OCTOBER 1, 2019
A major series of scientific reviews has found little evidence that the consumption of red meat is linked with cancer, diabetes and heart disease, casting doubt on dietary guidelines that recommend curtailing consumption.
The research published in the Annals of Internal Medicine, the journal of the American College of Physicians, finds that nutritional recommendations to reduce red meat consumption are based on “weak, low-certainty evidence” and that there are very few health benefits to cutting meat consumption.
The evidence is contrary to World Health Organisation recommendations which advise reducing the consumption of red meat. Australia’s current nutritional guidelines recommend limiting consumption to 455 grams per week, the equivalent of around three average-sized serves.
The series of reviews were carried out by a large international research team of physicians, dietitians and public health bodies with the aim of improving the quality of nutritional guidance on red and processed meat.
Study author Bradley Johnston, an associate professor at the Department of Community Health and Epidemiology at Dalhousie University in Canada, said the research by the NutriRECS consortium was a response to an increasing call for higher quality nutritional guidelines.
“Based on our systematic reviews assessing the potential harms of red and processed meat consumption, there is only low certainty evidence of a very small reduction in cancer, diabetes and heart disease from reducing red meat and processed meat consumption,” Professor Johnston said.
“Based on these reviews, we cannot say with any certainty that eating red meat or processed meat causes cancer, diabetes or heart disease.
“People who choose not to eat meat (vegetarians) report health as one of the main reasons for avoiding it. However, any health benefits from staying away from meat are uncertain, and, if they exist at all, are very small.
“For most people who enjoy eating meat, the uncertain health benefits of cutting down are unlikely to be worth it.”
Veganism has been increasing in popularity around the world in recent years, especially driven by concerns around climate change. The Intergovernmental Panel on Climate Change recently encouraged people around the world to move to eating a plant-based diet to address global warming.
However, today’s study did not consider ethical or environmental reasons for abstaining from meat in their recommendations. “These are valid and important concerns, (but they are not) concerns that bear on individual health,” the study authors said.
Australia’s National Health and Medical Research Council says it would welcome consideration of the new research in any nutritional guideline revisions. Australia’s nutritional guidelines are currently more than five years old and the council is currently seeking funding in order to update them.
The NHMRC said previous rigorous evidence reviews “suggested a correlation between red meat consumption at greater than 100-120g per day and an increased risk of colorectal cancer and an increased risk of renal cancer”.
The World Health Organisation International Agency for Research on Cancer has indicated that the consumption of red meat is ‘probably carcinogenic” to humans, and that processed meat is “carcinogenic”.
But the NutriRECS consortium found in its systematic reviews that these conclusions were not sound.
Among 12 randomised trials enrolling about 54,000 individuals, the researchers did not find a statistically significant association between meat consumption and the risk of cancer, heart disease or diabetes.
Among cohort studies following millions of participants, the researchers did find a very small reduction in risk among those who consumed three fewer servings of red or processed meat per week. However, the association was “very uncertain”.
The Cancer Council of Australia responded to the research by saying it continued to support recommendations that the consumption of red meat should be limited.
Clare Hughes, chair of the Cancer Council’s Nutrition and Physical Activity Committee, said that in 2015, the International Agency for Research on Cancer considered more than 800 studies on red meat, processed meat and cancer risk.
“They concluded that processed meat was carcinogenic and red meat was probably carcinogenic. Eating too much red and processed meats was most commonly associated with bowel cancer.
“The evidence was so compelling that the expert panel deemed consumption of processed meat of public health importance because of its contribution to global cancer incidence.
“Cancer Council will continue to be guided by the findings of the International Agency for Research on Cancer and recommend people consume only moderate amounts of red meat and limit processed meat consumption.”
The Heart Foundation’s chief medical advisor, Professor Garry Jennings, a cardiologist, said that “while the review adds to our understanding, overall, there is benefit from reducing excessive red meat consumption”.
“The Heart Foundation currently recommends eating one to three unprocessed red meat meals a week following a recent review of evidence-based research published between 2010 to 2018,” Dr Jennings said.
“The weight of evidence found high red meat consumption moderately increased the risks for heart disease and stroke and may lead to weight gain.
“The Heart Foundation’s current guidelines recognise that when it comes to eating, the big picture matters. It is important to regularly include a variety of other foods such as vegetables, wholegrains, legumes, fish and nuts in a healthy eating pattern, while cutting down on junk and takeaway foods.
Nutrition science is constantly evolving and while we recognise its limitations, healthy eating advice should be periodically updated to reflect the best available, evidence-based research.
We recognise the need for further good quality nutrition research and will continue to monitor the science to inform the Heart Foundation’s healthy eating advice.”