MnSOD and CAT polymorphisms modulate the effect of the Mediterranean diet on breast cancer risk among Greek-Cypriot women

Purpose Oxidative stress arises due to a cellular imbalance in oxidants and antioxidants and/or due to an altered activity of antioxidant enzymes, caused by SNPs. Oxidative stress increases susceptibility to breast cancer (BC) risk, and we previously showed that the Mediterranean diet (MD), which is rich in antioxidants, reduces BC risk in Greek-Cypriot women. Here, we investigated the effect of MnSOD (p.Val16Ala, rs4880) and CAT (-262C>T, rs1001179) SNPs on the association between the MD and BC risk in the case–control study of BC MASTOS in Cyprus. Methods Dietary intake data were obtained using a 32-item food frequency questionnaire, from which a dietary pattern was previously derived, using principal component analysis. This pattern included high loadings of vegetables, fruit, legumes and fish, a combination that closely resembles the MD and was used as our dietary variable. Results High vegetable intake lowered BC risk in women with at least one MnSOD Val allele (OR High vs. Low for Val/Val = 0.56, 95 % CI 0.35–0.88, for Val/Ala = 0.57, 95 % CI 0.39–0.82), or one CAT -262C allele (OR High vs. Low for -262CC = 0.66, 95 % CI 0.47–0.92, for -262CT = 0.53, 95 % CI 0.35–0.81). High fish intake conferred a decreased BC risk of CAT -262CC women (OR Q4 vs. Q1 0.66, 95 % CI 0.47–0.92) compared with the CAT -262TT women and low fish intake (OR Q2 vs. Q1 2.79, 95 % CI 1.08–7.17). Additionally, high fish intake reduced BC risk in MnSOD Val/Val women (OR Q4 vs. Q1 0.63, 95 % CI 0.40–0.98). p interaction values were, however, not statistically significant. Conclusion Our results demonstrate that the antioxidative effects of the MD against BC risk may be enhanced by the wild-type alleles of the MnSOD or CAT SNPs among Greek-Cypriot women.