Older women who consume two or more diet drinks daily may be at increased risk of having a stroke, particularly a stroke caused by a blocked blood vessel, according to a study published Thursday in Stroke, a journal published by the American Heart Association (AHA).
The study also found that women aged 50 and older who consume multiple diet drinks daily are at increased risk of heart disease and an early death from any cause.
It’s important to point out that this was an observational study, which means it can’t prove a direct cause-and-effect relationship between diet drinks and stroke and heart disease. But these findings add to a growing body of research that has linked the frequent consumption of artificially sweetened drinks with an increased risk of those and other diseases.
“Many well-meaning people, especially those who are overweight or obese, drink low-calorie sweetened drinks to cut calories in their diet. Our research and other observational studies have shown that artificially sweetened beverages may not be harmless and high consumption is associated with higher risk of stroke and heart disease,” says Yasmin Mossavar-Rahmani, the study’s lead author and a clinical epidemiologist at the Albert Einstein College of Medicine, in a released statement.
For the study, Mossavar-Rahmani and her colleagues analyzed data on more than 81,000 postmenopausal women (aged 50 to 79) who have participated in the Women’s Health Initiative (WHI), an ongoing national health study now in its third decade.
The women had filled out detailed health surveys, which included questions on how often in the previous three months they had consumed diet drinks, such as artificially sweetened colas, sodas and fruit drinks. Most of the women (64 percent) were infrequent consumers of diet drinks, which was defined as consuming less than one diet drink per week (or none at all). Only about 5 percent of the women consumed two or more artificially sweetened drinks per week.
The researchers examined how the women’s health fared during a period of nearly 12 years after they were enrolled in WHI. They found that 2,838 of the women had experienced a fatal or non-fatal stroke, 3,618 had had a heart attack or other type of non-stroke cardiovascular “event,” and 15,005 had died from all causes.
Then then compared the health outcomes for the women who were infrequent consumers of diet drinks with those who consumed two or more of the drinks daily. They found that the heavy consumers were 23 percent more likely (in relative risk) to have had a stroke and 31 percent more likely to have an ischemic stroke.
An ischemic stroke is caused when a clot forms in a blood vessel that supplies blood to the brain. It differs from a hemorrhagic stroke, which occurs when a vessel in the brain leaks blood or bursts open.
Ischemic strokes account for about 87 percent of all strokes, according to the AHA.
Most of the ischemic strokes among the heavy consumers of diet drinks in the study occurred in smaller blood vessels in the brain — a subtype of stroke that has been linked in other research to an increased risk of dementia.
These were the findings after the researchers adjusted the data for other factors linked to an increased risk of stroke, heart disease and early death, such as age, high blood pressure, smoking, alcohol use and physical activity levels.
The researchers also looked specifically at the risk for women without a previous history of heart disease or type 2 diabetes, which are two risk factors for stroke.
They found that women without those histories who consumed two or more diet drinks daily were two-and-a-half times more likely to have an ischemic stroke than women without those histories who were infrequent consumers of diet drinks.
The risk was almost four times greater among African-American women with no history of heart disease or stroke.
Limitations and implications
Again, this study is observational, so it can’t prove a direct causal relationship between the heavy consumption of soft drinks and an increased risk of stroke.
The study also involved only post-menopausal women, so the findings may not be applicable to younger women — or to men of any age.
In addition, the questionnaires did not ask the women to name their diet drinks.
Previous research on a possible link between cardiovascular disease (which includes stroke) and artificially sweetened beverages has been, as Mossavar-Rahmani and her colleagues point out in their paper, “limited” and “inconsistent.” But given the fact that diet drinks add nothing nutritional to people’s diets, avoiding them is probably the wisest step for consumers.
In a science advisory published in 2018, the AHA said that although diet drinks may help replace high-calorie sugary beverages for people who are trying to achieve or maintain a healthy weight, the best choice for a no-calorie beverage is water.
“Unfortunately, current research simply does not provide enough evidence to distinguish between the effects of different low-calorie sweeteners on heart and brain health,” says Rachel Johnson, who is professor emeritus of nutrition and food sciences at the University of Vermont and who chaired the panel that wrote the science advisory for the AHA
“This study adds to the evidence that limiting use of diet beverages is the most prudent thing to do for your health,” she adds.
FMI: You can read the study in full at Stroke’s website.