Digesting Data: Tracing the Chromosomal Imprint of Scientific Evidence Through the Development and Use of Canadian Dietary Guidelines

Conceptual Framework

I situate my study in what Donahue and Lillis (2014) referred to as a “social practice model” (p. 68) that conceptualizes, investigates, and theorizes about the “‘observable practice’ of writing, that is what people do with and around writing” (p. 69). To explore the social and ideological actions of the 2007 CFG’s standard paper-based document, I draw on concepts from rhetorical genre studies (RGS; e.g., Bazerman, 1988; Miller, 1984; Paré & Smart, 1994). Genres, from the perspective of RGS scholars, are typified and recognizable texts that exhibit similar purposes, features, and structures and develop in response to the needs of recurring, socially constructed situations. As such, genres are both shaped by and shape or reproduce social contexts (e.g., Bawarshi, 2000; Paré & Smart, 1994). Genres can be seen as “stabilized-for-now” (Schryer, 1993, p. 204) sites of ideological actions and rhetorical strategies, and they “strategically embody attitudes, values, and ways of doing” (Coe, Lingard, & Teslenko, 2002, p. 3).

But some RGS scholars have demonstrated that nonrecurring and nonroutine texts can also rely on and produce genre knowledge (Berkenkotter, 2001; Kain, 2005). Because there is limited research on the CFG from the rhetorical perspective and, thus, limited evidence to suggest that the CFG exemplifies a genre—that is, a routine and recurring activity—I draw on RGS to investigate the CFG as a nonrecurring and nonroutine text, as well as the many texts connected to, or implicated in, its production and use (cf. Kain, 2005). For this reason, I refer to written discourse not as genres but as text, which is “a unique material object” (Prior, 2004, p. 169) that represents ideas, actions, and social processes through symbols such as language, pictures, numbers, and so on.

A key concept that informs this study is antecedent genre, a prior genre that affects writers’ or readers’ abilities to recognize and respond appropriately to new situations (Jamieson, 1975). Jamieson’s research demonstrates how writers rely on past experience and antecedent genres when they encounter new situations because of perceived similarities between rhetorical situations. Jamieson observed that traces of the content and form of an antecedent genre, referred to as the “chromosomal imprint” (p. 406), pass from one genre to the next and can act as “powerful rhetorical constraints” on the “content, intent, and form” (p. 407) of the discourse that has taken up the antecedent genre. This chromosomal imprint of antecedent genres not only exerts rhetorical constraints over new situations but also creates expectations to which writers and readers respond. Jamieson also noted that a writer’s choice of antecedent genre might not always be appropriate or consistent with the needs and demands of a current situation and can constrain both the writer’s and the audience’s response. RGS scholars have explored the role of antecedent genres in constraining and enabling new or subsequent discourses (Devitt & Reiff, 2014; Dryer, 2008; Miller & Shepherd, 2009) and observed that the chromosomal imprint of antecedent genres can influence the form and substance, as well as the social and ideological actions, that new or subsequent genres perform.

Another important concept I rely on in this study is uptake. The notion of uptake in discourse stems from speech act theory, in particular, from Austin (1975), who described uptake as the effect of or response to an utterance. Freadman (1994, 2002) expanded on Austin’s concept of uptake by drawing on Searle’s (1969) notion of constitutive rules, which “create or define new forms of behaviour” (p. 33). Freadman (1994) likened these constitutive rules to a tennis game, in which the surrounding activities, such as place, timing, audience, and participant roles, create the game of tennis; the surrounding activities constitute the “rules for play” (p. 46). It is only within these rules for play that the passing back and forth of a ball becomes the passing of shots and the meaning of these shots becomes understood. Using this analogy of the tennis game, Freadman argued that a genre is a game, in which the rules for play, such as the time, place, audience, and purpose, determine the form and content of a text and the meaning of a text lies in its performance as it takes up and is taken up by other texts. Uptake then elucidates how people respond to a genre and whether they know what to do with, or how to act in response to, that genre (Freadman, 1994, 2002).

In contrast to Austin’s (1975) notion of uptake, Freadman (2002) argued that uptake involves agency and that a text cannot determine its uptake; rather, the uptake “selects, defines, or represents the object” (p. 48). That is, the meaning and use of a text is understood by its uptake. Freadman (2012) explained that uptake is also subject to historical and material considerations and that perceived recurrence (cf. Miller, 1984) does not mean that the situation is the same. For this reason, Freadman stated, “no genre can do more than predict the kind of uptake that would make it happy, and no speaker or writer can completely secure an uptake” (p. 560). Bawarshi (2016) highlighted the role of agency in Freadman’s conception of uptake, which he argued is inherent in uptake and subject to myriad factors. Bawarshi (2015) suggested that although uptake might be guided by genre knowledge, because uptake “takes place within a complex scene of agency, it also exceeds genre knowledge and may not always or often be textually visible” (p. 189). In other words, uptake does not only refer to textual uptake, it refers to any response to a text, for example, behavior or action. The concepts of antecedent genre (Jamieson, 1975) and uptake (Bawarshi, 2015; Freadman, 1994, 2002) help illuminate the social and ideological actions that the 2007 CFG’s standard paper-based document performs and how this nonrecurring and nonroutine text interacts with its social contexts.

Method

To study the CFG and the social contexts in which it was produced and now used by RDs, I conducted a qualitative study with a sequential design. I first conducted semistructured interviews with two groups of participants followed by a Multimodal Interactional (MMI) analysis (Norris, 2004, 2011) of the 2007 CFG’s standard paper-based document. The study received approval from the Carleton University Research Ethics Board (Project # 101294).

Findings

The findings of this study reveal that scientific representations play a profound role in the social and ideological actions that the CFG performs. A key scientific representation in the CFG is the Food Guide Serving, and indeed, it appears to be the core concept around which the dietary guidelines are constructed. Food Guide Servings, which use metric units to represent somewhat uniform amounts of food for each food group, first appeared in the 1977 CFG version (Health Canada, 2007a). In its current form, the Food Guide Serving is derived from the Canadian Nutrient File (Health Canada, 2016b), which typically describes nutrients for 100 g amounts of food, but the Food Guide Serving size is modified for some foods. According to a review of the 1992 CFG, the concept of the Food Guide Serving was particularly problematic for readers and thus became a key concern during the revision process for the 2007 CFG (Katamay et al., 2007). Much of the confusion over Food Guide Servings comes from the fact that an individual serving does not represent a recommended portion of food. Instead, the total number of servings per day represents the recommended amount of food from each food group that people should eat each day in order to meet their nutrient requirements, regardless of how much is eaten at one meal. The CFG’s Web site provides the following explanation for readers:

A Food Guide Serving is simply a reference amount. It helps you understand how much food is recommended every day from each of the four food groups. In some cases, a Food Guide Serving may be close to what you eat, such as an apple. In other cases, such as rice or pasta, you may serve yourself more than one Food Guide Serving. (Health Canada, 2007b, para. 1)

Developing the Food Guide Serving

Although the Food Guide Serving existed in previous CFG versions, the sizes and numbers of Food Guide Servings within different food groupings (i.e., vegetables and fruit, grain products, milk and alternatives, meat and alternatives), as well as the serving recommendations for specific age and sex categories, were updated and revised for the 2007 CFG. The revision included a complex process of transforming scientific evidence about the role of macronutrients and micronutrients in human health into a food-based model for healthy eating, known as the food intake pattern (Katamay et al., 2007). The first step in this transformation involved revising existing Dietary Reference Intakes (DRIs), the values of macronutrients and micronutrients that people require to maintain their health and help prevent chronic disease (Health Canada, 2013). DRIs were published in tables that list the values of specific nutrients (e.g., vitamin A, iron, magnesium) for different age and sex categories (see Figure 1).

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Figure 1.

Sample Dietary Reference Intakes table (Health Canada, 2010).

The DRI values represent macronutrients and micronutrients—not actual food—so the scientific evidence needed to be further transformed into a food intake pattern (Katamay et al., 2007), or as a KI puts it, a “model of…how healthy eating could be;…a model to help reach our nutrition requirements.” A KI noted that “we can’t just take [evidence] on its own, we need to look at it in a bigger context.” As such, the food intake pattern was developed through a complex process that relied on data from food consumption surveys that provide information about “what types of food…[are] most chosen by Canadians. It may not represent the individual, but it represents that Canadians at large tend to eat a lot of carrots” (KI). This process involved mapping the DRIs onto frequently eaten foods, forming the basis of 500 simulated diets for different age and sex groups to estimate healthy nutrient distributions (Katamay et al., 2007). The resulting food intake pattern represents the nutrient distributions that ensure adequate nutrient intake by providing the recommended number of Food Guide Servings within the four major food groupings for several age and sex categories (see Figure 2).

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Figure 2.

Food intake pattern (used with permission, Katamay et al., 2007).

After the food intake pattern was developed, the actual CFG resource needed to be revised and updated, which a KI explained was a process that “was really about the translation of the science into more lay language.” That is, from the KIs’ perspectives, revising the CFG was a knowledge translation activity, in which the food intake pattern needed to be translated into a resource intended for a wide audience. The CFG’s purpose and audience, then, were key factors in this final step in transforming the scientific evidence. KIs explained that the purpose of the CFG is “to promote healthy eating to Canadians” and more specifically, “to meet nutrient needs within an acceptable calorie range.” But they also noted that it “is only a guide [and]…needs to be flexible” and that the “audience is very vast,” so they needed to consider the cultural and socioeconomic diversity of the Canadian population.

Considering both the audience and the purpose of the CFG presented a number of difficulties during the revision process. For instance, the revised CFG needed to address the range of literacy and numeracy levels in Canada:

The other thing that is very difficult with nutrition in particular, is the whole bringing down the literacy level because the language of nutrition has a lot of complex words in it that you can’t really easily replace. And there’s a lot of numbers. And when you start incorporating numbers, people shut down. It’s very complicated. (KI)

As such, translating the food intake pattern into the CFG, in particular, deciding how to best represent the quantity and size of Food Guide Servings, presented a key obstacle during the revision process. To determine how to best represent a Food Guide Serving, CFG producers consulted with experts and conducted consumer tests of multiple potential representations (Ekos Research, 2006a, 2006b). KIs explained how, initially, they drew on their knowledge of typical nutrition education practices to represent examples of the Food Guide Serving:

What we thought was a more consumer-friendly way of looking at serving size [was] by having reference to the hand…we had also discussed in our group having reference to typical objects, and you see that sometimes in nutrition education, like a tennis ball, or a computer mouse or something like that.

But after consulting with experts, the CFG producers rejected the plan to represent Food Guide Servings with typical household objects for cultural reasons. One KI explained, “We moved away from that because we had some of our experts that said that not everybody could necessarily relate to the objects that we were using.” KIs also described how they chose not to use hands to represent a Food Guide Serving after consumer testing:

Consumers didn’t like the hand approach either because they got really confused. They were like, “yeah, but my husband, his hands are thicker than mine,” and then, like, “How do I know which hand to use?”…we thought it would be so much more simple, and it doesn’t have to be precise, but consumers wanted the precision.

As a result of these consumer tests and consultations with experts, Food Guide Servings are now represented by numbers and pictures in the 2007 CFG (see Figure 3). Despite being aware that the use of numbers adds to the complexity of the guidelines, the CFG producers relied on the original scientific measurements—that is, the precise metric units from the food intake pattern—to represent Food Guide Servings.

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Figure 3.

An example representation of a food guide serving in the standard 2007 Canada’s Food Guide (Health Canada, 2017a).

Representing the Food Guide Serving

While representing Food Guide Servings presented obstacles during the revision process, how these were represented had a profound influence over the structure and content and, more important, the rhetoric of the CFG. Although the representations of the Food Guide Servings are intended to clarify the dietary guidelines, my MMI analysis of the 2007 CFG’s standard document revealed how the use of Food Guide Servings as an organizing concept resulted in a rhetorically complex document.

First, the concept of the Food Guide Serving, and the way it is represented, contributes to the rhetorical complexity of the CFG through rhetorical silence. Rhetorical silence is similar to Huckin’s (2002) presuppositional textual silence, which assumes that information “is presumed to be already known or readily acceptable to the reader or listener and to be easily recoverable from the context” (p. 348). But unlike Huckin’s description, the silence in the CFG assumes that the intended uptake of the information is readily apparent or easily recoverable from the context, and therefore, the textual silences in the CFG can be interpreted much more broadly, as rhetorical silences. Specifically, there is a rhetorical silence in the CFG regarding the difference between Food Guide Servings and portion sizes. The representation of the Food Guide Servings demonstrates an assumption that readers can identify the difference between metric units and cooking measurements, the corresponding pictures, and the amount of food that a person typically eats at a given time. For example, the CFG indicates that a serving size of cereal is 30 g and includes a corresponding picture of a bowl of cereal (see Figure 3). The tacit assumption is that readers can identify if a Food Guide Serving, or 30 g, of cereal is less than their typical portion of cereal and if their typical portion is, for instance, two Food Guide Servings of grain products.

Second, a large portion of the inside pages of the 2007 CFG (see Appendix A) is dedicated to providing examples of Food Guide Servings within each food group, and several different types of information are presented within a table structure. The communicative functions that the modes or groups of modes perform within this table are presented in layers (see Figure 4). I refer to these layers of meaning as rhetorical laminations, a concept derived from the concept of chronotopic laminations (Bakhtin, 1981; Prior, 1998; Prior & Shipka, 2003), which describes “the simultaneous layering of multiple activity frames and stances…which are relatively foregrounded and backgrounded” (Prior & Shipka, 2003, p. 187). For example, in the foreground of Figure 4 are the following rhetorical moves (cf. Swales, 1990): the chart of recommended daily servings, examples of Food Guide Servings, and recommendations for choosing and preparing foods. Yet each of these rhetorical moves relies on the background layer to construct meaning by categorizing the foregrounded information by food groups. While the rhetorical lamination is an efficient use of limited space, it requires additional interpretation for readers and increases the complexity of the CFG.

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Figure 4.

Layered rhetorical moves in the standard 2007 Canada’s Food Guide.

Finally, the CFG also includes instructions for its interpretation and use. But these instructions are represented in two parts in two different places in the standard CFG version (see Appendix A and Figure 5). Since these two instruction parts perform one coherent communicative function yet are represented in two different places on the paper document, I view their representation as an example of what I call fragmented rhetoric. The first part of the instructions (see Figure 5, part a) appears on the inside pages of the CFG immediately below the chart it is meant to clarify; however, the second part of the instructions (see Figure 5, part b) appears on the back page, separate from the examples of Food Guide Servings that it clarifies. Both of these sections are important for interpreting and using the CFG. The rhetorical silences, rhetorical laminations, and fragmented rhetoric contribute to the rhetorical complexity of the CFG, which has implications for the way the resource is used by RDs who work with vulnerable populations.

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Figure 5.

Fragmented rhetoric of instructions in the standard 2007 Canada’s Food Guide (Health Canada, 2017a).

Using the Food Guide Serving

The development and representation of the concept of a Food Guide Serving was a common thread throughout my analysis of the KIs’ interviews and MMI analysis of the 2007 CFG, and this thread continued through my analysis of the RDs’ interviews. The RD participants explained that they use the CFG as a teaching tool to help people make “healthy changes” (RD9). But many of the people with whom RDs work face financial limitations, food insecurity, and overcrowded housing, and some have low literacy and numeracy or lack cooking skills. In addition, or perhaps as a result, the RDs reported, many people with whom they work lack the knowledge, experience, or skills required to fully understand and use the CFG (e.g., they might not have any prior experience with scientific representations or cooking). Thus, RDs indicated that when they use the CFG to teach people about healthy eating, the concept of the Food Guide Serving presents the biggest difficulty and requires a lot of attention. As RD6 observed, “I feel like we end up focusing on serving size.” One RD explained that much of the problem with Food Guide Servings is that the concept is not intuitive for people:

They do get confused about…the daily values more than anything…the whole idea of grams, and that is kind of weird for them, too. So, I try to point out 5 grams is like a teaspoon, and 15 grams is like a tablespoon, 125 grams is a half a cup. But I do try to make it more…concrete, let’s say. Something they can relate to a little bit better. ‘Cause to them, a gram, what the heck’s a gram, right? (RD7)

RDs indicated that they often have to explain to people the difference between a Food Guide Serving and a portion of food, which many people find confusing. To many, “the concept of you might have 2 servings of the same food at a meal is kind of a strange idea” (RD9). According to RDs, people often assume a Food Guide Serving and a portion are the same thing because it is not clear in the CFG. For example, RD2 explained, “if you have a full bagel, that’s 2 servings. It’s your portion of food you’re going to eat, but that’s 2 servings. So that’s where people get confused.” Because Food Guide Servings are often smaller than a typical portion, RDs noted, “when people talk about Canada’s Food Guide, they’re actually overwhelmed by the number of servings that they’re supposed to eat” (RD7).

While the representation of Food Guide Servings presents difficulties for RDs, they explained that using the concept of the Food Guide Serving to interpret and understand the dietary guidelines more broadly is also difficult. As RD7 observed, “people tend to…look at all those numbers and all that information and just kind of blank out.” RDs indicated that many people struggle with the multiple forms of information in the CFG, particularly people with little or no education:

It’s not a simple document. And especially with the patients who don’t even have…their elementary education, it’s really hard to explain the chart, and the serving sizes and food groups and there are just too many components. It’s not simple enough. (RD5)

According to some RDs, the difficulty many people experience lies in understanding the relationship between the many different forms of information in the CFG and being able to put them together:

You have to read a grid to figure out what age group you are and how many servings to have and then to take that information and apply it to the second page in the food guide. Then you have to figure out what a serving is. It’s too high level for a lot of our population. (RD10)

RDs reported that teaching people how to interpret the representations of Food Guide Servings and their role in the dietary guidelines is often time-consuming. For example, RD1 explained, “I’ll try to do a little bit of teaching on serving size versus portions versus total daily intake, which takes some time, and it’s probably one of the most complicated parts for people to really grasp.” Similarly, RDs reported that using the CFG not only takes time, but it also requires a lot of attention: “You have to really want to sit down and read the food guide and do some math and figure out what you should be having if you want to use that food guide” (RD10).

In addition, RDs illustrated some more practical implications of dietary guidelines based on the concept of a Food Guide Serving. For example, RD2 described how the concept of the Food Guide Serving affects how people think about their food practices:

It naturally gravitates people into thinking that they only can have one [serving] at a time. So, if you have to have seven servings of grain, people almost start to think they have to have one serving at breakfast, one serving at snack. Like it’s the portion versus serving, which is confusing.

Also, RDs indicated that many people are unsure how to apply the concept of the Food Guide Serving practically. RD9 explained, “There’s that missing step between here’s your numbers versus practically how can you use it.…It takes that extra step, which a lot of people don’t have the skills to do that.” Some RDs reported being often asked, “How do you assemble these into a meal?” (RD5). Given these concerns, RDs explained that they often need to provide practical examples of real meals and tips for different food practices or even to create opportunities for people to participate in healthy eating activities. For example, some RDs described how they provide tips for choosing and preparing foods in order to “take out the numbers and…the guesswork” (RD2). RDs commented that real-life examples and opportunities to participate in food practices, such as cooking classes or grocery store tours, are most effective for teaching nutrition. As RD2 explained, “That’s what people want because that’s what people do. We don’t eat nutrients, we eat food.”

When teaching about nutrition, many RD participants reported that they rely on other resources and ways of communicating to help clarify the concept of Food Guide Servings and the CFG in general. These other resources and ways of communicating help RDs not only to clarify the purposes of the CFG but to translate the science, particularly Food Guide Servings, and show people how the CFG applies to their everyday lives:

People aren’t aware of what a serving size is, and so I’ll try to explain very clearly, and I also pull out my food models and say, “Oh, this is a serving of yogurt; this is what half a cup of pasta looks like.” So, I supplement the pictures with actual models, or I’ll just pull out a measuring cup. (RD5)

When teaching about nutrition, then, RDs reported that they present the information in the CFG, particularly the concept of Food Guide Servings, in multiple ways or that they use other resources. Rather than just showing people the CFG, they will verbally explain the nutrition guidelines, or they will write and draw modifications on the CFG. For example, RD1 provided a sample CFG with the handwritten and drawn modifications she makes during consultations to help further explain how to choose foods and measure Food Guide Servings (see Figure 6). RDs also commonly employ the Zimbabwe Hand Jive (Family Health Magazine, 2012), a series of gestures that indicate the size of a Food Guide Serving for different kinds of food. For example, one fist represents an appropriate portion of grain products such as pasta. As RD4 explained, “I find it more practical than saying half a cup or a cup. It’s just easier.”

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Figure 6.

Sample of registered dietitian’s modified standard 2007 CFG (used with permission).

RDs reported that they rely on many other resources as well. These resources include plastic 3-D replicas of different types of food (see Figure 7), which sometimes, RD2 noted, “are set to be a serving.” Alternatively, RDs explained, they might use items such as a deck of cards to demonstrate a Food Guide Serving of meat. RDs also have extensive collections of other written resources that provide information for specific diets (e.g., vegetarian), health needs (e.g., diabetes), or cultural food practices (e.g., South Asian cooking). These resources help RDs show people how to adapt the CFG and healthy eating practices to their specific needs and circumstances and provide the RDs with alternative ways of describing portions and food groupings. RDs reported that they use these additional resources to supplement the information in the CFG to help further explain concepts such as the Food Guide Serving by translating them into something more practical. Such resources are also often used to connect the CFG to people’s lives and, in some cases, replace the CFG entirely in situations in which it is not effective or appropriate. In other words, RDs reported that the CFG is difficult to understand and interpret, prompting them to create new multimodal discursive activities.

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Figure 7.

Examples of plastic food models.

Discussion

The findings of this study provide insight into the social and ideological actions of the CFG, which can be determined by tracing the persistent and powerful “chromosomal imprint” (Jamieson, 1975, p. 406), or traces of the content, intent, and form, of scientific evidence that informs the CFG and, in turn, influences how RDs use it. The representations of this scientific evidence, as exemplified in the Food Guide Serving, reflect the ideologies of nutrition science, a science that studies the effects of macronutrients and micronutrients on health and the ways of knowing and talking about nutrition (e.g., Coe et al., 2002; Lynch & Woolgar, 1990). Despite attempts to represent the Food Guide Serving concept in more user-friendly ways, it is instead represented in typical scientific ways—by numbers indicating metric units and cooking measurements. These scientific representations have been inherited through a process that transformed scientific evidence about nutrients into DRIs and then into the food intake pattern (Katamay et al., 2007). Throughout this process, the content (required macronutrients and micronutrients for preventing disease and maintaining health) and form (numbers, charts, specialized terminology) of this evidence have demonstrated resilience, revealing a chromosomal imprint of scientific evidence from nutrition science. The original representations of scientific evidence and the subsequent DRI report and food intake pattern are antecedent scientific texts that have imposed powerful rhetorical constraints over the CFG, not only constraining the form and content of the CFG but also creating the particular views of what constitutes healthy eating to which the CFG producers and RDs have responded.

Similar to Tachino’s (2012) “intermediary genres,” or genres that facilitate the uptake of one genre by another, the DRI report and the food intake pattern facilitated the CFG’s uptake of scientific evidence through the concept of the Food Guide Serving. Thus, the concept of the Food Guide Serving was the means by which the chromosomal imprint of the scientific evidence appeared in the CFG. As this evidence was transformed, the DRI report and then the food intake pattern carried the chromosomal imprint of the scientific evidence that views healthy eating according to nutrient values, but the representations of the evidence became increasingly simplified and reductive the further away they moved from their original scientific context.

The CFG is considered a version of the food intake pattern that has been translated, or “recontextualized” (Calsamiglia & Van Dijk, 2004), for general audiences and as such carries the chromosomal imprint of the scientific evidence. As the food intake pattern was further simplified, or translated for lay audiences according to KIs, to enable Canadians to make healthier food choices and thereby reduce the risk of developing chronic disease and obesity, the scientific representations—the Food Guide Servings—became what Bourdieu (1992) called “scientistic representations” (p. 207). According to Bourdieu, scientific representations become scientistic if they obscure or oversimplify important information when presented to nonscientific audiences or are used in situations in which other ways of representing information might be more appropriate. In other words, in this case, the scientific representations of evidence from nutrition science became scientistic as they were removed from their original scientific contexts, transformed into Food Guide Servings, and then used within a resource—the CFG—intended for general audiences.

The scientistic representation of the Food Guide Serving, then, seems at odds with the purpose and audience for the CFG, and its use detracts from the CFG’s ability to respond appropriately to the needs and demands of the situations to which it responds. Similarly, the chromosomal imprint of scientific evidence also exerted powerful rhetorical constraints on the CFG producers’ abilities to respond in nonscientific ways to issues that arose during the revision process. For example, despite consistent confusion over the concept of the Food Guide Serving (Katamay et al., 2007), it remains an integral part of the dietary guidelines. KIs described how attempts to represent Food Guide Servings in less scientific ways in order to communicate their flexibility produced even more confusion for audiences during consumer testing. Rather than questioning the usefulness of the abstract concept of the Food Guide Serving to communicate messages about healthy eating, the CFG producers chose instead to represent them in typical scientific ways.

The findings suggest that the tension between the powerful rhetorical constraints of the concept and scientistic representation of the Food Guide Serving and the CFG’s purpose and audience resulted in a resource that is rhetorically complex and confusing for many readers. The difference between a Food Guide Serving and a portion was not made explicit in the 2007 CFG’s standard paper-based document, thus creating a rhetorical silence that complicates its interpretation and use. The table that provides an efficient representation of the food intake pattern and examples of Food Guide Servings for the four food groups resulted in rhetorical laminations that require further interpretation of these already complex concepts. To address this complexity, the CFG includes instructions; however, they are separated between two sections of the 2007 CFG’s standard paper-based document, creating fragmented rhetoric with no clear indication of each fragment’s relationship to the other or to the dietary guidelines. Thus, the findings suggest that, given the KIs explanation of the CFG’s purpose and audience and the RDs’ descriptions of their uptake of the CFG, the rhetorical silences, rhetorical laminations, and fragmented rhetoric prevent the 2007 CFG from producing its desired effect.

The scientistic representations of Food Guide Servings, carrying a chromosomal imprint of the scientific evidence for nutrition, appear to limit the CFG’s ability to address the needs of many Canadian populations who might be most at risk for developing obesity and diet-related chronic disease. Therefore, as yet another step in the knowledge translation process, RDs routinely need to reinterpret the concept of the Food Guide Serving. The scientistic representations of Food Guide Servings (i.e., the chromosomal imprint of scientific evidence) have a powerful influence over how RDs use the CFG. Their uptake, or response to, the CFG is more than textual (Bawarshi, 2015). By taking up the CFG, RDs also take up the rhetorical constraints of its scientistic representations. They report that, rather than using the CFG as a tool for teaching healthy eating, they spend most of their time discussing the concept of the Food Guide Serving with people. RDs find the process of explaining the dietary guidelines difficult because the CFG producers’ intended meaning of Food Guide Servings is not evident due to the complexity of the CFG. As a consequence, new discursive activities emerge during RDs’ interactions with people and new tools for interpreting the CFG are developed.

For example, RDs described how, because of the scientistic representations, they have to rely on discursive activities and tools, such as food models and the Hand Jive, to teach people how to interpret Food Guide Servings before the CFG can be used as a tool to teach healthy eating. Essentially, RDs have to further translate the scientistic representations in the CFG for people who are unfamiliar with typical scientific representations. In addition, the scientistic representations of the Food Guide Servings are being used within a context so dissimilar to the context in which the antecedent scientific representations were developed that RDs not only have to translate the science, they also have to make the Food Guide Serving more practical by relating it to a person’s life. Thus, RDs are faced with the task of reconstructing the concept of the Food Guide Serving and the CFG not as simplified, recontextualized versions of the scientific evidence but as everyday practices in which people can participate.

By taking up the CFG, RDs learn the rhetorical constraints of its scientistic representations and perspectives on food as nutrients. According to RDs, the concept and representation of the Food Guide Serving in the CFG constrain their interactions with the people with whom they work, seem inconsistent with the needs of many of these people, and do not seem to lead people toward a healthier lifestyle.

Conclusions and Implications

To investigate the social and ideological actions that the CFG performs, I explored how the CFG was produced and used. But to understand how context shaped the CFG and, in turn, how the CFG shapes RDs’ practice, I needed to look past the context in which the 2007 CFG was produced and go back to the original scientific basis of the CFG as well as its historical roots. Only after I had located a starting place (of sorts), was I able to trace my way back again using the consistent thread of scientific representations, as exemplified by the Food Guide Serving, that acted as what Jamieson (1975) called a chromosomal imprint in the CFG. The concept of the chromosomal imprint of antecedent genres illuminated problems that arose during the revision process, RDs’ reports about the CFG’s effects on their practice, and ultimately the social and ideological actions that the CFG performs.

The Food Guide Serving, and by extension the CFG, appears to be a scientific—or rather, a scientistic (Bourdieu, 1992)—representation of the evidence that embodies the ideologies of nutrition science, or particular ways of knowing and doing, in which healthy eating is viewed through the lens of nutrients rather than food. The ideologies of nutrition science, manifest in scientific representations, also shape the CFG producers’ perspectives on what healthy eating is and how it can be communicated. In other words, the CFG is an example of a scientistic representation—a reductive and contextualized form of scientific evidence—that communicates the ideologies of nutrition science in the hope that, by taking up the ways of knowing and doing in nutrition science, Canadians will make healthier lifestyle choices. Yet the scientistic representations and the ideologies of nutrition science appear to be inconsistent with the needs that many Canadians, particularly vulnerable populations, are facing. In this context, RDs are tasked with reconstructing the version of healthy eating presented in the CFG in a way that resonates with the people with whom they work. RDs, then, have become an important link in a chain that carries the chromosomal imprint of scientific evidence that leads to the creation of new discursive activities to reconstruct healthy eating—discursive activities that might not otherwise exist. More simply, the CFG performs the social and ideological actions (Schryer, 1993) of creating a way of talking about food and health as a matter of adequate nutrient intake, a way that might impede, rather than promote, healthier lifestyle choices.

Tracing the chromosomal imprint of the scientific evidence not only illuminates the CFG’s social and ideological actions; it might also provide clues to addressing the complexity and ineffectiveness of the CFG. To address the nutritional needs and barriers that Canadians face, the CFG requires more than a makeover. It requires us to look at its scientific basis and the ideologies that are communicated through different representations of the science. To extend the analogy of the chromosomal imprint, we need to look past the CFG’s observable traits and examine its genetic makeup. For example, representing the concept of the Food Guide Serving in more culturally appropriate or accessible ways does not address the fact that a Food Guide Serving is an abstract scientific construct. As the Canadian government works on revisions to the CFG (Health Canada, 2017b), it should critically examine approaches to nutrition science that focus on nutrients rather than food and explore how the multiple representations of this science create different and possibly unhelpful ways of viewing the relationship between food and health. It is important to understand how these representations are transformed by other resources and contextual factors, such as food consumption data, that might result in overly reductive perspectives on nutrition and health that in turn might contribute to, rather than mitigate, the problems they seek to address (Derkatch & Spoel, 2017; Spoel & Derkatch, 2016). Rather than making simple alterations to the representation of the Food Guide Serving, examining the genetic makeup of these scientistic representations of nutrition science and their interactions with other contextual factors might help break “the manacles of an inappropriate” (Jamieson, 1975, p. 414) approach to developing dietary guidelines and lead to more productive knowledge-translation activities that better address Canadians’ needs.

This study highlights how rhetorical genre studies and MMI analysis can provide theoretical and methodological perspectives that can benefit the work carried out in other fields, particularly knowledge translation activities, and that can also be woven into research investigating how nonroutine and nonrecurring texts interact with their social contexts. The concepts of antecedent genres (Jamieson, 1975) and uptake (Bawarshi, 2015; Freadman, 1994, 2002) together help illuminate tensions between the ideologies embedded in and inherited through the historical development of genres and the agency of people who choose to take up a genre in different, perhaps unexpected, contexts.