Total folate and unmetabolized folic acid in the breast milk of a cross-section of Canadian women,. Issue 5 (15th March 2017)

• Record Type: Journal Article
• Authors: Page, Rachael; Robichaud, André; Arbuckle, Tye E; Fraser, William D; MacFarlane, Amanda J
• Is Part Of: American journal of clinical nutrition. Volume 105:Issue 5(2017)
• Page Start: 1101
• Page End: 1109
• Publication Date: 2017-03-15
• Subjects: breast milk -- folate -- folic acid -- supplements -- unmetabolized folic acid; Diet therapy -- Periodicals; Nutrition -- Periodicals; Dietetics -- Periodicals; 613.205
• DOI: 10.3945/ajcn.116.137968
• Languages: English
• ISSNs: 0002-9165

Abstract

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.