primary studies published RCT Effect of double-blind crossover selenium supplementation on biological indices of selenium status in cystic fibrosis patients. Year: 1993 Date: 1993 Author: Portal B Source Clin Chem. 1993 Jun;39(6):1023-8. Study design (if review, criteria of inclusion for studies) RCT Related topics Omega-3 fatty acids, zinc and probiotics supplements in cystic fibrosis