# Longitudinal analysis of carotenoid content in preterm human milk

## TL;DR

This study tracks carotenoid levels in preterm human milk over time and finds that their content changes during lactation and differs in infant blood.

## Contribution

The study provides new insights into the dynamic nature of carotenoids in preterm human milk and their distribution in infant plasma.

## Key findings

- Carotenoid concentrations in human milk decrease as lactation progresses, with the highest levels in colostrum.
- Lutein and zeaxanthin become more prominent in mature milk, while lycopene and beta-carotene dominate early on.
- Infant plasma has a different carotenoid profile compared to human milk, with lutein being the most prevalent.

## Abstract

To describe the variability in carotenoid content of human milk (HM) in mothers of very to extremely low birth weight preterm infants throughout lactation and to explore the relationship between lutein in HM and the occurrence of retinopathy of prematurity (ROP) in preterm infants. We recruited healthy mothers along with their preterm infants that were born at gestational age 24 + 2 to 29 + 6 weeks or with a birth weight under 1500 g and were exclusively breastfed HM. Each participant provided up to 7 HM samples (2–10 ml) on day 0–3 and once a week until 6 weeks. Additionally, when possible, a blood sample was collected from the infant at week 6. Concentrations of the major carotenoids (lutein, zeaxanthin, beta-carotene, and lycopene) in all HM and blood samples were assessed and compared. Thirty-nine mother-infant dyads were included and 184 HM samples and 21 plasma samples were provided. Mean lutein, zeaxanthin, beta-carotene, and lycopene concentration decreased as lactation progressed, being at their highest in colostrum samples (156.9 vs. 66.9 vs. 363.9 vs. 426.8 ng/ml, respectively). Lycopene (41%) and beta-carotene (36%) were the predominant carotenoids in colostrum and up to 2 weeks post-delivery. Inversely, the proportion of lutein and zeaxanthin increased with lactation duration to account for 45% of the carotenoids in mature HM. Lutein accounted for 58% of the carotenoids in infant plasma and only 28% in HM. Lutein content of transition and mature HM did not differ between mothers of ROP and non-ROP infants.

Conclusion Carotenoid content of HM was dynamic and varied between mothers and as lactation progressed. Infant plasma displayed a distinct distribution of carotenoids from HM.

The online version contains supplementary material available at 10.1007/s00431-024-05485-8.

•Carotenoids have antioxidant properties and their contents is dynamic.

•Preterm infants are susceptible to oxidative damage, which is a key factor in the pathogenesis process of ROP.

The online version contains supplementary material available at 10.1007/s00431-024-05485-8.