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Bobrowski-Khoury N, Sequeira JM, Arning E, Bottiglieri T, Quadros EV. Absorption and Tissue Distribution of Folate Forms in Rats: Indications for Specific Folate Form Supplementation during Pregnancy. Nutrients 2022; 14:nu14122397. [PMID: 35745126 PMCID: PMC9228663 DOI: 10.3390/nu14122397] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/05/2022] [Accepted: 06/07/2022] [Indexed: 01/27/2023] Open
Abstract
Food fortification and folic acid supplementation during pregnancy have been implemented as strategies to prevent fetal malformations during pregnancy. However, with the emergence of conditions where folate metabolism and transport are disrupted, such as folate receptor alpha autoantibody (FRαAb)-induced folate deficiency, it is critical to find a folate form that is effective and safe for pharmacologic dosing for prolonged periods. Therefore, in this study, we explored the absorption and tissue distribution of folic acid (PGA), 5-methyl-tetrahydrofolate (MTHF), l-folinic acid (levofolinate), and d,l-folinic acid (Leucovorin) in adult rats. During absorption, all forms are converted to MTHF while some unconverted folate form is transported into the blood, especially PGA. The study confirms the rapid distribution of absorbed folate to the placenta and fetus. FRαAb administered, also accumulates rapidly in the placenta and blocks folate transport to the fetus and high folate concentrations are needed to circumvent or overcome the blocking of FRα. In the presence of FRαAb, both Leucovorin and levofolinate are absorbed and distributed to tissues better than the other forms. However, only 50% of the leucovorin is metabolically active whereas levofolinate is fully active and generates higher tetrahydrofolate (THF). Because levofolinate can readily incorporate into the folate cycle without needing methylenetetrahydrofolate reductase (MTHFR) and methionine synthase (MS) in the first pass and is relatively stable, it should be the folate form of choice during pregnancy, other disorders where large daily doses of folate are needed, and food fortification.
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Affiliation(s)
- Natasha Bobrowski-Khoury
- The School of Graduate Studies, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA;
| | - Jeffrey M. Sequeira
- Department of Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA;
| | - Erland Arning
- Center of Metabolomics, Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX 75204, USA; (E.A.); (T.B.)
| | - Teodoro Bottiglieri
- Center of Metabolomics, Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX 75204, USA; (E.A.); (T.B.)
| | - Edward V. Quadros
- Department of Medicine, SUNY Downstate Health Sciences University, Brooklyn, NY 11203, USA;
- Correspondence:
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Patanwala I, King MJ, Barrett DA, Rose J, Jackson R, Hudson M, Philo M, Dainty JR, Wright AJA, Finglas PM, Jones DE. Folic acid handling by the human gut: implications for food fortification and supplementation. Am J Clin Nutr 2014; 100:593-9. [PMID: 24944062 PMCID: PMC4095662 DOI: 10.3945/ajcn.113.080507] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Current thinking, which is based mainly on rodent studies, is that physiologic doses of folic acid (pterylmonoglutamic acid), such as dietary vitamin folates, are biotransformed in the intestinal mucosa and transferred to the portal vein as the natural circulating plasma folate, 5-methyltetrahydrofolic acid (5-MTHF) before entering the liver and the wider systemic blood supply. OBJECTIVE We tested the assumption that, in humans, folic acid is biotransformed (reduced and methylated) to 5-MTHF in the intestinal mucosa. DESIGN We conducted a crossover study in which we sampled portal and peripheral veins for labeled folate concentrations after oral ingestion with physiologic doses of stable-isotope-labeled folic acid or the reduced folate 5-formyltetrahydrofolic acid (5-FormylTHF) in 6 subjects with a transjugular intrahepatic porto systemic shunt (TIPSS) in situ. The TIPSS allowed blood samples to be taken from the portal vein. RESULTS Fifteen minutes after a dose of folic acid, 80 ± 12% of labeled folate in the hepatic portal vein was unmodified folic acid. In contrast, after a dose of labeled 5-FormylTHF, only 4 ± 18% of labeled folate in the portal vein was unmodified 5-FormylTHF, and the rest had been converted to 5-MTHF after 15 min (postdose). CONCLUSIONS The human gut appears to have a very efficient capacity to convert reduced dietary folates to 5-MTHF but limited ability to reduce folic acid. Therefore, large amounts of unmodified folic acid in the portal vein are probably attributable to an extremely limited mucosal cell dihydrofolate reductase (DHFR) capacity that is necessary to produce tetrahydrofolic acid before sequential methylation to 5-MTHF. This process would suggest that humans are reliant on the liver for folic acid reduction even though it has a low and highly variable DHFR activity. Therefore, chronic liver exposure to folic acid in humans may induce saturation, which would possibly explain reports of systemic circulation of unmetabolized folic acid.
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Affiliation(s)
- Imran Patanwala
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - Maria J King
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - David A Barrett
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - John Rose
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - Ralph Jackson
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - Mark Hudson
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - Mark Philo
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - Jack R Dainty
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - Anthony J A Wright
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - Paul M Finglas
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
| | - David E Jones
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom (IP, MH, and DEJ); the Institute of Food Research, Norwich Research Park, Norwich, United Kingdom (MJK, MP, JRD, AJAW, and PMF); the Centre for Analytical Bioscience, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom (DAB); and the Department of Radiology, Freeman Hospital, Newcastle upon Tyne, United Kingdom (JR and RJ)
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