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Designing low-cost “heart healthy bread”: optimization using linear programing and 15-country comparison

BMC Nutrition volume 2, Article number: 23 (2016) Cite this article

Abstract

Background

Bread is an important component of the diet in many countries and provides needed nutrients but also typically too much of other nutrients e.g., sodium. We therefore aimed to use linear programing to determine the optimal design of low-cost “heart healthy bread” (HHB) and to compare the results with commercial breads in 15 countries.

Methods

Optimization using linear programing focused on achieving set loaf prices (at NZ$1.5 and $3) and for a range of minimal sodium levels. Then within those constraints, levels of alpha-linolenic acid (ALA) were maximized, then dietary fiber, and then polyunsaturated fatty acids. Data from New Zealand (NZ) was used for the HHB designs and comparison nutrient and price data came from breads in 15 high-income countries.

Results

The optimized loaf costing NZ$1.50 in ingredients (HHB$1.5) was superior to the commercial white loafs in three out of the eight heart health nutrient categories. The optimized loaf that was high in linseed and cost NZ$3 in ingredients (HHB$3), was nutritionally superior to the commercial loafs with seeds/nuts in six out of the eight heart health categories (i.e., in terms of sodium, potassium, fatty acid ratio and fiber). In terms of value-per-weight, a commercial white loaf from the UK was slightly cheaper than the HHB$1.50 loaf (at US$0.07 vs US$0.10 per 100 g loaf). But compared to the other seed/nut loafs, the HHB$3 loaf was the best value at US$0.17 per 100 g, vs a mean of US$0.85 per 100 g across international comparators.

Conclusions

This proof-of-concept study suggests it is possible to design breads that are nutritionally superior to commercially available breads from a heart health perspective, as well as being lower cost. Such HHB designs could be promoted by health agencies and utilized in conjunction with a government-funded bread voucher system for those at high risk of cardiovascular disease.

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Background

The global burden of non-communicable diseases (NCDs) accounted for two of every three deaths (34.5 million) worldwide in 2010 [1]. Furthermore, a global estimate for 2013 indicated the high burdens of years lived with disability from: diabetes (29.5 million), cardiovascular disease (21.2 million) and cancer (6.7 million) [2].

Dietary risk factors are particularly important for NCDs such as cardiovascular disease (CVD) [3] and these include dietary intakes of sodium, fiber and types of fatty acids. One food which has all three of these nutrients is bread. It is also one of the most popular foods in many developed countries e.g., 8.7 % of total energy in the United States, albeit the combined category of “bread, rolls and crackers” [4]. Even more so in Canada, “refined breads” contributed more dietary energy than all the other food groups in those aged 18 to 65 years (range by age/sex groups: 10.5 to 11.8 %), with whole-grain breads contributing another few percent (range: 2.4 to 4.1 %) [5]. For men in the United Kingdom, white bread was the second highest non-beverage food in those aged 19–64 years (by weight with a median of 46 g per day; interquartile range [IQR]: 18–93) after vegetables [6]. But for women it was less at a median of 27 g per day (IQR: 9–61).

Based on commercial varieties of bread available, there appears to be substantial flexibility around the levels of the main ingredients (e.g., flour, yeast, salt) and also additional ingredients such as nuts and seeds. For example, a number of European governments aim to reduce sodium intakes by regulating the maximal level of sodium in bread [7, 8]. This action is supported by various modeling studies that suggest both health and economic advantages of reducing sodium in bread (e.g., for Argentina [9–11], Australia [12, 13], New Zealand [14] and South Africa [15]). Furthermore, there have been successful studies and interventions to replace sodium chloride in bread with potassium salts [16–18].

But other aspects of bread design can also be considered from a CVD prevention perspective given the evidence from systematic reviews around: increasing dietary fiber [19, 20] and increasing linseed (flaxseed) intake which is high in alpha-linolenic acid [21, 22]. Yet despite this evidence, our examination of the literature (as of June 2015) identified no optimization studies specifically relating to the design of heart healthy bread, and none concerning the design of low-cost healthier bread.

So to further progress thinking around this issue, we aimed to design optimized versions of low-cost “heart healthy breads” (HHBs). Our specific major aim was to determine, at a “proof-of-concept” level, if it was possible to design breads that had both improved nutrient levels from a CVD prevention perspective and which were relatively low-cost. Our secondary aims were: (i) to determine how these HHBs compared with commercial breads in 15 high-income countries; and (ii) to estimate the cost of mass production of HHB loafs using publicly-available data for the cost-structure data of bread manufacture.

We specifically aimed to use linear programing in our methods as this is an established tool in studying the optimization of food and diets where there are multiple nutritional and other objectives [23]. It has also been used previous around bread in diets e.g., for studying sodium and iodine in the diets of Indigenous Australians [24], for the inclusion of wholemeal bread in food aid in France [25], and for changing bread intake as part of improving nutrient intakes for the Italian population [26].

Methods

While more detailed steps follow, in summary this work began with literature searches for identifying potential bread ingredients and their nutritional value from a CVD prevention perspective. This was then followed by a determination of the specific nutrient constraints to be applied and optimization priorities set, for the analysis using linear programing. New Zealand nutrient and price data were used for the HHB designs and data for comparison with commercial breads were obtained for 15 high-income (OECD) countries from freely accessible nutrient databases that could be identified online. Publicly-available data for the cost-structure of bread manufacture from the Canadian baking industry was then used to better estimate the cost of mass production of HHB loafs.

Potential ingredients considered for bread designs

We considered the following potential bread ingredients from a CVD prevention perspective, based on how key bread components are described in the literature:

  • A high potassium salt substitute, as this type of salt has been associated with blood pressure reduction in a meta-analysis [27]. There is also evidence that potassium chloride can achieve flavor compensation that allows for large reductions in sodium levels in bread [28].

  • Wholemeal flour, given the evidence for reduced CVD risk as per three systematic reviews [19, 20, 29] and an analysis of two large prospective studies [30]. Although outside of the CVD perspective, we note that dietary fiber from whole grains also appears to protect against colorectal cancer in another systematic review [31].

  • Linseed, as this is high in dietary fiber, lignans and n-3 polyunsaturated fatty acids (PUFA) and there is some evidence for CVD-related benefits as per three reviews [32–34] and a recent trial [35]. More specifically, two meta-analyses report blood pressure reduction associated with linseed consumption [21, 22].

  • Walnut (English walnut), as there is evidence that this food can benefit cardiovascular health as per a systematic review [36] and another recent review [37]. Indeed, nut consumption more broadly is associated with reduced risk of both CVD and cancer according to a systematic review [38] and a large cohort study [39]. Given this we also considered the addition of other seeds that are known to be commonly used in commercial breads, i.e., sesame seeds, sunflower seeds and pumpkin seeds.

Potential ingredients not included

Plausible healthy bread ingredients from a CVD perspective identified in the literature included: soy protein [40], sourdough [41], and high phenolic olive oil [42]. But in this initial work we did not include these ingredients on the grounds of potentially relatively lower consumer acceptability.

Constraints and optimization approach used for the linear programing

Based on the above, the specific details on the constraints applied and optimization priorities are outlined in Table 1. To summarize, optimization focused on achieving two set loaf prices (at NZ$1.5 and $3) and for a range of minimal sodium levels. Then within those constraints, the first priority in the “objective function” was to maximize levels of alpha-linolenic acid (ALA) (an omega-3 fatty acid), followed by maximizing dietary fiber, and then maximizing polyunsaturated fatty acids (PUFA).

Table 1 Constraints and optimization targets for the design of the “heart healthy breads”
Full size table

The simplex algorithm was used to solve these linear programing problems (see Briend et al. [23] for a detailed description of the linear programing). The problem of multiple objectives with priority levels is addressed with lexicographic goal programing, which involves a sequence of linear programing steps [43]. Most of the scenarios were modeled in Microsoft Excel 2010 (Excel Solver, Simplex method), but where there was a high level of complexity with the food combination options the R programing language was used (version 2.15.0, lpSolve package).

Nutrient and price data for the HHBs

The nutrient data for the HHBs was sourced from a New Zealand food composition database [44]. But, in some cases we had to use other sources such as a study on levels of alpha-linolenic acid covering nuts and seeds [45] and from the nutrient panel on the packaging (i.e., for the salt substitute). For the price data for HHB ingredients, the cheapest retail source for the ingredients were used, with these typically being supermarkets and online stores in New Zealand.

Country comparisons of commercial breads

For country comparisons we considered just OECD countries and we conducted internet searches for those which had online documentation of nutrient profiles on commercial breads. In particular we used the EuroFIR database [46] which had 15 freely accessible nutrient databases. Ultimately, the only OECD countries with such databases were: Canada, Czech Republic, Denmark, Finland, Greece, Iceland, Italy, the Netherlands, New Zealand, Slovakia, Sweden, Switzerland, United States and the United Kingdom. For these countries the nutrient data on the most standard pre-packaged white bread was obtained. Only six of these countries had nutrient data on any breads containing seeds or nuts (Denmark, Finland, Iceland, Netherlands, New Zealand and Switzerland). Where there were multiple such breads, the one with the highest level of PUFA was selected as a proxy for the highest level of seeds/nuts.

Bread price information was sourced from online supermarkets in each country. At first, an attempt to identifying the largest supermarket chain in each country was made. Failing this, a search of the online supermarkets in the capital city was performed. Out of the breads marketed in these online supermarkets, the lowest priced most standard white pre-packaged loaf was selected for price information. For breads with seeds/nuts, the price data was from the one with the highest seed/nut level (based on the ingredient listing). For all the prices we calculated cost per 100 g and cost per 1000 kJ in US dollars using OECD exchange rates and purchasing power parity adjustments [47]. For specific nutrient and price methods details for each country see Additional file 1.

Estimating mass production costs of HHBs

To estimate the cost of mass production of HHB loafs, publicly-available data for the cost-structure data of bread manufacture from the Canadian baking industry was used. Such data are not readily available in other countries (including New Zealand), presumably due to reasons of commercial sensitivity. This Canadian cost-structure covered: “materials and supplies”, “energy, water and vehicle fuel” and “production worker wages” [48]. We applied this to the cost of the cheapest supermarket white bread from New Zealand (NZ$1.00 or US$0.68 for a 600 g loaf) and assumed at this price it was basically “cost price” i.e., with no profit. Using recipes for a white loaf of bread [49], we then estimated how much more cheaply the ingredients for this commercial bread might typically cost the baking industry, compared to ingredient prices in the supermarket. This scalar was then applied to all the HHB ingredients and varying levels of profit margin were also considered (for the manufacturer and retailer). We assumed HHBs would be mass produced by existing bread manufacturers with existing plant and machinery and distribution networks. Further details on the methods are shown with the tabulated results.

Results

Optimized HHB ingredient selection

The optimized HHB$1.5 loaf was characterized by having some wholemeal flour but the cost constraint resulted in only trivial levels of added seeds (Table 2, Fig. 1). The optimized HHB$3 loaf (Fig. 1) had up to the maximum weight of seeds permitted (150 g dry ingredients per loaf, 12.6 % of the final loaf weight). But linseed dominated over walnut and other seeds due to it being a low-cost source of ALA.

Table 2 Dry ingredients of the two optimized “heart healthy breads” per 100 g of dry ingredient weight
Full size table
Fig. 1
figure 1

The loaf on the left is the optimized HHB$1.5 loaf. The loaf in the middle is the optimized HHB$3 loaf which is high in ground linseed. The loaf on the right is one that is high in walnut (but which was subsequently excluded from further study due to its relatively high cost at NZ$5). (Photography: Pascale Otis)

Full size image

Heart health and other nutrients in the loafs

In indicative rankings, the HHB$1.5 loaf appeared to be superior to the commercial white loafs from the 15 high-income countries in three out of the eight heart health nutrient categories (Table 3, Fig. 2). That is, lower in sodium, and higher in potassium and the ratio of potassium to sodium. It ranked relatively highly in terms of lower saturated fatty acids (SFA) and a high PUFA/SFA ratio.

Table 3 Comparisons of the nutrient levels of the “heart healthy bread” loafs with commercial breads (nutrients and costs, all values per 100 g unless indicated otherwise)
Full size table
Fig. 2
figure 2

Levels of potassium and sodium in white bread loafs from 15 countries compared to the two “optimized” heart healthy bread (HHB) designs

Full size image

The HHB$3 loaf appeared to be nutritionally superior to the commercial loafs with seeds/nuts from six countries in six out of the eight heart health categories (Table 3, Fig. 2). While it had the best PUFA/SFA ratio, it did not have the highest levels of PUFA and lowest levels of SFA. It also appeared superior to the HHB$1.5 loaf in all eight heart health categories except for low saturated fat. Some of the differences were relatively large, such as the ALA level in the HHB$3 loaf being 26 times the median for the white loafs and 2.2 times the median for the commercial high seed/nut loafs.

In terms of other nutrients, the HHB$1.5 bread appeared to perform better than most commercial white breads (e.g., highest in iodide and zinc) (Table 3). But it was competing with some breads which were fortified with calcium, folate and iron. However, relative to the commercial seed breads, the HHB$3 loaf was in the top two rankings for: calcium, folate, iodide, iron, low sugars, and low energy density.

In terms of value-per-weight, a commercial white loaf from the UK was slightly cheaper than the HHB$1.50 loaf (at US$0.07 vs US$0.10 per 100 g loaf, Table 3). The HHB$1.5 loaf also performed relatively well in terms of price per kJ of food energy (fourth equal). But compared to the other seed/nut loafs, the HHB$3 loaf was by far the best value-per-weight at US$0.17 vs a mean of US$0.85 per 100 g.

Possible mass production costs of HHB loafs

From the documented cost-structure of the Canadian baking industry, we estimated that the New Zealand baking industry might be obtaining bread ingredients at around 72 % of supermarket prices that we used in costing the HHB loafs in the preceding analyses. We used this percentage to estimate that mass production of HHB (at zero profit) would be likely to reduce the cost of the various loafs to: US$0.99 for the HHB$1.5 loaf, and to US$1.75 for the HHB$3 loaf (Table 4). Such costs might approximate production costs for a non-profit institution such as a hospital kitchen with its own bakery.

Table 4 Estimated mass production costs for “heart healthy bread” designsa
Full size table

Where commercial manufacturers/retailers produced and sold HHB loafs (e.g., as per contracts for a government voucher system for provision of HHB) a profit margin would be relevant (Table 4). For example, a 25 % profit margin shared by producers and retailers would push up the price to: US$1.24 for the HHB$1.5 loaf and US$2.19 for the HHB$3 loaf (Table 4). Based on these estimates and a 25 % profit mark-up, the HHB$1.5 loaf at US$0.12 per 100 g would remain well under half that of the median for the commercial white loafs from the 15 high-income countries in Table 3. Likewise the HHB$3 loaf at this mark-up would still be the lowest cost per 100 g out of the seed/nut loafs in Table 3.

Discussion

Main findings and interpretation

This proof-of-concept work generated two potential HHB designs which were generally superior to commercial breads from 15 high-income (OECD) countries from a nutrient/CVD prevention perspective (i.e., in terms of sodium, potassium, fatty acid ratios and dietary fiber). The higher levels in the HHB$3 bread were often substantial e.g., 26 times the median ALA level of the white loafs. Furthermore, in principle the higher fiber levels in the HHBs could contribute to non-CVD benefits such as colorectal cancer prevention [31]. Similarly, the walnut in the HHB$3 loaf could potentially contribute in a small way to cancer prevention [38, 39], but obviously a diet designed to minimize cancer risk has many other aspects such as being high in fruit and vegetables.

Of relevance to food security, the HHB$1.5 loaf was better value-per-weight than all but one of the commercial white loafs from the 15 countries. The HHB$3 also outperformed all the seed/nut loafs at a fifth the cost per 100 g of the average. Furthermore, the relatively higher level of dietary fiber in the HHB loafs might mean they also provide better value in terms of inducing satiety. Such a satiety benefit has been reported in a study on wholegrain vs refined bread [50], but not in one of nut-enriched bread vs nut-free bread [51].

The mass production cost estimates (Table 4) suggest it would be feasible to produce the HHB$3 loaf in a place like a hospital kitchen at around US$1.75 per loaf. The voucher costs for government for this type of loaf might be US$2.19 per loaf when assuming a 25 % mark-up by the contracted manufacturer and retailers (or US$2.63 if a 50 % mark-up is assumed). At two loafs a week per person (e.g., for a patient at high risk of CVD) this would be US$274 per year in voucher costs for a 100 % subsidized loaf supply (albeit not including the voucher delivery and other administration costs). Whether this is justified from a funder perspective would depend on many issues such as the priority given to protecting public health and the health economics (e.g., the cost-effectiveness of such a program should ideally be modeled before any implementation).

Study strengths and limitations

This study was, to our knowledge, the first to study the issue of the optimized design of bread from a heart health and a low-cost perspective using linear programing. We consider that the constraints imposed, and the typical ingredients used, will help ensure that such designs have at least some acceptability in high-income countries where there is often a majority of adults who currently consume at least a light-grained bread (e.g., as per New Zealand [52]). Indeed, some countries currently have seed/nut breads sold commercially at up to 17 % seeds by weight (for Finland, see Table 1).

Nevertheless, this was still just a proof-of-concept study which only considered two potential designs of HHB. Indeed, the full “design-universe” of such potential breads is large and might include other relatively healthy additional ingredients such as: soy, sourdough, dried fruit, high phenolic olive oil, and extra fiber sources (e.g., wheat bran and rye flour), (see the Methods ). A version particularly suitable for women of child-bearing age could also include added folic acid for preventing neural tube defects.

A further limitation was the relatively simplistic nature of our cost estimates for mass production of the two HHB designs. Nevertheless, it is plausible that the cost-structure of Canadian bread manufacture is not markedly different from other high-income countries. Our costing estimates also didn’t consider administrative costs associated with setting up and running any HHB voucher system (e.g., for people with CVD risk factors). It also did not consider the environmental impact, as per Swedish work on emissions of oxides of carbon, sulfur and nitrogen from bread production [53]. Finally, we did not explore various other complexities with bringing any HHB to market. For example, consumer taste testing would be required (see below), and packaging would need to be designed. For example, packaging would probably need to display potassium levels to help people with renal disease or on particular medication such as diuretics to avoid excessive intake.

Implications for further research and policy

Consumer testing prior to mass production of any HHB could be done by a commercial bread manufacturer as part of their routine product development processes. Similarly, an institution such as a public hospital could “market test” the acceptability of various HHBs on staff in a hospital cafeteria. The latter could be done in conjunction with health orientated non-governmental organizations which exist in many countries and sometimes have “endorsement label programs” for heart healthy foods (e.g., as in New Zealand [54]). If there were concerns about public acceptability of bread design, then a more incremental approach could involve slowly phasing down the levels of white flour and sodium while phasing up the levels of linseed and salt substitute in the HHBs promoted for mass consumption. Final bread products could also be considered in terms of the health claims that could be justifiably made on HHB packaging or in marketing about these being “functional foods”. Many countries have rules around such claims with one example being the European Food Safety Authority’s process for European Union countries [55].

Epidemiological and economic modeling should also attempt to quantify the effectiveness (in quality-adjusted life-years gained) and cost-effectiveness of a government-run voucher system for a HHB version for those at increased CVD risk (and even for those at increased risk of cancer given the extra fiber and seeds in the HHB$3 loaf).

Conclusions

This proof-of-concept study suggests it is possible to design breads that are nutritionally far superior from a heart health perspective to commercially available breads as well as being lower cost. Such HHB designs could be utilized in conjunction with a government-funded voucher system for those at high risk of CVD. This could be one (albeit small) part of comprehensive CVD prevention programs which ideally should cover multiple nutritional and physical activity interventions.

Ethical review

This was not relevant for this modeling study which did not involve human subjects.

Consent to publish

Not applicable.

Availability of data and materials

All supporting data is in Additional file 1.

Abbreviations

ALA:

alpha-linolenic acid

CVD:

cardiovascular disease

HHB:

heart healthy bread

IQR:

interquartile range

NCDs:

non-communicable diseases

NZ:

New Zealand

OECD:

Organisation for Economic Co-operation and Development

PUFA:

polyunsaturated fatty acid

SFA:

saturated fatty acid

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Acknowledgements

We thank our work colleagues for their helpful comments on bread design issues, Pascale Otis for the photography, and the journal’s reviewers for constructive critique.

Funding

The Burden of Disease Epidemiology, Equity and Cost-Effectiveness Programme is funded by the Health Research Council of New Zealand (10/248).

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Authors and Affiliations

  1. Department of Public Health, University of Otago, Wellington, PO Box 7343, Wellington, New Zealand

    Nick Wilson, Nhung Nghiem, Sian Ryan, Christine Cleghorn, Nisha Nair & Tony Blakely

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  1. Nick Wilson
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  2. Nhung Nghiem
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  3. Sian Ryan
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  4. Christine Cleghorn
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Corresponding author

Correspondence to Nick Wilson.

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Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

Designing the study: NW, NNg, CC, and TB. Collecting the data: NW, SR. Data analyses: NNg, NW. Drafting the initial manuscript: NW. Manuscript revision: all authors. All authors read and approved the final manuscript.

Additional file

Additional file 1:

Additional Methods and Results for the Study on Health Healthy Bread. (DOCX 65 kb)

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Wilson, N., Nghiem, N., Ryan, S. et al. Designing low-cost “heart healthy bread”: optimization using linear programing and 15-country comparison. BMC Nutr 2, 23 (2016). https://doi.org/10.1186/s40795-016-0062-x

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Keywords

BMC Nutrition

ISSN: 2055-0928

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