Low-dose daily folic acid (400 μg) supplementation does not affect regulation of folate transporters found present throughout the terminal ileum and colon of humans : a randomized clinical trial

Copyright © 2023 American Society for Nutrition. Published by Elsevier Inc. All rights reserved..

BACKGROUND: Folic acid supplementation during the periconceptional period reduces the risk of neural tube defects in infants, but concern over chronic folic acid exposure remains. An improved understanding of folate absorption may clarify potential risks. Folate transporters have been characterized in the small intestine, but less so in the colon of healthy, free-living humans. The impact of folic acid fortification or supplementation on regulation of these transporters along the intestinal tract is unknown.

OBJECTIVE: The objective was to characterize expression of folate transporters/receptor (FT/R) and folate hydrolase, glutamate carboxypeptidase II (GCPII), from the terminal ileum and throughout the colon of adults and assess the impact of supplemental folic acid.

METHODS: In this 16-wk open-labeled randomized clinical trial, adults consumed a low folic acid-containing diet, a folate-free multivitamin, and either a 400 μg folic acid supplement or no folic acid supplement. Dietary intakes and blood were assessed at baseline, 8 wk, and 16 wk (time of colonoscopy). Messenger RNA (mRNA) expression and protein expression of FT/R and GCPII were assessed in the terminal ileum, cecum, and ascending and descending colon.

RESULTS: Among 24 randomly assigned subjects, no differences in dietary folate intake or blood folate were observed at baseline. Mean ± SD red blood cell folate at 16 wk was 1765 ± 426 and 911 ± 242 nmol/L in the 400 and 0 μg folic acid group, respectively (P < 0.0001). Reduced folate carrier, proton-coupled folate transporter, and folate-receptor alpha expression were detected in the terminal ileum and colon, as were efflux transporters of breast cancer resistance protein and multidrug resistance protein-3. Other than a higher mRNA expression of FR-alpha and GCPII in the 400 μg supplement group in the ascending colon, no treatment differences were observed (P < 0.02).

CONCLUSIONS: Folate transporters are present throughout the terminal ileum and colon; there is little evidence that a low dose of folic acid supplementation affects colonic absorption. This trial was registered at clinicaltrials.gov as NCT03421483.

Medienart:

E-Artikel

Erscheinungsjahr:

2024

Erschienen:

2024

Enthalten in:

Zur Gesamtaufnahme - volume:119

Enthalten in:

The American journal of clinical nutrition - 119(2024), 3 vom: 15. März, Seite 809-820

Sprache:

Englisch

Beteiligte Personen:

Farrell, Colleen C [VerfasserIn]
Khanna, Siya [VerfasserIn]
Hoque, Md Tozammel [VerfasserIn]
Plaga, Aneta [VerfasserIn]
Basset, Nancy [VerfasserIn]
Syed, Ishba [VerfasserIn]
Biouss, George [VerfasserIn]
Aufreiter, Susanne [VerfasserIn]
Marcon, Norman [VerfasserIn]
Bendayan, Reina [VerfasserIn]
Kim, Young-In [VerfasserIn]
O'Connor, Deborah L [VerfasserIn]

Links:

Volltext

Themen:

935E97BOY8
ATP Binding Cassette Transporter, Subfamily G, Member 2
Colon
Colonic absorption
Dietary supplement
Folate
Folate hydrolase
Folate metabolism
Folate transporter
Folic Acid
Folic Acid Transporters
Folic acid supplementation
Fortification
Journal Article
Neoplasm Proteins
RNA, Messenger
Randomized Controlled Trial

Anmerkungen:

Date Completed 05.03.2024

Date Revised 05.03.2024

published: Print-Electronic

ClinicalTrials.gov: NCT03421483

Citation Status MEDLINE

doi:

10.1016/j.ajcnut.2023.12.018

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM366486349