From the Academy
Evidence Analysis Center
Dietary Macronutrient Distribution and Nutrition Outcomes in Persons with Cystic Fibrosis: An Evidence Analysis Center Systematic Review

https://doi.org/10.1016/j.jand.2020.03.016Get rights and content

Abstract

Cystic fibrosis (CF) increases risk for undernutrition and malabsorption. Individuals with CF traditionally have been counseled to consume a high-fat diet. However, a new era of CF care has increased lifespan and decreased symptoms in many individuals with CF, necessitating a re-examination of the high-fat CF legacy diet. A literature search was conducted of Medline (Ovid), Embase, and CINAHL (EBSCO) databases to identify articles published from January 2002 to May 2018 in the English language examining the relationships between dietary macronutrient distribution and nutrition outcomes in individuals with CF. Articles were screened, risk of bias was assessed, data were synthesized narratively, and each outcome was graded for certainty of evidence. The databases search retrieved 2,519 articles, and 7 cross-sectional articles were included in the final narrative analysis. Three studies examined pediatric participants and 4 examined adults. None of the included studies reported on outcomes of mortality or quality of life. Very low certainty evidence described no apparent relationship between dietary macronutrient distribution and lung function, anthropometric measures, or lipid profile in individuals with CF. The current systematic review demonstrates wide ranges in the dietary macronutrient intakes of individuals with CF with little to no demonstrable relationship between macronutrient distribution and nutrition-related outcomes. No evidence is presented to substantiate an outcomes-related benefit to a higher fat-diet except in the context of achieving higher energy intakes in a lesser volume of food.

Section snippets

Methods

This SR followed the methods of the Evidence Analysis Center at the Academy of Nutrition and Dietetics, which are described in detail elsewhere.16 This process aligns with the criteria delineated by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.17 A brief description of methods including those specific to this SR are described below. This SR is part of a larger project addressing nutrition care in CF, which was registered prospectively at PROSPERO (CRD42018097373).18

Results

A Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow chart summarizing the results of the systematic search, including reasons for exclusion of full-text articles, is shown in Figure 2. The database searches identified 2,519 research articles with no additional records identified through other sources. After duplicates were removed, 2,409 titles/abstracts were screened and after the initial exclusion based on the titles and abstracts, 148 full-text articles were accessed

Discussion

Acceptable macronutrient distribution ranges for carbohydrate, fat, and protein for the general population are based on interventional trials and supportive epidemiological data to prevent or reduce risk of chronic diseases and to ensure sufficient dietary intakes of essential nutrients. Acceptable macronutrient distribution ranges for adults published in 2005 by the National Academy of Sciences are estimated to be 20% to 35% of total energy from fat and 45% to 65% from carbohydrates, with the

Conclusions

The current SR demonstrates wide ranges in the dietary macronutrient intakes of individuals with CF with little to no demonstrable effect of macronutrient distribution on nutrition-related outcomes. No evidence is presented to substantiate an outcomes-related benefit to a higher fat diet except in the context of achieving higher energy intakes in a lesser volume of food. The long-term consequences of a high-energy, high-fat, nutrient-poor diet for individuals with CF may be similar to the

Acknowledgements

The authors would like to acknowledge and thank the evidence analysts who extracted data for this systematic review. Primary institution where research was conducted: Academy of Nutrition and Dietetics.

Author Contributions

All authors were involved developing this systematic review from question formulation to evidence grading. C. M. McDonald, M. Rozga, E. K. Bowser, and K. Farnham wrote the first draft of this manuscript and all authors reviewed and commented on subsequent drafts of the manuscript.

C. M. McDonald is a clinical dietitian, Primary Children's Hospital, Salt Lake City, UT.

References (41)

Cited by (19)

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    PwCF with one or two G551D variants in phase 3 trials of ivacaftor had sustained increases in weight and BMI [32]. PwCF with one or two F508del variants aged ≥12 years on elexacaftor-tezacaftor-ivacaftor had significant increases in weight and BMI [82]. Real-world studies of pwCF treated with ivacaftor also found consistent increases in weight and BMI [83].

  • Updates in Nutrition Management of Cystic Fibrosis in the Highly Effective Modulator Era

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    More information is needed to determine how we can modify CF diets to reduce risk of cardiac disease in this population. The diet recommendations for PwCF have aimed for energy intake in 110% to 200% of non-CF individuals, with a high fat and high sodium intake to account for increased energy demands and sodium chloride losses in sweat41,42; this has become known as the legacy diet. There is a concern for age-related and metabolic conditions known to be associated with high fat, added sugar, high sodium diets, with low dietary quality.41,43

  • Improving nutrition in cystic fibrosis: A systematic literature review

    2022, Nutrition
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    Although the evidence identified in this review did not conclusively support a positive effect linked to using an app for CF nutritional management on anthropometric parameters, there was an improvement in QoL [25]. A recent systematic review was not able to identify and association between macronutrient distribution and BMI in adults [57] and a similar lack of association between anthropometric parameters and dietary contribution of protein, fat, and carbohydrates was observed in a pediatric study [41] identified in this review. However, evidence from a small RCT conducted by Gorji et al. suggests that deriving the carbohydrate contribution from low glycemic index sources enhances weight gain [22].

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C. M. McDonald is a clinical dietitian, Primary Children's Hospital, Salt Lake City, UT.

E. K. Bowser is an associate in pediatrics and faculty nutritionist, Pediatric Pulmonary Division, University of Florida College of Medicine, Gainesville.

K. Farnham is a clinical pediatric dietitian, Nemours Children's Specialty Care, Jacksonville, FL.

J. A. Alvarez is an assistant professor of medicine, Emory University School of Medicine, Atlanta, GA.

L. Padula is an advanced practice dietitian, Children's Hospital of Philadelphia, Philadelphia, PA.

M. Rozga is a nutrition researcher, Academy of Nutrition and Dietetics, Evidence Analysis Center, Chicago, IL.

STATEMENT OF POTENTIAL CONFLICT OF INTEREST J. A. Alvarez receives funding from the National Institutes of Health (R03 DK117246, K01 DK102851), and the Cystic Fibrosis Foundation (ALVARE19A0). No other potential conflict of interest was reported by the authors.

FUNDING/SUPPORT This work was supported by the Academy of Nutrition and Dietetics and the Medical Nutrition Dietetic Practice Group of the Academy of Nutrition and Dietetics.

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