- Email: [email protected]
Prevalence of Phosphorus-Based Additives in the Australian Food Supply: A Challenge for Dietary Education?
ORIGINAL RESEARCH
Prevalence of Phosphorus-Based Additives in the Australian Food Supply: A Challenge for Dietary Education? Jemma McCutcheon, BHlthSc,* Katrina Campbell, PhD, BHlthSc,†,‡,§ Maree Ferguson, PhD, MBA, BAppSc, GradDipNutDiet,‡,{ Sarah Day, BHlthSc,* and Megan Rossi, PhD, BHlthSc†,‡,** Objective: Phosphorus-based food additives may pose a significant risk in chronic kidney disease given the link between hyperphosphatemia and cardiovascular disease. The objective of the study was to determine the prevalence of phosphorus-based food additives in best-selling processed grocery products and to establish how they were reported on food labels. Design: A data set of 3000 best-selling grocery items in Australia across 15 food and beverage categories was obtained for the 12 months ending December 2013 produced by the Nielsen Company’s Homescan database. The nutrition labels of the products were reviewed in store for phosphorus additives. The type of additive, total number of additives, and method of reporting (written out in words or as an E number) were recorded. Main Outcome Measures: Presence of phosphorus-based food additives, number of phosphorus-based food additives per product, and the reporting method of additives on product ingredient lists. Results: Phosphorus-based additives were identified in 44% of food and beverages reviewed. Additives were particularly common in the categories of small goods (96%), bakery goods (93%), frozen meals (75%), prepared foods (70%), and biscuits (65%). A total of 19 different phosphorus additives were identified across the reviewed products. From the items containing phosphorus additives, there was a median (minimum-maximum) of 2 (1-7) additives per product. Additives by E number (81%) was the most common method of reporting. Conclusion: Phosphorus-based food additives are common in the Australian food supply. This suggests that prioritizing phosphorus additive education may be an important strategy in the dietary management of hyperphosphatemia. Further research to establish a database of food items containing phosphorus-based additives is warranted. Ó 2015 by the National Kidney Foundation, Inc. All rights reserved.
Introduction
E
LEVATED LEVELS OF serum phosphate, termed hyperphosphatemia, are common in chronic kidney disease (CKD) because of a decline in renal phosphate
* School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Queensland, Australia. † Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia. ‡ Department of Nutrition and Dietetics, Princess Alexandra Hospital, Brisbane, Queensland, Australia. § Faculty of Health Sciences and Medicine, Bond University, Robina, Queensland, Australia. { School of Human Movement and Nutrition Sciences, University of Queensland, St Lucia, Queensland, Australia. ** School of Medicine, University of Queensland, St Lucia, Queensland, Australia. Financial Disclosure: The authors declare that they have no relevant financial interests. Support: This work was supported by the 2014 Australia and New Zealand Society of Nephrology—Amgen Quality Assurance Grant. Address correspondence to Megan Rossi, PhD, BHlthSc, Department of Nephrology, Level 2, ARTS Building, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Brisbane, Queensland 4102, Australia. E-mail:
[email protected] Ó
2015 by the National Kidney Foundation, Inc. All rights reserved. 1051-2276/$36.00 http://dx.doi.org/10.1053/j.jrn.2015.04.003
Journal of Renal Nutrition, Vol -, No - (-), 2015: pp 1-5
excretion. It is well established that hyperphosphatemia is associated with an increased risk of mortality, cardiovascular disease, and disordered bone metabolism in CKD and dialysis patients.1–5 In fact, a meta-analysis of 47 cohort studies in the CKD population demonstrated that the risk of death increased by 18% for every 1 mg/dL increase in serum phosphate.6 Management of hyperphosphatemia in CKD involves dietary and medical intervention. Dietary phosphorus restriction is considered the first-line therapy, and practice guidelines suggest that CKD patients with elevated serum phosphate levels should restrict dietary phosphorus intake to 800 to 1000 mg/day.7,8 Dietetic practice has traditionally focused on targeting foods that are naturally high in organic forms of phosphorus. This includes high-protein animal and plant foods, such as meat, fish, dairy, legumes, and nuts. Without close dietetic monitoring, this conventional dietary approach may increase the risk of malnutrition.9 Furthermore, with an increasing preference and reliance on processed foods,10,11 attention has turned to the inorganic form of phosphorus found primarily in processed foods as additives. Phosphorus-based food additives have diverse applications in food manufacturing, including emulsification, leavening, raising, and flavor-enhancing qualities. Inorganic phosphorus 1
2
MCCUTCHEON ET AL
is highly bioavailable, absorbed at a rate close to 100%.12 In comparison, organic forms of phosphorus from plant and animal sources are only absorbed at a rate of 20% to 40% and 40% to 60%, respectively.12 Foods with higher bioavailability have been shown to significantly increase serum phosphate levels,13 and therefore, the high bioavailability of phosphorus-based food additives suggests that this additive form may significantly contribute to the prevalence of hyperphosphatemia in CKD and dialysis populations. Therefore, focusing dietary intervention on inorganic sources of phosphorus in typically low nutrient-dense processed foods may be a more effective target for hyperphosphatemia management. The prevalence of phosphorus-based additives in the food supply is not well documented. However, a recent study by Le on et al. 14 found that phosphorus-based food additives were present in 44% of best-selling grocery products in the United States. This landmark study has raised concerns, warranting further investigations into the use of phosphorus additives in the food supply, including Australia. The aim of the present study was to determine the prevalence of phosphorus-based additives in the Australian food supply. In addition, this study sought to investigate the reporting methods of phosphorus-based additives on food labels to inform patient education methods.
for use in Australia16 (Table S2), as well as added mineral phosphorus. Whether the phosphorus additives were present in the product was determined by reviewing the ingredient list for additive E numbers or the additive name in words. For each food or beverage product, the total number of different phosphorus additives contained in the item was recorded, as well as the additive names and corresponding E numbers. The method used to report the additives on the ingredient labels was also recorded and classified into 1 of 4 categories: (1) ‘‘words’’ (listed only as the written name of the additive), (2) ‘‘E number’’ (listed only using additive E numbers), (3) ‘‘both’’ (listed using both the written name of the additive and the E number), or (4) ‘‘combination’’ (products with $1 phosphorus additive that used a mixture of reporting methods, such as E number for 1 additive and words for another). The products that could not be located in store by either researcher were not reviewed online to eliminate potential discrepancies given the online information may be outdated or represent international products. For grocery items that contained multiple flavors or products, such as variety packs, each ingredient label listed on the single product was reviewed, and the total number of different phosphorus additives across these lists was reported as the total number of additives.
Methods
Statistical Analysis The data were collated and analyzed using MicrosoftÒ ExcelÒ (version 14.4.5, Microsoft Corporation, Redmond, WA). Results for each grocery item were entered and grouped according to each food or beverage category. All results were presented as numbers and percentages. Medians and the interquartile ranges were reported for nonparametric data.
Data Source The methods for this study were based on the approach described previously by Le on et al. 14 in the United States. A data set of grocery sales in Australia was obtained for the 12 months ending in December 2013 produced by the Nielsen Company’s Homescan database. The data set provided a statistically and demographically representative sample of the Australian population and comprised grocery sales data from 10,000 Homescan panel members.15 The data set was grouped into 82 Nielsen-defined categories, and all categories were ranked by unit sales from highest to lowest. The top 40 categories by unit sales were selected, and then categories were excluded if they were minimally processed, known to not contain additives, were not part of typical meals, or were not edible such as pet food and paper goods. From the remaining categories, the top 15 by unit sales were selected. Within each category, the top 200 grocery items by unit sales were obtained, creating a database of 3000 food and beverage items to review. A description of the 15 categories can be found in Table S1. Data Collection The items were located by 2 independent researchers at a variety of Australian grocery retail stores based on the product descriptions provided in the data set. Each of the products’ ingredient lists were reviewed for the presence of 23 phosphorus-based food additives. This included the 22 phosphorus-based food additives that have been approved
Results Grocery Item Sample The labels of 2532 best-selling food and beverage products (84%) in Australia were reviewed for the presence of phosphorus-based food additives. Four hundred sixtyeight grocery items (16%) were excluded (Fig. 1). Although the data set contained numerous identical products in different sized packages, these items were not excluded on the basis of duplication, given the individual products remained representative of the best-selling food or beverage products. Phosphorus Additive Prevalence Overall, phosphorus-based food additives were present in 1108 of the products (44%) reviewed (Table 1). There was wide variation in the presence of phosphorus additives between categories ranging from 9% to 96%. Phosphorus additives were particularly common in the categories of small goods (96%), bakery goods (93%), frozen meals (75%), prepared foods (70%), and biscuits (65%; Fig. 2).
3
PHOSPHORUS ADDITIVES IN THE AUSTRALIAN FOOD SUPPLY
beverages category, E number (33%) and combination (33%) were equally most common. Across the other 13 categories, E number was the most used approach. Lecithins (E number 322) were reported using only words in 28% of instances and made up 76% of the total 135 phosphorus additives reported using only words.
Figure 1. Flow chart of grocery product inclusion.
The items that contained phosphorus additives had a median (minimum-maximum) of 2 (1-7) additives. Products that contained phosphorus additives in the small goods and frozen meals categories had the highest median number of additives (Table 1). Conversely, all reviewed carbonated soft drinks and frozen vegetables did not contain .1 additive per item.
Reporting Methods Reporting of additives by E number (81%) was the most common method, followed by words (12%) and combination (7%). Less than 1% of reviewed products listed phosphorus additives using both words and E number. Reporting by only words was the most common method for products in the cereals and bars category (61%). In the
Phosphorus Additive Types From the 22 phosphorus-based food additives that are approved for use in Australia, 18 were identified in the products reviewed. Added mineral phosphorus was also identified in products from the beverages and cereals and bars categories, totaling 19 different phosphorus additives found across the assessed items. The 5 most common phosphorus-based food additives identified across all reviewed items can be seen in Table 2. The 2 most used additives (450 [pyrophosphates] and 322 [lecithins]) were each identified in 11 of the 15 food and beverage categories.
Discussion This study found that nearly half of the best-selling food and beverage items in the Australian food supply contained phosphorus-based additives. Furthermore, the number of phosphorus additives per item was considerable, with some foods containing up to 7 different additives. These findings have significant implications for hyperphosphatemia management in CKD. From the items reviewed, phosphorus-based food additives were most common in small goods, bakery goods, frozen meals, prepared foods, and biscuits. Conversely, these findings have also shown that additive prevalence was lowest in the frozen vegetable, cheese, and condiments categories. This knowledge can help target dietary
Table 1. Prevalence of Phosphorus-Based Food Additives and Reporting Methods by Food Category
Food Category Bakery goods Beverages Biscuits Carbonated soft drinks Cereals and bars Cheese Condiments Cooking needs Frozen meals Frozen vegetables Prepared foods Quick and easy meals Small goods Snacks Yogurt Total
Number of P Number of Additives per Maximum Number Listed Number Listed Items Items With P Item,* Median P Additives as E number, Number Listed as Combination, Assessed Additives, n (%) (IQR) per Item n (%) as Words, n (%) n (%) 137 182 178 182 181 186 183 183 185 171 188 123 142 168 143 2532
127 (93) 60 (33) 115 (65) 62 (34) 85 (47) 26 (14) 33 (18) 52 (28) 138 (75) 15 (9) 132 (70) 32 (26) 136 (96) 44 (26) 51 (36) 1108 (44)
IQR, interquartile range; P, phosphorus. *From those items that contained a phosphorus additive.
2 (2-3) 2 (1-2) 1 (1-2) 1 (1-1) 1 (1-1) 2 (2-3) 1 (1-1) 2 (1-3) 3 (2-3) 1 (1-1) 2 (1-3) 1 (1-3) 3 (2-3) 2 (1-2) 1 (1-1) 2 (1-3)
4 5 3 1 4 4 2 7 7 1 6 4 5 4 2 7
115 (90) 20 (33) 77 (67) 58 (94) 22 (26) 16 (62) 30 (91) 36 (69) 128 (93) 15 (100) 130 (98) 23 (72) 136 (100) 43 (98) 51 (100) 900 (81)
6 (5) 19 (32) 23 (20) 4 (6) 52 (61) 0 (0) 2 (6) 12 (23) 4 (3) 0 (0) 0 (0) 7 (22) 0 (0) 1 (2) 0 (0) 130 (12)
6 (5) 20 (33) 15 (13) 0 (0) 11 (13) 10 (38) 1 (3) 3 (6) 6 (4) 0 (0) 2 (2) 0 (0) 0 (0) 0 (0) 0 (0) 74 (7)
4
MCCUTCHEON ET AL Figure 2. Prevalence of phosphorus-based food additives by food category (n 5 2532 food items).
education for the CKD and dialysis populations by educating patients on the types of foods that are most likely to contain phosphorus additives, combined with the knowledge of foods that contain a naturally high phosphorus to protein ratio (i.e., cheese). The prevalence of phosphorus-based food additives reported in this study was similar to the findings from Le on et al.,14 who investigated the use of phosphorusbased additives in the US food supply. Although a similar methodology was followed, the best-selling 15 food and beverage categories and the category definitions differed slightly between the countries, limiting direct comparisons. Nonetheless, some differences were noted, for instance, this study found that the frozen vegetable category had the lowest prevalence of phosphorus additives (9%), whereas Le on et al. demonstrated that 43% of the frozen vegetable products contained the additives. This study was the first to explore the number of phosphorus additives present in best-selling grocery items. Overall, most products contained at least 2 different types of additives. The high prevalence of additives identified from this study is alarming given the significant effect that phosTable 2. Top 5 Most Common Phosphorus-Based Food Additives
E Number 450 322 451 452 1442
Additive Name Pyrophosphates Lecithins Tripolyphosphates Polyphosphates Hydroxypropyl distarch phosphates
Number of Times Reported (n 5 2146), n (%) 374 (17) 368 (17) 289 (13) 191 (9) 154 (7)
phorus additives can have on foods, increasing the phosphorus content by as much as 70%.12,14,17–21 However, although it is likely that the number of different phosphorus additives equates to a greater phosphorus content per 100 g of the product, the actual phosphorus content is unknown because of the nonmandatory reporting of phosphorus levels on nutrition panels. Furthermore, because of the relatively recent investigation of phosphorus additives, it is also suspected that current nutrition databases do not reflect the higher phosphorus content (secondary to the addition of additives) in the food supply.21 Nonetheless, the benefit of educating end-stage CKD patients to avoid phosphorus additives using a qualitative approach, i.e., restricting foods with the additives listed on the ingredient label, has been shown to result in modest improvements in serum phosphate levels when compared to those who received standard education on restricting only naturally occurring sources.22 This highlights the significant effect of phosphorus additives in CKD. The method of reporting the presence of phosphorus additives on product ingredient lists is another important finding from this study which can be used to guide dietary education. Across all grocery items reviewed, 19 different phosphorus-based food additives were identified. The majority (81%) of these phosphorus-based food additives were reported on ingredient lists using only additive E numbers; however, lecithins (E number 322), the second most common additive, were listed using only words in nearly onethird of instances. This highlights the need to consider both E numbers and names of common phosphorus-based additives in dietary phosphorus education interventions. A number of limitations of this study must be considered. First, the food and beverage products were reviewed at supermarkets within only 1 major Australian city. Therefore,
PHOSPHORUS ADDITIVES IN THE AUSTRALIAN FOOD SUPPLY
products that may have been available nationwide, but not in the city examined, may have been missed. Nonetheless, the number of missing products was ,12% of the grocery items obtained from the data set. Second, although the data set of food and beverage items reviewed included products from all Australian grocery stores, it did not include fast food and restaurant items, which are known to contain considerable amounts of phosphorus additives.23 Third, this study focuses on one form of a single nutrient, and although foods such as cheese and condiments had a lower prevalence of the additive in review, they are typically high in phosphorus and other nutrients, including sodium, and therefore, the results must be interpreted with caution. Finally, this study included 15 categories from the 82 possible categories, and therefore, it is likely other categories not reviewed represent significant sources of phosphorus additives in the Australian food supply. The findings from this investigation highlight the widespread prevalence of phosphorus-based food additives in the current Australian food supply and suggest that phosphorus additive education in the CKD and dialysis populations may lead to improved hyperphosphatemia management. This study’s finding with respect to the reporting method of additives indicates that the identification of phosphorus content in the Australian food supply is likely to be significantly challenging, thereby supporting the case for mandatory labeling of phosphorus content of foods. Moreover, until reporting of phosphorus content on nutrition panels is mandated, additional research to support the development of a database listing products containing phosphorus additives to support patient education is warranted.
Practical Application The prevalence of phosphorus-based additives reported in this study, coupled with their high bioavailability and presence in typically low nutrient-dense processed foods, suggests dietary intervention targeting these foods containing phosphorus additives may be an effective strategy for hyperphosphatemia management in CKD. In addition, the reporting method of these additives on product ingredient lists, most commonly as E numbers, should be used to guide patient education. Supplementary Data
Supplementary data related to this article can be found at http://dx.doi.org/10.1053/j.jrn.2015.04.003.
References 1. BlockGA, Hulbert-Shearon TE, Levin NW, Port FK. Associationofserum phosphorus and calcium x phosphate product with mortality risk in chronic hemodialysis patients: a national study. Am J Kidney Dis. 1998;31:607-617. 2. Block GA, Klassen PS, Lazarus JM, Ofsthun N, Lowrie EG, Chertow GM. Mineral metabolism, mortality, and morbidity in maintenance hemodialysis. J Am Soc Nephrol. 2004;15:2208-2218.
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3. Ganesh SK, Stack AG, Levin NW, Hulbert-Shearon T, Port FK. Association of elevated serum PO4, Ca 3 PO4 product, and parathyroid hormone with cardiac mortality risk in chronic hemodialysis patients. J Am Soc Nephrol. 2001;12:2131-2138. 4. Kalantar-Zadeh K, Kuwae N, Regidor D, et al. Survival predictability of time-varying indicators of bone disease in maintenance hemodialysis patients. Kidney Int. 2006;70:771-780. 5. Kestenbaum B, Sampson JN, Rudser KD, et al. Serum phosphate levels and mortality risk among people with chronic kidney disease. J Am Soc Nephrol. 2005;16:520-528. 6. Palmer SC, Hayen A, Macaskill P, et al. Serum levels of phosphorus, parathyroid hormone, and calcium and risks of death and cardiovascular disease in individuals with chronic kidney disease: a systematic review and meta-analysis. JAMA. 2011;305:1119-1127. 7. Dietitians Association of Australia (DAA). Evidence based practice guidelines for the nutritional management of chronic kidney disease. Nutr Diet. 2006;63:S33-S45. 8. National Kidney Foundation Kidney Disease Outcome Quality Initiative (K/DOQI) Advisory Board. K/DOQI clinical practice guidelines for chronic kidney disease: evaluation, classification, and stratification. Am J Kidney Dis. 2002;39(2 Suppl 1):S1-S266. 9. Shinaberger CS, Greenland S, Kopple JD, et al. Is controlling phosphorus by decreasing dietary protein intake beneficial or harmful in persons with chronic kidney disease? Am J Clin Nutr. 2008;88:1511-1518. 10. Fouque D, Casal MC, Lindley E, et al. Dietary trends and management of hyperphosphatemia among patients with chronic kidney disease: an international survey of renal care professionals. J Ren Nutr. 2014;24:110-115. 11. Monteiro CA, Moubarac JC, Cannon G, Ng SW, Popkin B. Ultraprocessed products are becoming dominant in the global food system. Obes Rev. 2013;14(Suppl 2):21-28. 12. Cupisti A, Benini O, Ferretti V, Gianfaldoni D, Kalantar-Zadeh K. Novel differential measurement of natural and added phosphorus in cooked ham with or without preservatives. J Ren Nutr. 2012;22:533-540. 13. Moe SM, Zidehsarai MP, Chambers MA, et al. Vegetarian compared with meat dietary protein source and phosphorus homeostasis in chronic kidney disease. Clin J Am Soc Nephrol. 2011;6:257-264. 14. Le on JB, Sullivan CM, Sehgal AR. The prevalence of phosphoruscontaining food additives in top-selling foods in grocery stores. J Ren Nutr. 2013;23:265-270. e2. 15. The Nielsen Company. Consumer Panels. http://www.nielsen.com/ au/en/solutions/measurement/consumer-panels.html. Accessed December 5, 2014. 16. Food Standards Australia New Zealand. Additives. http://www. foodstandards.gov.au/consumer/additives/additiveoverview/Pages/ default.aspx. Accessed December 4, 2014. 17. Benini O, D’Alessandro C, Gianfaldoni D, Cupisti A. Extra-phosphate load from food additives in commonly eaten foods: a real and insidious danger for renal patients. J Ren Nutr. 2011;21:303-308. 18. Carrigan A, Klinger A, Choquette SS, et al. Contribution of food additives to sodium and phosphorus content of diets rich in processed foods. J Ren Nutr. 2014;24:13-19. e1. 19. Sherman RA, Mehta O. Dietary phosphorus restriction in dialysis patients: potential impact of processed meat, poultry, and fish products as protein sources. Am J Kidney Dis. 2009;54:18-23. 20. Sherman RA, Mehta O. Phosphorus and potassium content of enhanced meat and poultry products: implications for patients who receive dialysis. Clin J Am Soc Nephrol. 2009;4:1370-1373. 21. Sullivan CM, Leon JB, Sehgal AR. Phosphorus-containing food additives and the accuracy of nutrient databases: implications for renal patients. J Ren Nutr. 2007;17:350-354. 22. Sullivan C, Sayre SS, Leon JB, et al. Effect of food additives on hyperphosphatemia among patients with end-stage renal disease: a randomized controlled trial. JAMA. 2009;301:629-635. 23. Sarathy S, Sullivan C, Leon JB, Sehgal AR. Fast food, phosphoruscontaining additives, and the renal diet. J Ren Nutr. 2008;18:466-470.
Prevalence of Phosphorus-Based Additives in the Australian Food Supply: A Challenge for Dietary Education? Jemma McCutcheon, BHlthSc,* Katrina Campbell, PhD, BHlthSc,†,‡,§ Maree Ferguson, PhD, MBA, BAppSc, GradDipNutDiet,‡,{ Sarah Day, BHlthSc,* and Megan Rossi, PhD, BHlthSc†,‡,** Objective: Phosphorus-based food additives may pose a significant risk in chronic kidney disease given the link between hyperphosphatemia and cardiovascular disease. The objective of the study was to determine the prevalence of phosphorus-based food additives in best-selling processed grocery products and to establish how they were reported on food labels. Design: A data set of 3000 best-selling grocery items in Australia across 15 food and beverage categories was obtained for the 12 months ending December 2013 produced by the Nielsen Company’s Homescan database. The nutrition labels of the products were reviewed in store for phosphorus additives. The type of additive, total number of additives, and method of reporting (written out in words or as an E number) were recorded. Main Outcome Measures: Presence of phosphorus-based food additives, number of phosphorus-based food additives per product, and the reporting method of additives on product ingredient lists. Results: Phosphorus-based additives were identified in 44% of food and beverages reviewed. Additives were particularly common in the categories of small goods (96%), bakery goods (93%), frozen meals (75%), prepared foods (70%), and biscuits (65%). A total of 19 different phosphorus additives were identified across the reviewed products. From the items containing phosphorus additives, there was a median (minimum-maximum) of 2 (1-7) additives per product. Additives by E number (81%) was the most common method of reporting. Conclusion: Phosphorus-based food additives are common in the Australian food supply. This suggests that prioritizing phosphorus additive education may be an important strategy in the dietary management of hyperphosphatemia. Further research to establish a database of food items containing phosphorus-based additives is warranted. Ó 2015 by the National Kidney Foundation, Inc. All rights reserved.
Introduction
E
LEVATED LEVELS OF serum phosphate, termed hyperphosphatemia, are common in chronic kidney disease (CKD) because of a decline in renal phosphate
* School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Queensland, Australia. † Department of Nephrology, Princess Alexandra Hospital, Brisbane, Queensland, Australia. ‡ Department of Nutrition and Dietetics, Princess Alexandra Hospital, Brisbane, Queensland, Australia. § Faculty of Health Sciences and Medicine, Bond University, Robina, Queensland, Australia. { School of Human Movement and Nutrition Sciences, University of Queensland, St Lucia, Queensland, Australia. ** School of Medicine, University of Queensland, St Lucia, Queensland, Australia. Financial Disclosure: The authors declare that they have no relevant financial interests. Support: This work was supported by the 2014 Australia and New Zealand Society of Nephrology—Amgen Quality Assurance Grant. Address correspondence to Megan Rossi, PhD, BHlthSc, Department of Nephrology, Level 2, ARTS Building, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Brisbane, Queensland 4102, Australia. E-mail:
[email protected] Ó
2015 by the National Kidney Foundation, Inc. All rights reserved. 1051-2276/$36.00 http://dx.doi.org/10.1053/j.jrn.2015.04.003
Journal of Renal Nutrition, Vol -, No - (-), 2015: pp 1-5
excretion. It is well established that hyperphosphatemia is associated with an increased risk of mortality, cardiovascular disease, and disordered bone metabolism in CKD and dialysis patients.1–5 In fact, a meta-analysis of 47 cohort studies in the CKD population demonstrated that the risk of death increased by 18% for every 1 mg/dL increase in serum phosphate.6 Management of hyperphosphatemia in CKD involves dietary and medical intervention. Dietary phosphorus restriction is considered the first-line therapy, and practice guidelines suggest that CKD patients with elevated serum phosphate levels should restrict dietary phosphorus intake to 800 to 1000 mg/day.7,8 Dietetic practice has traditionally focused on targeting foods that are naturally high in organic forms of phosphorus. This includes high-protein animal and plant foods, such as meat, fish, dairy, legumes, and nuts. Without close dietetic monitoring, this conventional dietary approach may increase the risk of malnutrition.9 Furthermore, with an increasing preference and reliance on processed foods,10,11 attention has turned to the inorganic form of phosphorus found primarily in processed foods as additives. Phosphorus-based food additives have diverse applications in food manufacturing, including emulsification, leavening, raising, and flavor-enhancing qualities. Inorganic phosphorus 1
2
MCCUTCHEON ET AL
is highly bioavailable, absorbed at a rate close to 100%.12 In comparison, organic forms of phosphorus from plant and animal sources are only absorbed at a rate of 20% to 40% and 40% to 60%, respectively.12 Foods with higher bioavailability have been shown to significantly increase serum phosphate levels,13 and therefore, the high bioavailability of phosphorus-based food additives suggests that this additive form may significantly contribute to the prevalence of hyperphosphatemia in CKD and dialysis populations. Therefore, focusing dietary intervention on inorganic sources of phosphorus in typically low nutrient-dense processed foods may be a more effective target for hyperphosphatemia management. The prevalence of phosphorus-based additives in the food supply is not well documented. However, a recent study by Le on et al. 14 found that phosphorus-based food additives were present in 44% of best-selling grocery products in the United States. This landmark study has raised concerns, warranting further investigations into the use of phosphorus additives in the food supply, including Australia. The aim of the present study was to determine the prevalence of phosphorus-based additives in the Australian food supply. In addition, this study sought to investigate the reporting methods of phosphorus-based additives on food labels to inform patient education methods.
for use in Australia16 (Table S2), as well as added mineral phosphorus. Whether the phosphorus additives were present in the product was determined by reviewing the ingredient list for additive E numbers or the additive name in words. For each food or beverage product, the total number of different phosphorus additives contained in the item was recorded, as well as the additive names and corresponding E numbers. The method used to report the additives on the ingredient labels was also recorded and classified into 1 of 4 categories: (1) ‘‘words’’ (listed only as the written name of the additive), (2) ‘‘E number’’ (listed only using additive E numbers), (3) ‘‘both’’ (listed using both the written name of the additive and the E number), or (4) ‘‘combination’’ (products with $1 phosphorus additive that used a mixture of reporting methods, such as E number for 1 additive and words for another). The products that could not be located in store by either researcher were not reviewed online to eliminate potential discrepancies given the online information may be outdated or represent international products. For grocery items that contained multiple flavors or products, such as variety packs, each ingredient label listed on the single product was reviewed, and the total number of different phosphorus additives across these lists was reported as the total number of additives.
Methods
Statistical Analysis The data were collated and analyzed using MicrosoftÒ ExcelÒ (version 14.4.5, Microsoft Corporation, Redmond, WA). Results for each grocery item were entered and grouped according to each food or beverage category. All results were presented as numbers and percentages. Medians and the interquartile ranges were reported for nonparametric data.
Data Source The methods for this study were based on the approach described previously by Le on et al. 14 in the United States. A data set of grocery sales in Australia was obtained for the 12 months ending in December 2013 produced by the Nielsen Company’s Homescan database. The data set provided a statistically and demographically representative sample of the Australian population and comprised grocery sales data from 10,000 Homescan panel members.15 The data set was grouped into 82 Nielsen-defined categories, and all categories were ranked by unit sales from highest to lowest. The top 40 categories by unit sales were selected, and then categories were excluded if they were minimally processed, known to not contain additives, were not part of typical meals, or were not edible such as pet food and paper goods. From the remaining categories, the top 15 by unit sales were selected. Within each category, the top 200 grocery items by unit sales were obtained, creating a database of 3000 food and beverage items to review. A description of the 15 categories can be found in Table S1. Data Collection The items were located by 2 independent researchers at a variety of Australian grocery retail stores based on the product descriptions provided in the data set. Each of the products’ ingredient lists were reviewed for the presence of 23 phosphorus-based food additives. This included the 22 phosphorus-based food additives that have been approved
Results Grocery Item Sample The labels of 2532 best-selling food and beverage products (84%) in Australia were reviewed for the presence of phosphorus-based food additives. Four hundred sixtyeight grocery items (16%) were excluded (Fig. 1). Although the data set contained numerous identical products in different sized packages, these items were not excluded on the basis of duplication, given the individual products remained representative of the best-selling food or beverage products. Phosphorus Additive Prevalence Overall, phosphorus-based food additives were present in 1108 of the products (44%) reviewed (Table 1). There was wide variation in the presence of phosphorus additives between categories ranging from 9% to 96%. Phosphorus additives were particularly common in the categories of small goods (96%), bakery goods (93%), frozen meals (75%), prepared foods (70%), and biscuits (65%; Fig. 2).
3
PHOSPHORUS ADDITIVES IN THE AUSTRALIAN FOOD SUPPLY
beverages category, E number (33%) and combination (33%) were equally most common. Across the other 13 categories, E number was the most used approach. Lecithins (E number 322) were reported using only words in 28% of instances and made up 76% of the total 135 phosphorus additives reported using only words.
Figure 1. Flow chart of grocery product inclusion.
The items that contained phosphorus additives had a median (minimum-maximum) of 2 (1-7) additives. Products that contained phosphorus additives in the small goods and frozen meals categories had the highest median number of additives (Table 1). Conversely, all reviewed carbonated soft drinks and frozen vegetables did not contain .1 additive per item.
Reporting Methods Reporting of additives by E number (81%) was the most common method, followed by words (12%) and combination (7%). Less than 1% of reviewed products listed phosphorus additives using both words and E number. Reporting by only words was the most common method for products in the cereals and bars category (61%). In the
Phosphorus Additive Types From the 22 phosphorus-based food additives that are approved for use in Australia, 18 were identified in the products reviewed. Added mineral phosphorus was also identified in products from the beverages and cereals and bars categories, totaling 19 different phosphorus additives found across the assessed items. The 5 most common phosphorus-based food additives identified across all reviewed items can be seen in Table 2. The 2 most used additives (450 [pyrophosphates] and 322 [lecithins]) were each identified in 11 of the 15 food and beverage categories.
Discussion This study found that nearly half of the best-selling food and beverage items in the Australian food supply contained phosphorus-based additives. Furthermore, the number of phosphorus additives per item was considerable, with some foods containing up to 7 different additives. These findings have significant implications for hyperphosphatemia management in CKD. From the items reviewed, phosphorus-based food additives were most common in small goods, bakery goods, frozen meals, prepared foods, and biscuits. Conversely, these findings have also shown that additive prevalence was lowest in the frozen vegetable, cheese, and condiments categories. This knowledge can help target dietary
Table 1. Prevalence of Phosphorus-Based Food Additives and Reporting Methods by Food Category
Food Category Bakery goods Beverages Biscuits Carbonated soft drinks Cereals and bars Cheese Condiments Cooking needs Frozen meals Frozen vegetables Prepared foods Quick and easy meals Small goods Snacks Yogurt Total
Number of P Number of Additives per Maximum Number Listed Number Listed Items Items With P Item,* Median P Additives as E number, Number Listed as Combination, Assessed Additives, n (%) (IQR) per Item n (%) as Words, n (%) n (%) 137 182 178 182 181 186 183 183 185 171 188 123 142 168 143 2532
127 (93) 60 (33) 115 (65) 62 (34) 85 (47) 26 (14) 33 (18) 52 (28) 138 (75) 15 (9) 132 (70) 32 (26) 136 (96) 44 (26) 51 (36) 1108 (44)
IQR, interquartile range; P, phosphorus. *From those items that contained a phosphorus additive.
2 (2-3) 2 (1-2) 1 (1-2) 1 (1-1) 1 (1-1) 2 (2-3) 1 (1-1) 2 (1-3) 3 (2-3) 1 (1-1) 2 (1-3) 1 (1-3) 3 (2-3) 2 (1-2) 1 (1-1) 2 (1-3)
4 5 3 1 4 4 2 7 7 1 6 4 5 4 2 7
115 (90) 20 (33) 77 (67) 58 (94) 22 (26) 16 (62) 30 (91) 36 (69) 128 (93) 15 (100) 130 (98) 23 (72) 136 (100) 43 (98) 51 (100) 900 (81)
6 (5) 19 (32) 23 (20) 4 (6) 52 (61) 0 (0) 2 (6) 12 (23) 4 (3) 0 (0) 0 (0) 7 (22) 0 (0) 1 (2) 0 (0) 130 (12)
6 (5) 20 (33) 15 (13) 0 (0) 11 (13) 10 (38) 1 (3) 3 (6) 6 (4) 0 (0) 2 (2) 0 (0) 0 (0) 0 (0) 0 (0) 74 (7)
4
MCCUTCHEON ET AL Figure 2. Prevalence of phosphorus-based food additives by food category (n 5 2532 food items).
education for the CKD and dialysis populations by educating patients on the types of foods that are most likely to contain phosphorus additives, combined with the knowledge of foods that contain a naturally high phosphorus to protein ratio (i.e., cheese). The prevalence of phosphorus-based food additives reported in this study was similar to the findings from Le on et al.,14 who investigated the use of phosphorusbased additives in the US food supply. Although a similar methodology was followed, the best-selling 15 food and beverage categories and the category definitions differed slightly between the countries, limiting direct comparisons. Nonetheless, some differences were noted, for instance, this study found that the frozen vegetable category had the lowest prevalence of phosphorus additives (9%), whereas Le on et al. demonstrated that 43% of the frozen vegetable products contained the additives. This study was the first to explore the number of phosphorus additives present in best-selling grocery items. Overall, most products contained at least 2 different types of additives. The high prevalence of additives identified from this study is alarming given the significant effect that phosTable 2. Top 5 Most Common Phosphorus-Based Food Additives
E Number 450 322 451 452 1442
Additive Name Pyrophosphates Lecithins Tripolyphosphates Polyphosphates Hydroxypropyl distarch phosphates
Number of Times Reported (n 5 2146), n (%) 374 (17) 368 (17) 289 (13) 191 (9) 154 (7)
phorus additives can have on foods, increasing the phosphorus content by as much as 70%.12,14,17–21 However, although it is likely that the number of different phosphorus additives equates to a greater phosphorus content per 100 g of the product, the actual phosphorus content is unknown because of the nonmandatory reporting of phosphorus levels on nutrition panels. Furthermore, because of the relatively recent investigation of phosphorus additives, it is also suspected that current nutrition databases do not reflect the higher phosphorus content (secondary to the addition of additives) in the food supply.21 Nonetheless, the benefit of educating end-stage CKD patients to avoid phosphorus additives using a qualitative approach, i.e., restricting foods with the additives listed on the ingredient label, has been shown to result in modest improvements in serum phosphate levels when compared to those who received standard education on restricting only naturally occurring sources.22 This highlights the significant effect of phosphorus additives in CKD. The method of reporting the presence of phosphorus additives on product ingredient lists is another important finding from this study which can be used to guide dietary education. Across all grocery items reviewed, 19 different phosphorus-based food additives were identified. The majority (81%) of these phosphorus-based food additives were reported on ingredient lists using only additive E numbers; however, lecithins (E number 322), the second most common additive, were listed using only words in nearly onethird of instances. This highlights the need to consider both E numbers and names of common phosphorus-based additives in dietary phosphorus education interventions. A number of limitations of this study must be considered. First, the food and beverage products were reviewed at supermarkets within only 1 major Australian city. Therefore,
PHOSPHORUS ADDITIVES IN THE AUSTRALIAN FOOD SUPPLY
products that may have been available nationwide, but not in the city examined, may have been missed. Nonetheless, the number of missing products was ,12% of the grocery items obtained from the data set. Second, although the data set of food and beverage items reviewed included products from all Australian grocery stores, it did not include fast food and restaurant items, which are known to contain considerable amounts of phosphorus additives.23 Third, this study focuses on one form of a single nutrient, and although foods such as cheese and condiments had a lower prevalence of the additive in review, they are typically high in phosphorus and other nutrients, including sodium, and therefore, the results must be interpreted with caution. Finally, this study included 15 categories from the 82 possible categories, and therefore, it is likely other categories not reviewed represent significant sources of phosphorus additives in the Australian food supply. The findings from this investigation highlight the widespread prevalence of phosphorus-based food additives in the current Australian food supply and suggest that phosphorus additive education in the CKD and dialysis populations may lead to improved hyperphosphatemia management. This study’s finding with respect to the reporting method of additives indicates that the identification of phosphorus content in the Australian food supply is likely to be significantly challenging, thereby supporting the case for mandatory labeling of phosphorus content of foods. Moreover, until reporting of phosphorus content on nutrition panels is mandated, additional research to support the development of a database listing products containing phosphorus additives to support patient education is warranted.
Practical Application The prevalence of phosphorus-based additives reported in this study, coupled with their high bioavailability and presence in typically low nutrient-dense processed foods, suggests dietary intervention targeting these foods containing phosphorus additives may be an effective strategy for hyperphosphatemia management in CKD. In addition, the reporting method of these additives on product ingredient lists, most commonly as E numbers, should be used to guide patient education. Supplementary Data
Supplementary data related to this article can be found at http://dx.doi.org/10.1053/j.jrn.2015.04.003.
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