ArticleThe American journal of clinical nutrition2009
Folate is absorbed across the colon of adults: evidence from cecal infusion of (13)C-labeled [6S]-5-formyltetrahydrofolic acid.
Article in The American journal of clinical nutrition, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 29 papers, 1 of them a synthesis that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
29 citing papers in PubMed, 1 synthesis or guideline pooled it, 85 citations in OpenAlex.
- A Systematic Review of Folate and the Human Enteric Microbiome: Biological Mechanisms and Clinical Implications.International journal of molecular sciences · 2026Pooled it
- Biological, dietetic and pharmacological properties of vitamin BNPJ science of food · 2025Review
- Approaches to dissect the vitamin biosynthetic network of the gut microbiota.Microbiome research reports · 2025Review
- Probiotics in the New Era of Human Milk Oligosaccharides (HMOs): HMO Utilization and Beneficial Effects ofMicroorganisms · 2024Review
- Recent Trends of Microbiota-Based Microbial Metabolites Metabolism in Liver Disease.Frontiers in medicine · 2022Review
- Building Robust Assemblages of Bacteria in the Human Gut in Early Life.Applied and environmental microbiology · 2021Review
- The Concept of Folic Acid in Health and Disease.Molecules (Basel, Switzerland) · 2021Review
- Determination of Folic Acid Using Biosensors-A Short Review of Recent Progress.Sensors (Basel, Switzerland) · 2021Review
- Gut microbial metabolites as multi-kingdom intermediates.Nature reviews. Microbiology · 2021Review
- A Role for Folate in Microbiome-Linked Control of Autoimmunity.Journal of immunology research · 2021Review
- Insights into the reason of Human-Residential Bifidobacteria (HRB) being the natural inhabitants of the human gut and their potential health-promoting benefits.FEMS microbiology reviews · 2020Review
- Bacteria increase host micronutrient availability: mechanisms revealed by studies in C. elegans.Genes & nutrition · 2020Review
- Upregulation of reduced folate carrier by vitamin D enhances brain folate uptake in mice lacking folate receptor alpha.Proceedings of the National Academy of Sciences of the United States of America · 2019Article
- Switching to a fibre-rich and low-fat diet increases colonic folate contents among African Americans.Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme · 2019Article
- Genes controlling the activation of natural killer lymphocytes are epigenetically remodeled in intestinal cells from germ-free mice.FASEB journal : official publication of the Federation of American Societies for Experimental Biology · 2019Article
- Microbial Metabolic Capacity for Intestinal Folate Production and Modulation of Host Folate Receptors.Frontiers in microbiology · 2019Article
- An Integrated Understanding of the Rapid Metabolic Benefits of a Carbohydrate-Restricted Diet on Hepatic Steatosis in Humans.Cell metabolism · 2018Article
- Metabolic programming of the epigenome: host and gut microbial metabolite interactions with host chromatin.Translational research : the journal of laboratory and clinical medicine · 2017Review
- Chemical signaling between gut microbiota and host chromatin: What is your gut really saying?The Journal of biological chemistry · 2017Review
- Why Don't All Infants Have Bifidobacteria in Their Stool?Frontiers in microbiology · 2016Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
9 authors at 4 institutions in 2 countries.
Funding
Abstract
backgroundFolate deficiency increases the risk of several human diseases. Likewise, high intakes of folate, particularly synthetic folic acid intake, may be associated with adverse health outcomes in humans. A more comprehensive understanding of the "input side" of folate nutrition may help to set dietary recommendations that strike the right balance between health benefits and risks. It is well known that the microflora in the colon produce large quantities of folate that approach or exceed recommended dietary intakes; however, there is no direct evidence of the bioavailability of this pool in humans.
objectiveThe objective was to determine whether, and to what extent, the natural folate vitamer 5-formyltetrahydrofolic acid is absorbed across the intact colon of humans.
designDuring screening colonoscopy, 684 nmol (320 microg) [(13)C]glutamyl-5-formyltetrahydrofolic acid was infused directly into the cecum of 6 healthy adults. Three or more weeks later, each subject received an intravenous injection of the same compound (172 nmol). Blood samples were collected before and after each treatment. The ratio of labeled to unlabeled folates was determined in plasma by tandem mass spectrometry.
resultsThe apparent rate of folate absorption across the colon of a bolus dose of [(13)C]5-formyltetrahydrofolic acid infused into the cecum was 0.6 +/- 0.2 nmol/h, as determined by the appearance of [(13)C(5)]5-methyltetrahydrofolic acid in plasma. In comparison, the rate of appearance of [(13)C(5)]5-methyltetrahydrofolic acid after an intravenous injection of [(13)C(5)]5-formyltetrahydrofolate was 7 +/- 1.2 nmol/h.
conclusionPhysiologic doses of natural folate are absorbed across the intact colon in humans.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.