Relations of glycemic index and glycemic load with plasma oxidative stress markers.
BACKGROUND
Recent data suggest that acute hyperglycemia may increase in vivo free radical production. This increased production has been implicated in many disease processes.


OBJECTIVE
The objective was to investigate whether a diet with a high glycemic index (GI) or glycemic load (GL) is associated with greater oxidative stress as measured by 2 lipid peroxidation markers, malondialdehyde (MDA) and F2-isoprostanes (IsoPs).


METHODS
Plasma MDA and IsoP concentrations were measured in 292 healthy adults, and dietary GI and GL were assessed by using a validated food-frequency questionnaire. Cross-sectional associations between GI, GL, and the 2 markers were examined by using multiple regression techniques with adjustment for potential confounding variables.


RESULTS
Dietary GI was positively associated with both plasma MDA and IsoPs. The mean multivariate-adjusted MDA concentrations increased from 0.55 to 0.73 micromol/L as GI increased from the lowest to the highest quartile (P for trend = 0.02); the corresponding IsoP concentrations increased from 0.034 to 0.040 ng/mL (P for trend = 0.03). GL was positively associated with both MDA and IsoPs, but the linear relation was significant only for MDA. In addition, a marginally significant interaction between overall GI and body mass index (BMI; in kg/m2) for plasma MDA was observed (P = 0.09). The positive association between overall GI and MDA was stronger in those with a BMI < 26.5 than for those with a BMI > or = 26.5.


CONCLUSIONS
Chronic consumption of high-GI foods may lead to chronically high oxidative stress. A low-GI diet, not a low-carbohydrate diet, appears to be beneficial in reducing oxidative stress.
Hu
Youqing
Y
Division of Epidemiology, School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA.
Block
Gladys
G
Norkus
Edward P
EP
Morrow
Jason D
JD
Dietrich
Marion
M
Hudes
Mark
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004040:Dietary Carbohydrates / Q000145:classification / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D028441:F2-Isoprostanes / Q000097:blood / Q000378:metabolism; D005260:Female; D038321:Glycemic Index; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D008315:Malondialdehyde / Q000097:blood / Q000378:metabolism; D008875:Middle Aged; D015999:Multivariate Analysis; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology*; D012044:Regression Analysis; D012907:Smoking; D011795:Surveys and Questionnaires; D014028:Tobacco Smoke Pollution
D004040:Dietary Carbohydrates; D028441:F2-Isoprostanes; D014028:Tobacco Smoke Pollution; D008315:Malondialdehyde