“Epistemic Certainty Surrounding Dietary Recommendations for Meat”

by Ellen M. Street | Xchanges 12.2/13.1

Results

Among the selected articles, I found a disparate ratio of hedges to boosters. True to Hyland’s explanation about the popular use of hedging in academic writing, directives, present indicative, and ambiguity take place of markers indicating certainty, such as boosters.

Dietary Guidelines for Americans 2015-2020

Overall trends in the 2015-2020 DGA indicate a lack of certainty, evident by the prevalent use of hedging and lack of boosters (see appendix table 3). The guidelines are phrased as suggestions without emphasis or authority, save for one directive in Chapter 2 written for teen boys and men. Verbs indicating low and medium degrees of modality include the use of can, for lean meats, and may for processed meats. The only booster included in the DGA is strong, used to describe the strength of evidence linking red meat, processed meats, and poultry to reduced CVD risk in adults. There is no source listed for this statement.

AHA Recommended Dietary Pattern

The AHA is a charity organization focused primarily on public health education, research, and professional training. The dietary pattern guidelines state that individuals “should consume a dietary pattern that emphasizes vegetables, fruits, and whole grains… and has limited intake of sweets, SSBs, red meats, and processed foods” (Van Horn et. al., 2016). The AHA/ACC do not use hedges to describe red meat and trans-saturated fat intake (see appendix table 4). Rather than boosters, the use of the directives limit and reduce indicate necessity whereas should, a deontic modal verb, expresses duty or obligation.

American Institute for Cancer Research

The second expert report, published jointly by the AICR/WCRF, outlines dietary and lifestyle guidelines for preventing cancer. The language used in the section on red and processed meats displays strong epistemic certainty and the use of boosters (see appendix table 5). “The strongest evidence… shows that red meat and processed meat are causes of colorectal cancer.” The overall trend in epistemic certainty is supported by boosters and directives such as convincing, limit, and avoid. Hedges are used to describe the link between red and processed meats with other types of cancer besides colorectal.

The Lancet Oncology

The Lancet Oncology monograph shows a distinct difference in epistemic certainty describing red and processed meat. Statements regarding red meat consumption and its link to cancer use hedges while statements linking processed meat to colorectal cancer show epistemic certainty (see appendix table 6). Unprocessed red meat is classified as “probably carcinogenic to humans,” considering “substantial” data and “strong mechanistic evidence” (Beland, 2015).

Archives of Internal Medicine

An Archives of Internal Medicine article, written by Pan et al., investigated associations between processed and unprocessed red meat consumption and mortality. The discussion of the study results primarily indicate probability, but do not make any certain claims until the last sentence of the comments section. High sodium content in processed meats “may increase CVD risk.” Dietary heme iron, sourced from red meat, is “positively associated with myocardial infarction and fatal coronary heart disease.”

American Journal of Epidemiology

The meta-analysis of 13 studies links the consumption of unprocessed and processed red meats with all-cause mortality. The findings reflect epistemic certainty in statements associating high consumption of processed meat to all-cause mortality and colorectal cancer: “Among cancer types, colorectal cancer has been most consistently associated with red meat and processed meat consumption.” Also, “In conclusion, findings from this meta-analysis showed a positive association between the consumption of red meat, particularly processed meat, and all-cause mortality.”