Individual Diet Optimization in French Adults Shows That Plant-Based “Dairy-like” Products May Complement Dairy in Sustainable Diets
, Florent Vieux 1, Anne Lluch 2, Stephanie de Vriese 3, Beatrice Trotin 2 and Nicole Darmon 4Round 1
Reviewer 1 Report
The authors provide a well-designed study of a model for optimized diets and discuss it in depth with its limitation. Nevertheless, it remains a model and as the authors also mention, would need to be proven with studies.
See my remarks below.
Introduction
Line 41: How can fish be more sustainable if there is already overfishing worldwide? I also doubt that fish farms are sustainable. However, this would need to be discussed elsewhere.
Some plant-based alternatives to dairy need high processing or addition of additives. Are the energy costs for processing considered?
Materials and methods
Line 122-123: Why were only soy-based alternatives for yogurt, desserts and PBDA included?
Results
Line 302: I suggest moving description £ before ¥ (in order of appearance in table)
Line 329: estimated from a…
Line 348: Any idea why cheese decreased? All types of cheese?
Line 398: estimated from…
Line 408-415: Would this mean that if you have a high dairy intake plant-based alternatives would not further optimize the diet?
Line 429-431: Any explanation for this?
Discussion
Line 446-447: How? This is a model and models need to be tested. Models are not “means to an end”.
Line 449-452: Often, plant-based foods are marketed with lower carbon footprint. This model actually “predicts” the same footprint in a complete diet. It would be interesting if this could be validated with data (sample studies, not a complete dietary study).
Line 451-462: Would be interesting to see the reason why cheese decreases.
Line 524-526: This would have been interesting since plant-based alternatives are usually still in a higher price range than dairy/meat.
Author Response
We thank the reviewer for accepting to comment this article and hope that the following answers will improve the quality of the submitted manuscript.
Introduction
Line 41: How can fish be more sustainable if there is already overfishing worldwide? I also doubt that fish farms are sustainable. However, this would need to be discussed elsewhere.
Answer: In the same document, FAO and WHO indicates that sustainable healthy diets are those that “avoid overfishing and overhunting”. Fish consumption is the unique source of omega-3 fatty acids providing beneficial effects on early brain development and cardiovascular health. As a consequence, including moderate amounts of fish in our food consumption is considered as more sustainable. Regarding fish farms, we are not able to identify the source of fish from dietary data. For these reasons, we did not amend the manuscript.
Some plant-based alternatives to dairy need high processing or addition of additives. Are the energy costs for processing considered?
Answer: Yes, LCA is a well-established standardized method to quantify the environmental impact of food products across the whole life cycle of a product. Therefore, energy costs were considered from farm production to processing and formulation.
Materials and methods
Line 122-123: Why were only soy-based alternatives for yogurt, desserts and PBDA included?
Answer: Soy was the first ingredient used for these plant-based “Dairy-like” (PBDL) products, other products were not available in the INCA2 dietary data used for this study (not or rarely consumed at INCA2 time). Since then, other sources are gaining popularity, including almond-based, oat-based, rice-based…. However, we ranked, using the most recent French dietary consumption database (INCA3), the frequency of consumption of PBDL. The 2 most consumed were the Soya-based alternative to yoghurt (34%) and Soya-based drink (24%). Soya-based dessert was more consumed than other alternatives to desserts.
Results
Line 302: I suggest moving description £ before ¥ (in order of appearance in table)
Answer: Thanks, we followed the reviewer advice.
Line 329: estimated from a…
Answer: Thank you, we deleted “of”
Line 348: Any idea why cheese decreased? All types of cheese?
Answer: Cheese category as classified in our database encompass cheeses such as Roquefort, semi-soft cheese (such as Mozzarella), melted cheese, Camembert and similar, Cantal cheese and similar, goat cheese, Edam cheese and Gruyere. We did not analyzed the data per cheese sub-categories; the cheese category is globally decreased in the optimized diets because of their high energy density, high content in Sodium and saturated fatty acids and their higher carbon impact per 100g than milk and yoghurt (between 403-640 g CO2/100g according to the type of cheese, compared to around 120 and 200 g CO2/100g for milk and yoghurt).
Line 398: estimated from…
Answer: Thank you, we deleted “of”
Line 408-415: Would this mean that if you have a high dairy intake plant-based alternatives would not further optimize the diet?
Answer: Yes it suggests that the introduction of PBDL is not chosen during optimization when dairy intake was high in the current diet because the optimization aims to stay close to the current diet with minimum changes to ensure acceptability.
Line 429-431: Any explanation for this?
Answer: Yes, PBDL are fortified in vitamin D, vitamin B12, Calcium and riboflavin which are micronutrients with deficiency in some population subgroups, and they are present in milk. Removing the fortification from PBDL induced an increased in milk.
Discussion
Line 446-447: How? This is a model and models need to be tested. Models are not “means to an end”.
Answer: Yes, this model is theoretical and we do not know if dietary shifts obtained would be acceptable in real life. The sentence was inserted in order to show that, using a different methodology (linear programming optimization) this study provides similar results than previous ones (i.e current diets were reduced in meats and increased in fruits & vegetables, wholegrains, nuts & seeds by the optimization). We believe results from simulation studies provide hypotheses of dietary changes that would need to be tested in real-life (see discussion part, lines 547-549: “acceptability of proposed dietary changes by the models was not ensured as none of the INCA2 participant was proposed to adopt his/her mathematically defined optimized diet in an intervention study.” and lines 555-556 “An intervention study would be needed to test how acceptable such dietary changes would be in real life.”). Also, sentences were added to indicate that such methodology can be transferred into a tool able to provides tailored dietary advice (lines 556-560 “Shifting individual optimization approach from a methodology to conduct public health research to a tool able to provides tailored dietary advice has been performed during a PhD thesis leading to an innovative prototype (Gazan, R. Development of a tailored nutrition counselling approach for individuals, taking into account several dimensions of diet sustainability, Montpellier, 2018). Such a tool needs to be further developed by testing it in intervention studies in order to assess the acceptability of dietary advices provided.”).
Line 449-452: Often, plant-based foods are marketed with lower carbon footprint. This model actually “predicts” the same footprint in a complete diet. It would be interesting if this could be validated with data (sample studies, not a complete dietary study).
Answer: At the level of foods, carbon footprint is usually expressed per weight (/kg) but other functional units can be used (/100 kcal, /100mg of Calcium …) which can totally change the level of environmental impact of a given food compared to others. This is one limit of reasoning at the food level. With a whole diet approach, such as in the present study, this limitation is reduced.
Line 451-462: Would be interesting to see the reason why cheese decreases.
Answer: As mentioned before, cheese decreased because of its high energy density, its high content in Sodium and Saturated fatty acids and its high carbon impact per 100g. Previous study based on individual optimization (but without constraint on carbon impact reduction) showed a decrease of the amount of cheese between observed and optimized diets (Maillot et al. Individual diet modeling translates nutrient recommendations into realistic and individual-specific food choices, AJCN, 2010). Adding the carbon impact constraint is likely to increase this phenomenon because cheese has, on average, a higher carbon impact than other dairy products (between 403-640 g CO2/100g for cheese compared to around 120 and 200 g CO2/100g for milk and yoghurt).
Line 524-526: This would have been interesting since plant-based alternatives are usually still in a higher price range than dairy/meat.
Answer: Yes, we acknowledged this limitation.
Reviewer 2 Report
The novelty character of the paper should be marked.
A graphical scheme of study approach should be inserted.
In section Results some introductory lines should be inserted to better introduce and describe the different types of results
Lines 286-295 lines describing results in supplementary files (S2-S4) should be added, and subparagraph "Description of observed diets" should be implemented.
The description of data on Sensitivity Analyses should be implemented.
More considerations and limits, advantages, practical applications and future directions of research should be implemented.
Author Response
Thank you for highlighting the novelty of the paper.
A graphical scheme of study approach should be inserted.
Answer: Thank you for proposing to insert a scheme that ease the understanding of the approach. A graphical representation of the approach was added to the manuscript (Figure 1).
In section Results some introductory lines should be inserted to better introduce and describe the different types of results
Answer: Thank you, we added the following sentences just before section 3.1.
“Observed diets’ nutritional quality, carbon impact and energy intake were compared between PBDL consumers and non-consumers. Then, among feasible diets, dietary changes due to optimization were analyzed. Energy intake, as well as observed and optimized food group quantities were compared between PBDL product tracking sub-populations.”
Lines 286-295 lines describing results in supplementary files (S2-S4) should be added, and subparagraph "Description of observed diets" should be implemented.
Answer: Supplemental file 2 describes all the results presented for men subpopulation. Rather than repeating the description of results for men, we opted to highlight the notorious differences between men and women. For example, lines 315 to 319: “Results for men were very similar to those obtained for women (Supplemental File S2). One difference was the carbon impact of diets, which was lower for PBDL product consumers than for non-consumers in men. Another difference between men and women involved nutritional quality indicators, which were not significantly different between PBDL product consumers and non-consumers in men, while they were in women.”
Supplemental file 3 is composed by some methodological aspects (Tables S1 to S3) and some additional results (Tables S4 to S7). Table S4 is described: “PBDL product consumers were older, more frequently had a partner but no children, and had a higher educational and physical activity level than non-consumers” (lines 297-298). Table S5 provide additional information for readers looking for detailed results that are out of scope from the main topic of the present paper (i.e PBDL and dairy products in optimized diets). Descriptions of Tables S6 (lines 434-436) and S7 (lines 550-554) are provided. We did not amend the manuscript.
The description of data on Sensitivity Analyses should be implemented.
Answer: Description of data on Sensitivity Analyses is presented in section 3.4
More considerations and limits, advantages, practical applications and future directions of research should be implemented.
Answer: Strengths (optimization applied at the individual level), limits (economic dimension not treated, carbon impact as only one environmental impact metric, acceptability of proposed dietary changes, old data) and future directions of research (integration of agribalyse data in order to better control environmental impact of optimized diets) are described in discussion and conclusion sections. In addition to the practical application indicating that consuming fortified PBDL products may help achieve more sustainable diets especially for individuals with low energy intakes, we have added sentences to indicate that such methodology (linear optimization) can be transferred into a tool able to provides tailored dietary advice :”Shifting individual optimization approach from a methodology to conduct public health research to a tool able to provides tailored dietary advice has been performed during a PhD thesis leading to an innovative prototype (Gazan, R. Development of a tailored nutrition counselling approach for individuals, taking into account several dimensions of diet sustainability, Montpellier, 2018). Such a tool needs to be further developed by testing it in intervention studies in order to assess the acceptability of dietary advices provided.” (lines 556-560).
