The study, presented at the European Society of Cardiology Congress, found that spending on other types of beverages — including green tea, black tea, coffee, cocoa, fruit or vegetable juice, fermented milk beverage, milk and mineral water — didn't appear to lead to the same risk.
Keijiro Saku, a study author and professor of cardiology at Fukuoka University, theorized that "the acid in carbonated beverages might play an important role in this association."
The battle over sugary drinks has come to a head in recent months with dueling studies and public health messaging campaigns about what soda does to your body.
In March, researchers quantified what diet soda does to your waistline, calculating that those who consumed daily and occasional diet soda were linked to nearly three times as much belly fat as those who didn't consume the drinks. In June, after a study in the journal Circulation by Tufts University researchers estimated that sugary beverages are responsible for 133,000 deaths from diabetes, 45,000 from cardiovascular disease and 6,450 from cancer, many doctors warned that people should cut down on those drinks.
In July, a former pharmacist's graphic representation on a blog of what happens to your body one hour after you drink a can of Coca-Cola went viral — spurring heated discussion about the accuracy of the analysis and the possible dangers of drinking too much soda.
Coca-Cola has been fighting back through a nonprofit that funds medical research with the message that it is not diet but lack of exercise that is to blame for America's obesity epidemic.
Saku emphasized that in the Japan study the researchers used expenditures on carbonated beverages as a proxy for consumption and that there was no way to determine a causal link. He said in an e-mail that the data was also limited because it did not contain information about the type of carbonated beverage purchased — whether it was a sugary soda like Coca-Cola or Pepsi, or mineral water like Perrier.
"Since this detailed information is not available in Japan, a large-scale population-based cohort study will be needed, but we think it is a very good evidence to warning children" to reduce intake of beverages like Coca-Cola, Pepsi, etc., he said.
The American Beverage Association, which represents America's non-alcoholic beverage industry, emphasized in a statement that "the researchers themselves admit that there is not sufficient evidence to make a causal link between carbonated beverages and heart attacks."
“There are numerous factors that contribute to heart attacks," the group said. "No single food, beverage or ingredient causes heart disease — or any other adverse health outcomes.”
This post has been updated.