Diet, iron biomarkers and oxidative stress in a representative sample of Mediterranean population

BACKGROUND The consumption pattern characterized by high consumption of vegetables, fruit, fish, olive oil and red wine has been associated with improvements in the total antioxidant capacity of individuals and reduced incidence of diseases related to oxidation. Also, high body iron levels may contribute to increase the oxidative stress by the generation of reactive oxygen species. The objective of this study is to analyze the relationship between antioxidant and pro-oxidant factors obtained from the diet and iron biomarkers on lipoprotein oxidation and total antioxidant capacity in a representative sample of the Mediterranean population. METHODS Cross-sectional prospective study, carried out with 815 randomly selected subjects (425 women and 390 men). Dietary assessment (3-day food records), iron biomarkers (serum ferritin, serum iron and transferrin saturation), biochemical markers of lipoperoxidation (TBARS), antioxidant capacity (ORAC) and CRP (C-Reactive Protein) were determined. Multiple Linear Regression (MLR) models were applied to analyze the association between diet factors and iron biomarkers on TBARS and ORAC levels. RESULTS We observed that lipoperoxidation measured by TBARS increased by age but no differences were observed by sex. Antioxidant capacity measured by ORAC is independent of age and sex. In general, increasing age, tobacco, heme iron intake from meat and fish and transferrin saturation were independently and positively associated with TBARS, while non-heme iron was negatively associated. Vegetables, vitamin C intake and serum ferritin were positively associated with ORAC, whereas saturated fatty acids and meat intake were negatively associated. CONCLUSIONS In our general population, we observed that oxidative stress is related to aging, but antioxidant capacity is not. The highest intake of dietary non-heme iron, vegetables and vitamin C intake exerts a protective effect against oxidation while the highest intake of dietary heme iron from meat and fish and saturated fatty acids are associated with increased oxidative stress. High levels of circulating iron measured by transferrin saturation are associated with increased oxidative stress in women however its association with the higher levels of serum ferritin is controversial.