Eating a diet rich in
carbohydrates that boost blood sugar levels -- foods such as cornflakes or
white bread -- may hamper the functioning of your blood vessels and raise
your risk of developing cardiovascular disease, a new study suggests.
And another study, released Thursday at the Endocrine Society's annual
meeting in Washington, D.C., found that people might actually feel
fuller -- and might therefore eat less -- if they cut back a bit on
carbohydrates in their diet.
In the first study, researchers from Israel's Chaim Sheba Medical
Center and elsewhere evaluated 56 healthy but overweight or obese men and
women, aged 35 to 60. None had diabetes or a history of hospitalizations
for cardiovascular disease.
The researchers fed the men and women on four different mornings,
following overnight fasts. They were served either glucose, cornflakes,
high-fiber cereal or water, in descending order of glycemic index.
Low-glycemic index foods include oatmeal, most fruits and vegetables,
legumes and nuts. White bread, cornflakes and instant potatoes are
high-glycemic indexes. The higher the glycemic index, the more that food
raises blood sugar levels.
Before and after the meals or the water, the team of researchers
measured the functioning of the endothelium, the layer of cells that line
the inside of blood vessels. If the endothelial function is poor, it is
thought to increase the risk of cardiovascular disease.
The measurement used is called brachial artery flow-mediated dilation
(FMD), which measures how well the endothelium is functioning. Researchers
also measured the participants' blood sugar levels.
The blood sugar levels before and two hours after the meals were
similar, but they were higher at 30 to 90 minutes after the high-glycemic
meals.
The FMD was reduced two hours after eating for all groups, but the
reduction was more marked after the high-glycemic meals.
The high-glycemic meals, the authors conclude, appeared to impair the
endothelial function.
"Based on our study, we do urge consumers to have low-glycemic index
carbohydrates instead of high-glycemic carbohydrates for better health and
less potential hazards for the vascular endothelial function," said Dr.
Michael Shechter, senior cardiologist at The Sackler Faculty of Medicine
at Tel Aviv University in Israel.
"The main take-home message is that high-glycemic index carbs are
dangerous since they reduce or inhibit endothelial function, which is the
'risk of the risk factors,' leading to atherosclerosis and potentially
leading to heart disease," Shechter said.
Previous research has found that high blood sugar levels after meals is
a risk factor for cardiovascular disease, not only in patients with
diabetes but in the general population. Declining endothelial function is
considered a key variable in the development of hardening of the arteries
and heart disease.
The study is published in the June 16 issue of the Journal of the
American College of Cardiology.
Another expert called the study "interesting" but added a caveat that
more research is needed to confirm the findings. "The cross-over design is
a real strength," said Barry Braun, director of the Energy Metabolism
Laboratory at the University of Massachusetts, in Amherst. But he said
some "dots" still need to be connected.
In the second study, researchers at the University of Alabama at
Birmingham investigated whether a small cutback in dietary carbohydrates
would actually boost that sense of satiety you get after eating.
Led by professor of nutritional sciences Barbara Gower, the team noted
that Americans typically get 55 percent of their daily calories from carbs
such as sugars, starches and fiber. This was the "control" diet used in
the study. The team had other adult participants go on a moderate carb
diet where 43 percent of calories came from carbohydrates. Protein intake
(a major influence on satiety) was the same for both diets, but people on
the moderate-carb diet took in a bit more fat to make up the
difference.
The results: after a month, the 16 participants on the moderate carb
diet had lowered blood insulin levels, more stable blood sugar, and a
longer duration of a sense of fullness after a meal than did the 14 people
on the control diet.
A longer time feeling full might translate into less snacking or eating
and perhaps fewer added pounds, the team said. So, "over the long run a
sustained modest reduction in carbohydrate intake may help to reduce
energy consumption and facilitate weight loss," Gower said in a meeting
news release.
More information
To learn more about glycemic index, visit the American
Diabetes Association
By Kathleen Doehny
http://news.yahoo.com/s/hsn/20090612/hl_hsn/cornflakeswhitebreadcouldboostheartrisk