Update on fat-soluble vitamins in cystic fibrosis.

PURPOSE OF REVIEW: We review and critique recent scientific advances in the understanding of fat-soluble vitamins and the care of people with cystic fibrosis.

RECENT FINDINGS: A shift in the conceptual approach to fat-soluble vitamin status has occurred. Vitamin status in cystic fibrosis had previously been discussed in terms of sufficiency versus insufficiency as compared with healthy populations. The discussion of vitamin status has now shifted to that of suboptimal versus optimal with respect to health outcomes. This is best illustrated by advances in the study of vitamin D. Newer metabolic and immunological roles and biomarkers have been identified. With supplementation of water-miscible formulations of preformed vitamin A, increased serum retinol has been observed, and may increase the risk for toxicity.

SUMMARY: A paradigm shift has occurred in defining fat-soluble vitamin status by utilizing different biomarkers and associations with health outcomes. Identification of additional biomarkers, redefining definitions of adequacy, optimal surveillance for toxicity as well as adequacy is needed for care of patients with cystic fibrosis.