A new research has found that drinking two or more diet drinks in a day increases the risk of heart diseases in older, but healthy postmenopausal women.
In fact, compared to women who never or only rarely consume diet drinks, those who consumed two or more a day were 30 percent more likely to suffer a cardiovascular event and 50 percent more likely to die from related disease.
Researchers analyzed diet drink intake and cardiovascular risk factors from 59,614 participants in the study, making this the largest study to look at the relationship between diet drink consumption, cardiac events and death.
Information on women's consumption of diet drinks was obtained through a questionnaire that asked them to report their diet drink consumption habits over the previous three months.
This information was assessed at follow-up year three of the study. Each drink was defined as the equivalent of a 12-ounce beverage and included both diet sodas and diet fruit drinks.
For the purposes of the analysis, researchers divided the women into four consumption groups: two or more diet drinks a day, five to seven diet drinks per week, one to four diet drinks per week, and zero to three diet drinks per month.
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After an average follow-up of 8.7 years, the primary outcome - a composite of incident coronary heart disease, congestive heart failure, heart attack, coronary revascularization procedure, ischemic stroke, peripheral arterial disease and cardiovascular death - occurred in 8.5 percent of the women consuming two or more diet drinks a day compared to 6.9 percent in the five-to-seven diet drinks per week group; 6.8 percent in the one-to-four drinks per week group; and 7.2 percent in the zero-to-three per month group.
The association persisted even after researchers adjusted the data to account for demographic characteristics and other cardiovascular risk factors and comorbidities, including body mass index, smoking, hormone therapy use, physical activity, energy intake, salt intake, diabetes, hypertension, high cholesterol and sugar-sweetened beverage intake.
Women who consumed two or more diet drinks a day were younger, more likely to be smokers, and had a higher prevalence of diabetes, hypertension and higher body mass index.
But lead investigator of the study Ankur Vyas, from the University of Iowa Hospitals and Clinics, said that the association between diet drinks and cardiovascular problems raises more questions than it answers, and should stimulate further research.
"We only found an association, so we can't say that diet drinks cause these problems," Vyas said, adding that there may be other factors about people who drink more diet drinks that could explain the connection.