Plain English Summary
Background and study aims
The symptoms of digestive discomfort after consuming dairy products are the main reasons for somebody to avoid commercial dairy products. Most suspect that post-dairy digestive discomfort is caused by lactose intolerance, but in fact some cases are because of a reaction to several types of milk proteins. Cow's milk contains two types of beta casein, A1 beta casein and A2 beta casein. The A1 beta casein type commonly found in commercial milk is broken down into beta-casomorphin-7 (BCM-7) in the digestive system and causes digestive discomfort. In contrast to A1 beta casein type, A2 beta casein type does not produce BCM-7 so it does not show similar symptoms. The aim of this study is to compare the effects of milk with different types of beta casein - i.e. milk containing beta casein combination A1 type and A2 type (A1A2 beta casein) and milk containing only A2 beta casein type (A2A2 beta casein) - on the symptoms of post-dairy digestive discomfort, stool frequency and consistency and also immune response.
Who can participate?
Undergraduate students of Faculty of Public Health, Universitas Indonesia, aged 17-25, who have symptoms of digestive discomfort after consuming dairy or cow’s milk products
What does the study involve?
Participants are assessed regarding symptoms of post-dairy digestive discomfort, diet, nutritional status and blood pressure. All participants receive both milk containing A1A2 beta casein and milk containing A2A2 beta casein. They are randomly allocated to receive the milk containing A1A1 beta casein then milk containing A2A2 beta casein (sequence 1) or milk containing A2A2 beta casein then milk containing A1A2 beta casein (sequence 2). Each participant consumes two bottles of 200 ml of milk daily for 2 weeks. Both types of milk are provided by ABC KOGEN. To ensure that the sample is actually consumed by participants, they have to consume the milk at the Center for Nutrition and Health room on weekdays and at weekdays the milk is taken home by the participants then they return the used bottle. There is a two-week break between consuming the two types of milk where the participants are not allowed to consume cow’s milk products in order to remove or clear the effects of the previous milk. Participants fill out two weekdays and one weekend food diary to monitor their diet. Participants are also given a list of foods as a substitute for the source of nutrition from dairy products. Participants fill out forms about the symptoms of post-dairy digestive discomfort and stool frequency and consistency, and provide blood samples before and after the intervention to measure their immune response.
What are the possible benefits and risks of participating?
Participants will get some benefit such as knowing their body's immune response to dairy products. Overall data collection has no risks. However, an error of the screening procedure may occur so that poses a risk to this research. To minimize the risk, all data are collected by trained personnel according to the standard procedures. In addition, all of the participants are insured and receive treatment if there are any health complaints during this study.
Where is the study run from?
When is the study starting and how long is it expected to run for?
August 2017 to April 2018
Who is funding the study?
Who is the main contact?
Dr Ahmad Syafiq
Comparison of milk containing A1A2 beta casein and milk containing A2A2 beta casein to the symptoms of post dairy digestive discomfort and milk-specific IgE among students of the Faculty of Public Health, Universitas Indonesia Depok (a double-blind randomized two-way cross-over study)
Milk containing A2A2 beta casein decreases the symptoms of post-dairy digestive discomfort and improves immune response more than milk containing A1A2 beta casein.
Committee of Ethics Research and Public Health Service, Faculty of Public Health, Universitas Indonesia, 13/10/2017, ref: 529/UN2.F10/PPM.00.02/2017
Interventional double-blind randomized two-way cross-over single-centre study
Primary study design
Secondary study design
Randomised cross over trial
Quality of life
Patient information sheet
Not available in web format, please use the contact details to request a patient information sheet
Post-diary digestive discomfort
All participants selected in this study received two interventions, that is milk containing A1A2 beta casein and milk containing A2A2 beta casein. Participants were randomized to decide who received the milk containing A1A2 then milk containing A2A2 (sequence 1) or milk containing A2A2 then milk containing A1A2 beta casein (sequence 2). Each participant consumed 200 ml milk twice a day for 2 weeks of intervention. Both types of milk were provided by ABC KOGEN. Before entering second intervention, there are a washout period (intervention-free). In this period, the participants will not get any intervention for 2 weeks to remove or clear the effects of previous intervention. The participants were not allowed to consume dairy products on the washout period during this study. Participants will be given a list of foods as a substitute for the sources of nutrition from dairy products. On intervention period, participants were asked to fill out the form of symptoms of post-dairy digestive discomfort and Bristol Stool Scale as well as taking blood samples. Blood samples were taken within a range of 12 hours before or after the intervention.
Primary outcome measure
1. Symptoms of post-diary digestive discomfort, measured by questionnaire that asked the participants how they felt after milk consumption, such as bloating, abdominal pain, flatulence, heavy stomach and borborygmi (stomach rumbling). The participants were asked to fill out each questionnaire after milk consumption (twice a day) during the intervention period. Each symptom was ranked on Likert scale, as never (score =0), rarely (score=1), moderate (score=2) and severe (score=3)
2. Immune response (milk-specific IgE antibodies), assessed by milk-specific IgE blood serum test. Blood serum sample was performed by the laboratory assistant as follows: blood samples were taken within a range of 12 hours before starting the intervention and after the intervention; laboratory assistant takes 5 ml of venous blood; samples were analyzed by ELISA (enzyme-linked immunosorbent assay) technique in the laboratory
Secondary outcome measures
Stool consistency and frequency, measured using The Bristol Stool Scale every day during the intervention. Stool consistency was rated on 7 type Likert scale:
Type 1: Separate hard lumps, like nuts (hard to pass)
Type 2: Sausage-shaped but lumpy
Type 3: Like a sausage but with cracks on its surface
Type 4: like a sausage or snake, smooth and soft
Type 5: Soft blobs with clear-cut edges (passed easily)
Type 6: Fluffy pieces with ragged edges, a mushy stool
Type 7: Watery, no solid pieces, entirely liquid
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
1. Students of Faculty of Public Health, Universitas Indonesia
2. Male or female, aged 17-25 years
3. Irregular milk consumption (FFQ screening)
4. Felt the symptoms of digestive discomfort after consume commercial dairy products
5. Have a normal blood pressure
6. BMI 19-27.5 kg/m2
7. Willing to follow all of the requirements and procedures of this study and agree to sign informed consent
Target number of participants
60 participants: 30 participants for sequence 1 and 30 participants for sequence 2
Participant exclusion criteria
1. Woman in pregnancy and breastfeeding
2. Consume anti inflammatory or immunosuppressive drugs within 4 weeks before screening
3. Have an allergy
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Centers for Nutrition and Health Faculty of Public Health Room 204, F Building, 2nd floor
Depok, West Java
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
American Journal of Clinical Trial; British Journal of Nutrition; Malaysian Journal of Nutrition
IPD sharing statement
The datasets generated during and/or analysed during the current study are not expected to be made available.
Intention to publish date
Participant level data
Not expected to be available
Basic results (scientific)