A New Way to Look at Carbohydrates

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A New Way to Look at Carbohydrates

JoAnn Guest

Jan 20, 2007 12:16 PST

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A New Way to Look at Carbohydrates

 

Carbohydrates are a varied combination of both very small and very

large molecules that comprise about 40 to 45 percent of the energy

supply for your body. In addition, certain types of carbohydrates,

such as fiber and resistant starches don't get taken into your body

for energy, but play important health-promoting roles in your

gastrointestinal tract, supporting digestion and absorption, and

helping you eliminate toxins and waste products.

 

Carbohydrates are are composed of carbon, hydrogen, and oxygen,

which are arranged into small units called sugars, or

monosaccharides. Small carbohydrates, like glucose or sucrose (table

sugar) are composed of one or two sugar units, respectively, and are

the molecules that give food a

sweet taste. These molecules are sometimes called " simple sugars "

because they are small (only one or two units), and are quickly

digested, providing immediate energy to the body.

 

Larger carbohydrate molecules, which include fibers and starches,

are

composed of at least 10 monosaccharides linked together. These large

carbohydrates, called polysaccharides (poly=many) may contain up to

several hundred monosaccharides linked together in different ways.

Another term commonly used to describe carbohydrates is

oligosaccharides, a type of carbohydrate molecule that is in-between

polysaccharides and monosaccharides in size, and features two to ten

monosaccharides bonded together.

 

Let's look at each of these types of carbohydrates and how the food

you eat influences the quality of these important nutrients you

receive.

 

The Simple Sugars: Monosaccharides and Disaccharides

Monosaccharides

Monosaccharides are true simple sugars since, as one sugar unit

only,

they exist in the form in which they can be directly absorbed into

your

body upon ingestion. Unlike the other carbohydrates, they don't

require

being broken down during digestion, so when you eat a food

containing

monosaccharides, these sugars quickly get into your bloodstream,

increasing your blood sugar and providing immediate energy. Examples

of

monosaccharides include glucose, fructose and galactose.

 

Monosaccharides are present in most foods in at least some amount,

but

are particularly high in foods such as ripe fruit, and honey.

Monosaccharides are an important energy source, but when too much of

these simple sugars are consumed at once--especially when they are

not

balanced by complex carbohydrates like oligosaccharides or

polysaccharides that take longer to digest and thus help maintain

longer-term energy production--monosaccharides can cause a large

increase in blood sugar, followed by an abrupt drop. The result is a

jolt of energy quickly followed by a feeling of being tired, shaky,

or

run-down soon afterward. This type of fluctuation in blood sugar, if

it

occurs frequently, can lead to blood sugar dysregulation conditions

such

as hypoglycemia and diabetes mellitus. Proceesed foods often add

high

amounts of monosaccharides such as fructose and glucose to promote a

sweet taste, which sells more product, but does not sustain health.

 

Disaccharides

Disaccharides contain two monosaccharides (di=two) bonded together,

and

include sugars such as lactose (milk sugar), sucrose (table sugar),

maltose and isomaltose (sugars formed from the breakdown of starch).

Disaccharides are similar to monosaccharides; that is, they provide

sweet taste to food and quick energy, which is why they are

considered

" simple sugars " as well. As such, disaccharides also are highly

represented in processed foods, and their frequent consumption can

lead

to blood-sugar disregulation, the same as monosaccharides.

 

Since these carbohydrates contain two sugars, disaccharides require

some

digestion to break them into two one-sugar units for absorption, and

since each disaccharide is unique, each has its own digestive

enzyme.

For example, the enzyme sucrase can cut sucrose into its two

individual

sugar units; lactase cuts lactose into its two sugars. For most

disaccharides, these enzymes area readily secreted into the

intestines

after consuming a meal, and digestion of the disacchrides proceeds

rapidly. The exception appears to be with lactose (milk sugar).

 

Many people lack the enzyme lactase and are therefore unable to

breakdown lactose, a condition called lactose intolerance, which

makes

the consumption of dairy products problematic for many people.

Lactose

intolerance, which occurs more frequently as we age, is quite common

in

adults. In lactose intolerance, the undigested lactose is not

absorbed

and can promote growth of unfriendly bacteria in the upper

intestinal

tract, a condition called small bowel overgrowth. These bacteria

ferment

the lactose, producing gas in the small intestine that causes great

discomfort, along with acid, which can cause heartburn and nausea.

Even

more problematic, the acid produced by this bacterial fermentation

can

degrade the lining of the small intestine, injuring the intestinal

tract

cells. This damage compromises the ability of the intestinal cells

to

produce enzymes for digestion, so even less disaccharide digesting

enzymes are produced, and a cycle of maldigestion is perpetuated.

Diets

that limit disaccharides may be of benefit for persons with these

concerns, and a person with lactose intolerance should not consume

lactose-containing foods without having a source of lactase either

in

the food or taken with the food. Some studies suggest that

Lactobacillus

supplements are beneficial in this respect as well.

 

The Polysaccharides: Starch, Fiber and Resistant Starch Starch

Plants store their energy by stringing together many glucose units

into

a long complex of several hundred to several thousand sugar

(glucose)

molecules. Plant foods that contain stored energy, for example seeds

that must provide energy for the young plant when it starts growing,

are

high in starch. When the young plant starts growing, the starch is

broken down into glucose for energy.

 

Starch

When you eat foods that contain starch, like corn or potatoes, your

body

uses this starch in much the same way. Since your body must

breakdown

this very large molecule to individual sugar units before they can

be

digested, the digestion of starch takes longer than that of

disaccharides; therefore, starch provides an extended, or sustained

source of energy. Because they do not lead to immediate bloodsugar

spikes followed by a low, but instead a more moderate, longer-term

elevation of blood sugar, starches are thought to be better for

health

and energy.

 

Starches are called complex carbohydrates because they are so large.

Two

main types of starches exist in food: amylose and amylopectin. These

starches differ in how the individual sugars they contain are linked

together. This difference results in differences in how easy it is

for

your body to cut the starches into their individual sugar units.

Amylopectin is more quickly digested than is amylose; therefore,

foods

that contain higer amylose than amylopectin are often suggested as

substitutions for people with bloodsugar control problems, like

diabetes.

 

Starch digestion is also influenced by how the starch is packed in

the

food. When food is whole, or in its natural state, marcromolecules

are

folded together, and starch can be encased in protein or fiber or

other

large molecules that must be digested before the starch itself

becomes

available for digestion. The result of this packaging, again, is to

slow

down the absorption of the individual sugar units from the starch,

and

to provide extended, sustained energy for a longer-term, moderate

rise

in blood sugar after a meal. In contrast, processed foods have

removed

this complex interaction. In processing, the macromolecules are

initially pulled apart from each other, then added back separately.

The

result is starch that is more accessible for quick digestion and

absorption, and causes quicker, higher rises in blood sugar, looking

more like a disaccharide than a starch. Therefore, people with blood

sugar control concerns, such as hypoglycemia, insulin resistance or

diabetes can benefit from eating whole foods and avoiding high-

starch,

processed foods.

 

Fiber

Dietary fibers are also polysaccharides and are, therefore,

considered

complex carbohydrates; however, the sugar units in fiber are linked

(bonded) together in such a way that your body can't break the bonds

and

digest them. Instead, fibers transit through your small intestines

and

make it all the way to your large intestine intact. This ability to

move

through your system to your large intestine helps speed the transit

times of wastes excreted from your body; for this reason, fiber

helps to

support your health by reducing constipation and promoting the

excretion

of toxins and wastes.

Fibers that promote overall healthy digestion and waste excretion

are

found in vegetables, grains, and legumes and are well represented in

whole foods. Often, when processed, foods have these fibers removed.

For

example, bran contains high levels of fibers and is removed when

grains

are processed. Fruit skins are also high in fiber, but are often

removed

when the fruit is processed for a fruit-containing product.

 

Much has been written about the health-promoting benefits of fiber,

and

ample numbers of studies support an association between high-fiber

diets

and a decrease in risk of many types of cancers, including colon

cancer

and breast cancer. Some of this benefit comes from the ability of

fiber

to bind and remove toxins, and to promote healthy digestion. Recent

research suggests, however, that fiber provides its health-

protecting

benefits in other ways as well, and one of the most important

appears to

be its ability to promote healthy intestinal tract bacteria.

 

Your large intestine contains a multitude of beneficial bacteria

that

are required for your body's health. They are called the " friendly

flora, " or the beneficial symbiotic microbes, and they support the

health of your whole body by promoting healthy immune function and

providing important molecules to your intestinal tract cells to

promote

their growth, thus sustaining overall intestinal tract integrity.

These

microbes use some of the fibers you eat as fuel for their own

growth,

and through their own metabolism produce molecules called short-

chain

fatty acids (SCFA). SCFA production by these friendly flora has been

associated with a decrease in cancerous colonic cells, reduction of

serum cholesterol, and maintenance of healthy blood sugar levels and

healthy intestinal tract cell walls.

 

Not all fiber is fermented by the friendly flora in your intestinal

tract. Some, as discussed above, goes through your entire system

unchanged, binding toxins and waste products as it goes, and

promoting

healthy elimination. Some fibers can be fermented by microbes of all

types, while other fibers are preferentially fermented by

the " friendly

flora, " the bacteria that are most beneficial to your body,

including

Bifidobacteria and Lactobacillus. When these friendly bacteria are

given

their favorite types of fibers, called " prebiotic fibers, " they will

flourish, significantly improving the health of your digestive

tract.

Excellent sources of these prebiotic fibers include foods such as

Jerusalem artichoke, chicory, rice fiber, and soy fiber.

 

The classical way of talking about fiber to divide it into two

types,

soluble or insoluble fiber, a classification determined by how much

water a type of fiber holds. New research, however, suggests that

fiber

has a multitude of activities besides holding water, and that this

classical distinction is not adequate. Providing a full range of all

types of fibers, including prebiotic fibers, will support your

immune

system, and enhance healthy digestion, absorption, and the removal

of

wastes and toxins. In fact, the health of your gastrointestinal

tract is

dependent upon your consumption of the variety of fibers

well-represented in the World's Healthiest Foods.

 

Resistant Starch

A final category of polysaccharides, or complex carbohydrates, is

that

of resistant starch. Resistant starch gets its name because,

although it

is starch, it is resistant to digestion in the small intestine. The

result of this resistance is that this type of starch acts more like

fiber than starch, and travels through the intestinal tract until it

reaches the large intestine where, like fiber, is may be fermented

by

the bacteria in the colon.

 

Research has shown that resistant starch promotes the generation of

SCFAs by the bacteria in the large intestine, and therefore has many

of

the same health-promoting abilities as fiber. Resistant starch is

found

in whole grains such as brown rice, barley, whole wheat, and

buckwheat.

http://www.whfoods.com/genpage.php?tname=george & dbid=115

 

JoAnn Guest

mrsjo-

www.geocities.com/mrsjoguest/Diets