Vitamin K supplementation for cystic fibrosis (Jagannath VA, et al.)
Cystic fibrosis is a genetic disorder that can lead to multi-organ dysfunction. Malabsorption of fat and fat-soluble vitamins (A, D, E, K) may occur and can cause subclinical deficiencies of some of these vitamins. Vitamin K is known to play an important role in both blood coagulation and bone formation.
Supplementation with vitamin K appears to be one way of addressing the deficiency, but there is very limited agreement on the appropriate dose and frequency of use of these supplements. To that end, Jagannath et al. sought to assess the effects of vitamin K supplementation in people with cystic fibrosis and to determine the optimal dose and route of administration of vitamin K for both routine and therapeutic use.
“We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group’s Trials Register comprising references identified from comprehensive electronic database searches,” said researchers, adding that handsearches of relevant journals and abstract books of conference proceedings were also included. The most recent search was conducted on October 8, 2014.
The selection criteria were randomized and quasi-randomized controlled trials of all preparations of vitamin K used as a supplement compared to either no supplementation (or placebo) at any dose or route and for any duration, in children or adults diagnosed with cystic fibrosis (by sweat test or genetic testing). Two authors independently screened papers, extracted trial details, and assessed their risk of bias.
According to researchers, two trials (total of 32 participants) each lasting one month were included in the review and were assessed as having a moderate risk of bias. One was a dose-ranging parallel group trial in children (aged 8 to 18 years); and the other (with an older cohort) had a cross-over design comparing supplements to no treatment, but no separate data were reported for the first intervention period.
“Neither of the trials addressed any of the primary outcomes (coagulation, bone formation and quality of life),” stated researchers. “Both trials reported the restoration of serum vitamin K and undercarboxylated osteocalcin levels to the normal range after one month of daily supplementation with 1 mg of vitamin K.
“Evidence from randomized controlled trials on the benefits of routine vitamin K supplementation for people with CF is currently weak and limited to two small trials of short duration. However, no harm was found and until further evidence is available, the present recommendations should be adhered to,” the authors concluded.
Dr. Katarzyna Maresz, president of the International Science and Health Foundation, is very excited that this new area of study, cystic fibrosis, is on the scientific community’s radar. However, she expressed that a possible drawback to the researchers’ conclusion is that they evaluated trials using 1 mg of Vitamin K1.
“Both trials reported the restoration of serum vitamin K and undercarboxylated osteocalcin levels to the normal range after one month of daily supplementation with 1 mg of vitamin K,” said Dr. Maresz. “What would likely be more beneficial would be a trial utilizing Vitamin K2, as an even lower dose would be necessary. However, it needs to be evaluated in the clinic. But this doesn’t undermine what an exciting new subject of study this represents.”
Reference: Jagannath VA, Fedorowicz Z, Thaker V, Chang AB. Vitamin K supplementation for cystic fibrosis. Cochrane Database Syst Rev. 2015 Jan 18;1:CD008482. [Epub ahead of print]