|
Pectin: A Versatile
Fiber
By Lark L. Burnham, Ph.D.
Animal Nutrition
Classification
Pectin, which is derived
from apples and citrus fruit, is a highly soluble fiber. In general,
different fiber sources are classified by their ability to absorb water.
They range from basically insoluble (high lignin fibers such as seed hulls)
to very soluble (pectin and other gel-forming fibers). Solubility is
important because it determines how well the fiber will be digested by the
gastrointestinal tract (GIT) microflora.
All mammals lack the
enzymes necessary to digest fiber. They depend on a synergistic
relationship with microorganisms to degrade it for them. The by-products of
microbial fermentation of fiber are short-chain fatty acids, primarily
acetic, propionic, and butyric acids.
Microorganisms require
water for viability and for fermentation. Greater water absorption by a
fiber means more extensive bacterial degradation or “digestibility”. Fibers
that have a very low solubility have digestibilities as low as 3%, while
highly soluble fibers are closer to 60% digestible. Wheat bran is
intermediate, with a digestibility of around 20%.
Microorganisms which
ferment fiber are usually either beneficial or at worst, benign. Dietary
fiber inclusion promotes the proliferation of these microorganisms. Their
predominance in the GIT, particularly in the colon, is directly related to
the proportion of fiber in the diet.
The role of fiber in
nonruminant mammals
Fiber has both direct and
indirect effects of GIT health. Some of these benefits have been known for
decades, if not centuries. The most obvious is its anti-constipation
bulking effect. Pectin, which is generally added in small amounts of a
tablespoon or less, provides bulk because it swells after mixing with
digesta. It also promotes the proliferation of beneficial microorganisms.
Because of this latter property, it can also be categorized as a “prebiotic”.
Highly soluble fibers
such as pectin have the additional benefit of stopping diarrhea. Their
ability to quickly absorb water on contact allows them to thicken digesta.
Pectin only works while it passes through the GIT, it must be continually
replaced to maintain this anti-diarrheal effect. It is better to consume
smaller doses of pectin throughout the day than take the full dose only
once. Pectin treats symptoms; it does not necessarily address the cause of
the diarrhea.
A less well-known
attribute of fiber is its ability to trap molecules within its matrix.
These molecules are then carried through the colon and excreted in the
feces. Two notable substances have been suggested to be removed by this
process: ammonia/urea (Corley et al., 1978; Fahey, 1976) and cholesterol.
Nitrogen, which is a
by-product of protein digestion, is generally excreted as ammonia in the
urine. After it is released from protein, the nitrogen is absorbed through
the GIT membrane as urea, which is actually two ammonia molecules stuck
together. It then makes it's way to the kidneys for excretion in the urine.
The entrapping fiber
matrix prevents a significant amount of ammonia from being absorbed into the
bloodstream, and is excreted via the feces instead. Likewise, cholesterol
molecules are trapped within the GIT and excreted in the feces (Roberfroid
and Delzenne. 1995).
Stress and the
gastrointestinal tract microflora
Stress has both direct
and indirect effects on the GIT microflora (Tannock, 1983). Stress-induced
hormones can change GIT pH and cause cessation of active nutrient movement.
Part of the flight-or-fight mechanism inherent in all mammals re-directs
available energy to the muscles. This can result in complete or partial GIT
shut down, which involves both the secretion of enzymes and nutrient flow.
Both pH changes and cessation of nutrient flow detrimentally impact
indigenous microflora. The severity of the stress will determine the extent
of the damage.
Another side effect of
the reduction in enzyme activity is the predominance of highly digestible
material that makes it's way into the colon. This situation can simulate
symptoms of exocrine pancreatic insufficiency (EPI).
Indigenous microflora
present both a physical and chemical barrier and actively combat pathogens.
They are the first line of defense against pathogens which enter the host
orally. Along with a healthy immune system, indigenous microflora prevent
the proliferation of opportunistic pathogens. Antibiotics can strip the GIT
of this protective barrier.
Potential uses for
pectin in medical practice
Diarrhea is a very
serious and debilitating condition. If left unchecked, diarrhea can kill.
I have used pectin to control diarrhea in a variety of mammalian species,
both livestock and pets. Pectin by itself is not enough to permanently
control diarrhea. The first victims of this condition are the GIT
microflora. Long-term treatment involves both the cessation of nutrient and
electrolyte loss, as well as the replacement of the indigenous
microorganisms. Probiotic microorganisms temporary fill the physical and
chemical roles performed by the indigenous microflora. They also allow
these beneficial microorganisms to proliferate.
Illnesses such as
irritable bowel syndrome (IBS), are marked by chronic diarrhea. I have used
a combination of pectin and probiotics to control and reverse this
stress-induced disease in dogs. People and dogs who suffer from EPI often
have chronic diarrhea. This is a result of highly digestible material
reaching the colon. Normally, less than 5% of these food components survive
passage of the small intestine Highly digestible material selects for
colon microflora which cause diarrhea and may be detrimental to the host in
other ways.
Additionally, conditions
that promote the development or urinary calculi are ameliorated by the
entrapment ability of fiber in general, and pectin in particular. The
entrapment quality of a fiber is enhanced by its degree of solubility.
Pectin is inert to the
host, it has no side effects and remains within the confines of the GIT. It
needs to be replenished on a daily basis to provide continuous benefit.
Pectin combined with a daily probiotic supplement will encourage GIT
health. Complicating conditions such as IBS and EPI will determine the
probiotic concentration employed.
MSE
Natural
Defense is a hypoallergenic pectin-based probiotic supplement for pets.
It is made from food-grade pectin and pure microbial cultures (4.0 x 108
cfu/g). It is available directly through
Natur’s Way.
References cited
Corley, J. R, R. A.
Easter, M. A. Roos and G. C. Fahey. 1978. Effect of various fiber sources
on gain, feed efficiency and nitrogen retention in the weanling pig. Nutr.
Rep. Internat’l 18:135.
Fahey, G. C. 1976.
Factors influencing the utilization and digestibility of hemicellulose.
Doctoral dissertation, West Virginia University, Morgantown.
Roberfroid and N.
Delzenne. 1995. Oligofructose supplemented diet lowers serum and VLDL
concentrations, triglycerides, phospholipids and cholesterol in rats.
Lipids 163-167.
Tannock, G. W. 1983.
Effect of dietary and environmental stress on the gastrointestinal
microbiota. In: Human intestinal microflora in health and disease (Hertges,
D. J., ed.), pp. 517 – 539, Academic Press, New York, NY
|
