“If our results are confirmed with future studies, then it would suggest that diet soda may not be the optimal substitute for sugar-sweetened beverages for protection against vascular outcomes.”
Strike another blow to drinking soda—this time the diet variety. Two new studies by University of Miami Miller School of Medicine researchers link diet soda and salt to increased risk of vascular events, including stroke.
In the first study, the scientists found that if you drink diet soda—instead of its sugar counterparts—you could still have a much higher risk of vascular events compared to people who do not drink soda. In the study involving 2,564 people of multi-ethnic backgrounds, the researchers said people who drank diet soda every day had a 61 percent higher risk of vascular events than those who reported they did not drink soda.
“If our results are confirmed with future studies, then it would suggest that diet soda may not be the optimal substitute for sugar-sweetened beverages for protection against vascular outcomes,” says Hannah Gardener, lead author and epidemiologist in the department of neurology at the Miller School.
In separate research involving 2,657 participants, scientists found that high salt intake, independent of the hypertension it causes, was linked to a dramatically increased risk of ischemic strokes, in which a blood vessel blockage cuts off blood flow to the brain. In the study, people who consumed more than 4,000 milligrams per day of sodium had more than double the risk of stroke compared to those consuming less than 1,500 milligrams per day.
Both studies, which were presented during the American Stroke Association’s International Stroke Conference 2011 in Los Angeles, were part of the Northern Manhattan Study, a collaborative effort by the Miller School and Columbia University launched in 1993 to examine stroke incidence and risk factors in a multi-ethnic urban population. A total of 3,298 participants over 40 years old (average age 69) were enrolled through 2001 and continue to be followed.
At the start of both studies, researchers assessed diet by a food frequency questionnaire.
In the soda study, researchers asked subjects at the outset to report how much and what kind of soda they drank. During an average follow-up of 9.3 years, 559 vascular events occurred (including ischemic and hemorrhagic stroke, which is caused by rupture of a weakened blood vessel). After accounting for a multitude of other factors, they found an increased risk of 48 percent.
In the sodium research, 187 ischemic strokes were reported during 9.7 years of follow-up. Stroke risk, independent of hypertension, increased 16 percent for every 500 mg of sodium consumed a day, the scientists calculated. Those figures were also adjusted for age, sex, race/ethnicity, education, alcohol use, exercise, daily caloric intake, smoking status, diabetes, high cholesterol, high blood pressure and previous heart disease.
Only a third of participants met the current dietary guidelines, which recommend daily sodium intake below 2,300 mg, or about a teaspoon of salt. Only 12 percent of subjects met the American Heart Association’s recommendations to consume less than 1,500 mg a day. Average intake was 3,031 milligrams. The findings point out the importance of limiting consumption of high sodium foods for stroke prevention, says Gardener.
At the start of both studies, researchers assessed diet by a food frequency questionnaire. The fact that participants reported their dietary behavior is a key limitation of both studies, says Gardener.
In the soda study, investigators also lacked data on types of diet and regular drinks consumed, preventing analysis of whether variations among brands or changes over time in coloring and sweeteners might have played a role.
February 10, 2011
http://www.burrillreport.com/article-diet_soda%e2%80%94risks_could_outweigh_rewards_.html