Factors Affecting Vitamin C Absorption Using Rat Everted Gut Sac Model

Abstract

Vitamin C (L-ascorbic acid), is water-soluble vitamin that is naturally present. Humans and guinea pig are unable to
synthesize ascorbic acid endogenously, due to series of inactivating mutations of the gene encoding gulonolactone
oxidase (GULO); this enzyme is responsible for vitamin C synthesis. Ascorbic acid is a potent reducing agent, it has
two major functions as an antioxidant and as an enzyme cofactor.
The study aimed to study different physiological factors as pH and temperature that may affect the absorption of
ascorbic acid in rat ileum; also the effect of nicotine on ascorbic acid absorption was studied. Everted gut sac model
was adopted throughout all the work. Each treated group is repeated for five times.
It is concluded that, ascorbic acid ideal absorption is at pH 7 (normal physiological condition). At acidic and alkaline
media ascorbic acid absorption is decreased. The highest absorption level of ascorbic acid was at 37o
C (normal
physiological condition); while the absorption is decreased when the temperature increase (39o
C) or decrease (35o
C).
Nicotine reduces the absorption of ascorbic acid significantly (P ≤0.05).