The optimal approach to nutrition and cystic fibrosis: latest evidence and recommendations.

PURPOSE OF REVIEW: Cystic fibrosis (CF) is a progressive genetic disease that affects multiple organ systems. Therapy is directed to maintain and optimize nutritional status and pulmonary function, as these are key factors in survival. In this review, the most recent findings regarding nutritional management associated with pulmonary function and outcome will be explored. RECENT FINDINGS: Evidence-based and expert-based guidelines emphasize the need for adequate nutritional intake to improve nutritional status. For infants and young children, the aim is to achieve the 50th percentile of weight and length for a healthy same-age population up to age 2 years. For older children and adolescents 2-18 years, the target is a BMI of at or above the 50th percentile for healthy children. For CF adults of at least 18 years, the target is a BMI of at or above 22 kg/m for women and at or above 23 kg/m for men. Recently, new drugs are developed with the aim to treat the malfunction of the cystic fibrosis transmembrane conductance regulator gene. This potentiator/corrector therapy improves lung function and nutritional status and decreases the number of infective exacerbations. As survival is improving and the CF population is aging, it is important to focus on micronutrient and macronutrient intake of CF patients in different age and disease stages. SUMMARY: Recent evidence-based nutritional guidelines and improved medical treatment support the nutritional monitoring and interventions in CF patients. Nutritional care should be personalized and provided by a specialized CF dietitian because patients' care needs may change dramatically during their disease progress.

Body Weight and Body Mass Index in Patients with End-Stage Cystic Fibrosis Stabilize After the Start of Enteral Tube Feeding.

BACKGROUND: Enteral tube feeding (ETF) is widely used in patients with cystic fibrosis (CF) and end-stage lung disease, but previous studies have been limited to investigating whether ETF improves outcomes in patients with moderately or mildly impaired pulmonary function. OBJECTIVE: This study investigated body weight, body mass index (BMI; calculated as kg/m2), pulmonary function, and the presence of CF-related diabetes before and after the start of ETF. DESIGN: This was a retrospective observational study. PARTICIPANTS/SETTING: Data from 26 adult patients in an outpatient setting who had end-stage CF (19 women) and had been using ETF for at least 6 months between 2000 and 2014 were analyzed. MAIN OUTCOME MEASURES: Body weight, BMI, pulmonary function (forced expiratory volume in 1 second as percent of predicted) and incidence of CF-related diabetes from 6 months before to 6 months after starting ETF. STATISTICAL ANALYSES PERFORMED: Time effects were tested with one-way analysis of variance for data that were normally distributed and the Friedman test for non-parametric data. Correlations were tested with Pearson's r or Spearman's ρ, depending on the distribution of the data. RESULTS: Mean body weight increased by 3.5 kg (95% CI 2.2 to 4.8 kg) after patients started ETF. In women, mean BMI decreased by 0.7 in the 6 months before the start of ETF (P<0.05) and increased by 1.4 in the 6 months thereafter (P<0.05). In men, BMI changes were similar (-0.8 and +1.1), but not statistically significant. Forced expiratory volume in 1 second as percent of predicted significantly decreased in time from a median of 28% to 26% at the start of ETF to 25% after 6 months (P=0.0013), with similar trends in women and men. There was no correlation between changes in weight and lung function. CF-related diabetes was already present in 12 patients and developed in 1 more patient after the start of ETF. CONCLUSIONS: ETF improved body weight and BMI but not pulmonary function in 26 patients with end-stage CF. Clinical outcomes were similar in women and men, but the sample size of men was too small to determine statistical significance.

Prediction Equations Underestimate Resting Energy Expenditure in Patients With End-Stage Cystic Fibrosis.

BACKGROUND: Resting energy expenditure (REE) is increased in patients with cystic fibrosis (CF) with end-stage lung disease due to chronic inflammation and pulmonary infections. After lung transplantation (LTx), energy expenditure is expected to be lower because inflammation will decrease. We assessed the agreement between measured and predicted REE in pre-LTx CF and post-LTx patients with CF and differences in REE in pre-LTx CF and post-LTx patients with CF in a cross-sectional study. METHODS: Included were 12 pre-LTx patients with CF (9 women; median age 31.6 years; interquartile range [IQR], 23.3-40.0) and 12 patients with CF within 2 years after LTx (6 women; median age 33.5 years; IQR, 22.3-40.3). REE was measured in a fasted state using indirect calorimetry. Values were compared with predicted REE calculated by formulas of Harris-Benedict (1919 and 1984), Schofield, and the World Health Organization (1985). A calculated REE between 90% and 110% of REE measured was considered adequate. RESULTS: Prediction equations underestimate REE in at least 75% of pre-LTx and 33% of post-LTx patients with CF. Mean (SD) REE measured by indirect calorimetry was 1735 (251) kcal pre-LTx and 1650 (235) kcal post-LTx ( P = .40). REE expressed per kilogram of fat-free mass (FFM) was 40.5 kcal/kg in pre-LTx patients with CF, which was higher than the 34.3 kcal/kg in post-LTx patients with CF ( P = .01). CONCLUSIONS: Prediction equations underestimate REE in patients with end-stage CF. REE per kg of FFM is lower post-LTx than pre-LTx in patients with CF. Measurement of REE is recommended for patients with CF, especially pre-LTx, to optimize energy requirements for improving nutrition status.

Self-reported use of vitamins and other nutritional supplements in adult patients with cystic fibrosis. Is daily practice in concordance with recommendations?

BACKGROUND: In cystic fibrosis (CF), prophylactic supplementation of the fat-soluble vitamins A, D, E, and K is recommended. Limited data is available describing vitamin prescription adherence by adult patients. The aim of this study was to assess the use of prescribed vitamins and other nutritional supplements by adult CF patients. METHODS: All adult CF patients (n=111) registered at the Utrecht CF Center were invited to participate in a telephone survey on supplement use. Supplemental vitamin intakes were compared with recommendations. In a subsample, associations between supplemental intake and serum vitamin D and E values were assessed. RESULTS: In this study 80% of the patients reported the use of vitamin and/or mineral supplements. Fat-soluble vitamins were used by 43% of pancreatic-sufficient (PS) and 81% of pancreatic-insufficient (PI) patients. Of PI patients reporting supplemental vitamin use, only 9% met the recommendations for vitamin A, 32% for vitamin D, 59% for vitamin E, and 81% for vitamin K. Multivitamin supplements were used by 42% of PI and by 29% of PS patients. Other nutritional supplements were rarely used. CONCLUSION: A high percentage of PI patients use fat-soluble vitamins below recommendations. Therefore adequate monitoring of vitamin supplementation and status is warranted.

Assessment of nutritional status in adult patients with cystic fibrosis: whole-body bioimpedance vs body mass index, skinfolds, and leg-to-leg bioimpedance.

OBJECTIVE: To investigate whether body mass index (BMI) or body fat percentage estimated from BMI, skinfolds, or leg-to-leg bioimpedance are good indicators of nutritional status in adult patients with cystic fibrosis. Body fat percentage measured by whole-body bioimpedance was used as the reference method. DESIGN: Cross-sectional study using four methods to estimate body fat percentage. All patients filled out a food frequency and a physical activity questionnaire for assessment of their habitual food intake and energy requirements, respectively. SUBJECTS/SETTING: Thirty-five adult patients (23 men/12 women) with cystic fibrosis, age range 18 to 46 years, were measured during their yearly visit at the outpatient clinic of the Cystic Fibrosis Center in Utrecht, the Netherlands. STATISTICAL ANALYSIS: Mean+/-standard deviation was calculated for all measurements and 95% confidence intervals for differences between methods. Bland-Altman plots were used to assess differences between the measures of body composition and Pearson correlation coefficients were calculated to determine the relationships between them, and between the energy requirements and the energy intakes. RESULTS: For men the whole-body body fat percentage reference was 14.1%+/-3.0, body fat percentage estimated from BMI was 15.8%+/-4.3, body fat percentage estimated from skinfolds was 8.6%+/-4.8, and body fat percentage estimated from leg-to-leg bioimpedance was 13.1%+/-4.9. For women the whole-body body fat percentage reference was 24.0%+/-5.9, body fat percentage estimated from BMI was 25.1%+/-4.0, body fat percentage estimated from skinfolds was 17.0%+/-4.8, and body fat percentage estimated from leg-to-leg bioimpedance was 25.0%+/-6.9. Body fat percentage estimated from BMI and body fat percentage estimated from skinfolds were significantly different from the reference value for body fat percentage (P <.05). The correlation coefficients between the reference body fat percentage and body fat percentage estimated from BMI, from skinfolds, and from leg-to-leg bioimpedance were all more than 0.72. In all but one patient, nutritional status was correctly assessed by BMI: those with a BMI less than 18.5 had body fat percentage less than 10% (men) or less than 20% (women). The mean energy intake of the men was 141% of the Recommended Dietary Allowance as proposed in European and Dutch guidelines. The mean energy intake of the women was 94% of the Recommended Dietary Allowance. CONCLUSIONS: A simple calculation of BMI is adequate to diagnose nutritional status in adult patients with cystic fibrosis. Bioimpedance measurements are only needed when nutritional therapy specifically focuses on lean body mass.