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  • Author: Kelsey H. Fisher-Wellman x
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Kelsey H. Fisher-Wellman and Richard J. Bloomer

Background:

Carbohydrate powder in the form of maltodextrin is widely used by athletes for postexercise glycogen resynthesis. There is some concern that such a practice may be associated with a postprandial rise in reactive oxygen and nitrogen species production and subsequent oxidation of macromolecules. This is largely supported by findings of increased oxidative-stress biomarkers and associated endothelial dysfunction after intake of dextrose.

Purpose:

To compare the effects of isocaloric dextrose and maltodextrin meals on blood glucose, triglycerides (TAG), and oxidative-stress biomarkers in a sample of young healthy men.

Methods:

10 men consumed isocaloric dextrose and maltodextrin powder drinks (2.25 g/kg) in a random-order, crossover design. Blood samples were collected premeal (fasting) and at 1, 2, 4, and 6 hr postmeal and assayed for glucose, TAG, malondialdehyde, hydrogen peroxide, nitrate/nitrite, and Trolox-equivalent antioxidant capacity.

Results:

Significant meal effects were noted for glucose total area under the curve (p = .004), with values higher for the dextrose meal. No other statistically significant meal effects were noted (p > .05). With respect to the 2 (meal) × 5 (time) ANOVA, no significant interaction, time, or meal effects were noted for any variable (p > .05), with the exception of glucose, for which a main effect for both meal (p < .0001) and time (p = .0002) was noted.

Conclusions:

These data indicate that carbohydrate meals, consumed as either dextrose or maltodextrin, pose little postprandial oxidative insult to young, healthy men. As such, there should be minimal concern over such feedings, even at high dosages, assuming adequate glucose metabolism.

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Richard J. Bloomer, Bradford Cole and Kelsey H. Fisher-Wellman

High-kilocalorie feedings induce oxidative stress. Acute exercise has the potential to attenuate postprandial oxidative stress. No study has determined whether there are racial differences in postprandial oxidative stress with and without a preceding bout of acute exercise.

Purpose:

To investigate the impact of acute exercise on blood oxidative- stress biomarkers, triglycerides (TAG), and glucose in African American (AA) and White (W) women.

Methods:

10 AA (age 29 ± 3 yr, body-mass index [BMI] 31 ± 3 kg/m2) and 10 W (age 30 ± 2 yr, BMI 30 ± 3 kg/m2) women consumed a meal of 1.2 g of fat and carbohydrate and 0.25 g of protein per kilogram body mass, on 2 occasions—with and without a session of aerobic exercise 15 min preceding the meal (45 min cycling at 65% heart-rate reserve)—in a random-order crossover design. Blood samples were collected premeal (fasted), and at 1, 2, 4, and 6 hr postmeal and assayed for TAG, glucose, xanthine oxidase activity, hydrogen peroxide (H2O2), and malondialdehyde (MDA). Area under the curve (AUC) was calculated for each variable.

Results:

AUC was lower for AA compared with W for both the exercise and the no exercise conditions for H2O2, MDA, and TAG (p < .01). However, acute exercise had no effect on decreasing the AUC for any variable in either AA or W women (p > .05).

Conclusions:

Postprandial lipemia and oxidative stress are lower in AA than in W overweight/obese women. However, acute exercise, performed at the intensity and duration in the current study, does not influence postprandial lipemia or oxidative stress in AA or W women.