Improved antioxidant and fatty acid status of patients with cystic fibrosis after antioxidant supplementation is linked to improved lung function.

The American journal of clinical nutrition. 2003;77(1):150-9

Plain language summary

Oxidative stress is elevated in patients with cystic fibrosis (CF). It has been hypothesised that supplementing with antioxidants reduces oxidative stress and therefore the rate of lung deterioration in CF patients. The aim of the study was to examine oxidative stress and antioxidant defences in CF patients after antioxidation supplementation in relation to fatty acid status, dietary intake and clinical status. Children with CF were given a high dose supplement containing 200mg vitamin E, 300mg vitamin C, 25mg beta-carotene, 90 micrograms selenium and 500 micrograms vitamin A for 8 weeks. The control group received low doses of vitamins A and E equal to the RDA, which is part of routine treatment for some CF patients. At the end of the study, the group taking the high dose antioxidant supplement showed significant increases in plasma concentrations of vitamin E, beta-carotene, selenium and glutathione peroxidase compared to the control group. Despite this, there were no significant differences in markers of lung function or wellbeing between the two groups. The researchers did however find correlations between both increased plasma fatty acids and antioxidant (beta-carotene and selenium) status and improved lung function, suggesting that antioxidant supplementation and high fat diets may be beneficial for CF patients. Since increased plasma fatty acids are linked to oxidative stress, the authors point out the importance of reducing oxidative stress in CF patients who are on a high-fat diet.

Abstract

BACKGROUND Oxidative stress, as measured by 8-iso-prostaglandin F(2)(alpha) (8-iso-PGF(2)(alpha)), and depleted antioxidant defenses were shown in stable cystic fibrosis (CF) patients. The plasma fatty acid status of CF patients was linked to oxidative stress after respiratory exacerbations. OBJECTIVE We examined changes in plasma 8-iso-PGF(2)(alpha), antioxidant defenses, plasma fatty acid status, and clinical markers resulting from short-term antioxidant supplementation. DESIGN Forty-six CF patients were randomly assigned to either group A [low dose of supplement (10 mg vitamin E and 500 micro g vitamin A)] or group B [high dose of supplement (200 mg vitamin E, 300 mg vitamin C, 25 mg beta-carotene, 90 micro g Se, and 500 micro g vitamin A)]. Plasma concentrations of 8-iso-PGF(2)(alpha), vitamins E and C, beta-carotene, zinc, selenium, and copper; plasma fatty acid composition; erythrocyte glutathione peroxidase (EC 1.11.1.9) and superoxide dismutase (EC 1.15.1.1) activities; lung function; and dietary intake were measured before and after 8 wk of supplementation. RESULTS Antioxidant defenses in group B improved, whereas those in group A did not: in groups B and A, the mean (+/- SEM) changes (Delta) in vitamin E were 10.6 +/- 1.5 and -1.9 +/- 0.9 micro mol/L, respectively (P < 0.001), (Delta)beta-carotene were 0.1 +/- 0.04 and -0.01 +/- 0.02 micro mol/L, respectively (P = 0.007), (Delta)selenium were 0.51 +/- 0.10 and -0.09 +/- 0.04 micro mol/L, respectively (P < 0.001), and (Delta)glutathione peroxidase activity were 1.3 +/- 0.3 and -0.3 +/- 0.6 U/g hemoglobin, respectively (P = 0.016). There were no significant differences between the groups in Delta8-iso-PGF(2)(alpha), (Delta)vitamin C, (Delta)fatty acid composition, (Delta)superoxide dismutase activity, (Delta)lung function, or (Delta)white cell count. Within group B, (Delta)beta-carotene correlated with (Delta)percentage of forced vital capacity (r = 0.586, P = 0.005), (Delta)selenium correlated with (Delta)percentage of forced expiratory volume in 1 s (r = 0.440, P = 0.046), and (Delta)plasma fatty acid concentrations correlated with (Delta)percentage of forced expiratory volume in 1 s (r = 0.583, P = 0.006) and Delta8-iso-PGF(2)(alpha) (r = 0.538, P = 0.010). CONCLUSIONS Whereas increased beta-carotene, selenium, and fatty acid concentrations are linked to improved lung function, increased plasma fatty acid concentrations are linked to oxidative stress. If oxidative stress is deemed to be important to the clinical outcome of CF patients, means of reducing oxidative stress while maintaining a high-fat, high-energy diet must be investigated.

Lifestyle medicine

Fundamental Clinical Imbalances : Immune and inflammation
Patient Centred Factors : Mediators/Oxidative stress
Environmental Inputs : Nutrients
Personal Lifestyle Factors : Nutrition
Functional Laboratory Testing : Blood
Bioactive Substances : Selenium ; Lung function ; Beta-carotene ; Vitamin C

Methodological quality

Jadad score : 3
Allocation concealment : Yes

Metadata

Nutrition Evidence keywords : Selenium ; Lung function ; Beta-carotene ; Vitamin C