| Most people understand the importance
of dietary fiber in their diet.
Much has been said about its importance
in heart health, diabetes, cancer
prevention, and even weight control.
What is less well understood is
how different types of fiber effect
the body. Some provide fecal bulk,
some are absorbed more quickly
into the blood stream than others,
and thus raise blood sugar levels
more quickly, and yet others provide
benefits to the heart. Thus, despite
the apparent simplicity, fiber
is a complex topic. And whilst
all types of fiber are important,
if you are looking at preventing
or managing specific conditions,
its not enough to just look at
the total dietary fiber as written
on food packaging. Dietary fiber
is broadly classified into soluble
and insoluble fiber. Soluble fiber
is fermented in the colon, and
plays a role in slowing the absorption
of glucose into the bloodstream.
It also encourages the growth
of the 'friendly' bacteria that
help break down bile, and are
involved in the creation of B
vitamins like folic acid, niacin,
and pyridoxine. Insoluble fiber,
on the other hand, acts a bit
like an intestinal broom. It provides
bulk to the stools, and makes
sure they pass through easily
and quickly. This is the type
of fiber that keeps you 'regular',
not insoluble fiber. Insoluble
fiber does provide a feeling of
fullness, however. This makes
it great for weight loss and controlling
hunger. It also keeps blood sugar
levels more stable, although research
into the rate at which carbohydrates
enter the bloodstream have found
there to be some significant differences
within the foods that make up
the fiber group. Dietary fiber
can thus be rated by its Glycemic
Index, which effectively ranks
fiber foods with each other on
a relative scale. The idea is
to try and include more low gylcemic
index foods. Foods with a high
glycemic index cause blood sugar
levels to spike, providing too
much energy to the blood in the
form of carbohydrates, which in
turn sets off the body's sugar
controlling hormone - insulin.
You thus get a 'high' followed
by a sudden drop. This in turn
leads the body to want more carbohydrates
to balance itself again, leading
to cravings and overeating, as
well as tiredness and moodiness.
Low glycemic index foods include
lentils, chickpeas, baked beans,
fruit loaf, salmon sushi, barley,
milk, low fat custard, soy milk,
yoghurt (not diet yoghurt), apples,
strawberries, grapes, spaghetti,
peas, carrots, fructose, strawberry
jam, and chocolate milk. Moderate
glycemic index foods include pea
soup, rye bread, porridge, muesli,
ice cream, bananas, pineapple,
kiwi fruit, new potatoes, beetroot,
white sugar, honey, and mars bars.
High glycemic index foods include
broad beans, bagels, white bread,
brown rice, watermelon, udon noodles,
desiree, pontiac and sebago potatoes,
and glucose. We need both soluble
and insoluble fiber, however.
A study published in the American
Journal of Clinical Nutrition
found that in a group of 6000
French men and women, those with
the highest levels of soluble
and insoluble fiber in their diet
had a lower risk of being overweight,
a lower risk of having blood pressure
problems, cholesterol problems,
and they had better levels of
triacylglycerols and homocysteine.
The last two are measure3 of heart
health. Fiber from cereals was
linked to lower body fat, lower
blood pressure, and lower levels
of homocysteine. Those with a
higher intake of vegetables, also
a source of fiber, had lower blood
pressure and lower homocysteine
levels. Fiber from fresh fruit
was associated with a lower waist
to hip ratio (good news for dieters!),
and lower blood pressure. And
fiber from dried fruit, nuts,
and seeds (like sesame seeds,
sunflower seeds, and pumpkin seeds)
was also linked to a lower waist
to hip ratio, lower body fat,
and a better fasting glucose concentration.
Fasting glucose relates to having
a steady level of glucose between
meals. If it dips too low, we
crave things, often sweets. Fiber
has another interesting benefit.
In people with type 2 diabetes,
it has been found to lower the
levels of 'bad' cholesterol, and
increase the levels of 'good'
cholesterol. It has already been
established that fiber supplements
will lower the levels of bad cholesterol
in people, whether they have diabetes
or not. But this new study found
that fiber supplements also decreased
the reabsorption of cholesterol
from meals. To get this benefit,
it is important to time taking
the fiber supplement in synch
with meals. The study participants
took a fiber supplement drink
before mealtimes, and this ensured
that the fiber was in the intestines
when the meal was being eaten.
The people in the study participated
for 90 days and their average
age was 59 years old. References:
1. Australian Healthy Food, November
2005 2. nutraingredients.com/news/ng.asp?id=64759
3. nutraingredients.com/news/ng.asp?id=57887
4. nutraingredients.com/news/ng.asp?id=64462
5. nutraingredients.com/news/ng.asp?id=59737
For more information on soluble
and insoluble dietary fiber supplements,
check out this article. Rebecca
Prescott presents the vitamin
and health site, http://www.vitaminstohealth.com
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