University of Washington School of Public Health
Diet drinks linked to high risk of stroke, heart attacks
Diet drinks, such as Diet Coke and diet fruit juice, are linked to an increased risk for stroke, and are particularly associated with blood clots of the small arteries, according to a new study published today in Stroke.
The study was co-authored by Shirley Beresford, senior associate dean and professor of epidemiology at the University of Washington School of Public Health. It was led by researchers from the Albert Einstein College of Medicine in the Bronx, New York.
Researchers looked at 81,715 women ages 50 to 79, who enrolled at 40 clinical sites across the United States between 1994 and 1998. The study found that compared with those who never or rarely drank diet beverages, women who drank two or more artificially sweetened drinks a day had a 31 percent increased risk of ischemic stroke, which occurs when a vessel supplying blood to the brain is blocked.
In women with no prior history of cardiovascular disease or diabetes, high intake of diet drinks more than doubled their risk of small artery occlusion, a specific type of ischemic stroke that occurs when blood flow is blocked to a very small arterial vessel. This is one of the first studies to look at links between diet drinks and the risk of a specific type of stroke.
Woman who consumed two or more diet drinks a day were also 23 percent more likely to have all strokes, 29 percent more likely to develop coronary heart disease and 16 percent more likely to die from any cause. Reasons for these links are not yet known; researchers say findings deserve further study.
“These are very interesting findings that raise many additional questions,” Beresford said. “Part of what makes this study important is that people who regularly drink soda or other sugary beverages tend to switch to artificially sweetened beverages to lose weight, when the ideal is to substitute with water.”
Researchers also found risks were higher for certain women. Heavy consumption of diet drinks more than doubled stroke risk in African-American women and obese women.
The cohort of women included in this study is from the Women’s Health Initiative, a long-term, national research effort focused on strategies for preventing heart disease, breast and colorectal cancer, and osteoporotic fractures in postmenopausal women. Beresford is well known for her leadership in the study, particularly of the Dietary Modification Advisory Committee and the Seattle Clinical Center.
Study participants initially filled out questionnaires on demographics, medical and family history and lifestyle factors, and had physical examinations. Researchers followed up with women every year with a survey asking about adverse health events in the previous 12 months and with a medical record review. Study doctors reviewed potential cardiovascular disease events. At the three-year follow up, women were invited for clinic visits to assess health outcomes and consumption of diet beverages. The study adjusted for demographics, cardiovascular disease history, Body Mass Index, health behaviors and overall diet quality.
“In this very large study, a modest increased risk for stroke was found, but it is too early to draw definite conclusions,” Beresford said. “There is still much to be learned.”
Researchers note that the study was observational, rather than a clinical trial; therefore, results must be interpreted with caution. Future studies are needed to replicate the findings to examine specific diet beverages in relation to stroke and other outcomes to guide clinical recommendations.
The study was led by Yasmin Mossavar-Rahmani and Sylvia Wasserheil-Smoller from the Albert Einstein College of Medicine. Co-authors are Victor Kamensky, also from Albert Einstein; JoAnn Manson from Brigham and Women’s Hospital and Harvard Medical School; Brian Silver from University of Massachusetts Medical School; Stephen Rapp from Wake Forest University School of Medicine; Bernard Haring from University of Würzburg; and Linda Snetselaar from the University of Iowa.