WebMD Medical News
Louise Chang, MD
July 23, 2007 -- People who drank soda every day -- even diet soda -- in a
recent study were more likely to develop risk factors for heart disease.
That is because a soda habit increases the risk of developing a condition
called metabolic syndrome, according to the new research, and that in turn
boosts the chance of getting both heart disease and diabetes.
"Even one soda per day increases your risk of developing metabolic
syndrome by about 50%," says Ramachandran Vasan, MD, professor of medicine
at Boston University School of Medicine and the senior author of the study,
published in the July 31 issue of the American Heart Association's journal
But other experts, including the American Heart Association, say heart
disease has many risk factors and there's not enough evidence to directly blame
To be diagnosed with
metabolic syndrome, three of five criteria must be met: a large waistline,
elevated blood pressure, elevated fasting blood sugar, elevated fasting
triglycerides, or reduced HDL or "good" cholesterol.
"This study adds to the wealth of scientific evidence that
sugar-sweetened beverages increase the risk of metabolic syndrome," says
Vasan. Already, he says, the rise in sugary drink consumption has been
linked to the epidemic of obesity and diabetes among children and teens and to
the development of high blood pressure in adults.
The food and beverage industry takes issue with the finding.
Roger Clemens, DrPH, a spokesperson for the Institute of Food Technologists,
calls the study findings "oversimplified."
"There are many attributes associated with the development of metabolic
syndrome," Clemens tells WebMD. "Some of which are part of lifestyle
choices, such as eating too many calories." Diet soda is a more appropriate
choice than regular soda, he says.
"It's way too soon to say stop drinking diet soda," says Clemens, a
professor of molecular toxicology at the University of Southern California
School of Pharmacy, Los Angeles, who is familiar with the new research.
"Diet soda, in moderation, can be part of a healthy lifestyle."
Vasan and his colleagues evaluated about 3,500 men and women participating
in the Framingham Offspring Study. The offspring study began in 1971, following
the original Framingham Heart Study launched in 1948. The offspring study
included 5,124 people in all.
The questions about soda and other dietary habits were asked at three
different exam periods, from 1987 to 1991, 1991 to 1995, and 1995 to 1998. The
average age of those who answered questions about their soft drink intake and
other health habits was 53 during the three exam periods, Vasan says.
At the first exam period, those who drank one or more soft drinks daily had
a 48% increased prevalence of having metabolic syndrome compared with those who
drank less than one a day, the researchers found.
As the study progressed, drinking one or more sodas a day was linked with a
44% higher risk of participants developing metabolic syndrome, Vasan's team
found, compared with drinking less than a soda a day.
The researchers looked at soda consumption and the person's risk of
developing each of the five criteria of metabolic syndrome. "Other than
elevated blood pressure, the risk of developing the other four increased from
about 20% to 30% with one soda a day," Vasan tells WebMD. They also found a
trend toward an increased risk of developing high blood pressure with soda
consumption, but it wasn't enough to be considered significant.
The link between soda consumption and heart disease risk factors "might
be reflecting dietary behavior," Vasan says. "We know people who drink
sodas have a greater intake of calories."
Soda drinkers, he says, are more likely to have a less healthy lifestyle
pattern, such as eating fries, chips, and other high-fat foods. "They tend
to smoke more and exercise less," he says.
Even after adjusting for intake of fat, fiber consumption, total calories,
smoking, and physical activity, he says, there was still a link between soft
drink intake and metabolic risk factors.
"We cannot rule out the possibility that consumption of soda is a marker
of risk -- meaning it tracks with behavior that promotes the risk of metabolic
syndrome -- rather than a true risk factor," Vasan says.
Other possible explanations: Drinking more sweet beverages could condition
you to have a greater preference for eating more sweets, Vasan says, which
could increase your weight and your waist size. Or if you drink a large
soft drink with a meal, you may be hungrier and eat more at the next meal.
The findings don’t surprise Paul Lachance, PhD, acting director of The
Nutraceuticals Institute at Rutgers, The State University of New Jersey, and a
diet and health expert for the Institute of Food Technologists. “It’s
plausible,” he says of the link between soda intake and increased risk of
But he wonders about the true root of the association. It may not be the
soda intake itself leading to the increased risk, he says. “People who
drink sodas may be giving up drinking healthier beverages,” he says, such as
juices, milk, wine, and other beverages.
In a prepared statement, the soft drink industry took issue with the
findings. "Blaming one food, beverage, or ingredient as the cause for
myriad health problems defies common sense and doesn't agree with the current
body of nutritional science," says Susan K. Neely, president and chief
executive officer of the American Beverage Association.
The Washington, D.C.-based industry group represents many companies that
make and distribute nonalcoholic beverages in the U.S.
"Metabolic syndrome and heart disease are complex problems that have no
single cause and no single solution," the statement continues. Soft
drinks can be part of a healthy way of life "when consumed in moderation
and as part of a balanced lifestyle," it states.
“We’re underscoring the point the researchers make that it’s an association,
not causal,” Neely tells WebMD. “The association found between diet soda and
metabolic syndrome is particularly implausible. Diet soda is a beverage with
zero calories, and it is 99% water.”
In a prepared statement issued Monday, the American Heart Association
(AHA) also notes that the study does not prove cause and effect.
More study is needed on sodas before formal recommendations can be made,
according to the AHA. Until then, the association views diet soda as “a good
option to replace caloric beverages that do not contain important vitamins and
minerals.” Diet soda, along with water and fat-free or low-fat milk, are better
choices than full calorie soft drinks, according to the AHA.
Is there a "safe" amount of soda? "We cannot really answer that
question," Vasan says. The research shows an association between soda
consumption and metabolic syndrome risk, Vasan says, but not cause-effect. More
study is needed.
Still, he adds, "the group without risk drank less than one soda a
His co-author, Ravi Dhingra, MD, a physician at the Alice Peck Day Memorial
Hospital, in Lebanon, N.H., and instructor of medicine at Harvard Medical
School in Boston, says: "If you are drinking more than one soft drink per
day, you may be increasing the metabolic risk factors for heart
SOURCES: Ramachandran S. Vasan, MD, professor of medicine, Boston University
School of Medicine. Dhingra, R. Circulation , July 31, 2007:
vol 116: pp 1-9. Statement, July 23, 2007, American Beverage Association,
Washington. Ravi Dhingra, MD, physician, Alice Peck Day Memorial
Hospital, Lebanon, N.H.; instructor of medicine, Harvard Medical School,
Boston. Susan Neely, president and chief executive officer, American Beverage
Association. Paul Lachance, PhD, acting director, The Nutraceuticals Institute
at Rutgers, The State University of New Jersey; diet and health expert,
Institute of Food Technologists. Roger Clements, DrPH, spokesperson, Institute
of Food Technologists; professor of molecular toxicology, University of
Southern California School of Pharmacy, Los Angeles. Statement, American Heart
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