"Epistemic Certainty Surrounding Dietary Recommendations for Meat"
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Ellen M. StreetEllen Street is a Ph.D. student in Nutrition at Oregon State University. Her graduate research is
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Literature Review
Epistemic modality in guidelines and recommendations "Epistemic modality" expresses an author's level of certainty or belief, and may be conveyed through markers like modal verbs, adverbials, hedges, and boosters to indicate likelihood, certainty, or confidence. The use of modal verbs, adverbs, and adjectives indicate the degree of certainty expressed. According to Ken Hyland, hedges are used to indicate a lack of complete commitment to the truth of a proposition, expressing tentativeness and possibility while boosters allow the reader to identify information that is explicitly presented as certain (Hyland, 1996a). However, in scientific publications, hedges are significantly more prevalent than boosters. Hyland describes this theme, stating “in science we often do not need to emphasize or stress our certainty with respect to specific claims . . . we can simply use the indicative present” (1996). Hedging can be used to avoid personal commitment and express information prudently, given that scientific conclusions can never be 100% definitive. Scientific research articles, government health, and public health organizations all utilize different rhetorical moves to support their writing. For scientific articles specifically, hedging plays a particularly critical role. Hyland (1996b) explains the use of hedging in scientific articles as a means of allowing the writer to ratify claims by presenting statements with appropriate accuracy, caution, and humility. This also helps “negotiate the perspective from which conclusions can be accepted” (p.2). Hedges may be used in anticipation to both content- and reader-oriented oppositions. Content-oriented hedges refer to hedging used to accurately and cautiously state uncertain scientific claims. The latter may be used when the writer is unwilling to commit to a conclusion in order to diminish their own connection or responsibility, to avoid consequential opposition. Reader-oriented hedging is associated with higher-level claims, according to Hyland, and actually diminishes the author's presence in a text, sacrificing precision of the claims (1996b). Comparing epistemic modality in research articles as opposed to government and public health recommendations presents a challenge, due to the distinctly different genres, each with different motivations for publishing and sharing information. Pastore and Dellantonio point out that scientific research articles use different approaches to argumentation and the frequency of markers indicating certainty does not always indicate whether the topic is considered more or less factual by the authors (2016). Registered dietitians, health professionals, and governing groups regulating the release of nutritional recommendations are not faultless. Dietary recommendations of the past, namely the American Heart Association 1968 recommendations, propagated groundless criticism and restriction for dietary cholesterol, which was still reflected in the Dietary Guidelines for Americans in 2010, stating that dietary cholesterol consumption should be reduced to no more than 300 milligrams per day (mg/d), a number based on misinterpreted, conflicting evidence (McNamara, 2015). Research continued to progress over the following fifty years, challenging the established cholesterol restrictions and exemplifying the benefits of egg consumption. Recently, the 2015 Dietary Guidelines for Americans (DGA, 2015) eradicated the cholesterol recommendations by definitively stating that cholesterol is no longer considered a nutrient of concern. Yet, the public stigma remains and, as a result, many are unknowingly avoiding the plethora of nutrients contained within egg yolks. This same propagation of misinformation occurred with saturated fatty acids (SFAs). The Seven Countries Study, directed by Ancel Keys, led to the hypothesis that SFAs in the diet caused coronary heart disease (CHD). So the dietary recommendations shifted to recommend reducing SFA intake. However, the logic was flawed. SFAs were shown to raise LDL cholesterol (LDL-C). High LDL-C is associated with increased CVD (cardiovascular disease) risk, so the conclusion was drawn that reducing dietary SFAs would reduce CVD risk. The dietary recommendations were based on this logic, but there was a lack of evidence to support it. Evidence from intervention and observational studies looking at the relation between dairy products and CVD did not support a positive association between dairy intake and CVD risk. However, evidence from a large, multi-ethnic study found that SFA from meat was associated with a greater CVD risk than with SFA from dairy. The dietary recommendations had suggested a reduced intake of full-fat dairy products, because of their high SFA content, but the current research showed that the recommendations did not take into consideration the source of SFAs. Still, to this day, the stigma surrounding SFAs persists, despite an influx of new evidence supporting SFAs from meat as the true link to CVD. Language surrounding meat recommendations: past versus present Examination of language describing meat recommendations in the 2010 DGA reveals a considerable shift in attitudes towards red and processed meat consumption since the most recent publication. The 2010 DGA does not mention red or processed meats as part of a healthy eating pattern, and uses directives to advise readers to reduce intake of dietary sources of saturated fat, later describing the cardiovascular disease risks related to consuming saturated and trans-saturated fatty acids. However, the DGAC “did not evaluate the components of processed meats that are associated with increased risk of colorectal cancer and cardiovascular disease” in the 2010 DGA. Lean meats and seafood are offered as nutrient-dense alternatives to meat and poultry. Choosing seafoods over meat or poultry is recommended in this version of the DGA as part of a healthy eating pattern. The sections following these recommendations evaluate the evidence supporting the recommendations and purported health benefits and provide clear explanations for the recommendations of lean meats over full-fat meats. The 2005 DGA also recommends making only lean-meat choices. This publication also offers specific quantitative recommendations for the ounces of meat, poultry, or fish recommended for discretionary calorie allowances (3-6oz). The 2000 DGA also recommends lean meat consumption and advises readers to limit high fat processed meats, organ, and liver meats to avoid high blood cholesterol. It is important to note that the recent publication of the DGA does not address the health risks related to the consumption of full-fat and processed red meats. In the past DGA examples, health risks associated with saturated and trans-fatty acid consumption are reinforced with evidence to support lean meat consumption and avoidance of full-fat and processed meats. Dietary recommendations do change over time, but through past versions of the DGA, this stance on red and processed full-fat meats has been consistent up until now. |