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Influence of Ascorbic Acid on the Thermic Effect of Feeding in Overweight and Obese Adult Humans
Author(s) -
Newsom Sean A.,
Paxton Roger J.,
Rynn Grant M.,
Bell Christopher
Publication year - 2008
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1038/oby.2008.304
Subject(s) - ascorbic acid , medicine , endocrinology , respiratory quotient , overweight , respiratory exchange ratio , thermogenesis , resting energy expenditure , postprandial , obesity , energy expenditure , heart rate , chemistry , blood pressure , insulin , food science
The thermic effect of feeding (TEF: increase in energy expenditure following acute energy intake) is an important physiological determinant of total daily energy expenditure and thus energy balance. Approximately 40% of TEF is believed to be mediated by sympathoadrenal activation and consequent β‐adrenergic receptor stimulation of metabolism. In sedentary adults, acute administration of ascorbic acid, a potent antioxidant, augments the thermogenic response to β‐adrenergic stimulation. We hypothesized that acute ascorbic acid administration augments TEF in sedentary overweight and obese adults. Energy expenditure was determined (ventilated hood technique) before and 4 h after consumption of a liquid‐mixed meal (caloric equivalent 40% of resting energy expenditure (REE)) in 11 sedentary, overweight/obese adults (5 men, 6 women; age: 24 ± 2 years; BMI: 28.5 ± 1.0 kg/m 2 (mean ± s.e.)) on two separate, randomly ordered occasions: during continuous intravenous administration of saline (placebo control) and/or ascorbic acid (0.05 g/kg fat‐free mass). Acute ascorbic acid administration prevented the increase in plasma concentration of oxidized low‐density lipoprotein in the postprandial state ( P = 0.04), but did not influence REE (1,668 ± 107 kcal/day vs.1,684 ± 84 kcal/day; P = 0.91) or the area under the TEF response curve (33.4 ± 2.4 kcal vs. 30.5 ± 3.6 kcal; P = 0.52) (control vs. ascorbic acid, respectively). Furthermore, acute ascorbic acid administration had no effect on respiratory exchange ratio, heart rate, or arterial blood pressure in the pre‐ and postabsorptive states (all P > 0.64). These data imply that the attenuated TEF commonly observed with sedentary lifestyle and obesity is not modulated by ascorbic acid‐sensitive oxidative stress.