Retinol-to-Fat Ratio and Retinol Concentration in Human Milk Show Similar Time Trends and Associations with Maternal Factors at the Population Level: A Systematic Review and Meta-Analysis.
What this study found
Overall, postpartum high-dose vitamin A increased human-milk retinol:fat and retinol versus controls, with effects persisting through about 12 and 24 weeks of lactation, respectively (P < 0.05). In the pooled time analysis, the intervention-control difference in retinol:fat declined linearly over time (r = 0.74, P = 0.002), with an x-intercept of 28.6 weeks, suggesting little further benefit beyond that point. Individual trials were consistent with this pattern: 400,000 IU given within 24 h of delivery increased retinol at 4, 14, and 26 weeks and retinol:fat at 4 weeks; 200,000 IU retinol…
- Study & population
- Systematic review and meta-analysis of studies in lactating women from diverse global settings, including Africa, Asia, the Americas, and Europe.
- Intervention
- The review evaluated maternal vitamin A and carotenoid supplementation during the postpartum period, mainly high-dose vitamin A given as 200,000-400,000 IU retinol or retinyl palmitate, usually as a single dose within 24 h of delivery or at 1-3 weeks postpartum, compared with placebo or control.
- Key limitation
- The included trials were heterogeneous in dose, formulation, timing, and outcome assessment, limiting direct comparability.
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Open PDFOriginal abstract
Vitamin A in human milk is critical for meeting infant requirements and building liver stores needed after weaning. A number of studies have measured 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 was 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 approach was used to search the available literature by using the US National Library of Medicine's MEDLINE/PubMed bibliographic search engine. Observational and intervention studies were included if the research was original and the retinol-to-fat ratio (retinol:fat) in human milk was measured at ≥1 time point during the first 12 mo of lactation. Retinol:fat and retinol were highest in colostrum, declined rapidly in early lactation, and achieved statistical stability by 2 and 4 wk lactation, respectively. In mature milk, retinol concentration was positively correlated with milk fat (r = 0.61, P = 0.008). 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 mo and retinol for 6 mo (P < 0.05). In populations, the 2 indexes show similar trends and associations with maternal factors. Future studies should monitor how the uptake of retinol into the mammary gland affects maternal vitamin reserves, particularly in women who are at risk of vitamin A deficiency.