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No need to cut red meat, say new guidelines

BMJ 2019; 367 doi: https://doi.org/10.1136/bmj.l5809 (Published 01 October 2019) Cite this as: BMJ 2019;367:l5809
  1. Owen Dyer
  1. Montreal

Adults should continue their current consumption of red meat and processed meat, say the recommendations of an international panel published in the Annals of Internal Medicine.1

The guideline—a striking departure from most existing recommendations—is based on the findings of four other papers published in the same issue, which review existing studies in the field to assess the risk of various cardiometabolic and cancer outcomes, incidence, and mortality.2345

A fifth paper provides a meta-analysis of studies examining people’s attitudes to meat and their resistance to dietary change.6 It concludes that “omnivores are attached to meat and are unwilling to change this behaviour when faced with potentially undesirable health effects.”

The findings are at odds with most other analyses, even those relying on the same data, largely because the researchers used a strict approach to weighing the certainty of evidence, leading them to downgrade the importance of observational cohort studies, which predominate in the field of nutrition. Randomised studies, although rarer and involving fewer participants, were given greater weight.

The analyses were performed by researchers from Dalhousie University and McMaster University in Canada, together with the Spanish and Polish Cochrane Centres. The final recommendations were the work of a 14 member panel comprising two members each from Britain, Canada, Germany, New Zealand, Poland, Spain, and the United States.

Three panel members were laypeople. And three members dissented from the main recommendation, preferring a “weak” recommendation to reduce red meat intake.

Hazard and risk

Gunter Kuhnle, a professor of nutrition and food science at the University of Reading, UK, who was not involved in the research, commented, “This is a very interesting set of publications of very good quality that investigate the effect of meat intake on health. The key limitation of these studies is that they use very narrow terms of reference which downgrade a large number of studies.”

The results, he said, “highlight in a nice way the difference between hazard and risk. While the [World Health Organization’s] International Agency for Research on Cancer has categorised processed and red meat as carcinogens or probable carcinogens—ie, a hazard to health—this study shows that the actual exposure to red and processed meat is for many people sufficiently small not to be of concern. This does not, however, mean that there is no risk associated with increasing intakes.”

Ian Johnson, a nutrition researcher at the Quadram Institute in Norwich who was also not involved in the research, said, “This is a comprehensive and meticulous analysis of virtually all the available evidence. Overall, the results of this major review are reasonably consistent with previous studies, but the dietary recommendations derived from the review are not.”

The authors had concluded, he said, that the low quality of available evidence and the small effect sizes seen “tend to reduce the confidence with which any recommendations for the overall health benefits of reducing meat consumption can be made.”

In an accompanying editorial in the Annals of Internal Medicine,7 Aaron Carroll and Tiffany Doherty, two researchers from the Indiana University School of Medicine in Indianapolis, USA, argue that relying on weak evidence to chide the public for eating meat is more likely to undermine confidence in science than improve public health.

Appeals to reduce red meat consumption might be better aimed at the environmental impact of beef and lamb production, a message to which the public is more receptive, the editorial argues. In Britain the Committee on Climate Change has said that a 20% reduction in beef and lamb production is necessary if the country is to reach net zero emissions.8

Carroll and Doherty acknowledge that the international panel’s key recommendation to keep eating red and processed meat as before “is sure to be controversial, but it is based on the most comprehensive review of the evidence to date . . . Those who seek to dispute it will be hard pressed to find appropriate evidence with which to build an argument.”

References

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