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

Abstract

Background: Oxidative stress, as measured by 8-iso-prostaglandin F2α (8-iso-PGF2α), 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-PGF2α, 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 μg vitamin A)] or group B [high dose of supplement (200 mg vitamin E, 300 mg vitamin C, 25 mg β-carotene, 90 μg Se, and 500 μg vitamin A)]. Plasma concentrations of 8-iso-PGF2α, vitamins E and C, β-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 (Δ) in vitamin E were 10.6 ± 1.5 and -1.9 ± 0.9 μmol/L, respectively (P < 0.001), Δβ-carotene were 0.1 ± 0.04 and -0.01 ± 0.02 μmol/L, respectively (P = 0.007), Δselenium were 0.51 ± 0.10 and -0.09 ± 0.04 μmol/L, respectively (P < 0.001), and Δglutathione 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 Δ8-iso-PGF2α, Δvitamin C, Δfatty acid composition, Δsuperoxide dismutase activity, Δlung function, or Δwhite cell count. Within group B, Δβ-carotene correlated with Δpercentage of forced vital capacity (r = 0.586, P = 0.005), Δselenium correlated with Δpercentage of forced expiratory volume in 1 s (r = 0.440, P = 0.046), and Δplasma fatty acid concentrations correlated with Δpercentage of forced expiratory volume in 1 s (r = 0.583, P = 0.006) and Δ8-iso-PGF2α (r = 0.538, P = 0.010). Conclusions: Whereas increased β-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.