Location: Obesity and Metabolism ResearchTitle: Retinol to fat ratio and retinol in human milk: a systematic review and meta-analysis
|DROR, DAPHNA - Consultant|
|Allen, Lindsay - A|
Submitted to: Advances in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2018
Publication Date: 5/29/2018
Citation: Dror, D., Allen, L.H. 2018. Retinol to fat ratio and retinol in human milk: a systematic review and meta-analysis. Advances in Nutrition. 9:332S-346S. https://doi.org/10.1093/advances/nmy021.
Interpretive Summary: Milk retinol (vitamin A) concentrations have been described in a number of studies – it is the most studied micronutrient in human milk. However two thirds of studies did not measure milk fat in the sample, although reportedly this influences milk retinol concentration. The purpose of this article was therefore to review studies (21 were selected for review and analysis) where human milk retinol concentrations were reported with and without adjustment for the concentration of milk fat in the sample over the course of lactation, and the influences of maternal nutritional and other factors, and maternal vitamin A supplementation on the ratio of retinol to fat. Retinol:fat and retinol were highest in colostrum then fell rapidly in early lactation, and achieved statistical stability by 2 and 4 weeks lactation, respectively. In mature milk, the concentration of retinol was positively correlated with milk fat. Breast milk retinol:fat and retinol were positively associated with maternal vitamin A intake, while an association with plasma retinol alone was present only in women with inadequate intake. Postpartum supplementation with high dose vitamin A (200,000-400,000 IU) resulted in significantly higher breast milk retinol:fat for 3 mo and retinol for 6 mo (p < 0.05).We conclude that milk retinol concentration, uncorrected for milk fat, can still serve as an indicator of population vitamin A status.
Technical Abstract: Vitamin A in breast milk is critical for meeting infant requirements and building liver stores needed after weaning. A number of studies have measured human milk retinol but only a subset have corrected for fat, which serves as the retinol carrier in breast milk. The purpose of the present work is to review and analyze studies in which human milk retinol concentrations were reported in relation to milk fat, and to compare these results with unadjusted breast milk retinol concentrations in terms of time trends over the course of lactation, influences of maternal nutritional and constitutional factors, and effects of maternal vitamin A supplementation. A systematic search of published literature was undertaken using the US National Library of Medicine’s MEDLINE/PubMed bibliographic search engine. Observational and intervention studies were included if research was original and retinol:fat in human milk was measured or reported at one or more time points during the first twelve months of lactation. Retinol:fat and retinol were highest in colostrum, declined rapidly in early lactation, and achieved statistical stability by 2 and 4 weeks lactation, respectively. In mature milk, retinol concentration was positively correlated with milk fat (r = 0.62, p = 0.02). Breast milk retinol:fat and retinol were positively associated with maternal vitamin A intake, but were associated with plasma retinol only when dietary intake was inadequate. Postpartum supplementation with high dose vitamin A (200,000-400,000 IU) resulted in significantly higher breast milk retinol:fat for 3 months and retinol for 6 months (p < 0.05). In populations, the two indices show similar trends and associations with maternal factors. Future studies should monitor maternal relative dose response 40 to determine how uptake of retinol into the mammary gland impacts maternal vitamin reserves, particularly in women who are at risk of vitamin A deficiency