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The impact of Mediterranean diet on MDA and 8-OHdG concentrations in urine of elderly persons: comparison in Croatian regions with different diet habits

Introduction: Free radicals and other reactive species are continuously generated in human organism causing oxidative damage. The most plausible theory of aging proposes that physiological changes of aging and higher rate of cancer are the consequence of the accumulation of random oxidative damage to DNA, lipids and proteins. It seems that the longevity and healthy aging in Mediterranean countries is the consequence of nutrition that contains natural antioxidans. The hypothesis of this study was that elderly residents on the Mediterranean part of Croatia have lower parameters of oxidative stress as compared to residents on the continental part. Methodology: For this study 22 apparently healthy residents of the Mediterranean (Omiš and island Vis, Dalmatian region) and 15 from continental part of Croatia (Virovitica and Zagreb regions) were selected from the initial group of 371 volunteers aged more than 74 years. Detailed clinical and laboratory check-up of blood and urine was performed in the whole initial group. The criteria for the participation in the study were: negative history for cardiovascular, respiratory, neurological or hepatic diseases, neoplasia, diabetes mellitus, arthritis, depression, alcoholism, and the absence of pathologic values in blood and urine parameters. In urine samples the concentrations of malondialdehyde (MDA) and 8-hydroxy-2’deoxyguanosine (8-OHdG) were analyzed using HPLC with UV-VIS and EC detectors, respectively. The distribution of both parameters of oxidative stress was normal (checked with Kolmogorof-Smirnov test) and the differences in urinary concentrations of MDA and 8-OHdG between the means of two groups were determined using two-tailed Student t-test. Probability values of p<0.05 were considered statistically significant. All subjects answered the detailed questionnaire on nutritional habits. Results: The concentration of MDA in urine of residents in continental part of Croatia (0.7910.106 mol/L ; MeanSEM) was significantly higher (P<0.05) than in the residents of Mediterranean part (0.4810.075 mol/L). The concentration of 8-OHdG in urine was also higher in continental part, but this difference was not significant (3.9300.644 nmol/L and 3.4900.593 nmol/L, respectively). The traditional Mediterranean diet contains different antioxidants that protect macromolecules from oxidative lesions in contrast to continental diet in Croatia which is based on higher meat and fat consumption. The consumption of fresh fruit and vegetables, as declared in the questionnaire was similar in both groups. About 47 % of subjects from continental region consume olive oil but the consumption of red wine is unusual (7%). In contrast, almost all subjects from Mediterranean group (96 %) consume olive oil and 41 % of subjects red wine. The Mediterranean group of subjects consumed much more frequently commodities containing antioxidants (sea-food, olive oil and red wine). Conclusion: Our results indicate that Mediterranean type of nutrition may have some beneficial effects in ageing and that in the protection from oxidative stress this type of diet should be complete.

oxidative stress; Mediterranean diet; MDA; 8-OHdG

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