Location: Obesity and Metabolism Research
Project Number: 2032-51530-025-027-T
Project Type: Trust Fund Cooperative Agreement
Start Date: Nov 18, 2016
End Date: Nov 1, 2021
Objective:
We propose to conduct a multi-center study to develop Reference Values for micronutrients, amino acids, and other constituents of human milk supported by measures of maternal and infant diet and status. This will: improve estimates of nutrient requirements and intake gaps for infants, young children and lactating women; enable evaluation of breast milk quality and its relationship to maternal diet and infant and maternal nutritional status across population groups; and provide a global tool with which to evaluate the need for and effects of maternal or infant supplementation, and food fortification. The proposed research follows on from our two previous grants from the Bill & Melinda Gates Foundation. The products of those grants were: development of methods for the efficient, valid analysis of micronutrients in milk samples; assessment of the effects of sample collection protocols on milk micronutrient concentrations; and a major review of the literature on micronutrients in milk including Systematic Reviews of three nutrients, which will be published as a series of seven journal articles. Overall the purpose of our previous work was to establish the need for, and feasibility of, conducting the currently proposed study to develop Reference Values for nutrients in human milk.
Approach:
We propose to collect breast milk samples from mothers age =18 to <40 years in a systematic, identical way in four countries, The Gambia, Brazil, Denmark and Bangladesh. The criteria for selection of the field sites are:
1) Mothers are healthy and well-nourished but not consuming mineral-vitamin supplements after mid-pregnancy or during lactation, or consuming substantial amounts of micronutrient-fortified foods. (Folic acid-iron supplements or fortification are permitted, as intake of these micronutrients does not affect their concentrations in breast milk). “Well-nourished” population groups will be identified during the pilot phase, using existing data or collecting new information in a relevant subsample: dietary data to estimate prevalence of inadequate intakes of specific and total micronutrients; anemia (Hemocue); a locally-validated food frequency questionnaire (usual consumption of animal source foods + a dietary diversity score); birth weights in the normal range and a low prevalence of stunting. A profile will be established for each country within the first 2-3 months, including data on supplement use, fortified foods, food and nutrient intakes, infant anthropometry, etc. After establishing that the populations are generally well-nourished, screening of individual participants will be required, and dietary and nutritional status markers collected throughout the study.
2) Exclusive breastfeeding is common through 4 months postpartum and breastfeeding typically continues through at least 10 months postpartum. An absolute requirement is ability to recruit 250 mother-infant dyads who are exclusively breastfed at 2 to 4 months and predominantly breastfeeding at 4 to 6 months. This will require enrollment of ˜500 mothers at delivery. Since a high proportion of mothers will not be exclusively breastfeeding after 6 months, the 8-10 month milk and serum samples can be collected from a cross-sectional sample of participants.
Maternal and infant anthropometry, diet, and breast milk samples will be collected at 1-2, 2-4, 4-6 and 8-10 months postpartum including measurement of milk volume with deuterated water in a subset of 30 women per site. Maternal and infant blood will be collected at 2-4, 4-6 and 8-10 months and urine at 2-4 months. Laboratory analyses will be conducted at the WHNRC for all 4 locations including: serum and milk retinol and vitamin E by HPLC; vitamins B1, B2, B3 and B6 by HPLC-MS/MS; and vitamin B12 by immunoassay. Milk and infant plasma samples will also be analyzed for free amino acids, choline, lactose and other metabolites using HPLC-MS/MS. Urinary and milk iodine will be measured at ETHZ in Zurich, Switzerland.
Milk micronutrient concentrations will be compared across sites, and combined if the sites are deemed to be equivalent; or combined for 2-3 sites if not. From the distributions of values of concentrations of each nutrient the 5th, 25th, 50th, 75th and 95th percentiles will be estimated. The study will enable the same calculations to be made for micronutrient concentrations in infant serum across the first 10 months of life.
