To add to the almost daily updates on eating – or not eating – red and processed meat, here comes a new study that pulls together all the evidence available today, concluding that at the current levels, it could be okay for adults to eat their meat. The scientists published their results in the Annals of Internal Medicine on September 30, 2019, along with an accompanying editorial and dietary recommendation which they describe as “weak” and supported by “low-certainty evidence”.
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The current work is focused on evolving dietary guidelines that take into consideration strong evidence of harm or benefit, the size of such benefit or danger, and thought for personal likes, dislikes and food-related values.
What they did
Using randomized controlled studies as well as observational studies that explored the effect of eating red meat and processed meat on cardiovascular, metabolic and cancer conditions, they carried out five systematic reviews in all.
The first review covered 54,000 people in 12 trials and concluded there was no link between these conditions and meat intake. The next three reviews included several million people and found a statistically uncertain and small risk-lowering effect associated with eating three less servings of red and processed meat in a week.
The fifth review was based on food- and health-related attitudes and values concerning eating these foods. In summary, people said they ate meat because they either liked it, perceived it as healthy food, or resisted dietary change. The researchers did not consider any issues unrelated per se to health, such as environmental damage or animal rights. Nonetheless, several of the researchers eat little or no meat because they sympathize with animal and environmental issues.
While admitting that the findings directly contradicted a lot of current food guidelines, researcher Brad Johnston says, “This is not just another study on red and processed meat, but a series of high-quality systematic reviews resulting in recommendations we think are far more transparent, robust and reliable.”
Older recommendations by the World Health Organization (WHO) International Agency for Research on Cancer treats red meat and processed meat as “probably carcinogenic” and “carcinogenic” to humans, respectively.
How this study is different
The strength of the study is its comprehensive scope, according to the authors, which leaves the opposing side little ground to stand on in order to argue the dangers of eating red or processed meat. They argue that the studies on which these recommendations are based are mostly observational, and therefore subject to serious error because of other interacting factors that could also influence the outcomes. The cause-effect relationship is in doubt as a result, and the size of either positive or negative effects are unknown.
The current guidelines were issued by other organizations without rigorously examining the data in a systematic way, or taking into consideration the values of the population involved. The researchers claim for themselves these virtues: independence, clinical and nutritional training, the ability to conduct systematic reviews and issue practice guidelines, and the use of techniques to avoid conflicts of interest. This has resulted in the formation of the Nutritional Recommendations (NutriRECS) international consortium.
Secondly, the 14-member multinational panel used strict criteria and analytic methods. They used GRADE techniques to translate study findings into recommendations about diet. They say that while nutrition is currently a matter of global concern, but “People need to be able to make decisions about their own diet based on the best information available.”
Why this recommendation was made
The researchers argue that with very low-grade evidence for a very small reduction in cardiovascular, metabolic, or cancer-related events with three less servings of red meat or processed meat per week, people are unlikely to be motivated to give up food to which they are so strongly attached. Hence, they recommend that on the present evidence, meat consumption at current levels need not be stopped or reduced. The motivation to reduce red meat or processed meat consumption is likely to proceed from an environmental or animal welfare perspective rather than from that of an adverse health outcome if these facts are properly presented.
Unprocessed red meat and processed meat consumption: dietary guideline recommendations from the nutritional recommendations (NutriRECS) consortium. Bradley C. Johnston et al. Annals of Internal Medicine. (2019). DOI: 10.7326/M19-1621. https://annals.org/aim/fullarticle/2752328/unprocessed-red-meat-processed-meat-consumption-dietary-guideline-recommendations-from