Biomedical Engineering Reference
In-Depth Information
Table 12.9
Enzymes that are used as digestive aids
Enzyme
Application
α
-Amylase
Aids in digestion of starch
Cellulase
Promotes partial digestion of cellulose
α
-Galactosidase
Promotes degradation of fl atulence factors
Lactase
Counteracts lactose intolerance
Papain Pepsin Bromelain
Enhanced degradation of dietary protein
Pancreatin
Enhanced degradation of dietary carbohydrate, fat and protein
The use of enzymes as digestive aids is only applied under specifi c medical circumstances.
Some medical conditions (e.g. cystic fi brosis) can result in compromised digestive function due
to insuffi cient production/secretion of endogenous digestive enzymes. Digestive enzyme prepara-
tions are often formulated in powder (particularly tablet) form, and are recommended to be taken
orally immediately prior, or during, meals. As the product never enters the blood stream, the
product purity need not be as stringent as enzymes (or other proteins) administered intravenously.
Most digestive enzymes are, at best, semi-pure preparations.
In some instances there is a possibility that the effi cacy of these preparations may be compro-
mised by conditions associated with the digestive tract. Most function at pH values approaching
neutrality. They would thus display activity possibly in saliva and particularly in the small intes-
tine. However, the acidic conditions of the stomach (where the pH can be below 1.5) may denature
some of these enzymes. Furthermore, the ingested enzymes would also be exposed to endogenous
proteolytic activities associated with the stomach and small intestine. Some of these diffi culties,
however, may be at least partially overcome by formulating the product as a tablet coated with an
acid-resistant fi lm to protect the enzyme as it passes through the stomach.
Pancreatin is a pancreatic extract usually obtained from the pancrease of slaughterhouse ani-
mals. It contains a mixture of enzymes, principally amylase, protease and lipase, and, thus, exhibits
a broad digestive capability. It is administered orally mainly for the treatment of pancreatic insuf-
fi ciency caused by cystic fi brosis or pancreatitis. As it is sensitive to stomach acid, it must be ad-
ministered in high doses or, more usually, as enteric-coated granules or capsules that may be taken
directly or sprinkled upon the food prior to its ingestion. Individual digestive activities, such as pa-
pain, pepsin or bromelains (proteases), or α-amylase are sometimes used in place of pancreatin.
Cellulase is not produced in the human digestive system. Cellulolytic enzyme preparations
obtained from
A. niger
or other fungal sources are available, and it is thought that their ingestion
may improve overall digestion, particularly in relation to high-fi bre diets.
α-Galactosides are oligosaccharides present in plant matter, particularly in beans. They are not
normally degraded in the human digestive tract due to the absence of an appropriate endogenous
digestive enzyme (i.e. an α-galactosidase). However, upon their entry into the large intestine, these
oligosaccharides are degraded by microbial
1-6 galactosidases, thus stimulating microbial fer-
mentation. The end-products of fermentation include volatile fatty acids, carbon dioxide, methane
and hydrogen, which lead to fl atulence. This can be avoided by minimizing dietary intake of food
containing α-galactosides. Another approach entails the simultaneous ingestion of tablets con-
taining
α
-galactosidase activity. If these 'fl atulence factors' are degraded before or upon reaching
the small intestine, then the monosaccharides released will be absorbed and, hence, will be subse-
quently unavailable to promote undesirable microbial fermentations in the large intestine.
α
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