Trial reportEuropean journal of clinical nutrition2014
Comparative effects of A1 versus A2 beta-casein on gastrointestinal measures: a blinded randomised cross-over pilot study.
Trial report in European journal of clinical nutrition, 2014. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to 3 registered trials, which are not on this map. Cited by 52 papers, 2 of them syntheses 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.
A1 Beta Casein Free Milk (a2 Milk) for Autism and Attention-deficit Hyperactivity Disorder
Effects of A2 Milk on Gastrointestinal Function of Volunteers Affected by Non-lactose Milk Intolerance
Comparing the Digestion of Milk With Different Beta-casein Protein Content by Dairy Intolerant Persons
Who cites it
52 citing papers in PubMed, 2 syntheses or guidelines pooled it, 136 citations in OpenAlex.
- The effects of dairy and dairy derivatives on the gut microbiota: a systematic literature review.Gut microbes · 2020Pooled it
- Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 β-Casein.Advances in nutrition (Bethesda, Md.) · 2017Pooled it
- Trial
- Effect of A1 protein-free formula versus conventional formula on acute respiratory infections and diarrhea in toddlers: A Randomized Controlled Trial.Journal of pediatric gastroenterology and nutrition · 2025Trial
- Trial
- Trial
- Circulatory amino acid responses to milk consumption in dairy and lactose intolerant individuals.European journal of clinical nutrition · 2022Trial
- Trial
- Trial
- Effects of Conventional Milk Versus Milk Containing Only A2 β-Casein on Digestion in Chinese Children: A Randomized Study.Journal of pediatric gastroenterology and nutrition · 2019Trial
- Lower Protein Intake Supports Normal Growth of Full-Term Infants Fed Formula: A Randomized Controlled Trial.Nutrients · 2018Trial
- Effects of cow's milk beta-casein variants on symptoms of milk intolerance in Chinese adults: a multicentre, randomised controlled study.Nutrition journal · 2017Trial
- A2 Milk Enhances Dynamic Muscle Function Following Repeated Sprint Exercise, a Possible Ergogenic Aid for A1-Protein Intolerant Athletes?Nutrients · 2017Trial
- Trial
- Ex Vivo Immune Response of Casein-Sensitized Lymphocytes to Bovine Milk Protein Composite Genotypes: Beyond the β-Casein A1/A2 Paradigm.Nutrients · 2026Article
- Review
- Effects of β-casein A1/A2 milk and β- and κ-casein genotypes on the performance, body composition, and fecal score of dairy calves.Scientific reports · 2025Article
- Circulating Food Allergen-Specific Antibodies, Beyond IgG4, Are Elevated in Eosinophilic Esophagitis.Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology · 2025Article
- Transcriptomic profiling of milk fat globules in cows with different β-casein genotypes.Scientific reports · 2025Article
- Electrochemistry as a Tool for Redox-Based Bio-Information Processing.Advanced science (Weinheim, Baden-Wurttemberg, Germany) · 2025Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
4 authors at 3 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
BACKGROUND/
objectivesAt present, there is debate about the gastrointestinal effects of A1-type beta-casein protein in cows' milk compared with the progenitor A2 type. In vitro and animal studies suggest that digestion of A1 but not A2 beta-casein affects gastrointestinal motility and inflammation through the release of beta-casomorphin-7. We aimed to evaluate differences in gastrointestinal effects in a human adult population between milk containing A1 versus A2 beta-casein. SUBJECTS/
methodsForty-one females and males were recruited into this double-blinded, randomised 8-week cross-over study. Participants underwent a 2-week dairy washout (rice milk replaced dairy), followed by 2 weeks of milk (750 ml/day) that contained beta-casein of either A1 or A2 type before undergoing a second washout followed by a final 2 weeks of the alternative A1 or A2 type milk.
resultsThe A1 beta-casein milk led to significantly higher stool consistency values (Bristol Stool Scale) compared with the A2 beta-casein milk. There was also a significant positive association between abdominal pain and stool consistency on the A1 diet (r=0.520, P=0.001), but not the A2 diet (r=-0.13, P=0.43). The difference between these two correlations (0.52 versus -0.13) was highly significant (P<0.001). Furthermore, some individuals may be susceptible to A1 beta-casein, as evidenced by higher faecal calprotectin values and associated intolerance measures.
conclusionsThese preliminary results suggest differences in gastrointestinal responses in some adult humans consuming milk containing beta-casein of either the A1 or the A2 beta-casein type, but require confirmation in a larger study of participants with perceived intolerance to ordinary A1 beta-casein-containing milk.
Indexed as
Identifiers
What Socratic holds
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 Socratic graph.