug/ml) and specifically lycopene (1.15 vs 0.23 ug/ml) (P < 0.001) occurred in the treatment vs. placebo group, respectively. Markers of inflammation and oxidation products were not altered by lycopene.

Conclusions: Obese patients showed abnormally higher markers of inflammation and oxidation products and lower plasma carotenoids. The lack of reduction of pro-inflammatory markers could be attributed to the short period of the study and the small number of participants. More studies are needed on the protective qualities of natural antioxidant-rich diets against obesity-related co-morbidities.