PC2034: Vitamin D Binding Protein and Its Presence in Human Milk

Background: Vitamin D Binding Protein (VDBP) can be found in all tissues and fluids in the body and is important in not only vitamin D metabolism, but also immune modulation.

Methods: The goal of this project was to study the relationship between VBDP, albumin, and immunoglobulins and attempt to relate it maternal and infant attributes. 48 lactating mothers from NICU, PICU, and newborn nursery were consented to provide human milk for analysis with 54 total samples obtained. Using nephelometry, VDBP concentration along with albumin and immunoglobulin levels were obtained. Data were analyzed using independent samples t-test with significance defined as a p-value < 0.05.

Results: In our analyses, VDBP concentration ranged from 0-256 µg/mL, with a mean of 60.3 standard deviation of 71.4. 7 out of 54 samples did not have VDBP detected, and 30 out of 54 samples did not have detectable concentrations of albumin. Of the samples with detectable concentrations, VDBP concentration correlated with albumin concentration (r = .80, p < 0.01), but did not correlate with immunoglobulin concentrations (IgA, IgG, and IgM). Albumin concentrations differed significantly between races (i.e., white versus not white; p = .05). However, VDBP did not differ by race. No significant differences in VDBP, albumin, and immunoglobulins were found between preterm versus term gestational age infants.

Conclusion: There are few reports on VDBP in human milk. In this small sample size, there appears to be no association between VDBP concentration and gestational age, race, or birth weight of the infant. Considering recent literature and the potential importance of vitamin D on infant microbiota, further research on its correlation with maternal vitamin D status, human milk VDBP, and infant microbiota needs to be performed.