Fructose transport mechanisms in humans
X Shi1, H P Schedl, R M Summers
1Department of Exercise Science and Internal Medicine, University of Iowa, Iowa City, USA.
Gastroenterology
|October 10, 1997
Summary
Fructose absorption in the human small intestine occurs via facilitated diffusion and glucose-activated solution drag, not a disaccharidase system. Glucose enhances fructose uptake, indicating a key role in nutrient transport.
Area of Science:
- Gastroenterology
- Human Physiology
- Nutrient Absorption
Background:
- Fructose transport mechanisms in the human small intestine remain incompletely understood.
- Potential pathways include diffusion, disaccharidase-related systems, and glucose-facilitated transport.
Purpose of the Study:
- To investigate the specific mechanisms of fructose transport in the human duodenojejunum.
- To differentiate between proposed fructose absorption pathways.
Main Methods:
- Perfusion studies were conducted in the duodenojejunum of seven male participants.
- Nine carbohydrate-electrolyte solutions were used, with acarbose and lactulose employed to assess transport systems.
Main Results:
- Fructose absorption was significantly higher with glucose present, regardless of acarbose.
- Lactulose absorption, indicating paracellular transport, was observed when glucose or sucrose was present.
- Acarbose did not inhibit free fructose and glucose transport.
Conclusions:
- Fructose is primarily transported via transcellular facilitated diffusion.
- Paracellular transport of fructose is influenced by glucose-activated solution drag.
- The disaccharidase system is not involved in free fructose and glucose transport in the human small intestine.
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