Exploring the Relationship between Environmental Impact and Nutrient Content of Sandwiches and Beverages Available in Cafés in a UK University

Round  1

Reviewer 1 Report

General comments

The changing diet pattern of consumers has implication on the environment. Therefore, this study, which explores the relationship between environmental impact and nutrient content of sandwiches and beverages available in café in a UK university, is important. I have provided some comments to improve the quality of the paper.

Introduction

The research problem and objective are clearly outlined. However, the authors did not provide adequate literature on the subject and identify the knowledge gap in the literature. I kindly encourage the authors provide such information to enable readers to appreciate their contribution to the body of knowledge.

Materials and methods

The authors have provided a detailed explanation of source of data and computations of ingredients, GHGE, and water footprint estimates.

Results

The results are well presented and interpreted.

Discussions

The results are discussed and placed in the existing literature. As already indicated, it would have necessary to provide current knowledge or literature on the subject in the introduction and then explain the gap as well as the contributions to the gap as indicated in the discussion.

Author Response

Reviewer 1, Point 1: The research problem and objective are clearly outlined. However, the authors did not provide adequate literature on the subject and identify the knowledge gap in the literature. I kindly encourage the authors provide such information to enable readers to appreciate their contribution to the body of knowledge.

Response 1.1: Thank you for your comment. We have included in the Introduction section (page 2, line 76-82) additional literature on the trends of out-of-home food and beverage consumption in the UK and highlighted the knowledge gap relating to the environmental impact of these products and its relation with nutritional content.

Lines 76-82: “Sandwiches comprise a large proportion of food consumed outside the home in Britain, with 4 billion pre-packed sandwiches sold in 2018 [19]. Furthermore, out-of-home consumption of non-alcoholic beverages continues to rise, with sales coffee products alone generating an estimated turnover of £3.2 billion pounds [20]. There has been insufficient research about the environmental impact associated with the consumption of these foods and drinks [21][22]. The very few studies that have explored the relationship between environmental impact and nutrition have considered the effect on climate [22,23], but have not investigated fresh water use”.

We have also added the following sentence to the discussion to explain how this paper addresses this knowledge gap:

Lines 64-66: “The majority of studies exploring dietary change for the environment have focused on a single environmental impact parameter, predominantly GHGE [32]. Here we have used a novel approach to assess how choice of sandwich and beverage could affect both water use and GHGE. The findings of this study contribute a broader understanding of the environmental impact of popular food and beverages consumed in the UK.”

Reviewer 2 Report

The environmental impact of the diet is a topic that can no longer be ignored. The planning of a sustainable diet now also passes through its weight on environmental sustainability. The manuscript focuses on the current topic of the exploitation of environmental resources and the introduction of greenhouse gases dependent on the food production chain. The use of a single parameter for the evaluation and comparison of the environmental impact of a food or a nutritional component is a winning approach for a rapid and effective evaluation.

The article is potentially interesting but has some limitations that must be resolved or better exposed for a better representation of the results obtained.

- The results are difficult to transfer to adequate nutrition for health support. Pre-packaged products and drinks frequently meet a hedonistic need but are not always nutritionally adequate. In such a background, the considerations on the environmental impact must always be considered in that specific system that does not fully reflect individual nutrition. This aspect must be underlined and highlighted. Furthermore, there are data in the literature that indicate that plant-based products, if derived from a long chain of industrial transformation, risk having the same environmental impact as animal-based foods.

- Lines 63-66 specify the importance of considering not only the greenhouse effect but also water consumption, to better understand the environmental impact of food. However, at lines 122-124, it is specified that WFII value for fish was not available. This is in contrast with the purpose of the article specifically which aims to use two parameters for environmental impact assessment. In any case, this limitation must be included in the materials and methods in the paragraph concerning WFII (2.2.2.).

- The overall assessment of the environmental impact of the various foods is strongly affected by the limitation mentioned above. In fact, the fish-based sandwiches are found in the first quartiles of Environmental Impact Score (Table S1). It could be considered an artefact and spoil the interpretation. An asterisk on water footprint values that do not have sufficient data to support would allow a more correct evaluation of the table. The risk, altogether, is to assign a score similar to plant-based dishes and fish-based dishes. Similarly, Figure 2A also risks erroneous interpretations.

- In Table 3, since vitamin B12 and calcium are not related to the environmental impact score of sandwiches, it is plausible that in beverages they are indirect indices of milk content. It is not so directly transferable to a general concept. The absence of data on the B12 content in the sandwiches does not allow a conclusion to be drawn and the correlations obtained from the drinks should not be transferred nor generalized in the abstract and in the conclusions without specifying that the results derive only from the drinks

- More plant-based food data would be needed to state that in this case there is a correlation between nutritional density and environmental impact. In the reference sample, only 2 of 101 vegetable sandwiches were present and therefore not very representative.

-What do the asterisks in figure 1 refer to? I think it should be specified in the description.

In conclusion, the results are interesting but should be managed with more caution, fewer generalizations and avoiding over-interpretation.

Author Response

Reviewer 2, Point 1- The results are difficult to transfer to adequate nutrition for health support. Pre-packaged products and drinks frequently meet a hedonistic need but are not always nutritionally adequate. In such a background, the considerations on the environmental impact must always be considered in that specific system that does not fully reflect individual nutrition. This aspect must be underlined and highlighted. Furthermore, there are data in the literature that indicate that plant-based products, if derived from a long chain of industrial transformation, risk having the same environmental impact as animal-based foods.

Response 2.1:  Thank you for suggesting this improvement. We have included the following sentences on page 10 in the discussion section.

Lines 116-122:

“This study explored the relationship between environmental impact and nutrient content of a small number of commonly consumed cafe options.  The study did not measure customers’ dietary intake, therefore it is not possible to conclude what the effect would be of choosing lower environmental impact options on nutrient intake and health outcomes at the level of the individual. Nevertheless, our results support the finding that low GHGE diets are associated with increased intakes of NMES and lower intakes of micronutrients, particularly calcium and vitamin B12 [12].”

 Lines 144-146:

“For catering establishments to foster healthy and sustainable dietary choices it is important to identify food and beverages that have a low environmental cost but are nutritionally optimal for health, whilst taking into account factors driving their consumption, such as taste and convenience.”

 Lines 149-151:

“Some plant-based meat alternatives incur considerable environmental impact during their production, thus they could have the same impact as animal-source foods[45]”

Point 2- Lines 63-66 specify the importance of considering not only the greenhouse effect but also water consumption, to better understand the environmental impact of food. However, at lines 122-124, it is specified that WFII value for fish was not available. This is in contrast with the purpose of the article specifically which aims to use two parameters for environmental impact assessment. In any case, this limitation must be included in the materials and methods in the paragraph concerning WFII (2.2.2.).

Response 2.2: Thank you drawing this important point to our attention. The lack of Water Footprint Impact Indicator data for seafood has been included in the materials and methods section lines 133-134 on page 3.  Lines 140-143 in the discussion have been amended so it now reads as follows:

“A further limitation is that the dataset used in this study did not include WFII values for fish or seafood therefore conclusions drawn with respect to seafood sandwiches are made with caution, since the WFII data are inherently underestimates as they do not include impacts associated with all the components of the sandwich.”

Point 3- The overall assessment of the environmental impact of the various foods is strongly affected by the limitation mentioned above. In fact, the fish-based sandwiches are found in the first quartiles of Environmental Impact Score (Table S1). It could be considered an artefact and spoil the interpretation. An asterisk on water footprint values that do not have sufficient data to support would allow a more correct evaluation of the table. The risk, altogether, is to assign a score similar to plant-based dishes and fish-based dishes. Similarly, Figure 2A also risks erroneous interpretations.

Response 2.3: Thank you for raising this point. As suggested an asterisk on the water footprint values that have insufficient data to provide an Environmental Impact Score have been added to Table 1 and Table S1 with the following explanation:

Table 1 legend:“*There are no WFII data for seafood, thus this value reflects the non-seafood components of these sandwiches”

Table S1 Legend: “As there are no WFII data for seafood, the WFII values and subsequent EIS score are based on values for the non-seafood sandwich components only and are therefore an underestimation of the true WF/EIS value of seafood sandwiches.”

Point 4- In Table 3, since vitamin B12 and calcium are not related to the environmental impact score of sandwiches, it is plausible that in beverages they are indirect indices of milk content. It is not so directly transferable to a general concept. The absence of data on the B12 content in the sandwiches does not allow a conclusion to be drawn and the correlations obtained from the drinks should not be transferred nor generalized in the abstract and in the conclusions without specifying that the results derive only from the drinks.

Response 2.4: Thank you for raising this point. The abstract has been amended to indicate that the association between Environmental Impact score and Calcium and Vitamin B12 results are for beverages only. The mention of an association with Calcium and Vitamin B12 has been removed from the conclusion.

Point 5- More plant-based food data would be needed to state that in this case there is a correlation between nutritional density and environmental impact. In the reference sample, only 2 of 101 vegetable sandwiches were present and therefore not very representative.

Response 2.5: Thank you for raising this point. I have addedthe following sentence to the Discussion line 147-149:

“Further studies to examine the effects of choosing low impact food and beverageon nutrient intakes are warranted. This analysis was specific to the sandwich offer in the studied cafes and the variety of plant-based sandwiches offered was limited.

Point 6- What do the asterisks in figure 1 refer to? I think it should be specified in the description.

Response 2.6: Thank you for drawing this to our attention. The asterisks refer to outliers that are more than 1.5 box widths from the edge of the box. I have amended the figure legend to clarify this.

Round  2

Reviewer 2 Report

Thank you for reviewing the manuscript. The answers are exhaustive and your work has a good relevance to the topic.