Systematic review of carotenoid concentrations in human milk and infant blood

Context: Dietary carotenoid intake is associated with vitamin A status and healthy visual and cognitive function in early life. To date, however, only limited population-level data on the concentrations of carotenoids in human milk or infant blood have been available to assess the dietary exposure of infants to carotenoids.

Objective: This systematic review seeks to define worldwide carotenoid concentrations in human milk and infant blood.

Data sources: The PubMed, Embase, and Web of Science databases were searched for original research articles published before February 2021.

Data extraction: Dietary carotenoid concentrations in human milk and in blood plasma or serum from healthy infants (≤1 year of age), along with study location, infant age, and lactation stage, were extracted. Means and 95%CIs were analyzed within and across variables.

Data analysis: Publications on carotenoid concentrations in infant blood (47 publications, n = 4553 unique individuals) and human milk (65 publications, n = 2871 unique individuals) described populations from 22 and 31 countries, respectively. Carotenoid species concentrations ranged from 0.3 to 20 µg/dL in blood and from 0.1 to 30 µg/dL in human milk, with carotenoid concentrations generally decreasing in milk across lactation stages and increasing in blood with infant age.

Conclusion: Concentrations of the major dietary carotenoids-β-carotene, lycopene, lutein, β-cryptoxanthin, zeaxanthin, and α-carotene-have been reported in both infant blood and human milk across infant ages and lactation stages, with β-carotene, lutein, and lycopene tending to be more abundant than other carotenoids. Despite heterogeneous amounts of data available for each outcome, infants worldwide are exposed to a variety of dietary carotenoids. The estimates of dietary carotenoids in human milk and infant blood can facilitate the interpretation of future studies and the design of nutritionally relevant experiments on dietary carotenoids and infant health.