In just two years, red meat is 36 times more harmful to health in the Global Burden of Diseases. There is something wrong, both in the method and in the transparency of the results. An international group of scientists asks for clarity through a letter published in The Lancet.

An international group of scientists, in a letter published in The Lancet, calls for clarity and more evidence on the claims related to the vertiginous increase in the risk of early mortality and reduced life attributed to red meat in the most recent Global Burden of Diseases (GBD) published in 2019. GBD is a global study that examines the diseases and risk factors that affect mortality and reduction of life. In this latest version, those related to the consumption of red meat have increased by 36 times, compared to the previous version of 2017.

The group, coordinated by Alice Stanton of the University of Dublin’s biomedical and pharmacological school, also includes Frédéric Leroy, Professor of Food Science and Technology at the University of Brussels. The authors point out that in 2017 excessive red meat consumption caused just 25,000 deaths, putting it in the last place compared to the other 21 factors with a much higher risk. Among these emerged, for example, obesity, following a diet too poor in fruits and vegetables, or deficient in seafood, sources of omega-3, lacking in fibre, seeds, legumes and whole foods, and with a diet too rich in sodium, trans fat or sugar at the top.

Incomprehensibly, in just two years, red meat has passed from the last place to the first place as a risk factor (to the seventh in particular) with an alleged responsibility for 896,000 deaths, while the weight of essential elements in the 2017 version decreased by more than 50%.

The scientists question the accuracy and reliability of these estimates, asking for explanations about the marked differences that occurred in such a short time. These estimates do not agree with recently published new systematic reviews and meta-analyses of high scientific quality. And there is no definite and concrete evidence that red meat is a cause of cardiovascular disease, stroke, heart attack, diabetes and cancer. Among the most important, we mention the NutriRECS study. Eating less red meat is useless for health reasons and counterproductive, and the latest report of the World Cancer Research Fund of 2018 showed no link between red meat intake and breast cancer.

In addition, it appears to be a significant discrepancy between the relative risk curves of GBD 2019 and the dose-response curves of peer-reviewed cohort studies, which examine the relationship between red meat intake and adverse outcomes. This divergence is particularly noticeable for moderate intake of red meat, up to 50 grams per day or up to three servings of red meat per week. In short, there seems to be no correspondence between the results of the latest high-quality scientific studies and the GBD 2019 estimates. That is why the international panel of scientists asks for explanations on highly divergent conclusions. It is not acceptable that such a thorough analysis as the GBD provides little information on the updated systematic reviews.

The Lancet, along with all other authoritative medical journals, rightly requires that global health estimates be reported according to the GATHER guidelines (Guidelines for Accurate and Transparent Health Estimates Reporting), a quality control system that ensures accuracy and transparency. In this case, there has been no compliance with the best practices of the system, which is highly worrying, according to scientists. The same applies to the failure to comply with the PRISMA 2020 guidelines (Preferred Reporting Items for Systematic reviews and Meta-Analyses).

In other words, red meat would be presented as an intrinsically harmful food, completely ignoring its well-documented benefits due to its essential nutrients and bioactive compounds. All this neglects the scientific literature that reports the damage from low meat consumption, especially in pregnant women, children and the elderly.

Replace the current recommendations advising moderate consumption of red meat as part of a balanced and healthy diet with the message that any intake of red meat is harmful will adversely affect public health. The risk is a higher incidence of iron deficiency anaemia, sarcopenia and infant and maternal malnutrition. These conditions are already responsible for a significantly more significant overall health burden than a diet high in red meat, especially in low- and middle-income countries.

The results of the latest revision of the epidemiological-nutritional document are considered extremely worrying by the six scientists co-signers of the letter and require an immediate and thorough review. The GBD is a reference for health policies and has already been used in many scientific papers. Many publications are quoting GBD data as a reference, attributing the cause of the increase in all diseases to the intake of red meat. This scientific bias amplifies the error in the scientific literature, with meat becoming a greater risk than diets high in salt, trans fat and sugary drinks.

In addition, given the significant influence of the GBD on the global decision-making process in the field of nutrition policy, the estimates contained therein must be critically examined to be based on rigorous testing and transparent calculation methods. For this reason, the six scientists call for clarification of all obscure points, including the peer-reviewed sources of the updated systematic reviews used. They also ask that the work fully meet the PRISMA and GATHER standards. The updated dose-response curves are provided of the relative risks of red meat for breast cancer, colorectal cancer, diabetes, heart disease and stroke.

Finally, the scientists believe that it would be highly inappropriate and unwise to use GBD 2019 food risk estimates in any national or international policy document and in any legislative decision until this has been clarified.

“The scientific community uses the method of ‘Letters to journals’ to criticize the works already published, even if they have passed through the referees”, Professor Giuseppe Pulina, President of Carni Sostenibili, comments: “With this paper, the authors extensively document the inadequacy of the method followed by the latest version of the GBD, and therefore its results. For this reason, they demand that the estimates are correct and well justified. The real debate of scientific topics occurs in journals, not on television, and even worse, social media. It is the correct way the scientific community detects errors (and also fraud) and asks to correct them, especially if public health is involved, as in this case”.