The guidelines, which were published yesterday (Sept. 30) in the journal Annals of Internal Medicine, contradict most other diet recommendations that typically advise people to eat less red or processed meat to reduce the risk of conditions such as cancer, diabetes and heart disease.
Public health officials for years have beseeched Americans to limit their consumption of red meat and processed meats, fearing they may be linked to certain diseases.
At the heart of the controversy is the way nutrition research is conducted compared with research into, say, prescription drugs.
So this should not change current recommendations to eat a healthy, balanced pattern of food that is limited in red and processed meat.
To assess those studies, the team used a research approach that rates the certainty of existing evidence, giving more weight to things like randomized controlled trials-in which one study group carries out a certain behavior, while another acts as a control group-and less weight to observational studies, which use patterns in a dataset to find associations between a behavior and an outcome.
An global panel of experts from seven countries is making its recommendations based on five large reviews of evidence.
Research writer Bradley Johnston, affiliate professor at Dalhousie College in Canada, stated: "Based on the research, we can not say with any certainty that eating red or processed meat causes cancer, diabetes or heart disease".
Among 12 clinical trials enrolling about 54,000 individuals, the researchers did not find any statistically significant or important association between meat consumption and the risk of heart disease, diabetes or cancer.
While there was some evidence for a small reduction in risk for those consuming three fewer portions a week, "the certainty of evidence was low to very low", he added.
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And though the recommendations are presumably "weak", they drew sharp attention to previous guidelines set by the American Heart Association regarding red meat and processed meat limitations.
Dr Giota Mitrou, director of research at the WCRF, warned people against interpreting the study to mean they could eat as much red meat as they want.
Aside from public health, calls are multiplying for people to cut back on meat consumption because of the climate emergency and the greenhouse gas emissions that come from animal farming.
For a while now, conventional wisdom has been that red meat is detrimental to your health.
Tim Key, professor of epidemiology and deputy director of the cancer epidemiology unit at the University of Oxford, said: "There's substantial evidence that processed meat can cause bowel cancer - so much so that the World Health Organisation has classified it as carcinogenic since 2015".
Science may be ending its years-long beef with red meat.
"Meat is a rich source of the micronutrients (vitamins and minerals) required for the manufacture of blood cells, and although it is possible to obtain these nutrients in plant-based diets, our results suggest that those reducing their meat intake need to ensure that their new diet contains a wide variety of fruit, vegetables, pulses and whole grains to provide these nutrients", stated Dr. Liz Simpson from the University of Nottingham's School of Life Sciences who is also the co-author of the study.
"There may be lots of reasons to decrease meat in your diet, but if you're decreasing it to improve your health, we don't have a lot of strong evidence to support that", Laine said. "I don't think an evidence-based position can be taken unless we know and adjust for the replacement food".
The comparable figure for those who ate 76g a day (about half a steak), was 48. By contrast, most nutrition research is observational, since it's hard logistically and ethically to ask people to change their eating habits to the extent and length necessary for a randomized controlled trial.