title: Vitamin B-12 Status Differs among Pregnant, Lactating, and Control Women with Equivalent Nutrient Intakes.
abstract: BACKGROUND
  Limited data are available from controlled studies on biomarkers of maternal vitamin B-12 status.
  
  
  OBJECTIVE
  We sought to quantify the effects of pregnancy and lactation on the vitamin B-12 status response to a known and highly controlled vitamin B-12 intake.
  
  
  METHODS
  As part of a 10-12 wk feeding trial, pregnant (26-29 wk gestation; n = 26), lactating (5 wk postpartum; n = 28), and control (nonpregnant, nonlactating; n = 21) women consumed vitamin B-12 amounts of ∼8.6 μg/d [mixed diet (∼6 μg/d) plus a prenatal multivitamin supplement (2.6 μg/d)]. Serum vitamin B-12, holotranscobalamin (bioactive form of vitamin B-12), methylmalonic acid (MMA), and homocysteine were measured at baseline and study-end.
  
  
  RESULTS
  All participants achieved adequate vitamin B-12 status in response to the study dose. Compared with control women, pregnant women had lower serum vitamin B-12 (-21%; P = 0.02) at study-end, whereas lactating women had higher (P = 0.04) serum vitamin B-12 throughout the study (+26% at study-end). Consumption of the study vitamin B-12 dose increased serum holotranscobalamin in all reproductive groups (+16-42%; P ≤ 0.009). At study-end, pregnant (vs. control) women had a higher holotranscobalamin-to-vitamin B-12 ratio (P = 0.04) with ∼30% (vs. 20%) of total vitamin B-12 in the bioactive form. Serum MMA increased during pregnancy (+50%; P < 0.001) but did not differ by reproductive state at study-end. Serum homocysteine increased in pregnant women (+15%; P = 0.009) but decreased in control and lactating women (-16-17%; P < 0.001). Despite these changes, pregnant women had ∼20% lower serum homocysteine than the other 2 groups at study-end (P ≤ 0.02).
  
  
  CONCLUSIONS
  Pregnancy and lactation alter vitamin B-12 status in a manner consistent with enhanced vitamin B-12 supply to the child. Consumption of the study vitamin B-12 dose (∼3 times the RDA) increased the bioactive form of vitamin B-12, suggesting that women in these reproductive states may benefit from vitamin B-12 intakes exceeding current recommendations. This trial was registered at clinicaltrials.gov as NCT01127022.
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY; and.
authors.forename: Sajin
authors.initials: S
authors.lastname: Bae
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY; and.
authors.forename: Allyson A
authors.initials: AA
authors.lastname: West
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY; and.
authors.forename: Jian
authors.initials: J
authors.lastname: Yan
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY; and.
authors.forename: Xinyin
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY; and.
authors.forename: Cydne A
authors.initials: CA
authors.lastname: Perry
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY; and.
authors.forename: Olga
authors.initials: O
authors.lastname: Malysheva
authors.affiliation: Department of Medicine and Division of Hematology, University of Colorado Health Sciences Center, Denver, CO.
authors.forename: Sally P
authors.initials: SP
authors.lastname: Stabler
authors.affiliation: Department of Medicine and Division of Hematology, University of Colorado Health Sciences Center, Denver, CO.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Allen
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY; and mac379@cornell.edu.
authors.forename: Marie A
authors.initials: MA
authors.lastname: Caudill
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D001942:Breast Feeding; D002794:Choline / Q000008:administration & dosage / Q000097:blood; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D002149:Energy Intake; D005260:Female; D064368:Healthy Volunteers; D006710:Homocysteine / Q000097:blood / Q000652:urine; D006801:Humans; D007774:Lactation / Q000097:blood; D008764:Methylmalonic Acid / Q000097:blood; D018977:Micronutrients / Q000008:administration & dosage*; D049590:Postpartum Period; D011247:Pregnancy; D064167:Recommended Dietary Allowances; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000097:blood*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D018977:Micronutrients; D006710:Homocysteine; D008764:Methylmalonic Acid; D002794:Choline; D014805:Vitamin B 12
keywords: controlled feeding study; holotranscobalamin; homocysteine; lactation; methylmalonic acid; pregnancy; reproductive state; vitamin B-12; women of reproductive age