TY - JOUR
T1 - Megadose of vitamin C delays insulin response to a glucose challenge in normoglycemic adults
AU - Johnston, Carol
AU - Yen, Mei Fang
PY - 1994/11
Y1 - 1994/11
N2 - The effect of a megadose of ascorbic acid (AA) on glucose and insulin responses after an oral-glucose-tolerance test (OGTT) is unknown. With a double-blind, placebo-controlled design, nine normoglycemic subjects (22 ± 1 y, x̄ ± SEM) consumed AA (2 g/d) or placebo for 2 wk after a 2-wk washout period with placebo, and an OGTT was performed after an overnight fast. This 4-wk protocol was repeated in a crossover fashion. Plasma glucose was significantly elevated 1-h postprandial in vitamin C-saturated subjects vs those taking a placebo. The plasma insulin response curve was shifted rightward in vitamin C-saturated subjects relative to baseline: plasma insulin was significantly depressed at 0.5 h postprandial but significantly elevated at 2 h postprandial. These data indicate that elevated plasma AA delays the insulin response to a glucose challenge in normoglycemic adults, thereby prolonging the postprandial hyperglycemia. These effects might be partially explained by the competitive inhibition of glucose transfer into pancreatic β cells by high concentrations of circulating AA.
AB - The effect of a megadose of ascorbic acid (AA) on glucose and insulin responses after an oral-glucose-tolerance test (OGTT) is unknown. With a double-blind, placebo-controlled design, nine normoglycemic subjects (22 ± 1 y, x̄ ± SEM) consumed AA (2 g/d) or placebo for 2 wk after a 2-wk washout period with placebo, and an OGTT was performed after an overnight fast. This 4-wk protocol was repeated in a crossover fashion. Plasma glucose was significantly elevated 1-h postprandial in vitamin C-saturated subjects vs those taking a placebo. The plasma insulin response curve was shifted rightward in vitamin C-saturated subjects relative to baseline: plasma insulin was significantly depressed at 0.5 h postprandial but significantly elevated at 2 h postprandial. These data indicate that elevated plasma AA delays the insulin response to a glucose challenge in normoglycemic adults, thereby prolonging the postprandial hyperglycemia. These effects might be partially explained by the competitive inhibition of glucose transfer into pancreatic β cells by high concentrations of circulating AA.
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U2 - 10.1093/ajcn/60.5.735
DO - 10.1093/ajcn/60.5.735
M3 - Article
C2 - 7942581
AN - SCOPUS:0028032791
SN - 0002-9165
VL - 60
SP - 735
EP - 738
JO - American Journal of Clinical Nutrition
JF - American Journal of Clinical Nutrition
IS - 5
ER -