Vitamin B12 concentrations vary greatly in milk donated to a large provincial milk bank, and are influenced by supplementation and parity

Abstract

Background & aims

Feeding parent's milk with supplemental donor milk (DM) is the optimal way to feed very low birth weight (VLBW) infants instead of formula; however, suboptimal neurodevelopment persists. This is believed due, in part, to suboptimal nutrition. Given vitamin B12's role in neurodevelopment and increased adoption of plant-based diets among females of child-bearing age, we aimed to determine the adequacy of vitamin B12 in DM (n = 380 donors) and associated donor characteristics.

Methods

Vitamin B12 was measured in consecutive raw DM donations received at the milk bank from March 2020–2021 using a validated competitive chemiluminescent enzyme immunoassay (IMMULITE 2000, Siemens). Donor characteristics were obtained from screening records and associations with milk vitamin B12 concentrations explored using a generalized additive model.

Results

Donors were 32 ± 4 years old (mean ± SD), and DM was expressed 98 ± 85 days postpartum. Vitamin B12 concentrations in DM had a median (25th, 75th percentile) of 232 (149, 373) pmol/L; 64 % had concentrations <310 pmol/L (common cut-off for inadequacy in healthy term-born infants). In a multivariable analysis, donors consuming a vitamin B12-containing supplement had higher DM vitamin B12 (β ± SE: 80.3 ± 25.4 pmol/L; p = 0.020) compared to those not taking a supplement. Primiparous donors had higher DM vitamin B12 than multiparous donors (36.7 ± 18.2 pmol/L greater; p = 0.044). No associations were observed for other donor characteristics.

Conclusion

Milk donated to a large human milk bank showed evidence of suboptimal vitamin B12; levels were associated with both donor vitamin B12-containing supplement use and parity. Further research as to whether and when milk bank donors are recommended to consume a supplement and the benefits and risks of routine vitamin B12 supplementation of DM-fed infants is warranted.