An interventional study of Milk containing A1 and A2 beta-casein and Milk containing only A2 beta-casein in Lactose Intolerance, sponsored by Purdue University. Completed at 1 site in United States. Open to participants aged 18 Years to 65 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-20.
Sponsored by Purdue University · Not applicable, Interventional, and Prevention
Cow's milk contains two types of β-casein: A1 and A2. It is evident from human clinical trials that milk with A1 protein produces more hydrogen and symptoms of lactose intolerance. A pro-inflammatory μ-opioid peptide BCM-7 is released from A1 but not from A2. Milk containing A1 β-casein produced more inflammatory markers than A2 β-casein. This is a double-blinded, randomized, controlled trial conducted to determine if there are changes in inflammatory markers following two weeks of milk feeding, due to milk containing A1 and A2 beta-casein as compared to milk containing only A2 beta-casein.
Recruitment:
Flyers, emails, and advertisements in local and university newspapers will be used for recruitment of study participants.
Phone screening:
Interested individuals will be contacted via phone by study staff to assess eligibility by asking questions listed in the inclusion and exclusion criteria.
Informed consent:
If the individual is eligible through phone screening, the study staff will read and explain the informed consent to the individual. Informed consent will contain all the information regarding study procedure, compensation, risks and benefits. If Informed Consent is granted, the participant will be contacted through their preferred method of contact (email or phone) to schedule a hydrogen breath test (HBT).
Screening lactose maldigesters via HBT:
Maldigestion will be classified by a rise of breath hydrogen concentration of greater than 20ppm after a challenge dose of 2% commercial milk containing 0.5g lactose per kg body weight. Participants will consume a low-fiber meal and then fast 12 hours prior to HBT. A breath sample will be obtained from participants just before drinking the milk dose. Participants will then consume milk containing 0.5 grams lactose per kilogram body weight. Breath samples will be obtained according to the following schedule: 0 hour (pre dose), 30 minutes, 1 hour, 90 minutes, 2 hours, 3 hours, 4 hours, 5 hours and 6 hours. Participants who exhibit a rise of breath hydrogen concentration of greater than 20ppm between any two timepoints of the 6-hour test will be classified as lactose maldigesters, and will be qualified to enter the intervention portion of the study.
Intervention:
There will be two phases in intervention. Each phase is 15 days long.
Phase 1:
Blood will be drawn from the participants before consumption of milk on day 1 of the phase. Participants will then consume the 500 ml of first randomized milk every day from day 1 to day 14 (14 days in total). Dietary intake, stool type and symptoms (abdominal pain, bloating, flatulence, fecal urgency, and diarrhea) severity will be recorded on each day from day 1 to day 14 after milk consumption.
Participants will consume a low-fiber dinner and fast for 12 hours prior to HBT on day 15. Participants will provide their first breath sample before consumption of milk. Participants will then consume a challenge dose of first randomized milk containing 0.5g lactose per kg body weight. Breath samples will be collected at 0 hour (pre dose), 30 minutes, 1 hour, 90 minutes, 2 hours, 3 hours, 4 hours, 5 hours and 6 hours. Participants will be asked to report and rate any symptoms including abdominal pain, bloating, flatulence, fecal urgency, and diarrhea they might experience during the 6 hour test. Blood will be drawn from participants at 0 hour (pre-dose), 1 hour, 2 hours and 3 hours time-point via catheter and serum will be isolated from whole blood for analyses of markers including hs-CRP, IgG, IgG1, Il-4, GSH and BCM-7.
Phase 2:
There will be at least a 6-day interval between Phase 1 and Phase 2. The same procedure from phase 1 will be followed in phase 2. Participants will consume the second randomized milk for 14 days and undergo HBT on day 15.
53 studies on the registry are indexed under Lactose Intolerance; 6 are open to participants now.
This study's enrollment of 24 is below the median of 41 across 41 interventional studies indexed under Lactose Intolerance.
Browse Lactose Intolerance studies →Purdue University is the lead sponsor of 175 studies on the registry; 21 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Agrees to refrain from all other treatments and products used for dairy intolerance (e.g., Lactaid® Dietary Supplements) during study involvement Willing to return for all study visits and complete all study related procedures Able to understand and provide written informed consent in English
Exclusion Criteria:
Currently pregnant Currently lactating Cigarette smoking or other use of tobacco or nicotine containing products within 3 months of screening Diagnosed with any of the following disorders known to be associated with abnormal gastrointestinal motility such as; Gastroparesis, amyloidosis, neuromuscular diseases (including Parkinson's disease), collagen vascular diseases, alcoholism, uremia, malnutrition, or untreated hypothyroidism History of surgery that alters the normal function of the gastrointestinal tract including, but not limited to: gastrointestinal bypass surgery, bariatric surgery, gastric banding, vagotomy, fundoplication, pyloroplasty [Note: history of uncomplicated abdominal surgeries such as removal of an appendix more than 12 months prior to screening will not be excluded] Past or present : Organ transplant, chronic pancreatitis, pancreatic insufficiency, symptomatic biliary disease, Celiac disease, chronic constipation, diverticulosis, inflammatory bowel disease (IBD), ulcerative colitis (UC), Crohn's disease (CD), small intestine bacterial overgrowth syndrome (SIBO), gastroparesis, gastro-esophageal reflux disease (GERD), Irritable Bowel Syndrome (IBS) or any other medical condition with symptoms that could confound collection of adverse events.
Active ulcers, or history of severe ulcers Diabetes mellitus (type 1 and type 2) Congestive Heart Failure (CHF) (HIV), or Height: ___ Weight: ___ : ___
o Weighing \<16.5 kg and BMI > 35 kg/m2
Recent bowel preparation for endoscopic or radiologic investigation within four weeks of screening (e.g., colonoscopy prep) Use of concurrent therapy(ies) or other products (e.g., laxatives, stool softeners, Pepto Bismol®, Lactaid® Dietary Supplements) used for symptoms of dairy intolerance within 7 days of screening Chronic antacid and/or PPI use Recent use of systemic antibiotics defined as use within 30 days prior to screening Recent high colonic enema, defined as use within 30 days prior to screening Any concurrent disease or symptoms which may interfere with the assessment of the cardinal symptoms of dairy intolerance (i.e., gas, diarrhea, bloating, cramps, stomach pain) History of ethanol (alcohol) and/or drug abuse in the past 12 months Currently undergoing chemotherapy Use of any drug or participation in any investigational study within 30 days prior to screening Prior enrollment in this study Any other conditions/issues noted by the study staff and/or Principal Investigator that would impact participation and/or protocol compliance
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis B tests
Hepatitis B is a virus that infects the liver. These are separate tests: HBsAg positive usually means a current infection (a recent vaccination can briefly cause it too); total anti-HBc (HBcAb) positive means an infection now or in the past; HBV DNA measures how much virus is in the blood.
Some studies accept a past infection if HBV DNA is undetectable, sometimes with antiviral medicine during the study. Check what this study allows.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hepatitis C tests
Hepatitis C is a virus that infects the liver. An HCV antibody test can stay positive after an infection has cleared (and is occasionally positive without one); an HCV RNA test shows whether the virus is there now.
After treatment, hepatitis C counts as cured when HCV RNA is still undetectable 12 weeks or more after the treatment ended. Studies often accept people cured this way.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Old World milk containing only a2 beta-casein vs. New World milk that includes both a1 and a2 beta-casein
Other: Milk containing only A2 beta-casein
Old World milk containing only a2 beta-casein vs. New World milk that includes both a1 and a2 beta-casein
Other: Milk containing A1 and A2 beta-casein
Milk dose for 2 weeks
Also known as: Commercial milk
Milk dose for 2 weeks
Difference in inflammation between commercial and A2 milk
The concentration of inflammatory markers hs-CRP, IL-4, IgG, IgG1, BCM-7, GSH in serum will be measured using ELISA kits, Cobas 400 plus analyzer and a Cobas e411 analyzer in nanometers.
Time frame: Baseline blood draw on day 1 and within the 3 hours following milk dose on day 15
Difference in hydrogen between commercial and A2 milk
Hydrogen concentration (ppm) will be measured in breath sample using a hydrogen breath analyzer.
Time frame: Within the 6 hours following milk dose on day 15
Difference in symptoms between commercial and A2 milk
Participants will record and rate abdominal pain, bloating, flatulence, diarrhea and fecal urgency using a 6-point Likert Scale during the 6-hour test. The scale ranges from a score of 0 to 5 (0 = none, 1 =slight, 2 = mild, 3 = moderate, 4 = moderately severe, 5 = severe).
Time frame: From day 1 to day 14 after 500 ml milk consumption and within the 6 hours following milk dose on day 15
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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