Both genetic and dietary factors underlie individual differences in DNA damage levels and DNA repair capacity.

The interplay between dietary habits and individual genetic make-up is assumed to influence risk of cancer, via modulation of DNA integrity. Our aim was to characterize internal and external factors that underlie inter-individual variability in DNA damage and repair and to identify dietary habits beneficial for maintaining DNA integrity. Habitual diet was estimated in 340 healthy individuals using a food frequency questionnaire and biomarkers of antioxidant status were quantified in fasting blood samples. Markers of DNA integrity were represented by DNA strand breaks, oxidized purines, oxidized pyrimidines and a sum of all three as total DNA damage. DNA repair was characterized by genetic variants and functional activities of base and nucleotide excision repair pathways. Sex, fruit-based food consumption and XPG genotype were factors significantly associated with the level of DNA damage. DNA damage was higher in women (p=0.035). Fruit consumption was negatively associated with the number of all measured DNA lesions, and this effect was mediated mostly by β-cryptoxanthin and β-tocopherol (p<0.05). XPG 1104His homozygotes appeared more vulnerable to DNA damage accumulation (p=0.001). Sex and individual antioxidants were also associated with DNA repair capacity; both the base and nucleotide excision repairs were lower in women and the latter increased with higher plasma levels of ascorbic acid and α-carotene (p<0.05). We have determined genetic and dietary factors that modulate DNA integrity. We propose that the positive health effect of fruit intake is partially mediated via DNA damage suppression and a simultaneous increase in DNA repair capacity.