By Dr. Raluca Mateescu, Professor
We all heard from our public health officials to limit consumption of red meat because of concerns that these foods are linked to heart disease, cancer and other illnesses. The Annals of Internal Medicine (Ann Intern Med. doi:10.7326/M19-1621, Oct 2019, https://annals.org/aim) has just published a cluster of systematic reviews and meta-analyses, all in the same issue, on the topic of eating meat and processed meat. The international collaboration of researchers concluded that this advice is not backed by good scientific evidence and the certainty of evidence for risk reduction from eating less beef and pork was low to very low. The group’s dietary guidelines recommendation is for adults to continue to consume red meat and processed meat at current levels of intake.
It is not surprising that these reports are already facing fierce criticism and indignation from some public health organizations, including the American Heart Association, the American Cancer Society, the Harvard T.H. Chan School of Public Health. Their indignation is though surprising because they do agree that studies of red meat as a health hazard have been problematic. In fact, when reading the cited research looking at possible links between red meat and different illnesses, the conclusion is that there is no reliable evidence.
At the heart of the debate is a dispute over nutritional research itself, and whether it is possible to ascertain the effects of just one component of the diet. The gold standard for medical evidence is the randomized clinical trial, in which one group of participants is assigned one drug or diet, and another is assigned a different intervention or a placebo. But asking people to stick to a diet assigned by a flip of a coin, and to stay with it long enough to know if it affects the risk for heart attack or cancer, is nearly impossible. The alternative is an observational study: investigators ask people what they eat and look for links to health. But it can be hard to know what people are really eating, and people who eat a lot of meat are different in many other ways from those who eat little or none. If individuals who habitually consume burgers for lunch typically also consume fries and a Coke, rather than yogurt or a salad and a piece of fruit, it is difficult to assign the health outcome to just one component of the diet. The bottom line is that observational studies cannot be used to determine cause and effect given the many confounders that are impossible to account for. Moreover, when well designed, randomized clinical studies are conducted, they often end up showing the exact opposite effect of the observational studies.
The importance of beef in the diet is extremely high: high quality protein, minerals and vitamins (including iron and vitamin B12), essential fatty acids. We need – and will continue to need – animal protein to sustain human life. Without it, we simply can’t get enough essential nutrients for our global population. But we should all be aware of the public conversation and be prepared and willing to take a stand and provide scientific arguments when different groups are recommending the exclusion of beef from the diet. It is also nice to see more and more evidence being published highlighting the lack of evidence against red meat.
Find more information about the UF/IFAS Department of Animal Sciences events on our website. Stay in touch with us on Facebook, Twitter, and Instagram. Any questions or inquiries regarding this piece should be directed toward Dr. Raluca Mateescu at raluca@ufl.edu. Read more stories like this one here: http://blogs.ifas.ufl.edu/animalsciencesdept/.
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