A claim you hear on longevity podcasts
The claim checked: A leaky gut lets undigested food reach the immune system, which is when you start getting sick and fat Hear it at 5:30
Most of the ten studies link a leakier gut to inflammation or autoimmune markers, mostly in patient groups. One found lower bacterial toxin levels in arthritis patients.
Computed from 10 studies that test this point, each judged by two readers, in full. 4 more studies are waiting for a full read and do not count yet.
“and is exposed to your immune system 60 of Which is right under that Lining When that happens your immune system goes ah and starts attacking these qu foreign molecules but It's really just food that you haven't properly digested or That Should have been broken down but It's suddenly exposed to your immune system and That's when you start getting Sick and fat”
other primary study · 2018
“Further, the high-zonulin group showed significantly increased inflammation markers such as CRP and IL-6.”
Gut microbiota, dietary intakes and intestinal permeability reflected by serum zonulin in women. Eur J Nutr
Who: 102 women aged 18-40 in Graz, Austria: anorexia nervosa (17), athletes (20), normal weight (25), overweight (21), obese (19)
PMID 30043185
controlled trial · 2025
“Hence, our findings suggest that gut bacteria alone are an unlikely cause of metabolic endotoxemia and support the conclusion that inflammation in the population with obesity is most likely related to dietary fat-induced changes in intestinal permeability properties rather than to increases in strains of Gram-negative bacteria producing inflammatory endotoxins in the gut.”
Short-term high fat diet-induced metabolic endotoxemia in older individuals with obesity: a randomized crossover study. Am J Clin Nutr
Who: adults aged 50-79 in New Jersey with obesity (BMI ≥30) or normal weight (BMI 18.5-24.9), without diabetes; mean age 64, 66% female
PMID 40480607
other primary study · 2023
“The findings of our study suggest that intestinal permeability may have systemic autoimmune responses, involving a diverse list of autoimmune target proteins, and may potentially play a role in polyglandular autoimmune disease.”
The Relationships between Intestinal Permeability and Target Antibodies for a Spectrum of Autoimmune Diseases. Int J Mol Sci
Who: 266 anonymized patients aged 19-87 (65% female) whose physicians sent serum to a US clinical autoimmune laboratory for permeability and autoimmunity screening
PMID 38003542
other primary study · 2026
“In contrast to expectations for a chronic inflammatory condition, patients with RA showed lower baseline serum levels of LPS and LBP than healthy controls.”
Association between intestinal permeability, systemic inflammation, and response to anti-TNF therapy in patients with rheumatoid arthritis: a prospective controlled study. Front Immunol
Who: biologic-naive adults with active rheumatoid arthritis starting a first anti-TNF agent (mostly white women, mean age ~55) vs age- and sex-matched healthy controls, Malaga, Spain
PMID 41972162
controlled trial · 2021 · landmark
“In our experimental conditions, we documented that the 8-week intervention with the PR-diet failed to modulate inflammatory markers, in line with other intervention studies with polyphenol-rich foods both in adults and older individuals [39-44].”
A polyphenol-rich dietary pattern improves intestinal permeability, evaluated as serum zonulin levels, in older subjects: The MaPLE randomised controlled trial. Clin Nutr
Who: Older subjects aged ≥ 60 y with increased intestinal permeability based on serum zonulin levels
PMID 33388204
other primary study · 2024 · landmark
“Correlation heat-maps (Fig. 3D and Supplementary Table 4) showed that intestinal integrity negatively (significantly, albeit weakly) correlated with accelerated biological aging and levels of inflammatory aging markers, while microbial translocation positively correlated with accelerated biological aging and levels of inflammatory aging markers.”
Distinct intestinal microbial signatures linked to accelerated systemic and intestinal biological aging. Microbiome
Who: People living with HIV on suppressive ART vs age-, sex-, BMI- and ethnicity-matched people without HIV at Rush University Medical Center (median age ~51-54, ~80% male)
PMID 38383483
controlled trial · 2009
“In contrast, the observed relations between the markers of intestinal barrier dysfunction and clinical outcome can not be seen as definite proof of a definite causal relationship but only as an association.”
Intestinal barrier dysfunction in a randomized trial of a specific probiotic composition in acute pancreatitis. Ann Surg
Who: Adult patients with predicted severe acute pancreatitis in the PROPATRIA trial (8 Dutch university and 7 teaching hospitals)
PMID 19801929
other primary study · 2015
“According to these results, we hypothesize that leaky gut and microbiome dysbiosis may be causally linked to pathogenesis of AIH.”
Abnormal intestinal permeability and microbiota in patients with autoimmune hepatitis. Int J Clin Exp Pathol
Who: 24 untreated patients with autoimmune hepatitis at different stages and 8 sex- and age-matched healthy volunteers, Tianjin, China
PMID 26191211
other primary study · 2021
“Notably, increased levels of leaky gut biomarkers in patients with initial GD, but not euthyroid GD, suggest that these changes may be due to an increase in the levels of thyroid hormones.”
Elevated Levels of Circulating Biomarkers Related to Leaky Gut Syndrome and Bacterial Translocation Are Associated With Graves' Disease. Front Endocrinol (Lausanne)
Who: 91 Chinese patients with Graves' disease (61 newly diagnosed, 30 euthyroid after treatment) and 44 healthy controls
PMID 34975767
controlled trial · 2000
“There was a significant positive correlation between portal endotoxaemia and intestinal permeability (rs=0.955; p=0.001).”
Intestinal manipulation during elective aortic aneurysm surgery leads to portal endotoxaemia and mucosal barrier dysfunction. Eur J Vasc Endovasc Surg
Who: 14 patients (13 men) undergoing elective infrarenal abdominal aortic aneurysm repair, randomised to transperitoneal or extraperitoneal approach
PMID 10873730
None.
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