Vitamin E supplementation in people with cystic fibrosis

α-Tocopherol Pharmacokinetics in Adults with Cystic Fibrosis: Benefits of Supplemental Vitamin C Administration

BACKGROUND

Numerous abnormalities in cystic fibrosis (CF) could influence tocopherol absorption, transportation, storage, metabolism and excretion. We hypothesized that the oxidative distress due to inflammation in CF increases vitamin E utilization, which could be positively influenced by supplemental vitamin C administration.

METHODS

Immediately before and after receiving vitamin C (500 mg) twice daily for 3.5 weeks, adult CF patients (n = 6) with moderately advanced respiratory tract (RT) disease consumed a standardized breakfast with 30% fat and a capsule containing 50 mg each hexadeuterium (d₆)-α- and dideuterium (d₂)-γ-tocopheryl acetates. Blood samples were taken frequently up to 72 h; plasma tocopherol pharmacokinetics were determined. During both trials, d₆-α- and d₂-γ-tocopherols were similarly absorbed and reached similar maximal plasma concentrations ~18-20 h. As predicted, during vitamin C supplementation, the rates of plasma d₆-α-tocopherol decline were significantly slower.

CONCLUSIONS

The vitamin C-induced decrease in the plasma disappearance rate of α-tocopherol suggests that vitamin C recycled α-tocopherol, thereby augmenting its concentrations. We conclude that some attention should be paid to plasma ascorbic acid concentrations in CF patients, particularly to those individuals with more advanced RT inflammatory disease and including those with severe exacerbations.

Brazilian Guidelines for Nutrition in Cystic Fibrosis

OBJECTIVE

To develop a scientific consensus on nutrition in cystic fibrosis.

METHODS

Sixteen coordinators elaborated relevant questions on nutritional therapy in cystic fibrosis, which were divided into six sections: nutritional assessment, nutritional recommendations, nutritional intervention, dietary counseling, special situations and enzyme replacement, and gastrointestinal manifestations. Two to three specialists in the field were responsible for each section and obtaining answers formulated based on standardized bibliographic searches. The available literature was searched in the PubMed®/MEDLINE database, after training and standardization of search strategies, to write the best level of evidence for the questions elaborated. Issues related to disagreement were discussed until a consensus was reached among specialists, based on the current scientific literature.

RESULTS

Forty-two questions were prepared and objectively answered, resulting in a consensus of nutritional therapy in cystic fibrosis.

CONCLUSION

This work enabled establishing a scientific consensus for nutritional treatment of cystic fibrosis patients.

The weak correlation between serum vitamin levels and chronic kidney disease in hospitalized patients: a cross-sectional study

Background

Chronic kidney disease (CKD) has become a global public health problem. Accumulating evidence suggested that vitamins play important roles in the progression of CKD.

Methods

A cross-sectional study was conducted to investigate the vitamin status of patients with CKD at stage 1–5. The serum concentrations of 9 vitamins, vitamin A, B1, B2, B6, B9, B12, C, D, and E were measured by electroanalytical method with a Multi-Vitamin Analyzer. Pearson correlation and multiple linear regression between serum level of vitamins were analyzed.

Results

The median levels of vitamin A, B1, B2, B6, B9, B12, C and E were within the reference ranges or on the borderline. Vitamin D deficiency was found in all patients. Weak correlation was found between vitamin A or vitamin D and estimated glomerular filtration rate (eGFR). The Pearson correlation coefficient were − 0.21766 and 0.19752, respectively. Hypertension, diabetes mellitus, and atherosclerosis were the major comorbidities.

Conclusions

For the first time, the serum levels of 9 vitamins were measured simultaneously in patients with CKD at different stages. Vitamin D deficiency was found in all patients. Weak correlation between vitamin A or vitamin D and eGFR was found.

Vitamin E supplementation in people with cystic fibrosis

BACKGROUND

People with cystic fibrosis are at an increased risk of fat-soluble vitamin deficiency, including vitamin E. Vitamin E deficiency can cause a host of conditions such as haemolytic anaemia, cerebellar ataxia and cognitive difficulties. Vitamin E supplementation is widely recommended for people with cystic fibrosis and aims to ameliorate this deficiency. This is an updated version of the review.

OBJECTIVES

To determine the effects of any level of vitamin E supplementation on the frequency of vitamin E deficiency disorders in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Group's Cystic Fibrosis Trials Register and also searched international online trial registries for any ongoing clinical trials that were not identified during our register search. Date of last search of the Register: 11 August 2020. Date of last search of international online trial registries: 20 July 2020.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials comparing any preparation of vitamin E supplementation to placebo or no supplement, regardless of dosage or duration.

DATA COLLECTION AND ANALYSIS

Two authors extracted outcome data from each study (published information) and assessed the risk of bias of each included study. They assessed the quality of the evidence using GRADE.

MAIN RESULTS

Four studies with a total of 141 participants were included in the review, two of these were in children (aged six months to 14.5 years), and two did not specify participants' age. All studies used different formulations and doses of vitamin E for various durations of treatment (10 days to six months). Two studies compared the supplementation of fat-soluble as well as water-soluble formulations to no supplementation in different arms of the same study. A third study compared a water-soluble formulation to a placebo; and in the fourth study a fat-soluble formulation of vitamin E was assessed against placebo. There was limited detail about randomisation and blinding in the included studies which compromises the quality of the evidence base for the review. The heterogeneous mix of the formulations with differing biovailabilities among these studies also limits the generalisability of the data to the wider cystic fibrosis population. None of the studies in either comparison report the review's primary outcomes of vitamin E total lipid ratio or the incidence of vitamin E-specific deficiency disorders, or the secondary outcomes lung function or quality of life. Water-soluble vitamin E Water-soluble vitamin E may improve serum vitamin E levels compared with control at six months, one study (45 participants), mean difference (MD) 19.74 umol/L (95% confidence interval (CI) 13.48 to 26.00) (low-quality evidence). Similar results were also seen at one month, two studies (32 participants), MD 17.66 umol/L (95% CI 10.59 to 24.74) and at three months, one study (45 participants), MD 11.61 umol/L (95% CI 4.77 to 18.45). Only one study (45 participants) reported weight (secondary outcome of growth and nutritional status) at one and six months, but showed no difference between treatment and control at either time point. Fat-soluble vitamin E Two studies (36 participants) reported higher levels of serum vitamin E at one month with fat-soluble vitamin E compared with control, MD 13.59 umol/L (95% CI 9.52 to 17.66); however, at three months one study (36 participants) showed no difference between treatment and control. No studies in this comparison reported on growth or nutritional status.

AUTHORS' CONCLUSIONS

Vitamin E supplementation may lead to an improvement in vitamin E levels in people with cystic fibrosis, although evidence we assessed was low quality. No data on other outcomes of interest were available to allow conclusions about any other benefits of this therapy. In future, larger studies are needed, especially in people already being treated with enteric-coated pancreatic enzymes and supplemented with vitamin E, to look at more specific outcome measures such as vitamin E status, lung function and nutritional status. Future studies could also look at the optimal dose of vitamin E required to achieve maximal clinical effectiveness.

Antioxidant supplementation for lung disease in cystic fibrosis

BACKGROUND

Airway infection leads to progressive damage of the lungs in cystic fibrosis (CF) and oxidative stress has been implicated in the etiology. Supplementation of antioxidant micronutrients (vitamin E, vitamin C, beta-carotene and selenium) or N-acetylcysteine (NAC) as a source of glutathione, may therefore potentially help maintain an oxidant-antioxidant balance. Glutathione or NAC can also be inhaled and if administered in this way can also have a mucolytic effect besides the antioxidant effect. Current literature suggests a relationship between oxidative status and lung function. This is an update of a previously published review.

OBJECTIVES

To synthesise existing knowledge on the effect of antioxidants such as vitamin C, vitamin E, beta-carotene, selenium and glutathione (or NAC as precursor of glutathione) on lung function through inflammatory and oxidative stress markers in people with CF.

SEARCH METHODS

The Cochrane Cystic Fibrosis and Genetic Disorders Group's Cystic Fibrosis Trials Register and PubMed were searched using detailed search strategies. We contacted authors of included studies and checked reference lists of these studies for additional, potentially relevant studies. We also searched online trials registries.Last search of Cystic Fibrosis Trials Register: 08 January 2019.

SELECTION CRITERIA

Randomised and quasi-randomised controlled studies comparing antioxidants as listed above (individually or in combination) in more than a single administration to placebo or standard care in people with CF.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies, extracted data and assessed the risk of bias in the included studies. We contacted study investigators to obtain missing information. If meta-analysed, studies were subgrouped according to supplement, method of administration and the duration of supplementation. We assessed the quality of the evidence using GRADE.

MAIN RESULTS

One quasi-randomised and 19 randomised controlled studies (924 children and adults) were included; 16 studies (n = 639) analysed oral antioxidant supplementation and four analysed inhaled supplements (n = 285). Only one of the 20 included studies was judged to be free of bias.Oral supplements versus controlThe change from baseline in forced expiratory volume in one second (FEV₁) % predicted at three months and six months was only reported for the comparison of NAC to control. Four studies (125 participants) reported at three months; we are uncertain whether NAC improved FEV₁ % predicted as the quality of the evidence was very low, mean difference (MD) 2.83% (95% confidence interval (CI) -2.16 to 7.83). However, at six months two studies (109 participants) showed that NAC probably increased FEV₁ % predicted from baseline (moderate-quality evidence), MD 4.38% (95% CI 0.89 to 7.87). A study of a combined vitamin and selenium supplement (46 participants) reported a greater change from baseline in FEV₁ % predicted in the control group at two months, MD -4.30% (95% CI -5.64 to -2.96). One study (61 participants) found that NAC probably makes little or no difference in the change from baseline in quality of life (QoL) at six months (moderate-quality evidence), standardised mean difference (SMD) -0.03 (95% CI -0.53 to 0.47), but the two-month combined vitamin and selenium study reported a small difference in QoL in favour of the control group, SMD -0.66 (95% CI -1.26 to -0.07). The NAC study reported on the change from baseline in body mass index (BMI) (62 participants) and similarly found that NAC probably made no difference between groups (moderate-quality evidence). One study (69 participants) found that a mixed vitamin and mineral supplement may lead to a slightly lower risk of pulmonary exacerbation at six months than a multivitamin supplement (low-quality evidence). Nine studies (366 participants) provided information on adverse events, but did not find any clear and consistent evidence of differences between treatment or control groups with the quality of the evidence ranging from low to moderate. Studies of β-carotene and vitamin E consistently reported greater plasma levels of the respective antioxidants.Inhaled supplements versus controlTwo studies (258 participants) showed inhaled glutathione probably improves FEV₁ % predicted at three months, MD 3.50% (95% CI 1.38 to 5.62), but not at six months compared to placebo, MD 2.30% (95% CI -0.12 to 4.71) (moderate-quality evidence). The same studies additionally reported an improvement in FEV₁ L in the treated group compared to placebo at both three and six months. One study (153 participants) reported inhaled glutathione probably made little or no difference to the change in QoL from baseline, MD 0.80 (95% CI -1.63 to 3.23) (moderate-quality evidence). No study reported on the change from baseline in BMI at six months, but one study (16 participants) reported at two months and a further study (105 participants) at 12 months; neither study found any difference at either time point. One study (153 participants) reported no difference in the time to the first pulmonary exacerbation at six months. Two studies (223 participants) reported treatment may make little or no difference in adverse events (low-quality evidence), a further study (153 participants) reported that the number of serious adverse events were similar across groups.

AUTHORS' CONCLUSIONS

With regards to micronutrients, there does not appear to be a positive treatment effect of antioxidant micronutrients on clinical end-points; however, oral supplementation with glutathione showed some benefit to lung function and nutritional status. Based on the available evidence, inhaled and oral glutathione appear to improve lung function, while oral administration decreases oxidative stress; however, due to the very intensive antibiotic treatment and other concurrent treatments that people with CF take, the beneficial effect of antioxidants remains difficult to assess in those with chronic infection without a very large population sample and a long-term study period. Further studies, especially in very young children, using outcome measures such as lung clearance index and the bronchiectasis scores derived from chest scans, with improved focus on study design variables (such as dose levels and timing), and elucidating clear biological pathways by which oxidative stress is involved in CF, are necessary before a firm conclusion regarding effects of antioxidants supplementation can be drawn. The benefit of antioxidants in people with CF who receive CFTR modulators therapies should also be assessed in the future.

Vitamin A and beta (β)-carotene supplementation for cystic fibrosis

BACKGROUND

People with cystic fibrosis (CF) and pancreatic insufficiency are at risk of a deficiency in fat-soluble vitamins, including vitamin A. Vitamin A deficiency predominantly causes eye and skin problems, while excessive levels of vitamin A can harm the respiratory and skeletal systems in children and interfere with the metabolism of other fat-soluble vitamins. Most CF centres administer vitamin A as supplements to reduce the frequency of vitamin A deficiency in people with CF and to improve clinical outcomes such as growth, although the recommended dose varies between different guidelines. Thus, a systematic review on vitamin A and vitamin A-like supplementation (carotenes or other retinoids) in people with CF would help guide clinical practice. This is an update of an earlier Cochrane Review.

OBJECTIVES

To determine if supplementation with vitamin A, carotenes or other retinoid supplements in children and adults with CF reduces the frequency of vitamin A deficiency disorders, improves general and respiratory health and affects the frequency of vitamin A toxicity.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Cystic Fibrosis Trials Register compiled from electronic database searches and handsearching of journals and conference abstract books. Additionally we searched several ongoing trials registries, including ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform and the International Standard Randomised Controlled Trial Number Registry.Most recent database searches: 01 June 2018.

SELECTION CRITERIA

All randomised or quasi-randomised controlled studies comparing all preparations of oral vitamin A, carotenes or retinoids (or in combination), used as a supplement compared to placebo at any dose, for at least three months, in people with CF (diagnosed by sweat tests or genetic testing) with and without pancreatic insufficiency.

DATA COLLECTION AND ANALYSIS

Two authors individually assessed study quality and extracted data on outcome measures. The authors assessed the quality of the evidence using the GRADE system. Investigators were contacted to retrieve missing quantitative data.

MAIN RESULTS

No studies of vitamin A or other retinoid supplementation were eligible for inclusion. However, one randomised study of beta (β)-carotene supplementation involving 24 people with CF who were receiving pancreatic enzyme substitution was included. The study compared successive β-carotene supplementation periods (high dose followed by low dose) compared to placebo. The results for the low-dose supplementation period should be interpreted with caution, due to the lack of a wash-out period after the high-dose supplementation.The included study did not report on two of the review's primary outcomes (vitamin A deficiency disorders and mortality); results for our third primary outcome of growth and nutritional status (reported as z score for height) showed no difference between supplementation and placebo, mean difference (MD) -0.23 (95% confidence interval (CI) -0.89 to 0.43) (low-quality evidence). With regards to secondary outcomes, supplementation with high-dose β-carotene for three months led to significantly fewer days of systemic antibiotics required to treat pulmonary exacerbations, compared to controls, MD -15 days (95% CI -27.60 to -2.40); however, this was not maintained in the second three-month section of the study when the level of β-carotene supplementation was reduced, MD -8 days (95% CI -18.80 to 2.80) (low-quality evidence). There were no statistically significant effects between groups in lung function (low-quality evidence) and no adverse events were observed (low-quality evidence). Supplementation affected levels of β-carotene in plasma, but not vitamin A levels. The study did not report on quality of life or toxicity.

AUTHORS' CONCLUSIONS

Since no randomised or quasi-randomised controlled studies on retinoid supplementation were identified, no conclusion on the supplementation of vitamin A in people with CF can be drawn. Additionally, due to methodological limitations in the included study, also reflected in the low-quality evidence judged following the specific evidence grading system (GRADE), no clear conclusions on β-carotene supplementation can be drawn. Until further data are available, country- or region-specific guidelines regarding these practices should be followed.

Metabolomic Analysis by Nuclear Magnetic Resonance Spectroscopy as a New Approach to Understanding Inflammation and Monitoring of Pharmacological Therapy in Children and Young Adults With Cystic Fibrosis

15-F2t-Isoprostane, a reliable biomarker of oxidative stress, has been found elevated in exhaled breath condensate (EBC), a non-invasive technique for sampling of airway secretions, in patients with cystic fibrosis (CF). Azithromycin has antioxidant properties in experimental models of CF, but its effects on oxidative stress in CF patients are largely unknown. Primary objective of this pilot, proof-of-concept, prospective, parallel group, pharmacological study, was investigating the potential antioxidant effects of azithromycin in CF patients as reflected by EBC 15-F2t-isoprostane. Secondary objectives included studying the effect of azithromycin on EBC and serum metabolic profiles, and on serum 15-F2t-isoprostane. In CF patients who were on maintenance treatment with oral vitamin E (200 UI once daily), treatment with oral azithromycin (250 or 500 mg depending on body weight) plus vitamin E (400 UI once daily) (group A) (n = 24) or oral vitamin E alone (400 UI once daily) (group B) (n = 21) was not associated with changes in EBC 15-F2t-isoprostane concentrations compared with baseline values after 8-weeks treatment or 2 weeks after treatment suspension. There was no between-group difference in post-treatment EBC 15-F2t-isoprostane. Likewise, no within- or between-group differences in serum 15-F2t-isoprostane concentrations were observed in either study group. NMR spectroscopy-based metabolomics of EBC shows that suspension of both azithromycin plus vitamin E and vitamin E alone has a striking effect on metabolic profiles in EBC. Between-group comparisons show that EBC metabolite distribution after treatment and 2 weeks after treatment suspension is different. Quantitative differences in ethanol, saturated fatty acids, acetate, acetoin/acetone, and methanol are responsible for these differences. Our study was unable to show antioxidant effect of azithromycin as add-on treatment with doubling the dose of oral vitamin E as reflected by 15-F2t-isoprostane concentrations in EBC. Add-on therapy with azithromycin itself does not induce EBC metabolite changes, but its suspension is associated with EBC metabolic profiles that are different from those observed after vitamin E suspension. The pathophysiological and therapeutic implications of these findings in patients with stable CF are unknown and require further research. Preliminary data suggest that EBC NMR-based metabolomics might be used for assessing the effects of pharmacological treatment suspension in stable CF patients.