Evidence for anti-inflammatory effects of combined administration of vitamin E and C in older persons with impaired fasting glucose: impact on insulin action.
OBJECTIVE
Vitamin E and C given separately improve insulin sensitivity due to an inhibitory effect on oxidative stress and inflammation, however their combined effect on glucose control and inflammation is unknown. To investigate combined effect of Vitamin E and C in elderly with Impaired Fasting Glucose (IFG) on insulin action and substrate oxidation.


METHODS
Controlled-trial administration of Vitamin E (1000 mg/day) and Vitamin C (1000 UI/day) for four weeks. Hyperinsulinemic euglycemic glucose clamp was performed before and following supplementation.


METHODS
Out-patient clinic.


METHODS
Thirteen older men with IFG.


METHODS
Variations in whole body glucose disposal (WBGD), anti-oxidant, and inflammatory cytokines plasma levels.


RESULTS
An increase in plasma Vitamin E (8.3 + 0.8 vs. 64.9 + 2.1 micromol/l; p < 0.001] and C (35.9 + 5.4 vs. 79.4 + 7.4 micromol/l; p < 0.001) was found. Vitamin administration reduced insulin, glucose, lipid, TNF-alpha and [8-]isoprostane levels. Increase in plasma vitamin E levels correlated with decline in both plasma [8-]isoprostane levels (r = -0.58; p = 0.048) and TNF-alpha levels (r = - 0.62; p = 0.025), while no correlations were found for Vitamin C. Whole body glucose disposal (WBGD) (22.7 + 0.6 vs. 30.4 + 0.8 mmol x kg-1 x min-1; p = 0.001) and non-oxidative glucose metabolism rose after supplementation. Rise in plasma levels of Vitamin C and E correlated with WBGD. Multivariate linear regression models showed independent associations among the change in Vitamin E and the decline in TNF-alpha and [8-]isoprostane levels.


CONCLUSIONS
Combined administration of Vitamin E and C lowered inflammation and improved insulin action through a rise in non-oxidative glucose metabolism.
Rizzo
Maria Rosaria
MR
Second University of Naples, Department of Geriatric Medicine and Metabolic Diseases, Naples, Italy.
Abbatecola
Angela Marie
AM
Barbieri
Michelangela
M
Vietri
Maria Teresa
MT
Cioffi
Michele
M
Grella
Rodolfo
R
Molinari
AnnaMaria
A
Forsey
Rosalyn
R
Powell
Jonathan
J
Paolisso
Giuseppe
G
D000368:Aged; D000893:Anti-Inflammatory Agents / Q000494:pharmacology* / Q000627:therapeutic use; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D001205:Ascorbic Acid / Q000494:pharmacology* / Q000627:therapeutic use; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D002318:Cardiovascular Diseases / Q000517:prevention & control*; D016207:Cytokines / Q000097:blood; D003924:Diabetes Mellitus, Type 2; D019587:Dietary Supplements; D005215:Fasting; D006801:Humans; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D007333:Insulin Resistance / Q000502:physiology; D008055:Lipids / Q000097:blood; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D014810:Vitamin E / Q000494:pharmacology* / Q000627:therapeutic use
D000893:Anti-Inflammatory Agents; D000975:Antioxidants; D001786:Blood Glucose; D016207:Cytokines; D007328:Insulin; D008055:Lipids; D014810:Vitamin E; D001205:Ascorbic Acid