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An apple a day…
study by scientists in the United States appears to support the age-old
adage: “An apple a day keeps the doctor away.”
The study by researchers at the University of Illinois touts the
benefits of soluble fibre – found in oats, apples and nuts. They say it
reduces the inflammation associated with obesity-related diseases and
strengthens the immune system.
“Soluble fibre changes the personality of immune cells – they go from
being proinflammatory, angry cells to anti-inflammatory, healing cells
that help us recover faster from infection,” said Gregory Freund, a
professor in the U of I’s College of Medicine and a faculty member in
the College of Agriculture, Consumer and Environmental Sciences’
Division of Nutritional Sciences.
This happens because soluble fibre causes increased production of an
anti-inflammatory protein called interleukin- 4, he explained.
In the experiment, laboratory mice consumed low-fat diets that were
identical except that they contained either soluble or insoluble fibre.
After six weeks on the diet, the animals had distinctly different
responses when the scientists induced illness by introducing a substance
(lipopolysaccharide) that causes the body to mimic a bacterial
“Two hours after lipopolysaccharide injection, the mice fed soluble
fibre were only half as sick as the other group, and they recovered 50%
sooner. And the differences between the groups continued to be
pronounced all the way out to 24 hours,” said Christina Sherry, who also
worked on the study.
“In only six weeks, these animals had profound, positive changes in
their immune systems,” she said.
Now Freund has a new question: Could soluble fibre offset some of the
negative effects of a high-fat diet, essentially immunising obese
persons against the harmful effects of fat?
Scientists have long known that obesity is linked to inflammatory
conditions, such as diabetes and heart disease.
Yet, in a recent study, the U of I scientists demonstrated that fat
tissue produces hormones that appear to compensate for this
inflammation. “There are significant anti-inflammatory components in fat
tissue and, if they were strategically unleashed, they could potentially
protect obese people from further inflammatory insults, such as a heart
attack or stroke. In obese animals, you can see the body compensating in
an effort to protect itself,” he said.
Not all fat is bad, the researcher noted. The Mediterranean diet, which
receives high marks for its health benefits, includes such foods as
olive oil; salmon, tuna, sardines, and trout, which contain important
omega-3 and -6 fatty acids; and plant sources of fat, such as flaxseed.
“Now we’d like to find a way to keep some of the antiinflammatory,
positive effects that develop over time with a high-fat diet while
reducing that diet’s negative effects, such as high blood glucose and
high triglycerides. It’s possible that supplementing a high-fat diet
with soluble fibre could do that, even delaying the onset of diabetes,”
Two valuable lessons
This study is one of the first to provide two valuable lessons, said
Sherry. The first, already noted, is that soluble fibre has direct
anti-inflammatory effects and builds up the immune system. The second is
that the amount of soluble fibre necessary to achieve these health
benefits is a reasonable, not a pharmacological, amount.
The recommended daily dietary recommendation is 28 to 35 grammes of
total fibre, but most of the FDA’s health claims are for insoluble fibre,
and that’s where things get a bit complicated, she said.
“Not all fibre is created equal, although you wouldn’t know that by
reading nutrition labels,” said Sherry. “Most manufacturers don’t tell
you how much of each type of fibre a food contains, and we think it’s
important that this information be included on a product’s packaging.”
Good sources of soluble fibre are oat bran, barley, nuts, seeds,
lentils, citrus fruits, apples, strawberries and carrots. “We used a
citrusbased pectin in our study,” Sherry said.
Insoluble fibre, found in whole wheat and whole-grain products, wheat
bran, and green, leafy vegetables, is also valuable for providing bulk
and helping food move through the digestive system, but it doesn’t
provide the boost to the immune system that soluble fibre provides.
● The study will appear in the May 2010 issue of Brain, Behavior, and
Immunity and is available online at:
of upload: 20th June 2010