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Biomedical subjects

A Jacobs

Publications and source records attributed to A Jacobs.

At least 433 records · Page 24Linked to original sources

The formation of iron complexes with bile and bile constituents.

Inorganic iron is able to form complexes with whole bile and with some bile constituents and these remain soluble at neutral pH. Ascorbic acid does not appear to play a part in this process. The formation of soluble complexes in vivo is an important factor in maintaining intraluminal iron in a form available for absorption, and bile may have some importance in this respect.

Bile↗

Intraluminal transport of iron from stomach to small-intestinal mucosa.

Inorganic iron rarely exceeds 10(-4) molar concentration in the stomach after a meal. Natural sugars, ascorbic acid, citric acid, and amino-acids form iron complexes, and if they are present in the meal complexing occurs when the gastric contents are neutralized. In their absence an iron complex is formed with gastric mucopolysaccharide, which acts as a carrier, stable at neutral pH. Iron can be detached from this carrier at neutral pH by some low molecular weight substances, of which citric acid, ascorbic acid, and cysteine are particularly effective at low concentrations. Under normal circumstances most of the iron released from food in the stomach becomes bound to the mucopolysaccharide carrier.

Amino Acids↗

Availability of food iron.

Iron has been extracted from 25 common foods under conditions resembling those prevailing in the stomach under physiological conditions. In most cases less than half the iron in the foods is released into solution. The soluble iron is mainly in ionizable form, except in the case of meat products and black pudding. The amount of food iron released is influenced by cooking and the presence of iron-binding substances in some foods. The total dietary iron probably does not represent the amount available for absorption.

Cooking↗