Do not reduce the current consumption of red meat or processed meat. These are the surprising recommendations contained in a new guide prepared by an international group of researchers that contradicts previous evidence on the subject. These recommendations have been published in the Annals of Internal Medicine.

Controversial recommendations on red meat consumption

If every time you ate a hamburger you did it with a feeling of guilt, this situation will not happen again. At least if you follow the new recommendations.

The new guidelines are based on the results of 4 studies that evaluate, in turn, the studies carried out on cardio metabolic and carcinogenic risk and mortality to meat consumption. In addition, a fifth study was considered that added information on population preferences concerning meat and other aspects related to resistance to assuming changes in diet.

Spain also participates in the new recommendations

The final recommendations were the work of a 14-member panel made up of two members from each of the participating countries. In addition to two researchers from our country, researchers from the United Kingdom, Canada, Germany, New Zealand, Poland, and the United States participated.

Why the new recommendations are questionable

The results reflected in these guidelines are in disagreement with the majority of current recommendations and studies carried out in this field in recent times. The main cause is the focus on the degree of evidence given to the different types of studies taken into account in the review.

In this way, the authors downplayed the importance of observational studies (predominant in the field of nutrition). In contrast, randomized experimental studies – fewer, with far fewer participants and of shorter duration – received greater statistical relevance.

In this sense, a methodological tool was used to assign the degree of scientific evidence according to the type of study (GRADE), a process of weighing the evidence designed more for drug trials than for epidemiological studies of public health.

Although randomized and controlled clinical studies are the maximum exponent of scientific evidence, in the field of food they respond to certain peculiarities. In this way, it is not possible to carry out a double-blind controlled trial in which there is a placebo of red meat or other foods and that can assess its relationship with cardiovascular disease or cancer as if the effectiveness of a drug it was.

Furthermore, the randomized trials included in this new review suffered from certain limitations. For example, there were relatively small differences in meat consumption between the intervention group and the control group.

Observational studies

The studies that in recent times have been linking meat consumption with an increased risk of cancer are mostly observational. This means that they are based on the observation of large population groups and their follow-up over time. These studies are not without flaws, either.

Thus, in this type of study, the consumption of red meat and processed meat is assessed through food consumption reminders or questionnaires of consumption frequency. In them, you often have to specify quantities of food consumed long after it has been done. This implies that the data collected may be unreliable.

On the other hand, within the foods included in the denomination of processed meats, there is great diversity, with great variability of nutrients, fat content, ingredients, and additives that make it very difficult to attribute common characteristics and effects to all of them.

Other factors to consider are cultural and geographic issues. These often determine that the results of a specific study cannot be extrapolated to other geographical areas. Cooking methods, the global characteristics of the diet (beyond the specific consumption of some food groups) and lifestyle habits differ substantially between different populations.

Finally, the main drawback of observational or non-experimental studies is that they do not allow causal relationships to be established. We can observe that among consumers of high amounts of meat the incidence of cancer is higher, but we cannot conclude that one circumstance is the cause of the other. For this, it is necessary to rely on other types of studies such as in vitro studies, with animals, and, mainly, randomized and controlled clinical studies.

In any case, in the field of nutrition, observational studies are usually the most reliable source for determining the relationship between the consumption of food and the risk of suffering from a specific disease.

Climate change doesn’t count

Another questionable issue about the new recommendations is that they have not taken into account aspects beyond the direct implication on human health, such as environmental health. In this sense, institutions such as the Committee for Climate Change of the United Kingdom indicate that a 20% reduction in the production of beef and lamb is necessary for the country to reach a level of zero emissions.

The lead author in question

Another shadow looming over the new study involves one of its authors. As recently learned, the lead author of the article, Bradley Johnston, an epidemiologist at Dalhousie University in Canada, participated in another article in 2016 questioning the benefits of limiting sugar intake.

As it became known later, this article was funded by the industry with direct interests in the matter. However, the author did not disclose this prior funding in the conflict of interest statement for the new guidelines on red meat consumption. This practice can be considered unethical.

How much red meat and processed meat is recommended

The panel of experts participating in the new guidelines comes to say that there is no evidence on the benefits derived from reducing the consumption of red meat or processed meat. Thus, it is suggested that adults continue their current consumption of raw red meat (weak recommendation level, with a low degree of evidence). Similarly, the panel suggests that adults continue current processed meat consumption (weak recommendation level, with a low degree of evidence).