| Too much fructose may skew appetite hormones
By Alison McCook
NEW YORK (Reuters Health) - Consuming too much fructose -- a form
of sugar found in corn syrup, honey and fruit -- appears to alter
levels of hormones involved in appetite regulation in such a way
as to encourage overeating, a new study suggests.
After people in the study ate a meal followed by a drink flavored
with the same amount of fructose found in two cans of soda, they
showed relatively low levels of insulin and leptin, hormones that
help people know that they are full.
On the other hand, they showed relatively high levels of ghrelin,
a hormone that stimulates eating.
These hormonal changes "we think could promote overeating,"
and subsequently obesity, study author Dr. Karen L. Teff told Reuters
Health.
Teff explained that sugar occurs in two forms, fructose and glucose.
Glucose, but not fructose, stimulates insulin secretion, which in
turn regulates leptin production.
Both fructose and glucose are naturally found in fruit and fruit
juices. However, over the years manufacturers have sweetened sodas
and some foods with corn syrup, which contains concentrated amounts
of fructose, she said.
"If people are drinking five sodas a day, they're getting
a huge amount of calories, plus they're getting a large amount of
fructose," she said.
Based on these findings, Teff recommended that people limit their
intake of soda and other drinks containing large amounts of fructose.
"I've changed my eating patterns because of this, honestly,"
she said in an interview.
To investigate whether drinking fructose plays a role in obesity,
Teff and her colleagues asked 12 normal-weight women to wash down
balanced meals with drinks sweetened with either fructose or glucose.
When the women drank the fructose drink, their levels of insulin
and leptin were lower than when they consumed a drink flavored with
glucose, and levels of ghrelin were higher, the researchers report
in the Journal of Clinical Endocrinology and Metabolism.
In addition, drinking the fructose drink was associated with a
spike in levels of blood fats, a known risk factor for cardiovascular
disease.
Teff, who is based at the Monell Chemical Senses Center in Philadelphia,
explained that drinking glucose-sweetened beverages may not encourage
overeating as much as fructose drinks because glucose triggers insulin
release from the pancreas, which tells people they are no longer
hungry. Moreover, glucose is metabolized in a healthier way by the
liver than fructose, she noted.
Teff emphasized that there is no way to avoid fructose, which is
a natural molecule. But drinking large amounts of it in soda, without
any other nutrients, is not natural, she said.
"I don't think there's anything wrong with (fructose), it's
just that people are drinking it in large quantities," Teff
noted.
SOURCE: Journal of Clinical Endocrinology and Metabolism, June
4, 2004.
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