TITLE:
Effect of Ginkgo biloba Extract Ingestion on Plasma Total Cortisol Levels during an Oral Glucose Tolerance Test in Normal Glucose Tolerant Individuals
AUTHORS:
George B. Kudolo
KEYWORDS:
Ginkgo biloba Extract, Cortisol, Acute Hyperglycemia
JOURNAL NAME:
Food and Nutrition Sciences,
Vol.5 No.16,
August
27,
2014
ABSTRACT: Protracted periods
of increased cortisol production, as may be seen in an acute illness, may lead
to transient hyperglycemia. Increasing evidence suggests that cortisol may then
mediate the development of insulin resistance and potentially lead to the
development of overt diabetes. Evidence in animal studies also suggests that
under conditions of stress Ginkgo biloba extract could reduce plasma cortisol production and so the primary aim of this
study was to determine the effect of Ginkgo
biloba extract ingestion on plasma cortisol production during an acute
period of glucose challenge. Healthy non-diabetic, glucose tolerant volunteers
(n = 30, (10/20, M/F); age, 45.7 ± 9.9 years old) completed a randomized,
double-blind, placebo-controlled crossover study when they ingested Ginkgo biloba extract (120 mg/day as a
single dose) and placebo during each 3-month arm. A standard 75 g oral glucose
tolerance test was performed at the end of each cycle and blood was collected
and used to measure plasma glucose, insulin, c-peptide and cortisol. Fasting
plasma cortisol was significantly lower after the Ginkgo biloba cycle than the placebo cycle (326 ± 149 vs. 268 ± 121
nmol/L, respectively; p = 019). The plasma cortisol area under the curve during
the 2-hour test (AUC0-2) was also significantly lower after
ingestion of the Ginkgo biloba cycle
compared to the placebo (668 ± 265 vs. 530 ± 213 nmol/L/h, respectively; p Ginkgo biloba extract has effect on the
hypothalamic-pituitary-adrenal axis leading to reduced basal cortisol levels
and reduced cortisol production in response to acute hyperglycemic challenge.