Relationship between dietary antioxidant index (DAI) and antioxidants level in plasma of Kraków inhabitants

BACKGROUND: Some literature data indicate that antioxidant-rich food may significantly increase antioxidants in serum and decrease the oxidative stress but results are ambiguous. OBJECTIVES: The aim of this study was to estimate the total antioxidant capacity of food intake among the inhabitants of Krakow, Poland on the basis of dietary antioxidant index (DAI) and evaluation the relation between DAI and the level of antioxidants in plasma. MATERIAL AND METHODS: Examination included 70 (37 women and 33 men) non-smoking inhabitants of Krakow aged 46.4 ± 13.7 years. DAI was investigated on the basis of Food Frequency Questionnaire including 145 food items. DAI was measured using the method by Benzi and expressed as FRAP (mMol/L). In plasma samples total antioxidant status (TAS) expressed as FRAP and malondialdehyde (MDA) concentration as a marker of lipids peroxidation were measured. RESULTS: The mean value of DAI of all examined persons was 46.74 ± 25.5 mMol/L (in female group: 54.13 ± 27.7 mMol/L; in male group: 37.83 ± 19.5 mMol/L; p < 0.05). The highest contribution in total DWA value had fruits (48.7%) opposite to vegetables (9.3%). Statistically significant positive correlations between DAI and FRAP in plasma was found in all: r = 0.42 and in female: r = 0.54 groups (not significant in men group: r = 0.20). Statistically significant negative correlation of DAI with MDA (malonylaldehyde) in female (-0.49) and male (-0.51) groups. CONCLUSIONS: The obtained results confirmed the hypothesis that the intake of antioxidants in daily diet (measured as DAI) might increase antioxidants defense (measured by TAC as FRAP) and decrease oxidative stress (measured by MDA concentration in plasma). The dietary modification towards higher consumption of antioxidants (especially in men) should be highlighted in prevention of diseases in which oxidative stress play considerable role.