Evidence map›Paper›PMID 41703973›Full record

ArticleAmerican journal of human biology : the official journal of the Human Biology Council2026

Impaired Intestinal Function Among Indigenous Shuar Children of Amazonian Ecuador: Evidence From Lactulose:Mannitol Tests of Absorption and Permeability.

Marcela Pfaff-Nash, Alejandro J Ramirez, Elizabeth Y Kim, Hannah N Cantrell, Melissa A Liebert, Felicia C Madimenos, J Josh Snodgrass, Lawrence S Sugiyama, Samuel S Urlacher

Abstract read
In one paragraph

Article in American journal of human biology : the official journal of the Human Biology Council, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

0numbers the graph read from it
0cells of the map it votes in
2citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from 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.

2 · The registry

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.

3 · Its place in the literature

Who cites it

2 citing papers in PubMed.

  1. The Shuar Health and Life History Project: Overview at 20 Years and Introduction to the Special Issue.American journal of human biology : the official journal of the Human Biology Council · 2026
    Article
  2. Article
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

9 authors.

Marcela Pfaff-NashDepartment of Anthropology, Baylor University, Waco, Texas, USA.ORCID 0009-0003-0398-6768
Alejandro J RamirezMass Spectrometry Center, Baylor University, Waco, Texas, USA.
Elizabeth Y KimDepartment of Biology, Baylor University, Waco, Texas, USA.
Hannah N CantrellDepartment of Anthropology, University of Oregon, Eugene, Oregon, USA.
Melissa A LiebertDepartment of Anthropology, Northern Arizona University, Flagstaff, Arizona, USA.ORCID 0000-0001-8013-6773
Felicia C MadimenosDepartment of Anthropology, Queens College (CUNY), Queens, New York, USA.ORCID 0000-0001-5442-232X
J Josh SnodgrassDepartment of Anthropology, University of Oregon, Eugene, Oregon, USA.
Lawrence S SugiyamaDepartment of Anthropology, University of Oregon, Eugene, Oregon, USA.
Samuel S UrlacherDepartment of Anthropology, Baylor University, Waco, Texas, USA.ORCID 0000-0002-6489-4117

Funding

Baylor University
6 · The paper itself

Abstract

objectivesIntestinal function is an important but often overlooked aspect of human biological variation, with the intestines serving as both a barrier against external pathogens/contaminants and the primary conduit of nutrient extraction from food. Impaired intestinal function among children is viewed as a key contributor to growth faltering globally. However, few studies have investigated children's intestinal function in rural settings or beyond infancy. To address this limitation, we conducted a pilot study to describe the intestinal function of school-age Indigenous Shuar children of Amazonian Ecuador and to assess the feasibility of implementing the widely utilized lactulose:mannitol (L:M) test of absorption and permeability with this group.

methodsThe urinary L:M test was performed with 23 rural-living Shuar children aged 4-12 years. Ultra-performance liquid chromatograph-high-resolution mass spectrometry was used to determine L:M ratios, lactulose recovery, and mannitol recovery. Age and sex patterns were investigated using linear regression models.

resultsChildren's mean L:M ratio was 0.33 ± 0.32, a ratio comparable to values reported for children in other low- and middle-income settings. 35%-91% of children were categorized as having impaired intestinal function using common cut-off values. Children's lactulose (0.14% ± 0.17%) and mannitol (2.60% ± 2.22%) recoveries did not differ by sex but increased with age (p < 0.05) and indicated diminished intestinal absorptive capacity and increased permeability.

conclusionsIntestinal function appears to be considerably impaired among school-age Shuar children living in a low-resource, rural setting. Children living in unsanitary, non-industrialized contexts may routinely experience intestinal permeability-related immune activation and malabsorption-related energy/nutrient loss. More research is needed to explore the breadth of global variation in children's intestinal function and to investigate its many evolutionary and public health implications.

Indexed as

Intestinal AbsorptionIntestinesLactuloseMannitolChildChild, PreschoolEcuadorFemaleHumansIndians, South AmericanMalePermeabilityPilot ProjectsLactuloseMannitoldual sugar testenteropathyenvironmental enteric dysfunctiongut functionleaky gut

Identifiers

PMID41703973
PMCPMC12914155

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LicenceCC BY-NC-ND
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Registered trials

None linked

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.