A diet rich in carbohydrates that are quickly
transformed into sugar in the blood raises the risk of heart disease
for women, a new Italian study finds.
The same effect, however, is not seen in men, according to the report, published April 12 in the Archives of Internal Medicine.
The study, by researchers at Italy's National
Cancer Institute, looked not only at total carbohydrate intake but also
at what is known as the glycemic index of those carbohydrates -- a
measure of how quickly and to what extent blood sugar rises after
intake of specific carbohydrates.
Carbohydrate foods with similar calorie content
can show widely different scores on the glycemic index. Carbohydrates
with a high glycemic index include corn flakes, white bread and white
rice. Those with lower scores include whole wheat products and sweet
potatoes.
"A high glycemic index is known to increase the
concentration of triglycerides and lower the concentration of HDL
cholesterol, the good kind," explained Victoria J. Drake, director of
the Micronutrient Information Center at the Linus Pauling
Institute of Oregon State University, who has studied the subject.
"Those adverse effects make it a stronger risk factor for heart
disease."
The Italian researchers got their information on
dietary intake from questionnaires filled out by 15,171 men and 32,578
women. Following them for nearly eight years, the researchers found
that women who consumed the most carbohydrates overall had about twice
the incidence of heart disease as those who consumed the least. Closer
analysis showed that the risk was associated with higher intake of
high-glycemic foods.
"Thus, a high consumption of carbohydrates from
high-glycemic index foods, rather than the overall quantity of
carbohydrates consumed, appears to influence the influence of
developing coronary heart disease," the researchers wrote.
Previous studies have seen the same effect in
other groups of women, Drake said. They include the Nurses Health
Study, done in the United States, and studies of women in the
Netherlands.
No effect from total carbohydrate consumption or
consumption of foods with a high-glycemic index was seen in men in the
Italian study, a pattern also seen in other studies, Drake added.
"There is definitely a gender difference," she noted.
The difference might be due to the action of sex
hormones, the researchers speculate. Male hormones, androgens, appear
to slow the transformation of carbohydrates into blood sugar, whereas
the female hormone estrogen speeds the process, she said.
Dr. Suzanne Steinbaum, director of women and
heart disease at Lenox Hill Hospital in New York City, said the study
shows the need for women to be more aware of the nature of the
carbohydrates in their diet.
"An emphasis needs to be placed on a diet that
is not simply low in carbohydrates but rather low in simple sugars, as
measured by the glycemic index," Steinbaum said.
There's a simple way to determine the glycemic index of a food, she said.
"Look at the label," Steinbaum said. "It says
'carbohydrates.' Under that, it says 'sugars.' When you have a high
number for sugars, that's a way to know what the glycemic index is."
That index can differ widely in foods that don't
appear to be different, she said. One breakfast cereal may have a sugar
content of 16 grams, but another may have just 3 grams to 6 grams.
"If you see a high level of sugar, that's the one to stay away from," Steinbaum said.
News release courtesy of USAtoday.com.
