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Is
This Any Way to Choose Foods?
Glycemic index is a term bandied about a lot these days.
The Atkins, South Beach, Zone, and Sugar Busters diets advise
against foods high on the glycemic index, and thus against
many grain products, fruits, and vegetables. People with
diabetes may hear about it. Is it something you really need
to bother about?
The index is not an easy concept. To understand it you
have to start with carbohydrates, and most people have only
a hazy idea what these are and which foods are rich in them.
In fact, about half our foods are high in carbs -- orange
juice, beans, sugar, milk, pears, strawberries, all types
of flour, broccoli, soda pop, apple pie, corn, biscuits,
green peas, muffins, honey, sweet potatoes, and so much
more.
Simple and not simple
Carbohydrates are the main source of calories in virtually
every diet worldwide (the other calorie-providing components
of foods are protein and fat). Most come from plant-based
foods; dairy products are the only animal-derived foods
with lots of carbs. All carbohydrates (except for fiber)
are transformed by the body into blood sugar (glucose),
the body's basic fuel.
There are two general types of carbohydrates: simple and
complex. The simple ones are sugars: glucose and fructose
from fruits and some vegetables, lactose from milk, sucrose
from cane or beet sugar, and others. Many of the simple
carbs are sugars added to processed foods such as sodas
and cookies. Complex carbs, which are chains of sugars,
consist primarily of starches, the storage form of carbohydrates
in plants. Foods rich in complex carbs include grains and
grain products (such as bread and pasta), beans, potatoes,
corn, and some other vegetables.
This is where the glycemic index comes in. It ranks foods
by how fast their carbs are digested into glucose and absorbed,
and thus how rapidly and how high they cause blood sugar
to rise—which in turn affects insulin levels. The higher
the number, the greater the food's effect on blood sugar.
You might think that simple carbs such as table sugar would
cause blood glucose to shoot up the most, but not necessarily.
Instant rice is at the top of the list for fast release
of sugar, along with white potatoes, watermelon, raisins,
carrots, pretzels, rice cakes, most breakfast cereals and
crackers, and white breads. Beans and unrefined grains are
generally low on the list.
A guide, but to what?
If you were eating one food at a time, the index might
be of some use. In real life, however, we usually eat mixed
meals, and many factors come into play that can make hash
of the glycemic index. The factors that alter the digestion
and absorption of carbs, and thus the blood sugar levels
that result, include the amount of fiber, fat, and protein
in the food, how refined the ingredients are, whether the
food was cooked, and what other foods are eaten at the time.
Potatoes are high on the index, but if you eat them with
meat or cheese, or make them into chips, they are digested
more slowly. If you mash a potato, it moves up even higher.
The riper the fruit is, the higher on the index. Adding
vinegar to a meal can reduce its glycemic impact. Surprisingly,
adding plain old sugar to a meal has no effect on the glycemic
index of the meal. Because of all these variables, the glycemic
index is of little practical use for designing an eating
plan.
Moreover, it's not even clear that avoiding foods high
on the index is beneficial. Some research suggests that
diets high on the glycemic index are more likely to lead
to diabetes, heart disease, and obesity, but the evidence
is mixed. Thus, the American Diabetes Association, for instance,
does not recommend using the index in the prevention or
treatment of diabetes. The notion that foods high on the
index make people feel hungrier sooner remains unproven.
But, you may ask, if a food promotes high levels of glucose,
which in turn provokes the release of high levels of insulin,
which in turn is associated with insulin insensitivity and
diabetes, shouldn't a person avoid those foods? Perhaps
so. The trouble is, the glycemic index does not accurately
predict how much insulin the body will release in response
to blood sugar, according to a review of studies by Dr.
Xavier Pi-Sunyer, a well-known expert on diabetes at St.
Luke's Roosevelt Hospital Center in New York City. Portion
size is more important than the specific foods a person
eats. It all breaks down into confusion when you learn that
lentils (low on the index) provoke higher insulin levels
than potatoes (high on the index).
Dr. Pi-Sunyer's conclusion: People (and the experts advising
them on nutrition) can find more worthwhile issues to concentrate
on than the glycemic index.
Practical lessons
Don't try to build your diet around the glycemic index.
The main problems: it deals with single foods eaten by themselves,
and its health benefits remain unproven. Yes, it's good
to limit your intake of (or avoid) some high-index foods,
such as white bread. But there is no reason to avoid all
foods high on the index—many are very nutritious, such
as carrots. Moderation is the key. If foods high on the
glycemic index play any role in diabetes, it may be simply
that people eat too much of them and gain weight.
Choose foods rich in fiber and unrefined complex carbohydrates—that
is, fruits, vegetables, beans, and whole grains. They are
nutritious, filling, and relatively low in calories. Many
are also low on the glycemic index. If you're trying to
lose weight, calories do count, far more than the glycemic
index. In fact, all the current diets built around the index
have another thing in common—they get you to cut calories,
even as they tell you that calories don't count.
Article Source: Berkley Wellness
Article Author: N/A
Net Reference 98
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