Vitamin A dynamics in breastmilk and liver stores: A life history perspective

Authors

  • Masako Fujita,

    Corresponding author
    1. Department of Anthropology, Michigan State University, East Lansing, Michigan
    • Michigan State University, Department of Anthropology, 328 Baker Hall, East Lansing 48824, MI, USA
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  • Bettina Shell-Duncan,

    1. Department of Anthropology, University of Washington, Seattle, Washington
    2. Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington
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  • Philip Ndemwa,

    1. Centre for Public Health Research, Kenya Medical Research Institute, Nairobi, Kenya
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  • Eleanor Brindle,

    1. Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington
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  • Yun-Jia Lo,

    1. Department of Counseling, Educational Psychology and Special Education, Michigan State University, East Lansing, Michigan
    2. Center for Statistical Training and Consulting, Michigan State University, East Lansing, Michigan
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  • Yeri Kombe,

    1. Centre for Public Health Research, Kenya Medical Research Institute, Nairobi, Kenya
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  • Kathleen O'connor

    1. Department of Anthropology, University of Washington, Seattle, Washington
    2. Center for Studies in Demography and Ecology, University of Washington, Seattle, Washington
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Abstract

Objectives:

Newborns are dependent on breastmilk vitamin A for building hepatic stores of vitamin A that will become critical for survival after weaning. It has been documented that vitamin A concentrations in breastmilk decline across the first year postpartum in both well-nourished and malnourished populations. The reason for this decline has been assumed to be a sign of concurrently depleting maternal hepatic stores. This study investigates this assumption to clarify why the decline occurs, drawing on life history theory.

Methods:

A cross sectional survey was conducted among lactating mothers in Kenya in 2006. Data were used to examine (1) the relationship between liver vitamin A and time, (2) if the relationship between milk and liver vitamin A varies by time, and (3) by maternal parity.

Results:

The relationship between liver vitamin A and time fits the quadratic pattern with marginal significance (P = 0.071, n = 192); the liver vitamin A declined during early postpartum then recovered in late postpartum time, controlling covariates. The milk-liver vitamin A relationship varied by postpartum time periods (P = 0.03) and by maternal parity (P = 0.005). Mothers in earlier postpartum or higher parity had a stronger positive relationship between milk and liver vitamin A than mothers in later postpartum or lower parity.

Conclusions:

Our observations are consistent with life history tradeoffs and negate the assumption that maternal hepatic and milk vitamin A decline together. Rather, maternal liver vitamin A has a dynamic relationship with milk vitamin A, particularly depending on postpartum time and maternal parity. Am. J. Hum. Biol., 2011. © 2011 Wiley-Liss, Inc.

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