Possible Interaction: Glucose and Vitamin C

“Significance: Vitamin C bioavailability may be inhibited by dietary factors, such as glucose and phytochemicals.”

“To determine if ascorbic acid or its oxidized form can inhibit tissue uptake of glucose , the brain uptake index (BUI) and muscle uptake index of glucose were determined by single arterial injection tissue-sampling technique.”

“We conclude that dehydroascorbic acid, but not ascorbic acid , inhibits in vivo brain but not muscle uptake of glucose , suggesting a common carrier system at the level of the blood-brain barrier.”

“The data clearly show that ascorbic acid uptake is inhibited instantly by glucose in a concentration dependent fashion.”

“ Glucose in concentrations of 20 mg% (or greater) significantly inhibited 14C-labelled ascorbic acid (1.25 mg%) uptake in endothelial cells in the presence of insulin (1600 microU/ml).”

“Increased ascorbic acid concentrations (two-fold) in the absence of insulin (1) significantly enhanced uptake, and (2) reversed the inhibition of glucose.”

“ Ascorbic acid is reported to interfere with the measurement of glucose , total cholesterol, triglycerides, and uric acid [2,3,4,5].”

“Pharmacological doses of VC induce oxidative stress, GSH depletion, and increased glucose flux through the oxidative pentose phosphate pathway (PPP) in erythrocytes.”

“Inhibition of vitamin C transport by glucose had a cytotoxic effect on the cells.”

“ POC glucose monitoring should be avoided during and after vitamin C therapy.”

“ Ascorbic acid prevented the decreased response to acetylcholine after glucose , the response to nitroprusside was unaffected by ascorbic acid.”

“Treatment with ascorbic acid prevented the decrease in hyperemia after glucose , detected with laser Doppler and plethysmography.”

“Moreover, Title et al (2000) reported …-mediated dilation in healthy subjects by oral glucose … vitamins C and E. It has also been reported that administration of (6R)-5,6,7,8-tetrahydrobiopterin, but …-tetrahydrobiopterin, can reverse the transient glucose-induced endothelial dysfunction in healthy individuals (Ihlemann et al 2003).”