01:55am Thursday 21 September 2017

Related studies point to the illusion of the artificial

SAN DIEGO — In the constant battle to lose inches or at
least stay the same, we reach for the diet soda. Two studies presented
Saturday [June 25] at the American Diabetes Association’s Scientific
Sessions suggest this might be self-defeating behavior.

Epidemiologists
from the School of Medicine at The University of Texas Health Science
Center San Antonio reported data showing that diet soft drink
consumption is associated with increased waist circumference in humans,
and a second study that found aspartame raised fasting glucose (blood
sugar) in diabetes-prone mice.

“Data from this and other
prospective studies suggest that the promotion of diet sodas and
artificial sweeteners as healthy alternatives may be ill-advised,” said
Helen P. Hazuda, Ph.D., professor and chief of the Division of Clinical
Epidemiology in the School of Medicine. “They may be free of calories
but not of consequences.”

Human study: The San Antonio Longitudinal Study of Aging
To
examine the relationship between diet soft drink consumption and
long-term change in waist circumference, the Health Science Center team
assessed data from 474 participants in the San Antonio Longitudinal
Study of Aging, or SALSA. This is a large, population-based study of the
disablement process in elderly Mexican Americans and European
Americans. Dr. Hazuda, senior author of the presentation, is SALSA’s
principal investigator and has led the study for two decades.

Measures
of height, weight, waist circumference and diet soda intake were
recorded at SALSA enrollment and at three follow-up exams that took
place over the next decade. The average follow-up time was 9.5 years.
The researchers compared long-term change in waist circumference for
diet soda users versus non-users in all follow-up periods. The results
were adjusted for waist circumference, diabetes status, leisure-time
physical activity level, neighborhood of residence, age and smoking
status at the beginning of each interval, as well as sex, ethnicity and
years of education.

Diet soft drink users, as a group,
experienced 70 percent greater increases in waist circumference compared
with non-users. Frequent users, who said they consumed two or more diet
sodas a day, experienced waist circumference increases that were 500
percent greater than those of non-users.

Abdominal fat is a major
risk factor for diabetes, cardiovascular disease, cancer and other
chronic conditions. “These results suggest that, amidst the national
drive to reduce consumption of sugar-sweetened drinks, policies that
would promote the consumption of diet soft drinks may have unintended
deleterious effects,” the authors wrote.

Co-authors include
Sharon P. Fowler, M.P.H., faculty associate, and Ken Williams, M.S.,
P.Stat., adjunct assistant professor and biostatistician, in the
Division of Clinical Epidemiology.

Mouse study: Aspartame consumption in diabetes-prone mice
In
the related project, Ganesh Halade, Ph.D., Gabriel Fernandes, Ph.D.,
the senior author and professor of rheumatology and clinical immunology,
and Fowler studied the relationship between oral exposure to aspartame
and fasting glucose and insulin levels in 40 diabetes-prone mice.
Aspartame is an artificial sweetener widely used in diet sodas and other
products.

One group of the mice ate chow to which both aspartame
and corn oil were added; the other group ate chow with the corn oil
added but not the aspartame. After three months on this high-fat diet,
the mice in the aspartame group showed elevated fasting glucose levels
but equal or diminished insulin levels, consistent with early declines
in pancreatic beta-cell function. The difference in insulin levels
between the groups was not statistically significant. Beta cells make
insulin, the hormone that lowers blood sugar after a meal. Imbalance
ultimately leads to diabetes.

“These results suggest that heavy
aspartame exposure might potentially directly contribute to increased
blood glucose levels, and thus contribute to the associations observed
between diet soda consumption and the risk of diabetes in humans,” Dr.
Fernandes said.

These two translational research studies resulted
from collaboration between Fowler and Drs. Hazuda and Fernandes and
their research teams. The Institute for the Integration of Medicine and
Science (IIMS) funded the work. IIMS is the Health Science Center entity
that oversees the university’s Clinical and Translational Science Award
(CTSA), a National Institutes of Health-funded program to encourage the
rapid translation of scientific discoveries from the laboratory through
the testing process and to practical application for the health of
communities.

# # #

The University of Texas Health Science Center at San Antonio,
one of the country’s leading health sciences universities, ranks in the
top 3 percent of all institutions worldwide receiving federal funding.
Research and other sponsored program activity totaled $228 million in
fiscal year 2010. The university’s schools of medicine, nursing,
dentistry, health professions and graduate biomedical sciences have
produced approximately 26,000 graduates. The $744 million operating
budget supports eight campuses in San Antonio, Laredo, Harlingen and
Edinburg. For more information on the many ways “We make lives better®,”
visit www.uthscsa.edu.


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