Two servings of red and processed meat per week can increase cardiovascular risk by up to 7%. Poultry also caused a significant, though lower, increase of risk.
In the past few decades, studies have consistently shown that regular consumption of meat (especially red processed meat) has a detrimental effect on human health. Even in low quantities, meat can increase the risk of diseases (including heart disease and some types of cancer).
However, every once in a while, an outlier comes out. A study published in 2019 concluded that red meat isn't dangerous for human health. That study was widely criticized both for its interpretation of data and for the fact that scientists didn't report a potential conflict of interest. That study was widely picked up by the media and many saw it as a justification for meat-eating habits. "Meat isn't bad," many publishers were quick to say, without sparing a second thought for anything else.
Now, new research casts even more doubts on that idea. The newly-published study found that two servings of red meat or processed meat -- but not fish -- per week was associated with a 3% higher risk of all causes of death.
It's not a huge difference, but it's something worth considering, researchers note.
"It's a small difference, but it's worth trying to reduce red meat and processed meat like pepperoni, bologna and deli meats," said senior study author Norrina Allen, associate professor of preventive medicine at Northwestern University Feinberg School of Medicine. "Red meat consumption also is consistently linked to other health problems like cancer."
The study looked at the data from six cohorts who were followed for up to three decades. After the data from different was adjusted and harmonized to fit a single analysis, researchers ended up with 29,682 participants.
The participants self-reported on diet data (what they had eaten in the previous month or previous year), after which their cardiovascular health was followed.
Researchers found a 3 to 7% higher risk of cardiovascular disease and premature death for people who ate red meat and processed meat two servings a week. Furthermore, there was a 4% higher risk of cardiovascular disease for people who ate two servings per week of poultry -- but the evidence was less clear. Researchers refrain from making a clear recommendation about poultry intake. evidence so far is not sufficient to make a clear recommendation about poultry intake, noting that the effect might be owed to the cooking method and consumption of chicken skin rather than the chicken meat. Notably, there seemed to be no association between eating fish and cardiovascular disease or mortality.
Replacing some of the animal products in our diets with plant-based equivalents can make a significant difference, researchers conclude.
"Modifying intake of these animal protein foods may be an important strategy to help reduce the risk of cardiovascular disease and premature death at a population level," said lead study author Victor Zhong, assistant professor of nutritional sciences at Cornell, who did the research when he was a postdoctoral fellow in Allen's lab.
The researchers also commented on the previous study -- emphasizing that there is a lot of evidence indicating the risks associated with red meat.
"Everyone interpreted that it was OK to eat red meat, but I don't think that is what the science supports," Allen said.
"Our study shows the link to cardiovascular disease and mortality was robust," Zhong added.
Of course, as with any nutritional study, there are also limitations. Participants reported on their own meals, which likely contains inaccuracies as people are unlikely to recall their diet with accuracy. In addition, the study also did not consider cooking methods. Frying foods, instead of boiling them for instance, can contribute to the intake of fatty and trans-acids, which in turn contribute to the risk of cardiovascular disease.
Nevertheless, the pile of evidence suggesting that meat consumption is bad for you (especially red/processed meat), it's nothing short of convincing. Plant-based diets are, in general, healthier -- and more sustainable -- than meat-rich diets.
The study was published in JAMA Internal Medicine.