Hear from the scientist who says red meat might not be so bad for us after all

Is red and processed meat bad for our health or not? 

A controversial new set of studies — what has been called "the most comprehensive review of evidence to date" — suggests red and processed meat might not be so bad for us after all. 

The new studies reviewed existing data about the health effects of red and processed meat by "studying studies" in five different literature reviews and meta-analyses. 

Bradley Johnston, an associate professor of epidemiology from Dalhousie University who directed the studies, told Quirks & Quarks host Bob McDonald that they've concluded that the risk of eating red or processed meat as "very small."

"We looked at what the risk reduction is for cancer, heart disease and diabetes among those who consume three fewer servings of red or processed meat per week," said Johnston. 

They found those who ate fewer servings of red and processed meat did reduce the risk to their health, but the effect was very small and the quality of evidence is "low to very low." 

Problems with many nutritional studies

Most of the research they reviewed were observational studies. In this kind of study individuals are observed over time for risk factors and health outcomes. 

One issue with this sort of study is the effect of secondary risk factors that might bias the data. For example, people who tend to eat more red meat also have a tendency to consume alcohol, smoke and exercise less, which he said can be hard to separate out from the observed results. 

The one review they did of higher quality studies, like randomized controlled trials, came to the same conclusion. 

"Even the evidence base for the randomized trials is low quality or low certainty."

Relative versus absolute risk

Johnston said in their reviews, they only focused on "absolute" risk, not "relative" risk.

If there is a two per cent risk of cancer and by not eating meat, that risk drops by one per cent, from a relative perspective, that's a 50 per cent risk reduction, which Johnston said sounds very compelling, but the effect is actually very small. 

"From an absolute perspective however, the risk is a one per cent difference."

Controversy over these studies

Scientists from Harvard University released a statement describing Johnston's advice based on these new studies as "irresponsible and unethical."

Johnston said they're "happy that there's now more debate on this topic."

"If you arm rational people with the risk reductions and they understand that it's very small — if it exists at all — and that the certainty of evidence is low (...) they can make their own decisions."