Cochrane: We
reviewed the evidence to see whether supplementing vitamin K in people
with cystic fibrosis counteracts the effects of deficiency on blood
clotting, bone strength and quality of life in people with cystic
fibrosis. We tried to determine the best dose needed to prevent this
deficiency.
Background
Cystic fibrosis is an inherited condition which causes disease, most
noticeably in the lungs, digestive system and pancreas. In people with
cystic fibrosis, the pancreas often does not produce enough enzymes to
allow the body to absorb digested food properly and this may also be
linked to deficiencies of fat-soluble vitamins like vitamin K. Vitamin K
is needed for adequate blood clotting, bone formation and some
metabolic functions.
Search date
The evidence is current to: 08 October 2014.
Study characteristics
We included two trials (total of 32 participants) in the review. In one trial (14 children aged 8 to 18 years old) for one month half of the participants were given oral vitamin K supplements at a dose of 1 mg/day and the other half were given 5 mg/day. In the second trial all the 18 volunteers (aged 13 to 35 years) were given 5 mg oral
vitamin K supplement or nothing for one month and then they swapped to
the other group for another month. Unfortunately, we could not analyse
the data from this second trial because the investigators did not report data just from the first part of the trial (only from the end of the trial when all volunteers had been in both groups), so we could not tell if the effects were due to supplements or no supplements.
Key results
Neither trial addressed any of the review's
primary outcomes (blood clotting, bone formation and quality of life).
Both trials reported that in patients who had low levels of vitamin K
measured in the blood and also another laboratory marker of vitamin K
(undercarboxylated osteocalcin), these levels returned to the normal
range after one month of daily supplementation with 1 mg of vitamin K.
Quality of the evidence
We were satisfied that both trials reported all the outcomes they planned to and that the results were not at risk
of being biased due to volunteers dropping out of the trials. We did
not have enough details to decide whether results would be affected by
the way the trials were set up or in case volunteers could tell which
treatment they were receiving (it would be obvious in the trial comparing supplements to no treatment),
- See more at: http://summaries.cochrane.org/CD008482/CF_vitamin-k-supplementation-for-cystic-fibrosis#sthash.XTxbw1hi.dpuf