Correspondence RESEARCH LETTER Phosphorus Content of Popular Beverages To the Editor: High phosphorus intake is associated with an increased risk of mortality in the general US population.1 Dietary phosphorus intake may influence levels of serum phosphorus and FGF-23,2 a
phosphaturic hormone linked to left ventricular hypertrophy.3 Further, elevated serum phosphorus levels have been associated with an increased risk of cardiovascular disease and mortality4 in individuals with and without kidney disease.5 Phosphorus-based ingredients are commonly used in processed food for moisture retention, leavening, flavoring, emulsification, coloring, etc.6 These additives contribute substantially to American dietary phosphorus intake; a recent study found them in 44% of bestselling grocery items.7
Table 1. Measured Phosphorus Content and Reference Values of Popular Beverages
Beverage Carbonated drinks Coke Cherry Coke Dr. Pepper Diet Dr. Pepper Pepsi Diet Pepsi AMP Energy Fruit-Flavored Drinks Crystal Light, Classic Orangea Crystal Light, Raspberry Icea Crystal Light, Fruit Puncha Tang, Orangea Kool-Aid, Tropical Puncha Kool-Aid, Black Cherrya Kool-Aid, Grapea Hawaiian Punch, Fruit Juicy Red Sunny-D, Tangy Original Sunny-D, Smooth Coffee Drinks Starbucks Doubleshot Energy, Mochab Starbucks Doubleshot Energy, Vanillab Iced Teas Gold Peak Iced Tea, Sweet Teab Gold Peak Iced Tea, Lemonb Lipton Brisk Iced Tea, Sweet Teab Lipton Brisk Iced Tea, Lemonb Lipton Brisk Iced Tea, Raspberryb Lemonade Crystal Light, Raspberry Lemonadea Country Time, Lemonadeb Country Time, Pink Lemonadeb Kool-Aid, Pink Lemonadea Flavored Waters Vitamin Water, Power C Dragonfruit Vitamin Water, Revive Fruit Punch Vitamin Water, Focus Kiwi Strawberry Vitamin Water, Essential Orange-Orange Vitamin Water, Defense Raspberry Appleb Vitamin Water Zero, Squeezed Lemonadeb Vitamin Water Zero, Rise Orangeb Mio Fit, Arctic Grapea,b Mio Fit, Berry Blasta,b SoBe Lifewater, Blood Orange Mangob Aquafina Flavor Splash, Mixed Berryb Propel Zero, Berry Sports Drinks Gatorade, Frost Glacier Freeze (powder)a Gatorade, Orange (powder)a Powerade Zero, Fruit Punchb Powerade Zero, Orangeb Powerade, Fruit Punch Powerade, Orange
Mean 6 SD Measured P (mg/8 fl oz)
NDSR 2014 Reference Value for P (mg/8 fl oz)
Absolute Difference (mg/8 fl oz)
% Difference
37.5 6 0.2 33.8 6 0 25.9 6 0.2 27.1 6 0.5 31.2 6 0.7 24.1 6 0.3 30.9 6 0.8
25 25 25 21 25 21 40
112.5 18.8 10.9 16.1 16.2 13.1 29.1
150% 135% 14% 129% 125% 115% 223%
100.5 6 16.0 2.4 6 0.1 10.9 6 0.5 91.1 6 5.0 2.7 6 0.3 2.4 6 0.1 4.7 6 0.6 77.4 6 0.3 68.8 6 0 69.0 6 0.5
10 10 10 39 0 0 0 7 4 4
190.5 27.6 10.9 152.1 12.7 12.4 14.7 170.4 164.8 165.0
1905% 276% 19% 1134% NA NA NA 11,005% 11,621% 11,624%
131.2 6 0.2 130.2 6 1.5
13 13
1118.2 1117.2
1909% 1902%
6.7 6 0.2 2.5 6 0.2 105.2 6 0.8 56.9 6 0.5 83.6 6 3.8
2 2 2 2 2
14.7 10.5 1103.2 154.9 181.6
1233% 127% 15158% 12745% 14082%
8.0 6 0.7 15.8 6 0.0 14.1 6 0.2 7.3 6 0.1
10 0 0 0
22.0 115.8 114.1 17.3
220% NA NA NA
1.0 6 0 261.4 6 1.7 0.9 6 0 63.4 6 0.7 1.5 6 0.1 86.2 6 1.2 97.7 6 1.7 12.4 6 2.1 14.4 6 1.6 43.9 6 0.5 56.3 6 0.7 54.9 6 0.3
0 0 0 0 0 0 0 82 82 0 62 59
11.0 1261.4 10.9 163.4 11.5 186.2 197.7 269.6 267.6 143.9 25.7 24.1
NA NA NA NA NA NA NA 285% 282% NA 29% 27%
20.9 6 3.2 21.0 6 4.4 18.0 6 0.2 18.6 6 0.1 18.7 6 0.2 18.9 6 0.1
0 0 24 24 24 24
120.9 121 26 25.4 25.3 25.1
NA NA 233% 229% 228% 227%
Note: Two samples used for each beverage except for Crystal Light, Classic Orange (5 samples). a Prepared from powder or concentrated liquid according to package instructions. b Exact match unavailable in NDSR; closest substitute was selected.
Am J Kidney Dis. 2015;-(-):---
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Correspondence Products with phosphorus-based additives often contain more phosphorus than similar products without such additives.6,7 However, this is not always apparent to consumers because including phosphorus content on the nutrition facts label is optional.6 Product-specific data are often lacking because considerable time and expense is required to monitor the constant stream of new products and reformulations. Here, we report the measured phosphorus content of several popular beverages containing phosphorus-based additives. The Study of Dietary Additive Phosphorus on Proteinuria and FGF-23 (SODA-POP; ClinicalTrials.gov #NCT02020785) is a randomized, double-blind, crossover study of the effect of phosphorus-based additives in commercially available foods and beverages on albuminuria and FGF-23 in patients with albuminuria and eGFR $ 45 mL/min/1.73 m2. To inform the study design, popular beverages containing phosphorus additives were purchased in central Pennsylvania between September and December 2013. Powdered beverages and water enhancers were prepared according to package instructions. Samples were weighed on a scientific grade scale, packaged in sealed containers, and shipped to Medallion Laboratories Inc. Phosphorus content was determined by ashing samples at high temperature, digesting them in acid, and using inductively coupled plasma. Measured phosphorus content was compared with reference values from the Nutrition Data System for Research (NDSR).8 NDSR combines data from the US Department of Agriculture (USDA), food manufacturers, and scientific literature and includes more individual product-level data than the USDA National Nutrient Database.8 Eighteen (39%) of the 46 products lacked exact matches in NDSR, so the closest beverage was substituted (eg, Country Time Lemonade coded as “regular lemonade and lemon drinks, purchased ready-to-drink”). All products had measurable phosphorus, ranging from 1 to 261 mg per 8 fl oz. Most (78%) products had higher measured phosphorus than the NDSR reference values (Table 1). Phosphorus content per NDSR was zero for 16 (35%) products, many of which had measured phosphorus content on the higher end of the range we observed (Table 1). The absolute difference in phosphorus content between measured and reference values ranged from 28 to 1261 mg per 8 fl oz. There was a wide range in phosphorus content even among products within the same brand and category. For example, phosphorus content of the 7 Vitamin Water flavors that were measured ranged from 0.9 to 261.4 mg per 8 fl oz. Among the iced tea beverages, phosphorus ranged from 3 to 105 mg per 8 fl oz. In summary, current nutritional databases capture phosphorus content poorly in many popular beverages with phosphorus-based additives. Furthermore, phosphorus content is high in a number of these products, which often come in 12– to 20–fl oz containers. The USDA and NDSR release updates to their databases yearly, but face considerable challenges due to an ever-changing marketplace. NDSR updates nutrient data periodically, prioritizing products likely to undergo frequent formulation changes. Many products may not be updated for several years, such as Crystal Light, which has not been updated since 1998 (J. Klein, BS, e-mail communication, February 2015). To illustrate the challenges involved in maintaining these databases, more than 85,000 uniquely formulated foods are estimated to be in the marketplace,9 and the cost of nutrient analysis on a single food item sampled nationwide costs w$17,000 to $20,000.8 Given these constraints, USDA staff have suggested that updating these databases requires collaboration between public and private stakeholders.10 For patients and their providers, avoidance of processed foods may be a relatively simple message to moderate phosphorus consumption, but effective dietary education and management cannot be 2
achieved until accurate phosphorus measurements become more readily available. Though our study was limited to a sampling of popular beverages in Pennsylvania measured at a single laboratory, our findings highlight the need for more information about the phosphorus content of beverages containing phosphorus-based additives. Such information could help patients with kidney disease and their health care providers make informed decisions, given potential harms of high phosphorus intake. Further research is needed to better understand the effects of diets high in phosphorus-based additives on kidney and cardiovascular health. Melissa Moser, RD,1 Karen White, MS, RD1 Bobbie Henry, RD,1 Susan Oh, MS, MPH, RD1 Edgar R. Miller, MD, PhD,1 Cheryl A. Anderson, PhD, MPH, MS2 Jonathan Benjamin, BS,1 Jeanne Charleston, RN, BSN1 Lawrence J. Appel, MD, MPH,1 Alex R. Chang, MD, MS3 1 Johns Hopkins University, Baltimore, Maryland 2 University of California, San Diego, San Diego, California 3 Geisinger Health System, Danville, Pennsylvania Corresponding author:
[email protected]
Acknowledgements Support: This work was supported by the Geisinger Clinic Research Fund and a Satellite Dialysis Clinical Investigator Grant of the National Kidney Foundation. The sponsors had no role in study design; collection, analysis, and interpretation of data; writing the report; or the decision to submit the report for publication. Financial Disclosure: The authors declare that they have no other relevant financial interests. Contributions: Research idea and study design: ARC, KW, SO, ERM, CAA, JC, LJA; data acquisition: ARC, MM, KW, BH, SO, JB, JC; data analysis/interpretation: ARC, MM, SO, ERM, CAA, LJA; statistical analysis: ARC, MM; supervision or mentorship: ERM, CAA, LJA. Each author contributed important intellectual content during manuscript drafting or revision and accepts accountability for the overall work by ensuring that questions pertaining to the accuracy or integrity of any portion of the work are appropriately investigated and resolved. ARC takes responsibility that this study has been reported honestly, accurately, and transparently; that no important aspects of the study have been omitted, and that any discrepancies from the study as planned have been explained.
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Correspondence in people with coronary disease. Circulation. 2005;112(17): 2627-2633. 6. Leon JB, Sullivan CM, Sehgal AR. The prevalence of phosphorus-containing food additives in top-selling foods in grocery stores. J Ren Nutr. 2013;23(4):265, 270.e2. 7. Calvo MS, Uribarri J. Contributions to total phosphorus intake: all sources considered. Semin Dial. 2013;26(1): 54-61. 8. Schakel SF, Sievert YA, Buzzard IM. Sources of data for developing and maintaining a nutrient database. J Am Diet Assoc. 1988;88(10):1268-1271.
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9. Ng SW, Popkin BM. Monitoring foods and nutrients sold and consumed in the United States: dynamics and challenges. J Acad Nutr Diet. 2012;112(1):41-45.e4. 10. Ahuja JK, Moshfegh AJ, Holden JM, Harris E. USDA food and nutrient databases provide the infrastructure for food and nutrition research, policy, and practice. J Nutr. 2013;143(2):241S-249S. Received January 12, 2015. Accepted in revised form February 20, 2015. Ó 2015 by the National Kidney Foundation, Inc. http://dx.doi.org/10.1053/j.ajkd.2015.02.330
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