Based on the five systemic reviews of 12 randomised trials involving about 54,000 individuals, which include some Australian and NZ data, an accompanying guideline recommends most adults should continue to eat their current levels of red and processed meat—a finding that is contrary to almost all the other guidelines that exist.
The studies, led by researchers in Canada and published in Annals of Internal Medicine, say the actual risk reductions were often trivial for people lowering their red or processed meat consumption by three servings per week, and any links between meat consumption and negative health effects are uncertain. The reviews also found people did not change their meat eating habits easily.
While many consumers will cheer these viewpoints, the research has left a number of scientists Down Under nonplussed.
Nick Wilson, a professor in Otago University’s department of public health, said the findings were “out of sync” with other major reviews and failed to take into account an “urgent need” for a global shift to plant-based diets for “planetary health reasons”.
“The current patterns of meat consumption are completely unsustainable and are damaging the climate, polluting waterways and depleting water supplies,” he said.
“From the direct human health risk perspective these new review findings are also out of sync with other major reviews.”
The evidence for predominantly plant-based diets being healthy is overwhelming, Wilson added.
“We need both healthy diets and a liveable planet, which is why shifting to sustainable food systems should be the dominant consideration around the world.”
Colleague Jim Mann, professor of medicine and Human nutrition at Otago University, was similarly critical.
"In my opinion the 'weak recommendations' based on 'low certainty' evidence that adults 'continue current consumption of unprocessed red meat and processed meat' are potentially unhelpful and could be misleading,” he said in his assessment.
Mann complained that a review panel of 14 members opted to consider personal preferences along with cancer and cardiovascular outcomes but did not take into account environmental and animal welfare issues when forming their guidelines.
“It is irresponsible not to consider sustainability and planetary health—a key, if not the major, determinant of the health of future generations—when developing nutrient and food-based dietary guidelines,” he added.
In Australia, Clare Collins, director of research at the School of Health Sciences at the University of Newcastle, was equally scathing.
"You have to question the recommendations made given that the data presented in the papers does not support it!” she said.
Of concern is that some major studies have been omitted and that the authors have not presented evidence that national dietary guidelines need updating. With poor eating habits the leading cause of death worldwide, she asserted the report would simply confuse the public.
“In Australia, current data shows that the burden of disease would drop by 62% for heart disease, 41% for type 2 diabetes, 34% for stroke, and 22% for bowel cancer if all Australian ate like the dietary guidelines recommend. People need more support to adopt the healthiest eating patterns they can.”
However Rachel Ankeny, deputy dean of research at Adelaide University and an expert in food ethics and the relationship of science to food habits, expressed more moderate views.
“Food is never just about nutrition or fuel: our food habits are aligned with our values and understandings, and we make our choices for a variety of reasons,” she said.
Thus a key issue about any attempts to encourage changes in people's eating habits relates to the sociocultural meanings attached to meat.
As research has shown, in Australia many people associate meat with care or comfort, affluence, and even necessity as part of a good diet.
“Hence these recent and perhaps surprising findings are likely to be welcomed by many Australians who might find it difficult to change their consumption behaviours, particularly in relation to meat, even in the face of evidence about undesirable health effects,” she added.