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Nutr J. 2017 Oct 25;16(1):72. doi: 10.1186/s12937-017-0275-0.

Effects of cow's milk beta-casein variants on symptoms of milk intolerance in Chinese adults: a multicentre, randomised controlled study.

Author information

1
Beijing Research Institute for Nutritional Resources, Beijing, China.
2
Clinical Nutrition Center, Huadong Hospital Affiliated to Fudan University, Shanghai, China.
3
Department of Nutrition, School of Public Health, Sun Yat-Sen University, Guangzhou, China.
4
Department of Food Nutrition, National Institute for Nutrition and Health, Chinese Center for Disease Control and Prevention, Beijing, China. yxyang@263.net.
5
Chinese Nutrition Society, 6# Guang An Men Nei. Street, Fenghua Square, Building A, Unit 5, Room 1601/1602, Xuanwu District, Beijing, 100053, People's Republic of China. yxyang@263.net.

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.

KEYWORDS:

Beta-casein; Intolerance; Lactase; Lactose

PMID:
29070042
PMCID:
PMC5657040
DOI:
10.1186/s12937-017-0275-0
[Indexed for MEDLINE]
Free PMC Article

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