(Written by Chaitanya Poolla)
Like most dilemmas in life, sensationalism in news reporting comes in shades of grey. Ironically, such reports manage to convey clear but polarising views to the readers. A classic example arose recently when a few news reports mentioned that meat-eaters have better mental health than vegetarians, attempting to cite findings from a recently published scientific paper. At first glance, the reports seem to reveal a scientific breakthrough, but a thorough study reveals that is not the case.
The reports quote several claims ranging from “meat consumers are less likely to be depressed when compared to vegetarians and vegans” to “in general, if you want to avoid increased risk of depression, anxiety and self-harm behaviour then do eat meat”. Unfortunately, these claims misrepresent the findings from the paper, resulting in an unwarranted twist. Interestingly, the paper itself details the important limitations and assumptions involved, yet they do not manage to find a place in the reports. Consider the following.
The paper mentions, “the evidence linking vegetarianism with mental disorders is not unequivocal… investigators found that with respect to some facets of mental health assessment, vegetarians were healthier than meat-consumers”. Therefore, reports of unequivocal claims amount to cherry-picking inferences from the paper without accurately depicting the scientific conclusions.
The paper relies on the analysis of self-reported data, which even if not intentionally erroneous, might still be unreliable on account of possibly low mental/emotional awareness of the participants. For example, I may feel differently about my mental health due to factors such as smoking or alcohol habits, behaviour, social norms, or life events which may have nothing to do with my dietary preference. That is, mental conditions can be a result of several non-dietary factors as clearly acknowledged multiple times in the paper: “Clearly, diet is not the only determinant of psychological health” and that “The extant literature suggests that there are numerous factors that may explain the contradictory associations of meat-abstention and health.”
The underlying studies examined in the paper are primarily cross-sectional in nature, which mean that even if the above evidence was assumed to be reliable, it still does not help determine if meat consumption or lack thereof causes mental disorders. Accordingly, the paper does not claim that meat avoidance causes depression, rather it infers “across all studies, there was no evidence to support a causal relation between the consumption or avoidance of meat and any psychological outcomes”. In conclusion, the paper states that “study designs and/or a lack of rigour precluded inference of causal relations and none should be inferred.”
Redefining the concept of meat leads to critical implications in the interpretation of the findings. For example, the paper states “meat consumption is often inconsistently classified in research and national surveillance settings as well as across languages”. Further, even the most rigorous study reviewed in the paper is acknowledged to be terminologically inconsistent. This study consists of a sample of German adults and the paper acknowledges, “… in German, the term meat excludes poultry”. Thus, the reported findings do not lend themselves to be taken at face value.
Effectively, the paper neither claims that meat abstinence results in mental disorders nor that meat obstinance results in mental welfare. Rather, it highlights the complexity of the problem, while warning that no causal conclusions should be inferred. Thus, the news reports which portray otherwise, are not representative of the scientific conclusions. These misconceptions are especially dangerous in countries with substantial vegetarian and/or vegan populations, at a time when the root cause of the COVID19 pandemic is suspected to be a meat market. Thus, it is important to bring to the attention of the readers the difference between real science and reported science in this subject matter.
It may also be noted that the scientific effort was funded in part by “… an unrestricted research grant from the Beef Checkoff, through the National Cattlemen’s Beef Association”. Of course, the implications related to conflict of interest are debatable and hence left to the reader’s wisdom.
The writer is a data scientist at Intel Corporation. Views are personal.