Processed meats are preserved by smoking, curing, salting or adding preservatives. Examples include cold cuts (ham, salami), sausage, bacon and hot dogs.
"Processed red meat commonly contains sodium, nitrates, phosphates and other food additives, and smoked and grilled meats also contain polycyclic aromatic hydrocarbons, all of which may contribute to the increased heart failure risk," Alicja Wolk, D.M.Sc., senior author of the study and professor in the Division of Nutritional Epidemiology at the Institute of Environmental Medicine, Karolinska Institutet in Stockholm, Sweden said.
"Unprocessed meat is free from food additives and usually has a lower amount of sodium," Wolk said.
The Cohort of Swedish Men study - the first to examine the effects of processed red meat separately from unprocessed red meat - included 37,035 men 45-79 years old with no history of heart failure, ischemic heart disease or cancer.
Participants completed a questionnaire on food intake and other lifestyle factors and researchers followed them from 1998 to the date of heart failure diagnosis, death or the end of the study in 2010.
After almost 12 years of follow-up, researchers found heart failure was diagnosed in 2,891 men and 266 died from heart failure.
Men who ate the most processed red meat (75 grams per day or more) had a 28 percent higher risk of heart failure compared to men who ate the least (25 grams per day or less) after adjusting for multiple lifestyle variables.
Men who ate the most processed red meat had more than a 2-fold increased risk of death from heart failure compared to men in the lowest category, the study found.
For each 50 gram (e.g. 1-2 slices of ham) increase in daily consumption of processed meat, the risk of heart failure incidence increased by 8 percent and the risk of death from heart failure by 38 percent.
The risk of heart failure or death among those who ate unprocessed red meat didn't increase.
The study is published in Circulation: Heart Failure, an American Heart Association journal.