Eating hot dogs, bacon, sausage or deli meats increases the chance of heart disease by 42 percent, US researchers said in a report out Monday.
Eating processed meat is also linked to a 19 percent higher risk of Type 2 diabetes, said the study, which appeared in the journal Circulation.
However researchers found no higher risk of heart disease or diabetes among people that ate unprocessed red meat such as from beef, pork, or lamb.
Most healthy eating guidelines already recommended limited meat consumption, but until now "studies have shown mixed results for relationships between meat consumption and cardiovascular diseases and diabetes," said Renata Micha, the lead author of the study.
"Most prior studies also did not separately consider the health effects of eating unprocessed red versus processed meats," said Micha, a research fellow in the department of epidemiology at the Harvard School of Public Health (HSPH).
The team reached their conclusions by studying information from 1,600 reports from around the world involving some 1.2 million people.
On average, each 50 gram (1.8 ounce) daily serving of processed meat (about one to two slices of deli meats, or one hot dog) was associated with the higher heart disease and diabetes risk, the researchers said.
Lifestyle factors associated with eating unprocessed red meats and processed meats "were similar, but only processed meats were linked to higher risk," said report co-author Dariush Mozaffarian, assistant professor in the department of epidemiology at HSPH.
While unprocessed red and processed meats eaten in the United States contained similar average amounts of saturated fat and cholesterol, researches found that processed meats "contained, on average, four times more sodium and 50 percent more nitrate preservatives," said Micha.
"This suggests that differences in salt and preservatives, rather than fats, might explain the higher risk of heart disease and diabetes seen with processed meats, but not with unprocessed red meats," she said.
In order to decrease heart attack and diabetes risk, it would be best to avoid processed meats such as bacon, salami, sausages, hot dogs and processed deli meats.
"Based on our findings, eating one serving per week or less would be associated with relatively small risk," said Micha.