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This is a 3-sites, double-blinded, randomized, 2X2 cross-over study aiming to compare effects of milk containing only A2 type beta casein versus milk containing both A1 and A2 beta casein proteins on the gastrointestinal symptoms for the health people who self-reported to be lactose intolerant.
Study sites: Shanghai, Guangzhou, Beijing
Eligible subjects were enrolled in the study and randomized into one of the 2 study arms:
Sequence A1-A2: Oral consumption of milk containing both A1 and A2 type beta casein at Visit 1 and milk containing only A2 type beta casein at Visit 2; Sequence A2-A1: Oral consumption of milk containing only A2 type beta casein at Visit 1 and milk containing both A1 and A2 type beta casein at Visit 2.
Washout period: 2 weeks between Visit 1 and Visit 2
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Sequence A1-A2 | Experimental | Dietary Supplement: Oral consumption of milk with sequence A1-A2 |
|
| Sequence A2-A1 | Experimental | Dietary Supplement: Oral consumption of milk with sequence A2-A1 |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Oral consumption of milk with sequence A1-A2 | Dietary Supplement | Oral consumption of 300 ml of milk containing both A1 and A2 type beta casein at 8:00 a.m. on Visit 1 (after 12-hour fasting) and 300 ml of milk containing only A2 type beta casein at 8:00 a.m. on Visit 2 (after 12-hour fasting). |
| Measure | Description | Time Frame |
|---|---|---|
| Gastrointestinal Symptom VAS scores at 3 hours | Gastrointestinal symptoms were self-measured by study subjects on a scale from 0 (not at all) to 9 (severe) at 3 hours after product consumption at Visit 1 and Visit 2. Data was analyzed as a repeated measures design using a mixed effects ANOVA with symptom VAS scores at 3-hour as outcome, study product (A1 or A2) and study visit (1 or 2) as fixed effects, and a random subject effect nested within the sequence of study treatment (A1-A2 or A2-A1) , and adjusted for baseline symptom scores. Type III tests of fixed effects were used for testing the effect of study products. Contrast tests were generated to compare means for each product. | Three hours after product intervention at each of Visit 1 and Visit 2 |
| Measure | Description | Time Frame |
|---|---|---|
| The percentage of improvement in gastrointestinal symptoms after drinking A2 versus A1 | The improvement in gastrointestinal symptoms after drinking A2 versus A1 were classified into 4 mutually exclusive categories according to the following definition:
The frequency and percentage in each category of improvement for each single gastrointestinal symptom, as well as that for all symptoms, are summarized. |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Andrew J Clarke, PhD | a2 Milk Company Ltd. | Study Director |
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| PubMed Identifier | Type | Citation | Retractions |
|---|---|---|---|
| 29070042 | Derived | He M, Sun J, Jiang ZQ, Yang YX. Effects of cow's milk beta-casein variants on symptoms of milk intolerance in Chinese adults: a multicentre, randomised controlled study. Nutr J. 2017 Oct 25;16(1):72. doi: 10.1186/s12937-017-0275-0. |
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| ID | Term |
|---|---|
| D007787 | Lactose Intolerance |
| ID | Term |
|---|---|
| D008286 | Malabsorption Syndromes |
| D007410 | Intestinal Diseases |
| D005767 | Gastrointestinal Diseases |
| D004066 | Digestive System Diseases |
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| ID | Term |
|---|---|
| D008892 | Milk |
| ID | Term |
|---|---|
| D001628 | Beverages |
| D000066888 | Diet, Food, and Nutrition |
| D010829 | Physiological Phenomena |
| D003611 | Dairy Products |
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|
| Oral consumption of milk with sequence A2-A1 | Dietary Supplement | Oral consumption of 300 ml of milk containing only A2 type beta casein at 8:00 a.m. on Visit 1 (after 12-hour fasting) and 300 ml of milk containing both A1 and A2 type beta casein at 8:00 a.m. on Visit 2 (after 12-hour fasting). |
|
| 1 hour and 3 hours after product intervention |
| Urinary galactose concentration | Urinary galactose (U-gal) concentration was measured at baseline and 3-hour of each of Visit 1 and Visit 2. Data was analyzed as a repeated measures design using a mixed effects ANOVA with fixed effects of study product (A1 or A2) and study visit (1 or 2) and a random subject effect nested within the sequence of study treatment (A1-A2 or A2-A1) , and adjusted for baseline symptom scores. Type III tests of fixed effects were used for testing the effect of study products. Contrast tests were generated to compare means for each product. The U-gal measurements over the whole study period (both Visit 1 and Visit 2) for all subjects were also summarized by study product. Product difference was evaluated using one-way ANOVA. | baseline and 3 hours after product intervention of each of Visit 1 and Visit 2 |
| Gastrointestinal Symptom VAS scores at 1 hour | Gastrointestinal symptoms were self-measured by study subjects on a scale from 0 (not at all) to 9 (severe) at 1 hour after product consumption at Visit 1 and Visit 2. Data was analyzed as a repeated measures design using a mixed effects ANOVA with symptom VAS scores at 1-hour as outcome, study product (A1 or A2) and study visit (1 or 2) as fixed effects, and a random subject effect nested within the sequence of study treatment (A1-A2 or A2-A1) , and adjusted for baseline symptom scores. Type III tests of fixed effects were used for testing the effect of study products. Contrast tests were generated to compare means for each product. | One hour after product intervention at each of Visit 1 and Visit 2 |
| Change of urinary galactose concentration from baseline at 3 hours <0.27 mmol/L (Yes/No) | Based on the results of urinary galactose test, subjects were classified as lactose malabsorbers if they had an increase in urinary galactose concentration of <0.27 mmol/L at 3 hours after oral consumption of 15g lactose (corresponding to 300 ml of product A1). And those with an increase in urinary galactose concentration of ≥0.27 mmol/L at 3-hour were classified as lactose absorbers. | 3 hours after product intervention of each of Visit 1 and Visit 2 |
| D002239 | Carbohydrate Metabolism, Inborn Errors |
| D008661 | Metabolism, Inborn Errors |
| D030342 | Genetic Diseases, Inborn |
| D009358 | Congenital, Hereditary, and Neonatal Diseases and Abnormalities |
| D008659 | Metabolic Diseases |
| D009750 | Nutritional and Metabolic Diseases |
| D005502 |
| Food |
| D019602 | Food and Beverages |