Eating red and processed meat is linked to higher rates of heart disease and death, says a large new study – a finding that would be met with a big “duh” if it didn’t come on the heels of a controversial report suggesting people don’t necessarily need to eat less meat.

The new research, published in the journal Jama Internal Medicine, found that eating two servings of red meat or processed meat weekly is associated with a 3 per cent to 7 per cent higher risk of cardiovascular disease, such as heart attack and stroke, and a 3 per cent higher risk of death from all causes.

Eating two servings of poultry weekly was also linked to higher heart disease risk, but not overall mortality, said the study, conducted at Feinberg School of Medicine at Northwestern University in the United States. The study’s authors urged more research on poultry before making any recommendations on intake because the study didn’t look at how the food was prepared, such as whether it was grilled or fried.

Fish was not associated with ill health effects.

The findings are consistent with prior research that has linked meat with poor health outcomes, but can feel like whiplash given that a report, published in October in the Annals of Internal Medicine, said there was insufficient evidence to recommend people reduce meat intake. Some public health experts questioned the accuracy of those conclusions and some of the authors were later called out for not disclosing industry funding on other projects.

That report’s authors included researchers from Dalhousie University in Nova Scotia and McMaster University, both in Canada, among others.

Such conflicting conclusions can paralyse consumers trying to make healthful choices, erode trust in nutrition science or encourage some people to throw up their hands and indulge in steaks and burgers with abandon.

Norrina Allen, associate professor of epidemiology and paediatrics at Northwestern’s medical school, and senior author of the new study, points out that the reports try to answer different questions. Her study examined whether people who eat meat are more likely to get sick and die, whereas the October 2019 report summarised existing literature to determine if there is enough evidence to show reducing meat intake makes a difference.

Asked for a takeaway, Allen said: “I hope people consider eating red and processed meat in moderation and try and consume more fruits and vegetables and whole grains.”

Nearly 30,000 men and women were included in the Northwestern study, which followed participants from six different long-term research cohorts for up to 30 years. It goes a few steps further than prior studies to isolate the effect of meat by controlling for individual risk factors and other aspects of a person’s diet, Allen said.

While the increased risk from two weekly servings is small – a serving being, for example, four ounces (113 grams) of unprocessed red meat or two strips of bacon – the risk increases the more meat people eat, the study said. The study does not establish causality.

The research has several limitations. A major one was that it was based on a self-assessment of what participants ate over a month at the start of the project, so any changes they made to their diets over the years were not taken into account. Participants were followed for a median of 19 years.

Allen said it’s notable that there remained a significant relationship between illness and death and people’s diets decades before.

“There is still a risk based on what you ate 20 years ago,” she said.