If you have a penchant for
drinking sugary sodas, you might be raising your risk for kidney disease, new
Employees at a university
in Japan who consumed more than two sodas a day were more likely to have
protein in their urine when compared to those who had fewer or no sodas on a
daily basis. Protein in the urine is considered an early, but reversible,
marker of kidney damage.
The new study showed an association
between drinking soda and an increased risk of kidney damage, but it didn't
necessarily prove that soda is the culprit.
The study included more
than 12 000 university employees who underwent their annual check-ups at their
health centre. As part of the exam, their urine was tested for evidence of
Nearly 11% of employees who
said they drank two or more soft drinks per day had protein in their urine
during three years of follow-up. In contrast, 8.4% of those who did not any drink
soda and roughly 9% of those who drank about one can a day tested positive for
protein in their urine.
Unhealthy side effects
A related study in rats
found that moderate consumption of a sugar called fructose increases the
kidney's sensitivity to a protein that regulates salt balance.
According to the Case
Western Reserve University researchers, this leads to increased salt
reabsorption by cells in the kidneys, which might explain why soda consumption
has been linked to diabetes, obesity, kidney failure and high blood pressure.
Both studies were scheduled
for presentation Saturday at the annual meeting of the American Society of
Nephrology, in Atlanta.
Research presented at meetings typically is
considered preliminary until published in a peer-reviewed medical journal.
Experts said the new
findings add to a growing body of evidence on the unhealthy side effects of
drinking too much soda.
Protein in the urine may be
a marker for more than just kidney disease, said Dr Orlando Gutierrez, a kidney
specialist at the University of Alabama at Birmingham.
"We now understand
that protein in the urine may be a really early marker for heart disease,
stroke and heart failure," he said.
"We can assume that
this is a healthy population, so I think the results are relative to healthier
people, not just those with kidney disease," Gutierrez said.
Risk for damage
Dr Anil Agarwal, a kidney
specialist at Ohio State University, agreed. "The new study suggests that
even individuals with normal kidney function are at risk for damage if they
drink too much soda," he said.
And soft drinks sweetened
with high-fructose corn syrup may be the most dangerous.
"Fructose is sweeter
than glucose, and doesn't cause feelings of satiety," he said. It may
cause damage via a different pathway than glucose. Instead of increasing
blood-sugar levels, fructose may affect the kidneys, he said.
"There is no safe
amount of soda," Agarwal said. "If you look at the recommended
amounts of sugar we can safely consume every day, one can of soda exceed the
American Heart Association
guidelines state that the recommended daily sugar intake is 9 teaspoons for
adult men, 5 teaspoons for adult women and 3 teaspoons for children. A 12-ounce
can of non-diet soda has about 7 teaspoons of sugar, Agarwal said.
Dr Jaime Uribarri, a kidney
specialist at the Icahn School of Medicine at Mount Sinai Medical Centre in New
York City, said the new findings "reaffirm an association between soda and
health problems." He added that diet soda also can cause health problems.
The bottom line? "Drink
water instead of soda," Uribarri said.
The National Kidney
Foundation has more on kidney disease.