Trial reportNutrition journal2016
Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows' milk.
Trial report in Nutrition journal, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. An erratum has been issued. It is linked to 7 registered trials, which are not on this map. Cited by 93 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.
Comparative Effects of Milk With A2 Type Beta Casein Versus Milk With A1 and A2 Beta Casein Proteins on Gastrointestinal Physiology, Symptoms and Cognitive Behavior for the Health People Who Are Intolerant to Traditional Cow Milk
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 Gastric Transit of Commercial Milk Containing A1 Beta-casein and A2 Milk Containing Only A2 Beta-casein Using Magnetic Resonance Imaging (MRI)
Comparing the Acute Effects of A1 Containing Commercial Milk and A2 Milk on Inflammation, Lactose Intolerance and Lactose Maldigestion in Lactose Maldigesters
Comparing Inflammation, Lactose Intolerance and Lactose Maldigestion in Lactose Maldigesters on Consumption of Commercial Milk Containing A1 and A2 Beta-Casein and A2 Milk Containing Only A2 Beta-Casein for Two Weeks
A Double-blind, Parallel Designed, Randomized Controlled Trial to Investigate Effects of Conventional Vs A2 Milk on Breastmilk Composition and Subsequent Infant Gut Health, Crying and Sleep Patterns in Healthy, Full-term Infants
Who cites it
93 citing papers in PubMed, 2 syntheses or guidelines pooled it, 223 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
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- 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
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- Circulatory amino acid responses to milk consumption in dairy and lactose intolerant individuals.European journal of clinical nutrition · 2022Trial
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- Evaluation of breath, plasma, and urinary markers of lactose malabsorption to diagnose lactase non-persistence following lactose or milk ingestion.BMC gastroenterology · 2020Trial
- 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
- Effects ofNutrients · 2019Trial
- 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
- A Sensitive LC-MS/MS Method for Quantifying Beta-Casomorphin 5 in Pasteurized Milk.Food science & nutrition · 2026Article
- Ex Vivo Immune Response of Casein-Sensitized Lymphocytes to Bovine Milk Protein Composite Genotypes: Beyond the β-Casein A1/A2 Paradigm.Nutrients · 2026Article
- Bioactive Substances in Sheep's Milk and Related Products as Components of Functional Foods.Molecules (Basel, Switzerland) · 2026Review
- KetoFLEX 12/3 Diet and Cognitive Health: A Precision-Nutrition Perspective on Mechanisms, Emerging Evidence, and Future Directions.Nutrients · 2026Review
- β-Casein Polymorphism in Serbian Holstein-Friesian and Busha Cattle and Its Association with Milk Production Traits.Animals : an open access journal from MDPI · 2026Article
33 more citing papers are in PubMed but not listed here.
Corrections and comments
- Erratum issued
Authors and funding
6 authors at 4 institutions in 2 countries.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundCows' milk generally contains two types of β-casein, A1 and A2 types. Digestion of A1 type can yield the peptide β-casomorphin-7, which is implicated in adverse gastrointestinal effects of milk consumption, some of which resemble those in lactose intolerance. This study aimed to compare the effects of milk containing A1 β-casein with those of milk containing only A2 β-casein on inflammation, symptoms of post-dairy digestive discomfort (PD3), and cognitive processing in subjects with self-reported lactose intolerance.
methodsForty-five Han Chinese subjects participated in this double-blind, randomized, 2 × 2 crossover trial and consumed milk containing both β-casein types or milk containing only A2 β-casein. Each treatment period was 14 days with a 14-day washout period at baseline and between treatment periods. Outcomes included PD3, gastrointestinal function (measured by smart pill), Subtle Cognitive Impairment Test (SCIT), serum/fecal laboratory biomarkers, and adverse events.
resultsCompared with milk containing only A2 β-casein, the consumption of milk containing both β-casein types was associated with significantly greater PD3 symptoms; higher concentrations of inflammation-related biomarkers and β-casomorphin-7; longer gastrointestinal transit times and lower levels of short-chain fatty acids; and increased response time and error rate on the SCIT. Consumption of milk containing both β-casein types was associated with worsening of PD3 symptoms relative to baseline in lactose tolerant and lactose intolerant subjects. Consumption of milk containing only A2 β-casein did not aggravate PD3 symptoms relative to baseline (i.e., after washout of dairy products) in lactose tolerant and intolerant subjects.
conclusionsConsumption of milk containing A1 β-casein was associated with increased gastrointestinal inflammation, worsening of PD3 symptoms, delayed transit, and decreased cognitive processing speed and accuracy. Because elimination of A1 β-casein attenuated these effects, some symptoms of lactose intolerance may stem from inflammation it triggers, and can be avoided by consuming milk containing only the A2 type of beta casein.
trial registrationClinicalTrials.gov/NCT02406469.
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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.