Abstract | BACKGROUND: A major protein component of cow's milk is β- casein. The most frequent variants in dairy herds are A1 and A2. Recent studies showed that milk containing A1 β- casein promoted intestinal inflammation and exacerbated gastrointestinal symptoms. However, the acute gastrointestinal effects of A1 β- casein have not been investigated. This study compared the gastrointestinal effects of milk containing A1 and A2 β- casein versus A2 β- casein alone in Chinese adults with self-reported lactose intolerance. METHODS: In this randomised, crossover, double-blind trial, with a 3-day dairy washout period at baseline, subjects were randomised to consume 300 mL of milk containing A1 and A2 β- casein (ratio 58:42; conventional milk) or A2 β- casein alone; subjects consumed the alternative product after a 7-day washout period. Urine galactose was measured at baseline after a 15 g lactose load. Subjects completed 9-point visual analogue scales for gastrointestinal symptoms (borborygmus, flatulence, bloating, abdominal pain, stool frequency, and stool consistency) at baseline and at 1, 3, and 12 h after milk consumption. RESULTS: A total of 600 subjects were included. All six symptom scores at 1 and 3 h were significantly lower after consuming A2 β- casein versus conventional milk (all P<0.0001). At 12 h, significant differences remained for bloating, abdominal pain, stool frequency, and stool consistency (all P<0.0001). Symptom scores were consistently lower with A2 β- casein in both lactose absorbers (urinary galactose ≥0.27 mmol/L) and lactose malabsorbers (urinary galactose <0.27 mmol/L). CONCLUSION: Milk containing A2 β- casein attenuated acute gastrointestinal symptoms of milk intolerance, while conventional milk containing A1 β- casein reduced lactase activity and increased gastrointestinal symptoms compared with milk containing A2 β- casein. Thus, milk-related gastrointestinal symptoms may result from the ingestion of A1 β- casein rather than lactose in some individuals. TRIAL REGISTRATION: NCT02878876 , registered August 16, 2016. Retrospectively registered.
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Authors | Mei He, Jianqin Sun, Zhuo Qin Jiang, Yue Xin Yang |
Journal | Nutrition journal
(Nutr J)
Vol. 16
Issue 1
Pg. 72
(Oct 25 2017)
ISSN: 1475-2891 [Electronic] England |
PMID | 29070042
(Publication Type: Journal Article, Multicenter Study, Randomized Controlled Trial)
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Chemical References |
- Calcium, Dietary
- Caseins
- Dietary Carbohydrates
- Dietary Fats
- Dietary Proteins
- Fatty Acids
- Sodium, Dietary
- Lactase
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Topics |
- Adult
- Animals
- Asian People
- Calcium, Dietary
(administration & dosage)
- Caseins
(administration & dosage)
- Cross-Over Studies
- Diet
- Dietary Carbohydrates
(administration & dosage)
- Dietary Fats
(administration & dosage)
- Dietary Proteins
(administration & dosage)
- Double-Blind Method
- Fatty Acids
(administration & dosage)
- Female
- Food Analysis
- Gastrointestinal Diseases
(etiology)
- Humans
- Lactase
(metabolism)
- Lactose Intolerance
(complications)
- Male
- Middle Aged
- Milk
(chemistry)
- Milk Hypersensitivity
(complications, diagnosis)
- Sodium, Dietary
(administration & dosage)
- Young Adult
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