Drinking two or more sweetened drinks a day could increase a man's risk of heart failure by 23%, a new study has found.
Heart failure affects about 900,000 people in the UK. It can affect people of all ages, but it is more common in older people - particularly those over the age of 75.
Researchers found that two 200ml servings of sweetened drinks was associated with an increased risk of developing heart failure compared with drinking none at all.
This is the first time sweetened drinks have been linked to heart failure, they wrote in the journal Heart.
Heart failure is a condition caused by the heart failing to pump enough blood around the body at the right pressure. It usually occurs because the heart muscle has become too weak or stiff to work properly.
The new study observed the eating and drinking habits of more than 42,000 men, aged 45-79, in Sweden.
They asked the men how many soft drinks or sweetened juice drinks they consumed each day throughout the week - not including fruit juice, sugary tea or coffee.
They study did not distinguish between drinks sweetened with sugar and those that were sweetened with artificial sweeteners.
The study spanned an average of 12 years. During that time, 3,604 new cases of heart failure were diagnosed and 509 people died from the condition.
Researchers analysed a wide range of lifestyle factors, but their most striking finding was that two 200ml servings of sweetened drinks was associated with a 23% increased risk of developing heart failure compared with drinking none at all.
A more in-depth analysis, excluding people diagnosed with heart failure in the first five years, showed the link was still prevalent.
Despite the results, researchers said that no conclusion could be drawn to say sweetened drinks definitely caused heart failure. They also stressed that the study only involved older white men and may not be applicable to younger age groups, women, or certain ethnic groups.
But they said the findings could help doctors in giving out dietary advice to prevent heart failure.
Francesco Cappuccio, professor of cardiovascular medicine at the University of Warwick, said there were limitations to the study.
He told the Press Association that high sugary drinks can contribute to heart failure by increasing weight gain and diabetes.
"An alternative explanation - not discussed in the paper - is that high salt intake increases thirst, hence increased drinking including sweetened drinks," he explained.
"The increase in heart failure could therefore be a consequence of higher salt intake, higher blood pressure and higher heart failure risk."
Meanwhile Dr Gavin Sandercock, a reader in clinical physiology at the University of Essex, said that the results from the study are "interesting" because they show there is no difference in the effects of drinks which do or do not contain any sugar (sweetened vs artificially sweetened), on the risk of men developing heart failure.
"The 23% higher risk of developing heart failure is clearly not, therefore, anything to do with sugar per se," said Dr Sandercock.
He said that drinking sweetened beverages is "an indicator of a poor diet overall".
"The adults who drank two sweetened drinks a day also drank the most coffee, ate the most processed meat, ate the least vegetables and they had more family history of heart disease," he said.
"Trying to decide if sweetened drinks are the single cause of heart failure is impossible when diet and heart failure are both such complicated issues."
This isn't the first time fizzy and sweetened drinks have been flagged as a health issue.
A study published earlier this year linked sweetened drink consumption to non-alcoholic fatty liver disease (NAFLD).
Researchers believe that those who drink more than one fizzy drink a day increase their risk of NAFLD.