foodconsumer.org: Dietary fructose linked to metabolic syndrome and diabetes mellitus

Dietary fructose linked to metabolic syndrome and diabetes mellitus
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admin on 09/06/2011 00:30:00
 
By David Liu, Ph. D. and editing by Aimee Keenan-Greene
Mondsay Sept 5, 2011 (foodconsumer.org) -- A new animal study in the Aug 2011
issue of Clinical and Translational Science suggests eating too much fructose
may boost risk of insulin resistance and type 2 diabetes mellitus.
Previous studies have established an association between fructose consumption
and elevated risk of diabetes mellitus, mostly in rodents.  The current study
was conducted in primates, which are believed to be closer to humans thus the
results should be more relevant.
In the study led by Andrew A. Bremer M.D., Ph.D. of Vanderbilt University in
Nashville, Tennessee, a diet with 30 percent of total energy from fructose was
given to 29 adult male rhesus monkeys aged 12 to 20 years for a period of 12
months.
Starting at six months and by the end of the 12-month feeding study, one hundred
percent of the monkeys developed certain metabolic syndrome components including
body adiposity, insulin resistance, and dyslipidemia and four monkeys or 15
percent of the total population developed type 2 diabetes mellitus, which is
defined as a condition in which the fasting blood glucose concentration is equal
to or greater than 126 mg/dl.
The monkeys had less than 100 mg/dL of fasting blood glucose at baseline,
meaning that they were free of type 2 diabetes mellitus before the diet
intervention.
The study funded by The National Institute of Health and the American Diabetes
Association had some limitations the researchers acknowledged.
First, the monkey diet consisted of 30 percent of its energy from fructose.  
Most Americans do not use more than 25 percent of energy from fructose.
The researchers cited one report published by L.C. Dolan in 2010 in Critical
Review of Food Science and Nutrition suggesting that consumption of up to 140
grams of fructose per day or 25 percent of energy from fructose may not pose any
risk in humans.
However, the researchers also said other studies invalidated the conclusion by
Dolan et al. suggesting fructose may still have some effect on type 2 diabetes
mellitus.
Another limitation is that the current study did not use a control group, which
means that it is unknown how many cases of metabolic disorders were actually
caused by fructose.
Researchers said one study they conducted earlier in overweight/obese people
showed only consumption of fructose sweetened beverages, but not glucose
sweetened beverages, for 10 weeks increased insulin insensitivity. This means
that it is certain that fructose increases insulin resistance.
what is metabolic syndrome?
Whether or not a person has metabolic syndrome depends upon his status in a
number of parameters including abdominal obesity, serum triglycerides, high
density cholesterol, blood pressure and fasting blood glucose.  When the
conditions get worse, the risk for cardiovascular disease increases.
What is fructose?
In the U.S. dietary fructose comes mostly in the form of high fructose corn
syrup.   Food consumers should know that high fructose corn syrup differs from
corn syrup.  The latter contains no fructose but multiple forms of sweet
carbohydrates including glucose, maltose,and higher oligosaccharides.
Fructose is also present in sucrose like beet sugar and table sugar.  That is,
when sucrose is enzymatically hydrolyzed, one fructose molecule and one glucose
molecule are released.  Because high fructose corn syrup contains almost equal
amounts of fructose and glucose, the industry claims that high fructose corn
syrup is similar to sucrose.  Studies show they are not exactly the same.
Photo credit: wikipedia.org