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Phytase activity in the human and rat small intestine
T H Iqbal1, K O Lewis, B T Cooper
1Gastroenterology Unit, Dudley Road Hospital, Birmingham.
Gut
|September 1, 1994
Summary
The human small intestine has very limited phytase activity, suggesting poor digestion of phytates. Undigested phytate reaching the colon may offer protection against colon cancer.
Area of Science:
- Biochemistry
- Gastroenterology
- Human Physiology
Background:
- Phytate, a major phosphorus storage form in seeds, is a common dietary component.
- Excessive phytate ingestion can lead to mineral deficiencies in humans.
- Phytic acid exhibits antineoplastic properties in animal models for colon and breast carcinoma.
Purpose of the Study:
- To quantify phytase activity and distribution in the human small intestine.
- To compare human small intestinal phytase activity with that of rat intestine.
- To investigate the implications of limited human phytase activity on mineral absorption and colon health.
Main Methods:
- In vitro analysis of phytase and alkaline phosphatase activity.
- Use of mucosal homogenates from human small intestinal specimens (transplant donors).
- Comparative study including rat intestinal tissue.
Main Results:
- Phytase activity was detected in the human small intestine but at very low levels.
- Human small intestinal phytase activity was approximately 30-fold lower than in rat intestine.
- Phytase activity was highest in the duodenum and lowest in the ileum, significantly lower than alkaline phosphatase.
- Alkaline phosphatase activity was substantially higher than phytase activity in the human small intestine.
Conclusions:
- The human small intestine possesses a limited capacity to digest undegraded phytates.
- This limited digestion may contribute to mineral imbalances due to impaired mineral absorption.
- The presence of undigested phytate in the colon might play a protective role against colonic carcinoma development.
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