Even one serving daily of a sugary soft drink is associated with higher risk of cardiovascular disease.
That's according to a new study published Wednesday in the Journal of the American Heart Association.
In the study, researchers cataloged answers from about 106,000 women who filled out a food questionnaire. The survey included questions about how often they drank sweetened beverages, including sodas, sports drinks and sweetened bottled waters.
The participants, whose average age was 52, hadn't been diagnosed with heart disease, stroke or diabetes when they entered the study. Based on follow-ups over two decades, however, many began to show signs of those conditions.
The researchers concluded that drinking one or more sugary beverages each day was associated with a nearly 20% greater likelihood of having a cardiovascular disease, when compared with women who either didn't drink or rarely drank sugary beverages.
Some drinks are worse than others
Those who consumed fruit drinks with sugar added on a daily basis had a 42% greater likelihood of experiencing cardiovascular disease compared with those who didn't drink sugary beverages at all. (The study's definition of "fruit drink" excluded fruit juices and only included flavored fruity drinks in which sugar was added.)
Frequent soda drinkers had less risk, clocking in at a 23% greater likelihood for cardiovascular disease overall.
The American Heart Association recommends that women try to limit their added sugar intake to no more than 100 calories daily, or 25 grams. Men shouldn't have more than 150 calories, or 38 grams.
Sugar can narrow the arteries
"We hypothesize that sugar may increase the risk of cardiovascular diseases in several ways," said lead author Cheryl Anderson, a professor of family and public health at University of California San Diego.
"It raises glucose levels and insulin concentrations in the blood, which may increase appetite and lead to obesity, a major risk factor for cardiovascular disease."
She noted that excessive sugar is associated with inflammation, insulin resistance and type 2 diabetes.
These conditions are linked to the development of atherosclerosis, which is the narrowing of arteries that forms the basis for most cardiovascular disease.
For the purposes of this study, researchers defined cardiovascular disease as the first instance of a heart attack, undergoing a revascularization procedure (such as a coronary artery bypass) or having a fatal or nonfatal stroke.
The women in this study were pulled from the California Teachers Study. That project kicked off in 1995 when 133,478 women, who were either active or former teachers, filled out a questionnaire as part of a study about links between smoking and breast cancer.
Since then, the large longitudinal cohort study has followed the same women who first entered 25 years ago, gleaning insights into a range of associations between risk factors and health outcomes. The study has resulted in more than 200 academic publications over the past 25 years.
In this study related to cardiovascular disease, researchers extracted survey data from all the women in the California Teachers Study cohort. They tracked the women until those participants had experienced a cardiovascular event, died, moved out of California or quit following up with questionnaire mailings.
One key strength of this study is that the "period of observation is longer — 20 years," said Dr. Bob Eckel, a past president of the American Heart Association and a professor emeritus of medicine at the University of Colorado.
He also praised it for the level of detailed information generated about how much each type of beverage may contribute to risk as people go through life.
One limitation of the study is that it is observational, and therefore can't establish a direct cause and effect relationship between sugary drinks and cardiovascular disease.
Water is the best drink
In a statement, a spokesperson for the American Beverage Association said the beverage industry has been supporting consumer efforts to provide options with lower sugar content and to provide "smaller package sizes and clear calorie information right up front."
To avoid sugary drinks, the AHA says that people should read nutrition labels and look out for additives such as sucrose, maltose and syrups, and keep an eye on whether the serving size listed isn't the full bottle, so you don't accidentally drink two or three times the amount listed.
The AHA recommends water as the best thing to sip on throughout the day, and if you're looking to take in something sweeter, making a fruit smoothie is a healthier way to add more taste without gulping down certain negative health consequences at the same time.
Follow a heart-healthy dietary pattern such as Mediterranean or Dietary Approaches to Stop Hypertension "with lots of fresh fruit and vegetables, whole grains, lean poultry and fish, legumes and fiber," Eckel said.
Sugar-sweetened beverages "have a small place in these dietary patterns."