Diabetes & Byetta

WHAT THE GLYCEMIC INDEX
OF CARBS CAN TELL US

By Karen Collins, MS, RD, CDN

In recent years, researchers have looked more and more at
how the type and amount of carbohydrates that we eat can
affect our health. A recent study helps build the case that
the kind of carbohydrates and the quantity in our diet can
influence our risk for cancers of the colon, uterus and
stomach. But care is needed in evaluating what the research
in this area that centers around concepts called glycemic
index and glycemic load really says.

Glycemic index refers to how a particular food affects the

body’s sugar and insulin levels. Common sense says that sugars
in foods always raise blood sugar more than starches, but
glycemic index testing shows that potatoes can raise blood
sugar and insulin levels at least as much as pure sugar.
Trying to eat foods with low glycemic index readings, however,
is tricky. A food’s effect on one’s blood sugar depends on
what else is eaten, the portion size, and how it’s prepared.

The term glycemic load, on the other hand, tries to calculate
the combined value of one or more foods’ glycemic index
readings and how much of them a person eats. It can be used
to describe the effects of one food, a meal, a whole day’s
eating, or eating over many days. In many recent studies, the
glycemic load of a person’s overall diet is more significant
than the glycemic index of individual foods.

For example, one recent report from the large national Women’s
Health Study shows that women with the highest glycemic load
are nearly three times as likely to develop colorectal cancer
in the next eight years than those with the lowest glycemic
load. In an earlier study, men and women with the highest
glycemic load were 80 percent more likely to develop colon
cancer compared to those with the lowest load.

A high glycemic load may also raise the risk of uterine and
stomach cancer by 24 to more than 100 percent, compared to those
with lower glycemic loads. Researchers think that diets that
repeatedly raise blood sugar levels cause insulin levels to
soar. Insulin and insulin-related growth factors, in turn,
appear to promote the development of some cancers.

The positive link between low-glycemic-load eating habits and
better health helps explain why populations around the world
who eat plant-based diets that emphasize vegetables, fruits,
whole grains and beans have fewer cancers and heart disease
than we have in the U.S. In contrast to the low-carbohydrate
diets popular here, these foreign populations eat
high-carbohydrate diets. Their carbohydrates, however,
are not our 24-ounce soft drinks and super-size baked goods
made with refined flour.

It is important to note in the connection between glycemic
load and disease that a low-glycemic diet will not in itself
protect against disease. It makes a difference whether such
a diet comes from ample portions of vegetables, fruits and
unrefined whole grains or massive amounts of meat. Either
one can have a low glycemic load value.

Some people embrace a low-glycemic diet in an attempt to lose
weight. But selecting foods with a low glycemic load will not
bring automatic weight loss. Whether you gain or lose weight
depends on the balance between the calories you consume and
the calories you burn up. It doesn’t matter if you are strict
and eat only meals and snacks with a low-glycemic load. If you
overeat, you’ll still gain weight if you don’t exercise more.

In sum, the glycemic theory offers a way for people to examine
and think about their eating habits. But it does not lay out a
plan for good nutrition. To improve what you eat and decide the
appropriate amounts of food, you should turn to a nutrition
authority like the American Institute for Cancer Research,
or a registered dietitian.

This entry was posted on Friday, April 6th, 2007 at 4:19 am and is filed under Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.