title: Total folate and unmetabolized folic acid in the breast milk of a cross-section of Canadian women.
abstract: Background:Folate requirements increase during pregnancy and lactation. It is recommended that women who could become pregnant, are pregnant, or are lactating consume a folic acid (FA)-containing supplement.Objectives:We sought to determine breast-milk total folate and unmetabolized folic acid (UMFA) contents and their relation with FA-supplement use and doses in a cohort of Canadian mothers who were enrolled in the MIREC (Maternal-Infant Research on Environmental Chemicals) study.Design:Breast-milk tetrahydrofolate (THF), 5-methyl-THF, 5-formyl-THF, 5,10-methenyl-THF, and UMFA were measured with the use of liquid chromatography-tandem mass spectrometry (n= 561). Total daily supplemental FA intake was based on self-reported FA-supplement use.Results:UMFA was detectable in the milk of 96.1% of the women. Total daily FA intake from supplements was associated with breast folate concentration and species. Breast-milk total folate was 18% higher (P< 0.001) in supplement users (n= 401) than in nonusers (n= 160), a difference driven by women consuming >400 μg FA/d (P≤ 0.004). 5-Methyl-THF was 19% lower (P< 0.001) and UMFA was 126% higher (P< 0.001) in supplement users than in nonusers. Women who consumed >400 μg FA/d had proportionally lower 5-methyl-THF and higher UMFA than did women who consumed ≤400 μg FA/d.Conclusions:FA-supplement use was associated with modestly higher breast-milk total folate. Detectable breast-milk UMFA was nearly ubiquitous, including in women who did not consume an FA supplement. Breast-milk UMFA was proportionally higher than 5-methyl-THF in women who consumed >400 μg FA/d, thereby suggesting that higher doses exceed the physiologic capacity to metabolize FA and result in the preferential uptake of FA in breast milk. Therefore, FA-supplement doses >400 μg may not be warranted, especially in populations for whom FA fortification is mandatory.
authors.affiliation: Nutrition Research Division.|Department of Biology, Carleton University, Ottawa, Ontario, Canada; and.
authors.forename: Rachael
authors.initials: R
authors.lastname: Page
authors.affiliation: Regions and Programs Branch, and.
authors.forename: André
authors.initials: A
authors.lastname: Robichaud
authors.affiliation: Population Studies Division, Health Canada, Ottawa, Ontario, Canada.
authors.forename: Tye E
authors.initials: TE
authors.lastname: Arbuckle
authors.affiliation: Sainte-Justine University Hospital Research Center, University of Montreal, Montreal, Quebec, Canada.
authors.forename: William D
authors.initials: WD
authors.lastname: Fraser
authors.affiliation: Nutrition Research Division, amanda.macfarlane@canada.ca.|Department of Biology, Carleton University, Ottawa, Ontario, Canada; and.
authors.forename: Amanda J
authors.identifier: 0000-0002-3208-3483
authors.initials: AJ
authors.lastname: MacFarlane
mesh_terms: D000328:Adult; D001940:Breast; D002170:Canada; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007774:Lactation / Q000378:metabolism*; D008895:Milk, Human / Q000378:metabolism*; D009751:Nutritional Requirements; D011247:Pregnancy; D013763:Tetrahydrofolates / Q000378:metabolism; D014803:Vitamin B Complex / Q000378:metabolism / Q000494:pharmacology
chemical_list: D013763:Tetrahydrofolates; D014803:Vitamin B Complex; D005492:Folic Acid; C005984:5-methyltetrahydrofolate
keywords: breast milk; folate; folic acid; supplements; unmetabolized folic acid