Journal
JOURNAL OF NUTRITIONAL BIOCHEMISTRY
Volume 24, Issue 1, Pages 196-203Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.jnutbio.2012.04.015
Keywords
Vascular endothelial function; Flow-mediated dilation; Hyperglycemia; gamma-Tocopherol
Funding
- International Life Sciences Institute
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Postprandial hyperglycemia induces oxidative stress responses, impairs vascular endothelial function (VEF) and increases the risk of cardiovascular disease. We hypothesized that the antioxidant and anti-inflammatory activities of a gamma-tocopherol-rich mixture of tocopherols (gamma-TmT) would protect against vascular dysfunction that is otherwise caused by postprandial hyperglycemia by decreasing oxidative stress and proinflammatory responses, and improving nitric oxide (NO center dot) homeostasis. In a randomized, crossover study, healthy men (n=15; 21.8 +/- 0.8 years) completed a fasting oral glucose challenge (75 g) with or without prior supplementation of gamma-TmT (5 days). Brachial artery flow-mediated dilation (FMD), plasma glucose, insulin, antioxidants, malondialdehyde (MDA), inflammatory proteins, arginine and asymmetric dimethylarginine (ADMA) were measured at regular intervals during a 3-h postprandial period. Supplementation of gamma-TmT increased (P<.05) plasma gamma-T by threefold and gamma-carboxyethyl-hydroxychroman by more than ninefold without affecting alpha-T, glucose, arginine or ADMA. Baseline FMD, MDA, arginine and ADMA were unaffected by gamma-TmT (P>.05). Postprandial FMD decreased 30%-44% (P<.05) following glucose ingestion, but was maintained with gamma-TmT. Supplementation of gamma-TmT also attenuated postprandial increases in MDA that occurred following glucose ingestion. Plasma arginine decreased (P<.05) in both trials to a similar extent regardless of gamma-TmT supplementation. However, the ratio of ADMA/arginine increased time-dependently in both trials (P<.05), but to a lesser extent following gamma-TmT supplementation (P<.05). Inflammatory proteins were unaffected by glucose ingestion or gamma-TmT. Collectively, these findings support that short-term supplementation of gamma-TmT maintains VEF during postprandial hyperglycemia possibly by attenuating lipid peroxidation and disruptions in NO center dot homeostasis, independent of inflammation. Published by Elsevier Inc.
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