title: Acute effects of dietary glycemic index on antioxidant capacity in a nutrient-controlled feeding study.
abstract: Oxidative stress, caused by an imbalance between antioxidant capacity and reactive oxygen species, may be an early event in a metabolic cascade elicited by a high glycemic index (GI) diet, ultimately increasing the risk for cardiovascular disease and diabetes. We conducted a feeding study to evaluate the acute effects of low-GI compared with high-GI diets on oxidative stress and cardiovascular disease risk factors. The crossover study comprised two 10-day in-patient admissions to a clinical research center. For the admissions, 12 overweight or obese (BMI: 27-45 kg/m(2)) male subjects aged 18-35 years consumed low-GI or high-GI diets controlled for potentially confounding nutrients. On day 7, after an overnight fast and then during a 5-h postprandial period, we assessed total antioxidant capacity (total and perchloric acid (PCA) protein-precipitated plasma oxygen radical absorbance capacity (ORAC) assay) and oxidative stress status (urinary F(2alpha)-isoprostanes (F(2)IP)). On day 10, we measured cardiovascular disease risk factors. Under fasting conditions, total antioxidant capacity was significantly higher during the low-GI vs. high-GI diet based on total ORAC (11,736 +/- 668 vs. 10,381 +/- 612 micromol Trolox equivalents/l, P = 0.002) and PCA-ORAC (1,276 +/- 96 vs. 1,210 +/- 96 micromol Trolox equivalents/l, P = 0.02). Area under the postprandial response curve also differed significantly between the two diets for total ORAC and PCA-ORAC. No diet effects were observed for the other variables. Enhancement in plasma total antioxidant capacity occurs within 1 week on a low-GI diet, before changes in other risk factors, raising the possibility that this phenomenon may mediate, at least in part, the previously reported effects of GI on health.
authors: Department of Medicine, Children's Hospital Boston, Boston, Massachusetts, USA.
authors: Diego
authors: D
authors: Botero
authors: Cara B
authors: CB
authors: Ebbeling
authors: Jeffrey B
authors: JB
authors: Blumberg
authors: Judy D
authors: JD
authors: Ribaya-Mercado
authors: Mark A
authors: MA
authors: Creager
authors: Janis F
authors: JF
authors: Swain
authors: Henry A
authors: HA
authors: Feldman
authors: David S
authors: DS
authors: Ludwig
mesh_terms: D000293:Adolescent; D000328:Adult; D000975:Antioxidants / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001786:Blood Glucose / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology; D018592:Cross-Over Studies; D050528:Diet, Carbohydrate-Restricted; D004040:Dietary Carbohydrates / Q000009:adverse effects*; D002149:Energy Intake; D028441:F2-Isoprostanes / Q000652:urine; D005215:Fasting / Q000097:blood; D038321:Glycemic Index; D006801:Humans; D006943:Hyperglycemia / Q000097:blood* / Q000209:etiology; D007328:Insulin / Q000097:blood; D008297:Male; D009765:Obesity / Q000097:blood / Q000150:complications / Q000178:diet therapy*; D018384:Oxidative Stress; D019518:Postprandial Period; D013997:Time Factors; D055815:Young Adult
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D028441:F2-Isoprostanes; D007328:Insulin