THE publisher of a controversial study alleging deaths attributable to red meat-intake had increased 36-fold in two years is facing renewed calls to reconsider the methods it used.
World Cancer Research Fund International has joined a group of scientists in raising concerns about a 2019 Global Burden of Disease study in The Lancet journal. The study reported that 896,000 deaths were caused by a diet high in red meat, a dramatic change from only 25,000 deaths in 2017.
The GBD reports are a globally recognised scientific reference for health and disease risk and are often in the formation public policy. The study of concern has been cited hundreds of times since its publication.
WCRF recently had a letter published in The Lancet highlighting its concerns with the 2019 GBD. The organisation believes the increase in red meat-related deaths was more attributable to a change in methodology to calculate them.
“When the assumptions used within a study are not clearly stated and explained, the results become questionable, and replication difficult,” the letter said.
“Further, insufficient clarity of such assumptions potentially reduces their use within policy development.”
The letter went on the explain what the WCRF had found in its studies looking at the links between red meat and cancer.
“Nevertheless, neither WCRF nor other international organisations recommend complete avoidance of meat. In many diets worldwide, red meat is an important source of several nutrients. Removing meat from such diets is impractical and unrealistic and carries a risk of nutritional deficiency judged to outweigh future cancer risk.
“The absence of an explicit rationale for the assumptions underlying the GBD estimates is troublesome, unsupported by the evidence, and unrealistic.”
Scientists challenged GBD
The GBD has come under intense scrutiny from the science community before, with The Lancet publishing a letter from a group of six international scientists – Alice Stanton, Ireland; Frederic Leroy, Brussels; Christopher Elliot, Ireland; Neil Mann, Australia; Patrick Wall, Ireland and Stefaan De Smet, Belgium – who also raised concerns about the overcooked claims.
In short, the group called on the authors of the study to publicly release the peer-reviewed studies it used to come to its findings and highlight the numerous health risks attached of eliminating red meat from diets
“Unless, and until, all new or updated reviews and meta-analyses pertaining to all dietary risk factors are published, having undergone comprehensive independent peer review, we think it would be highly inappropriate and imprudent for the GBD 2019 dietary risk estimates to be used in any national or international policy documents, nor in any regulatory nor legislative decisions,” the letter said.
Authors reply to letter
Christopher Murray, one of the authors of the GBD study, penned a response to the concerns raised by the six scientists. He detailed some of the changes the GBD researchers wish to make for the next edition – including a star-rating system based on the strength of the evidence.
Prof Murray said the group had released the peer-reviewed studies used to come to its finding.
“Stanton and colleagues claim that detailed citations are not available for the 92 sources used in the analysis of red meat. This is incorrect,” his letter said.
“Overall, GBD uses hundreds of thousands of sources. To make it tractable to meet the requirements of the Guidelines for Accurate and Transparent Health Estimates Reporting in an efficient manner, we note in the papers that GBD sources are available in the GBD 2019 Data Input Sources Tool, which provides detailed citations.”
Prof Murray said it must also be noted the GBD studies were based on people over the age of 25.
“Stanton and colleagues also raise questions about the value of meat as a source of protein, particularly for children,” he said.
“For a governing body developing dietary recommendations, these are important considerations. The role of GBD, however, is not to balance the totality of considerations but rather to follow the science on what level of exposure is associated with the lowest level of risk. Our diet analysis explicitly addresses the effect of red meat consumption in people over the age of 25 years. We estimate zero deaths attributable to red meat below that age.”
The WCRF said it was keen to see the results of the next GBD study.
“We look forward to reading the results of GBD 2020, which incorporate adjustments to the methodology, and welcome the investigators’ transparency,” the organisation said.