Psyllium versus Guar Gum: Facts and Comparisons - Practical ...

A SPECIAL ARTICLE
Psyllium versus Guar Gum:
Facts and Comparisons
by T.S. Dharmarajan
INTRODUCTION
Dietary fiber is a term that denotes components of
plant origin that are resistant to digestion by gastrointestinal
enzymes in humans. Based on its
solubility in water, fiber may be classified as soluble
or insoluble. Soluble fiber, the basis for discussion
here, is a plant ingredient that stores water. Besides
storing water, its properties include the ability to ferment
and to increase viscosity (1,2).
Psyllium and guar gum are two forms of soluble
fiber that make an interesting comparison. Psyllium,
mainly cultivated in Iran and India, is used in the management
of several medical disorders and also as an
herbal remedy. Psyllium is a member of the plant family
Plantaginaceae. Its common names include flea
seed and ispaghula while the botanical names are
Plantago ovato and Plantago ispaghula. Psyllium
seeds contain up to 30% mucilage; swelling of the
husk occurs in contact with water, resulting in a gelatinous
mass and an increase in bulk that keeps feces
hydrated and soft (3). Psyllium husks are pure dietary
fiber that is mainly composed of hemicellulose. This
component of fiber is not digested in the small intestine,
but instead it is broken down in the colon where
it acts as a food source for the intestinal flora. The bacterial
mass and water contribute to an increase in stool
weight. The husks absorb water to form a soft bulky
T.S. Dharmarajan, M.D., FACP, AGSF, Chief, Division
of Geriatrics, Director, Geriatric Medicine Fellowship
Program, Our Lady of Mercy Medical Center,
Bronx, New York, Professor of Medicine, New York
Medical College, Valhalla, NY.
stool mass, which floats in the toilet rather than sinking
while the unfermented gel from psyllium functions
as an emollient and lubricant.
Guar gum is extracted from the seeds of the shrub
Cyamopsis tetragonolobus wherein it acts as a food
and water store. The annual plant, which flourishes in
India, Pakistan and the West, is drought resistant and
thrives in sandy soil. Guar gum is an economical
thickener, emulsifier and stabilizer that hydrates
rapidly in cold and hot water to give solutions high
viscosity. It retards ice crystal growth and is resistant
to oils and solvents. Milk reactivity is in question.
Guar gum is approved for use in foods, pharmaceuticals
and cosmetics. In the food industry, examples
include bakeries and dairies. It is a common ingredient
for dressings and sauces and as a stabilizer for drinks
and juices. Guar gum serves as a thickener for shampoos
and toothpastes. It is also used in the textile and
paper industries (Table 1).
BENEFITS IN HEALTH AND DISEASE
Hyperlipidemia
In numerous studies, psyllium has been found to be
beneficial in lowering total and LDL (“bad”) cholesterol
(4). However, HDL (“good”) cholesterol does not
appear to be affected (5). The benefits of psyllium in
hyperlipidemia are secondary to its soluble component.
In a meta-analysis of 8 controlled trials, psyllium supplements
caused significant reductions in total and LDL
cholesterol in subjects on a low-fat diet (6). Other soluble
fibers, such as guar gum (besides pectin and oat
bran), also decrease total and LDL cholesterol. How-
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ever, practical use of many of the latter
forms of fiber is limited by the lack of
palatable preparations (7). In a study in
rats comparing 10 different fibers, psyllium
use was associated with the lowest
serum cholesterol levels (8). The Food
and Drug Administration has authorized
the use of “the association of psyllium
and a reduced risk of coronary heart disease”
on health labels. This health claim
was attributed to a lowering of cholesterol
levels, based on the assumption
that 4 servings of dietary fiber per day
would reduce cardiovascular risk (9).
Table 1
Properties of Psyllium and Guar Gum
Property Psyllium Guar Gum
Botanical name P. ovato, P. ispaghula C. tetragonolobus
Structure Non starch polysaccharide Non starch polysaccharide
Solubility Soluble Soluble
Component Mucilage, hemicellulose Gum
Thickening effect Effective Very effective
Palatability Several choices Limited
Gas, bloating Less problematic More problematic
Diabetes
In type 2 diabetes, addition of psyllium to dietary measures
has been shown to improve glycemic control (4).
The benefit appears to result from a slowing of glucose
absorption from the small intestine. Psyllium treatment
should be individualized for maximum effect (10). In a
study comparing ispaghula husk (psyllium) with guar
gum, mean serum postprandial insulin levels
decreased for both, but the area under the glucose
curve was reduced significantly for psyllium but not
for guar gum (11).
Constipation and Other Gastrointestinal
Transit Disorders
Many studies have revealed the benefit of psyllium in
alleviating constipation by speeding the transit of stool
through the intestines. Its use is standard practice for
constipation. Psyllium increases stool mass more than
common fiber sources such as oat bran and wheat bran
(12,13). A comparison of psyllium as ispaghula husk
with other laxatives revealed that ispaghula use was
associated with a higher percentage of well-formed
and less hard stools, as well as less soiling, diarrhea
and abdominal discomfort (14). As a bulk-forming
agent, psyllium also helps manage mild diarrhea by
providing a stool firmer that slows transit time. In
ulcerative colitis, psyllium seeds (10 grams twice
daily) were as effective as mesalamine in maintaining
remission in one trial (15). Another benefit that has
also been demonstrated is the regulation of stool frequency
in irritable bowel syndrome. Aside from these
examples of relief in transit disorders, in ventilatordependent
septic patients, soluble fiber in the form
of guar gum added to enteral feeding reduced the
incidence of diarrhea (16). The addition of guar gum
(7 g daily) to a standard tube feeding formula
decreased stool frequency and helped normalize stool
flora (17). The relief of constipation and resultant
long-term regular bowel habits with soft stools from
the use of fiber provides relief to individuals suffering
from hemorrhoids.
Hunger, Food Intake and Weight Loss
Psyllium reduces the feeling of hunger and thereby
energy intake. The mechanism of action may entail
increasing the time for intestinal absorption and flattening
of glucose, insulin and triglyceride curves without
altering gastric emptying for solids or liquids (18).
Hence, it is conceivable that psyllium may help in
weight loss, inducing a feeling of stomach fullness
without providing calories. The addition of guar gum
to meals has also been shown to prevent an increase in
appetite, hunger and desire to eat (19).
Blood Pressure
Soluble fiber administered as psyllium (12 g/d)
reduced 24-hour and awake systolic blood pressure.
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Psyllium Versus Guar Gum
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Table 2
Psyllium and Guar Gum in Health Care
Disorder Psyllium Guar Gum
Hypercholesterolemia Lowers LDLC, TC Lowers LDLC, TC
Diabetes Significant benefit Significant benefit
Constipation Significant benefit Some benefit
Diarrhea Some benefit Some benefit
Irritable bowel syndrome Some benefit Role not clear
Ulcerative colitis Some benefit Role not clear
Weight loss May be helpful May be helpful
Blood pressure Beneficial in Benefit in post-prandial
hypertension? hypotension?
This finding may have implications in long-term treatment
of hypertension (20). In quite the opposite setting,
through a slowing of gastric emptying and glucose
absorption, guar gum reduced the magnitude of a
drop in blood pressure after an oral glucose load. This
finding may provide a novel approach to the management
of post-prandial hypotension (21).
ADMINISTRATION
Fiber is an important dietary ingredient,
but the precise dietary requirements
for protective benefits are not
clear. In general, it is advisable to consume
fiber from natural sources before
resorting to supplements. The American
Dietetic Association recommends
the consumption of 20 to 35 grams of
fiber per day. A combination of soluble
and insoluble fiber is recommended
(1,2). Where the dietary
intake of fiber is inadequate, commercial
preparations supplement fiber
intake to match the recommended
amounts.
Standard forms of psyllium are
available in dry seed and husk form. Psyllium is taken
one to three times a day with plenty of water a half
hour before or at least an hour after meals. Husks can
be added to soups or sauces as a thickener. Psyllium
should be taken with a full 8 oz glass of water, and it
(continued on page 76)
Miscellaneous Considerations
In one study, the consumption of fiber (as P.
ovata) has been associated with a reduced risk
of colon cancer (22). However, the data from
numerous trials evaluating the relationship
between dietary fiber and colorectal cancer
are at best conflicting (1,23). Fiber, particularly
the insoluble component, has been associated
with a decreased risk of diverticular
disease. In patients in whom adequate intake
of insoluble fiber is not possible, preparations
such as psyllium may be helpful.
Psyllium use is not habit forming. As a
pure fiber, the husks contain only trace calories,
vitamins and minerals. Unlike wheat
bran and some other fiber, excessive bloating
attributable to gas formation is less likely to
occur with psyllium. Gastrointestinal side
effects appear to be more common with guar
gum (2) (Table 2).
Table 3
A Comparison of Two Forms of Soluble Fiber
Konsyl
Benefiber
Ingredient Psyllium Hydrolyzed guar gum
Serving Size 1 teaspoon 1 tablespoon
Serving Size (grams) 6 g/teaspoon 4 g/tablespoon
Fiber (g/serving) 5 grams 3 grams
Calories 3 per serving 16 per serving
Sodium 4.1 mg 15 mg
Potassium 42 mg 15 mg
Calcium 48 mg none
Carbohydrate 0.05 g 4.0 g
Protein 5.3% none
Fat 2.7% none
Sugars none none
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(continued from page 74)
is essential that at least 6 to 8 glasses of water be consumed
over the day to avoid constipation. Excessive
fiber intake to the tune of 50 to 60 grams daily may
result in gastrointestinal side effects and malabsorption
of nutrients and drugs. Medication intake is best
avoided at the same time as fiber to minimize a delay
or malabsorption of drugs.
Hydrolyzed guar gum is added to foods and beverages
as a fiber supplement to regulate bowel movements.
It may be mixed with water or juices and soft
foods. In particular, it may be supplemented with tube
feedings on an individualized basis for the purpose of
regulating bowel function (Table 3).
SUMMARY
Psyllium and guar gum are two forms of soluble fiber
that are available as commercial preparations, but they
have somewhat different properties. While both forms
of fiber are helpful in the management of hyperlipidemia,
psyllium appears to be more suitable in the
management of motility disorders, such as constipation
and irritable bowel syndrome. Psyllium (as in Konsyl)
offers a higher concentration of fiber per serving, in
addition to fewer calories and lower sodium and carbohydrate
content. These properties are significant in the
management of coexisting hypertension and diabetes.
Fewer gastrointestinal side effects seem to be encountered
with psyllium. On the other hand, guar gum (as in
Benefiber) may have better utility as a thickener, particularly
in the food and textile industry. ■
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