Past studies on red and processed meat's potential health effects have been chalked up to "well, people who eat a lot of that stuff lead unhealthy lifestyles to begin with." Same thinking goes for vegetarians, who are known to live longer than meat-eaters, but who also generally lead healthier lifestyles.
But now, a new observational study is teasing out processed meat's effect in particular on health, and shows that not only is it the sort of person who eats a lot of processed meat that has the negative health risks, but the processed meat itself.
The study, published in the journal BMC Medicine and conducted by researchers from the University of Zurich, shows an association between processed meat and higher risks of dying from heart disease and cancer.
The results are based on an analysis of 448,568 men and women between ages 35 and 69, who did not have cancer and who had not suffered a stroke or heart attack when they entered the study. Researchers gathered information on their diets, exercise, body mass index and smoking status. The participants came from 10 countries.
Researchers found strong associations between unhealthy lifestyle choices and high consumption of processed meat; such lifestyle choices including eating little produce and being more likely to smoke (among men and women), and drinking higher amounts of alcohol (among men).
However, researchers were able to tease out processed meat consumption specifically to see how that affected risk of premature death. Even after taking into account other factors, processed meat consumption was still shown to raise risk of dying from heart disease and cancer.
"We estimated that 3.3 [percent] of deaths could be prevented if all participants had a processed meat consumption of less than 20 [grams] per day," the researchers wrote in the study. The Atlantic pointed out that 20 grams of processed meat is the equivalent of a "matchbook-sized portion" of sausage.
Meanwhile, researchers did not find an association between poultry consumption and increased risk of premature death.
Eating little or no red meat, like beef and pork, was actually associated with higher all-cause mortality than very moderate consumption, presumably because red meat does contain important vitamins and nutrients (protein, iron, zinc, vitamins A and B, essential fatty acids). This range, the authors also believe, most accurately reflects people who attempt to optimize their diet, whereas vegetarian diets may be poorly balanced.
BBC News pointed out that processed meat in the study was not just fresh meat that had been put through a grinder -- it was meat that had something added to it (whether it's salt, or something else).
"If you eat lots of processed meat, try to vary your diet with other protein choices such as chicken, fish, beans or lentils," heart health dietitian Tracy Parker, of the British Heart Foundation, told BBC News.
Previously, processed meat has been linked with an increased risk of pancreatic cancer. A British Journal of Cancer study showed that people who eat an extra 50 grams of processed meat (the equivalent of a sausage) a day can raise the risk of the condition by 19 percent, and people who ate an extra 100 grams of processed meat a day can raise their risk by 38 percent.
Meanwhile, another study from Harvard researchers showed that regularly eating processed meat could actually affect your body's ability to use and produce insulin -- thereby raising risk of Type 2 diabetes.