Vitamin B₁₂ Status in Children With Cystic Fibrosis and Pancreatic Insufficiency

Abstract

Objective Unexpectedly high serum B12 concentrations were noted in most study subjects with cystic fibrosis (CF) and pancreatic insufficiency (PI) participating in a nutrition intervention at the baseline evaluation. The objectives of this study were to determine dietary, supplement-based and enzyme-based B12 intake, serum B12 concentrations, and predictors of vitamin B12 status in children with CF and PI. Study Design Serum B12 status was assessed in subjects (5-18 yrs) and categorized as elevated (Hi-B12) or within reference range (RR-B12) for age and sex. Serum homocysteine, plasma B6, red blood cell folate, height, weight, and body mass index Z scores, pulmonary function, energy, dietary and supplement-based vitamin intake were assessed. Results 106 subjects, mean age 10.4 ± 3.0 years participated. Median serum B12 was 1083 pg/ml, with 56% in the Hi-B12 group. Dietary and supplement-based B12 intake were both high representing 376% and 667% Recommended Dietary Allowance (RDA). The Hi-B12 group had significantly greater supplement-based B12 intake than the RR-B12 group (1000 vs. 583% RDA, p<0.001). By multiple logistic regression analysis, high supplement-based B12 intake and age >12 years increased risk for Hi-B12, while higher FEV1 decreased risk (Pseudo-R2=0.18, P<0.001). Conclusions Serum B12 was elevated in the majority of children with CF and PI. Supplement-based B12 intake was 6 to 10 times the RDA, and strongly predicted elevated serum B12 status. The health consequences of lifelong high supplement-based B12 intake and high serum B12 are unknown and require further study, as does the inversed correlation between serum B12 and FEV1.

Choline supplementation alters some amino acid concentrations with no change in homocysteine in children with cystic fibrosis and pancreatic insufficiency

“…Serum B 12 concentrations were above reference ranges in > 50% of subjects as previously reported. [10] Growth status improved and REE declined in both LXS and placebo groups as previously reported. [15] FEV 1 declined over the 12 months as the subjects aged, with no differences between randomization groups (data not presented).…”

“…Children in the higher serum B 12 group were older and had poorer growth status as indicated by BMIZ and lower lung function. [10] The current findings of high cysteine and low homocysteine may be due to enhanced remethylation and trans-sulfuration related to the unusually high B 12 and B 6 intake common in current CF clinical care.…”

“…[45] High serum B 12 has been reported in the majority of children with CF and PI and was likely related to the high vitamin B 12 content of CF-specific vitamin and mineral products. [10] There is no clinical indication for high B 12 doses in CF. These CF products are commonly used to provide high fat soluble vitamin doses to compensate for the chronic fat malabsorption in CF.…”

“…[8,9] Little is known about the effect of choline supplementation on amino acid status, particularly in the CF care setting where the daily intake from CF-specific vitamin products results in serum vitamin B 12 concentrations that are relatively high. [10] In a study by Innis et al [11], high dose choline supplementation for two weeks in children with CF improved choline status, reduced plasma homocysteine and increased methionine concentrations. These effects may be explained by remethylation of homocysteine to methionine in two interrelated pathways that involve choline, folic acid and vitamin B 12 .…”

Pancreatic insufficiency in Cystic Fibrosis

“…PT/INR is generally used to assess adequate vitamin K levels, with the known limitation that this is an insensitive method. Testing for vitamin B12 deficiency should not be necessary unless the individual has prolonged untreated PI [49]. Supplementation should be directed by the test results (see below).…”