Association between healthy dietary patterns and markers of oxidative stress in the Sister Study

Purpose: We assessed the cross-sectional association between healthy dietary patterns [alternate Mediterranean diet (aMED), Dietary Approaches to Stop Hypertension (DASH), alternative Healthy Eating Index (aHEI), and Healthy Eating Index 2015 (HEI-2015)] and urinary biomarkers of oxidative stress.Methods: Between 2003 and 2009, the Sister Study enrolled 50,884 breast cancer-free US women aged 35 to 74 (non-Hispanic White, 83.7%). Data were analyzed for 844 premenopausal and 454 postmenopausal women who had urine samples analyzed for F-2-isoprostanes and non-missing covariate data. Food frequency questionnaire responses were used to calculate dietary pattern scores. Concentrations of 8-iso-prostaglandin F-2 alpha (8-iso-PGF(2 alpha)) and its metabolite (8-iso-PGF(2 alpha)-M) were measured in urine samples by GC/MS for premenopausal women and LC/MS for postmenopausal women. Multivariable linear regression models were used to estimate associations between aMED, DASH, aHEI, and HEI-2015 and urinary F-2-isoprostanes by menopausal status. Effect modification by sociodemographic, lifestyle, and clinical characteristics was also evaluated.Results: Among premenopausal women, the four dietary indices were inversely associated with 8-iso-PGF(2 alpha) (aMED beta(Q4vsQ1): - 0.17, 95% CI - 0.27, - 0.08; DASH beta(Q4vsQ1): - 0.18, 95% CI - 0.28, - 0.08; aHEI beta(Q4vsQ1): - 0.20, 95% CI - 0.30, - 0.10; HEI-2015 beta(Q4vsQ1): - 0.19, 95% CI - 0.29, - 0.10). In contrast, inverse associations with 8-iso-PGF(2 alpha)-M were found for the continuous aMED, aHEI, and HEI-2015. Associations between dietary indices and 8-iso-PGF(2 alpha) were generally stronger among younger women, women with lower income, and women with higher BMI. Similar results were observed among postmenopausal women, though only the continuous DASH and aHEI models were statistically significant.Conclusion: Healthy dietary patterns were associated with lower levels of oxidative stress.