Folate-status response to a controlled folate intake in nonpregnant, pregnant, and lactating women

• Published in: The American journal of clinical nutrition 2012-10, Vol.96 (4), p.789-800
• Main Authors: West, Allyson A, Yan, Jian, Perry, Cydne A, Jiang, Xinyin, Malysheva, Olga V, Caudill, Marie A
• Format: Article
• Language: English
• Subjects: Adult; at-risk population; Biological and medical sciences; Biomarkers - blood; Biomarkers - metabolism; Biomarkers - urine; blood serum; breast milk; clinical nutrition; Diet; Dietary supplements; Dietary Supplements - adverse effects; dose response; excretion; Feeding. Feeding behavior; Female; folic acid; Folic Acid - administration & dosage; Folic Acid - blood; Folic Acid - metabolism; Folic Acid - urine; Food; Food, Fortified; Fundamental and applied biological sciences. Psychology; Genetic Association Studies; Humans; lactating women; lactation; Lactation - blood; Lactation - metabolism; Lactation - urine; Methylenetetrahydrofolate Reductase (NADPH2) - genetics; Methylenetetrahydrofolate Reductase (NADPH2) - metabolism; Milk, Human - metabolism; New York; Nutritional Status; Patient Compliance; Polymorphism, Single Nucleotide; Pregnancy; Pregnancy Trimester, Third; pregnant women; Prenatal Nutritional Physiological Phenomena; Tetrahydrofolates - blood; Tetrahydrofolates - metabolism; Tetrahydrofolates - urine; urine; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin B; Women
• ISSN: 0002-9165; 1938-3207
• DOI: 10.3945/ajcn.112.037523

Background: Folate dose-response studies in women of childbearing age who consumed a folic acid (FA)–containing multivitamin in the era of FA fortification are lacking.Objective: We sought to investigate folate-status response to a known folate dose comprising an FA-containing prenatal supplement (750 μg/d) plus natural food folate (400 μg/d) in third-trimester pregnant women, lactating women 5–15 wk postpartum, and nonpregnant women.Design: Pregnant (n = 26), lactating (n = 28), and nonpregnant (n = 21) women consumed the study folate dose under controlled intake conditions for 10–12 wk. Blood, urine, and breast milk were collected at baseline, study midpoint, and study end.Results: Study-end serum total folate concentrations averaged ∼30 ng/mL and did not differ by physiologic group (P = 0.876). Study-end urinary folate excretion represented ∼9–43% of total folate intake and ranged from 100 to 500 μg/d. Third-trimester pregnant women excreted less urinary folate than did lactating (P = 0.075) and nonpregnant (P < 0.001) women. Lactating women excreted less (P < 0.001) urinary FA than did nonpregnant women. Breast-milk total folate concentrations remained constant (P = 0.244; 61.8 ng/mL at study end), whereas breast-milk FA concentrations increased (P = 0.003) to 24.1 ng/mL at study end.Conclusions: The consumption of the study folate dose yielded a supranutritional folate status regardless of the physiologic state. Based on urinary folate excretion, folate use was greatest to least: pregnant > lactating > nonpregnant women. Breast-milk folate species were responsive to maternal folate intake, and FA made up ∼40% of breast-milk total folate at study end. These findings warrant revisiting prenatal supplement FA formulation in populations exposed to FA-fortification programs. This trial was registered at clinicaltrials.gov as NCT01127022.