Longitudinal Survey of Carotenoids in Human Milk from Urban Cohorts in China, Mexico, and the USA

Abstract

Emerging evidence indicates that carotenoids may have particular roles in infant nutrition and development, yet data on the profile and bioavailability of carotenoids from human milk remain sparse. Milk was longitudinally collected at 2, 4, 13, and 26 weeks postpartum from twenty mothers each in China, Mexico, and the USA in the Global Exploration of Human Milk Study (n = 60 donors, n = 240 samples). Maternal and neonatal plasma was analyzed for carotenoids from the USA cohort at 4 weeks postpartum. Carotenoids were analyzed by HPLC and total lipids by Creamatocrit. Across all countries and lactation stages, the top four carotenoids were lutein (median 114.4 nmol/L), β-carotene (49.4 nmol/L), β-cryptoxanthin (33.8 nmol/L), and lycopene (33.7 nmol/L). Non-provitamin A carotenoids (nmol/L) and total lipids (g/L) decreased (p<0.05) with increasing lactation stage, except the provitamin A carotenoids α- and β-cryptoxanthin and β-carotene did not significantly change (p>0.05) with lactation stage. Total carotenoid content and lutein content were greatest from China, yet lycopene was lowest from China (p<0.0001). Lutein, β-cryptoxanthin, and β-carotene, and lycopene concentrations in milk were significantly correlated to maternal plasma and neonatal plasma concentrations (p<0.05), with the exception that lycopene was not significantly associated between human milk and neonatal plasma (p>0.3). This enhanced understanding of neonatal exposure to carotenoids during development may help guide dietary recommendations and design of human milk mimetics.

Fig 1. Carotenoid species identified in milk.

C atoms are labeled to indicate positions of cis- isomers.

Fig 2. Chromatogram at 450 nm of carotenoids.

Milk (top), neonatal plasma (middle), and maternal plasma (bottom) from the same family in the USA cohort at week 4. Peak identification: (a) 13- or 13’-cis-lutein (b) 13’- or 13-cis-lutein, (c) all-trans- lutein, (*) unidentified, (d) all-trans-zeaxanthin, (e) 9- or 9’-cis- lutein, (f) α-cryptoxanthin, (g) β-cryptoxanthin, (h) echinenone internal standard,(i) 15-cis-β-carotene, (j) 13-cis-β- carotene, (k) α-carotene, (l) all-trans-β- carotene, (m) 9-cis-β-carotene, (n,o) cis-lycopene isomers, (p) all-trans-lycopene, (q) 5-cis-lycopene.

Fig 3. Box plots of major carotenoid species (sum of all identified cis and trans isomers) contents (nmol/L) by country and lactation stage.

Boxes represent 25^th, 50^th, and 75^th percentiles. Circle represent mean. Whiskers represent either minimum/maximum or 25^th/75^th minus/plus 1.5 x interquartile range, whichever is closer to the median.

Fig 4. Total lipid content (g/L) by country and lactation stage.

Boxes represent 25^th, 50^th, and 75^th percentiles. Circle represent mean. Whiskers represent either minimum/maximum or 25^th/75^th minus/plus 1.5 x interquartile range, whichever is closer to the median.

Fig 5. Scatterplots representing correlations between major carotenoids in milk (nmol/g lipid) and maternal/ neonatal plasma (nmol/L).

Beta-carotene and lycopene represent sum of cis and trans isomers. All-trans-lutein was used for correlations instead of sum of isomers because cis-lutein isomers were below the detection limit in neonatal plasma.