Background: Dietary factors, such as antioxidant nutrients, contribute significantly to the maintenance of an appropriate balance between antioxidant defense and free radical production in the body. Objective: The objective of this study was to examine the relation between oxidative stress as assessed by plasma F2- isoprostane (IsoP) concentration, glycemic load (GL), glycemic index (GI), intake of antioxidant nutrients, dietary fiber, and polyunsaturated fatty acids (PUFAs). Methods: This study was a cross-sectional secondary analysis of baseline data collected from a random sample of 269 postmenopausal women participating in the Minnesota Green Tea Trial. GL, GI, and dietary variables were calculated from the diet history questionnaire. Subjects filled out surveys about the use of anti-inflammatory drugs and physical activity. Plasma IsoP concentration was assessed by GC-mass spectrometry. IsoP concentrations were compared across quartiles of GL, GI, insoluble fiber, PUFAs, and antioxidant nutrients with the use of linear regression. Results: Antioxidant supplement intake, including zinc, copper, vitamin C and vitamin E, was reported by > 60% of the participants. Mean intake of PUFAs was 12.5 g. Mean plasma IsoP concentrations increased from 34 to 36.7 pg/mL in the lowest quartiles of GL and GI, respectively, to 45.2 and 41.6 pg/mL, respectively, in the highest quartiles (P-trend = 0.0014 for GL and P-trend = 0.0379 for GI), whereasmean IsoP concentrations decreased from41.8 pg/mL in the lowest quartile of PUFAs to 34.9 pg/mL in the highest quartile (P-trend = 0.0416). Similarly, mean IsoP concentrations decreased from 44.4 pg/mL in the lowest quartile of insoluble fiber to 36 pg/mL in the highest quartile (P-trend = 0.0243) after adjustment for potential confounders. Conclusions: We concluded that dietary PUFAs and insoluble fiber are inversely associated with oxidative stress whereas GL and GI are positively associated with oxidative stress in postmenopausal women.
Bibliographical noteFunding Information:
Supported by National Cancer Institute, NIH grant R01 CA127236. Author disclosures: AYA, HS, MG, and MSK, no conflicts of interest. Address correspondence to AYA (e-mail: email@example.com). Abbreviations used: DHQI, diet history questionnaire I; GI, glycemic index; GL, glycemic load; IsoP, F2-isoprostane; MET, metabolic equivalent.
© 2017 American Society for Nutrition.
- Glycemic index
- Glycemic load
- Oxidative stress
- Polyunsaturated fatty acids
- Postmenopausal women