Vascular consequences of a high-fat meal in physically active and inactive adults


Journal Title (Medline/Pubmed accepted abbreviation): Appl Physiol Nutr Metab
Year: 2011
Volume: 36
Page numbers:368-375
doi (if applicable):

Summary of background and research design

Hypothesis: The authors cited some data indicating that physically active people have a lesser increase in postprandial triglyceridemia compared with inactive persons consuming the same meal. They also stated that regular physical activity can improve endogenous antioxidant defenses. Thus, the authors hypothesized that physically active people would have a less negative response (i.e., lower postprandial triglycerides, less oxidative stress, better endothelial response) to a high fat meal compared with inactive control subjects.

Subjects: 14 subjects (7 physically active, 7 inactive; 4 males and 3 females in each group) were matched for body mass index (BMI), height, weight, and age. Subjects were nonsmokers, and healthy. Subjects were classified as active if they participated in physical activity 3 or more times per week for at least 30 min per session at an intensity defined as moderate or greater. Inactive subjects participated in less than 30 min of moderate physical activity per week.

Experimental design: Independent groups

Treatments:The subjects were fed a fatty meal challenge containing 940 kcal, 48 g fat (46% total energy), 16.5 g saturated fat, 4.5 g trans fat, 280 mg cholesterol, 91 g carbohydrate, 33 g protein, and 2200 mg sodium. The meal was served with water ad libitum.

Protocol:Subjects reported to the laboratory at 0700 hours after fasting overnight for 12 hours and having abstained from exercise for 24 hours. At 0730 and 4 hours after the fatty meal challenge, blood samples were collected and flow mediated vasodilation measures were obtained. The fatty meal challenge was fed at 0800 hours. Blood samples were analyzed for markers of oxidative stress (thiobarbituric acid reactive substances, or TBARS), antioxidant activity (superoxide dismutase),and lipemia (plasma triglycerides). Flow mediated vasodilation was measured in the brachial artery as a marker of endothelial function using an ultrasound technique.
 
Summary of research findings
  • Both groups experienced significant increases in plasma triglycerides after the fatty challenge meal compared with baseline.  However, although the increase in triglycerides was somewhat greater in the inactive group, the difference in magnitude of change between the two groups was not significant.
  • TBARS were significantly lower at baseline in the inactive group versus the active group.  There were no differences between groups in the magnitude of change after the fatty challenge meal.
  • Superoxide dismutase activity was lower in the inactive group at both baseline and after the fatty challenge meal compared with the active group.
  • Only the inactive group experienced a decline in flow mediated vasodilation after the fatty challenge meal compared with baseline.

Interpretation of findings/Key practice applications

Although the between group comparisons were generally not significant, it appeared that the physically active subjects better tolerated the fatty meal challenge. There were a number of limitations in this study, however. First, because of differences at baseline, analysis of covariance with transformed data (baseline as the covariate) might have been a more appropriate statistical technique. Second, there was only 1 postprandial blood draw at 4 h post and a full lipid profile was not performed. Third, feeding of labeled fatty acids would have helped determine if the rise in postprandial triglycerides actually comprised the fat that had just been eaten. Some evidence indicates that the rise in postprandial triglycerides is actually due to fat consumed at meals occurring before the most immediate meal.

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