Controversial study puts red meat back on the table

Evelyn Lewin

2/10/2019 4:10:06 PM

A new study recommends continuation of current consumption of both processed and unprocessed red meat, but it has drawn strong criticism from experts.

Different red meats
New research has concluded evidence on reducing red meat and its effect on lowering risk of cancer, cardiovascular disease, and early death was, in most cases, ‘low to very low certainty’.

Carnivores have been hit with increasingly bad news recently.
The Heart Foundation issued new advice in April, recommending a reduction in red meat intake.
This followed on from research suggesting that even eating small amounts of red and processed meat could increase a person’s risk of death, and other findings that red meat was associated with a higher risk of cancer.
But now the tide may be turning – again.
That is because new guidelines based on five reviews of existing evidence suggesting that people can continue to eat processed and unprocessed red meat without having to fear as much for their health.
The guidelines, published in the Annals of Internal Medicine, was formulated by a panel of authors that included 14 diet and nutrition specialists who form part of independent research group, the Nutritional Recommendations (NutriRECS) Consortium.
The researchers decided to re-evaluate existing evidence about the relationship between red meat consumption and negative health outcomes for many reasons, including concerns that the current recommendations are based primarily on observational studies that often cannot establish cause and effect.
For the new paper, four systematic reviews addressed the health effects associated with consumption of red and processed meat, and one systematic review addressed people’s health-related values and preferences regarding meat consumption.
In four of the five reviews, the researchers looked at whether a realistic reduction in red meat intake – which they defined as a reduction by three servings a week – had any effect on the risk of certain negative health outcomes.
The researchers concluded the evidence on reducing intake of processed and unprocessed red meat and its effect on lowering the risk of cancer, cardiovascular disease, and early death was, in most cases, ‘low to very low certainty’.
In the fifth systematic review, the researchers looked at people’s attitudes and values surrounding the consumption of red meat, and concluded that omnivores ‘enjoy eating meat and consider it an essential component of a healthy diet’.
Consequently, the panel came to the conclusion that adults can continue ‘current’ processed and unprocessed red meat consumption.
‘For the majority of individuals, the desirable effects – a potential lowered risk for cancer and cardiometabolic outcomes – associated with reducing meat consumption probably do not outweigh the undesirable effects – impact on quality of life, burden of modifying cultural and personal meal preparation and eating habits),’ the authors wrote.
They noted these recommendations are for human health only, and did not take into consideration animal welfare or environmental concerns.
Associate Professor Mark Morgan, Chair of the RACGP Expert Committee – Quality Care (REC–QC), spoke to newsGP about the findings.
‘It’s an interesting study and it appears to have been conducted well,’ he said. ‘What they concluded is that there’s a need to be a little bit cautious about pushing dietary advice at people where the need to change diets is not clear.
‘Most people would conclude that if they’re willing and prepared to reduce their red meat, there might be some health benefits.
‘We just don’t know for sure.’
Associate Professor Morgan said a downfall of this study is the fact it does not include recommendations based on other factors, such as the effect on the climate.
‘I think that the medical response to climate change might be to encourage a reduction in meat-based diet,’ he said.

Associate Professor Mark Morgan believes the SNAP approach is more important for individuals than their consumption of red meat.

Since it was published, the new paper has come under fire from experts around the world.
‘We stand by our rigorous research of the last 30 years and urge the public to follow the current recommendations on red and processed meat,’ Dr Giota Mitrou, Director of Research at the World Cancer Research Fund, which has warned against red and processed meats since 2010, said.
‘The recommendation that adults continue current red and processed meat consumption is based on a skewed reading and presentation of the scientific evidence.’
Professor Clare Collins, a National Health and Medical Research Council Senior Research Fellow and Director of Research in the School of Health Sciences, and Acting Director of Priority Research Centre in Physical Activity and Nutrition at the University of Newcastle, also voiced concerns.
‘When you look past the headline, all the papers indicate that higher intakes of processed and red meat are associated with a higher risk for all-cause mortality, heart disease, type 2 diabetes and some cancers,’ she said.
‘You have to question the recommendations made given that the data presented in the papers does not support it.’
Professor Collins also expressed concern that major studies, such as the Predimed study and the Diabetes Prevention Program, were omitted from the new body of research.

‘The authors question the validity of observational studies, but ignore the fact that this is the study design used to assess long-term harm, just like we used to discover the link between smoking and lung cancer,’ she said.
Professor Collins is also concerned about how this paper will be interpreted.

‘Poor eating habits are the leading cause of death worldwide,’ she said. ‘This report will confuse the public.’

Professor Collins went on to explain that current data shows 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 Australians ate according to Dietary Guidelines recommendations.
‘People need more support to adopt the healthiest eating patterns they can,’ she said.
The Harvard School of Public Health also published a response to the new findings, asking its experts to take a closer look at the research.
‘The new guidelines are not justified as they contradict the evidence generated from their own meta-analyses,’ Harvard School of Public Health experts wrote.
They went on to voice their concern over the potential implications of publishing this paper.
‘The publication of these studies and the meat guidelines in a major medical journal is unfortunate because following the new guidelines, may potentially harm individuals’ health, public health, and planetary health,’ they wrote.
‘It may also harm the credibility of nutrition science and erode public trust in scientific research.
‘In addition, it may lead to further misuse of systematic reviews and meta-analyses, which could ultimately result in further confusion among the general public and health professionals.’
While controversy remains over this paper’s findings, Associate Professor Morgan is keen to note the role of a GP is to individualise such advice for their patients.
‘I think what we’re seeing here is the challenge of medical advice as a population level – what should the policy be – versus individual people’s medical advice,’ he said.
‘When you do these large cohort studies that are used to formulate guidelines, we’re really talking about population health approach and it’s really hard to translate that into direct individual choice.’
The bottom line, Associate Professor Morgan said, is not whether the research shows a change in advice on red meat consumption, but how important such advice is compared to other health measures.
‘There are much higher priorities for individuals, such as smoking, overall nutrition, alcohol intake and physical activity,’ he said.
‘So the SNAP approach is much, much more important when you’re counselling individuals about choices.’

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Dr Giuseppe Antonio Pagliaro   3/10/2019 12:44:52 PM

Do we ever get to see the full discussion--the thrust and parry of interpretation or misinterpretation of the metanalyses stats? Science is not supposed to be controversial--incomplete , yes but not controversial. As for association and causation, how can we not be suspicious of entrenched advice if association is all it has going for it?

Dr Rodney Paul Jones   5/10/2019 10:43:19 AM

"Meta analysis" has to be chock full of publication bias, let alone the selection agendas of the authors