title: γ-Tocopherol abolishes postprandial increases in plasma methylglyoxal following an oral dose of glucose in healthy, college-aged men.
abstract: Postprandial hyperglycemia contributes to the risk of cardiovascular disease in part by increasing concentrations of the reactive dicarbonyl methylglyoxal (MGO), a byproduct of glucose metabolism. Oxidative stress increases MGO formation from glucose in vitro and decreases its glutathione-dependent detoxification to lactate. We hypothesized that the antioxidant γ-tocopherol, a form of vitamin E, would decrease hyperglycemia-mediated postprandial increases in plasma MGO in healthy, normoglycemic, college-aged men. Participants (n=12 men; 22.3±1.0 years; 29.3±2.4 kg/m(2)) received an oral dose of glucose (75 g) in the fasted state prior to and following 5-day ingestion of a vitamin E supplement enriched in γ-tocopherol (500 mg/day). γ-Tocopherol supplementation increased (P<.0001) plasma γ-tocopherol from 2.22±0.32 to 7.06±0.71 μmol/l. Baseline MGO concentrations and postprandial hyperglycemic responses were unaffected by γ-tocopherol supplementation (P>.05). Postprandial MGO concentrations increased in the absence of supplemental γ-tocopherol (P<.05), but not following γ-tocopherol supplementation (P>.05). Area under the curve for plasma MGO was significantly (P<.05) smaller with the supplementation of γ-tocopherol than without (area under the curve (0-180 min), -778±1010 vs. 2277±705). Plasma concentrations of γ-carboxyethyl-hydroxychroman, reduced glutathione and markers of total antioxidant capacity increased after supplementation, and these markers and plasma γ-tocopherol were inversely correlated with plasma MGO (r=-0.48 to -0.67, P<.05). These data suggest that short-term supplementation of γ-tocopherol abolishes the oral glucose-mediated increases in postprandial MGO through its direct and indirect antioxidant properties and may reduce hyperglycemia-mediated cardiovascular disease risk.
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269-4017, USA.
authors.forename: Christopher
authors.initials: C
authors.lastname: Masterjohn
authors.forename: Eunice
authors.initials: E
authors.lastname: Mah
authors.forename: Yi
authors.initials: Y
authors.lastname: Guo
authors.forename: Sung I
authors.initials: SI
authors.lastname: Koo
authors.forename: Richard S
authors.initials: RS
authors.lastname: Bruno
mesh_terms: D000284:Administration, Oral; D000975:Antioxidants / Q000008:administration & dosage*; D002839:Chromans / Q000097:blood; D019587:Dietary Supplements; D005947:Glucose / Q000008:administration & dosage; D006801:Humans; D006943:Hyperglycemia / Q000378:metabolism; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D019518:Postprandial Period; D011765:Pyruvaldehyde / Q000097:blood*; D055815:Young Adult; D024504:gamma-Tocopherol / Q000008:administration & dosage* / Q000097:blood
chemical_list: D000975:Antioxidants; D002839:Chromans; C483420:carboxyethyl-hydroxychroman; D011765:Pyruvaldehyde; D024504:gamma-Tocopherol; D005947:Glucose