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

Background: Oxidative stress, as measured by 8-iso-prostaglandin F-2alpha (8-iso-PGF(2alpha)), 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(2alpha), 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 mug vitamin A)] or group B [high dose of supplement (200 mg vitamin E, 300 mg vitamin C, 25 mg beta-carotene, 90 mug Se, and 500 mug vitamin A)]. Plasma concentrations of 8-iso-PGF(2alpha) vitamins E and C, P-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 mumol/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 Deltaglutathione 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(2alpha), Deltavitamin C, Deltafatty acid composition, Deltasuperoxide dismutase activity, Deltalung function, or Deltawhile cell count. Within group B, Deltabeta-carotene correlated with Deltapercentage of forced vital capacity (r = 0.586, P = 0.005), Deltaselenium correlated with Deltapercentage of forced expiratory volume in 1 s (r = 0.440, P = 0.046), and Deltaplasma fatty acid concentrations correlated with Deltapercentage of forced expiratory volume in 1 s (r = 0.583, P = 0.006) and Delta8-iso-PGF(2alpha) (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.