General Description
Pectins are a class of plant cell wall polysaccharides that are
water-soluble and form gels when mixed with sugars and water at
the proper pH. In plants, pectin helps ripening fruits stay firm
and retain their shape. As fruit becomes overripe, the pectin is
broken down into simple sugars and the fruit becomes soft and begins
to lose its shape. Purified forms of pectin, derived from apple
peels and the inner rinds of citrus fruits, are used in the preparation
of jams and jellies and as a suspending agent in pharmaceutical
preparations. As a dietary supplement, pectin serves as a concentrated
source of soluble fiber.
Health Applications
- Diabetes
- High cholesterol
- Cancer prevention
Diabetes
A number of small studies suggest that pectin may pay a useful
role in the dietary management of both insulin-dependent (type
1) and noninsulin-dependent (type 2) diabetes. Diabetic subjects
given pectin with a meal showed a smaller increase and a slower
rate of increase in serum glucose levels than when they consumed
the same amount of calories without pectin.1-3
In one study conducted on four insulin-dependent diabetic subjects,
seven grams of pectin taken with a meal (60 grams of carbohydrates)
reduced insulin demand by 35 percent.4 While
the results of these preliminary studies appear promising, further
large-scale studies are needed before the usefulness of pectin
in diabetes management can be determined.
High Cholesterol
Several studies indicate that pectin may help reduce high blood
cholesterol levels, a major contributor to cardiovascular disease.
In studies conducted on human subjects with mild to moderate hypercholesterolemia,
pectin alone 5,6 or in combination with vitamin C7
or guar gum8 reduced total serum cholesterol
and LDL (the "bad cholesterol") without reducing HDL ("good cholesterol")
levels. In one study, patients given apple pectin with a cholesterol-lowering
drug had a greater reduction in LDL and total cholesterol levels
than subjects given the drug alone.9 In addition
to its effect on cholesterol levels, some studies suggest that
pectin may protect subjects with high cholesterol levels against
the development of atherosclerosis by altering fibrin networks.6,10,11
Cancer Prevention
The role of pectin and other soluble fibers in cancer prevention
(particularly colon cancer) has long been the subject of debate;
and studies in this area have produced conflicting results. While
some animal studies indicate that pectin may reduce the incidence
and progression (metastasis) of chemically induced colon 12-16
and prostate17,18 cancer, other studies suggest
pectin may actually promote colon tumor growth.19-21
It appears that the type of pectin used may be a significant factor,
as some studies have found apple pectin to have a colon-protective
effect not found in citrus pectin.15,16 Due
to conflicting preliminary results and the lack of human-based
studies, additional research is needed before the pectin's usefulness
as an antitumor agent can be determined.
Dosage/Toxicity
Clinical trials on pectin supplementation have commonly used dosages
of 15 grams per day.6,7,11 Pectin has very
low toxicity and is generally well tolerated at this dosage. Because
increases in dietary fiber can cause flatulence and abdominal
discomfort in individuals unaccustomed to high fiber diets, some
nutrition experts recommend starting with a dosage of 1 or 2 grams
(with meals) and gradually increasing the dosage to 5 grams.22
It is important to consume adequate amounts of water when taking
any fiber supplement, especially in pill form. Pectin pills are
not recommended for individuals with esophageal disorders because
the pills may expand in the esophagus, leading to obstruction
of the intestinal tract.22 |
