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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.
Farrell, Colleen C; Khanna, Siya; Hoque, Md Tozammel; Plaga, Aneta; Basset, Nancy; Syed, Ishba; Biouss, George; Aufreiter, Susanne; Marcon, Norman; Bendayan, Reina; Kim, Young-In; O'Connor, Deborah L.
Afiliação
  • Farrell CC; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.
  • Khanna S; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.
  • Hoque MT; Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
  • Plaga A; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.
  • Basset N; Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
  • Syed I; Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
  • Biouss G; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada; Developmental and Stem Cell Biology Program, The Hospital for Sick Children, Toronto, Ontario, Canada.
  • Aufreiter S; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada.
  • Marcon N; Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada.
  • Bendayan R; Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada.
  • Kim YI; Division of Gastroenterology, Department of Medicine, St. Michael's Hospital, Toronto, Ontario, Canada; Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, Ontario, Canada.
  • O'Connor DL; Department of Nutritional Sciences, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada; Translational Medicine Program, The Hospital for Sick Children, Toronto, Ontario, Canada. Electronic address: deborah.oconnor@utoronto.ca.
Am J Clin Nutr ; 119(3): 809-820, 2024 03.
Article em En | MEDLINE | ID: mdl-38157986
ABSTRACT

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.
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Texto completo: 1 Base de dados: MEDLINE Assunto principal: Ácido Fólico / Proteínas de Neoplasias Limite: Adult / Humans Idioma: En Ano de publicação: 2024 Tipo de documento: Article

Texto completo: 1 Base de dados: MEDLINE Assunto principal: Ácido Fólico / Proteínas de Neoplasias Limite: Adult / Humans Idioma: En Ano de publicação: 2024 Tipo de documento: Article