Comparative effects of A1 versus A2 beta-casein on gastrointestinal measures: a blinded randomised cross-over pilot study
Comparative effects of A1 versus A2 beta-casein on gastrointestinal measures: a blinded randomised cross-over pilot study
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DOI：
10.1038/ejcn.2014.127
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发表时间：
2014-09-01
影响因子：
4.7
通讯作者：
Pal, S.
中科院分区：
文献类型：
--
作者：
Ho, S.;Woodford, K.;Pal, S.
背景/目的：目前，关于牛奶中A1型β-酪蛋白与其前身A2型相比对胃肠道的影响存在争议。体外和动物研究表明，A1而非A2 β-酪蛋白的消化通过β-酪啡肽-7的释放影响胃肠蠕动和炎症。我们的目的是评估在成人人群之间的牛奶含有A1与A2 β-casein.SUBJECTS/METHODS：41名女性和男性被招募到这个双盲，随机8周的交叉研究胃肠道的影响差异。参与者进行了为期2周的乳制品清洗（米奶取代奶制品），随后2周牛奶（750 ml/天），其含有A1或A2型的β-酪蛋白，然后进行第二次冲洗，接着是最后2周的替代A1或A2型牛奶。与A2 β-酪蛋白牛奶相比，A1 β-酪蛋白牛奶导致显著更高的粪便稠度值（布里斯托粪便量表）。A1饮食组腹痛和大便粘稠度之间也存在显著正相关（r = 0.520，P = 0.001），而A2饮食组则无此相关（r =-0.13，P = 0.43）。这两种相关性之间的差异（0.52对-0.13）是非常显著的（P < 0.001）。此外，有些人可能对A1 β-酪蛋白敏感，这可以通过较高的粪便钙卫蛋白值和相关的不耐受措施来证明。这些初步结果表明，在一些成年人中，食用含有A1或A2 β-酪蛋白类型的β-酪蛋白的牛奶时，胃肠道反应存在差异，但需要在一项更大的研究中证实，该研究的参与者对普通的含A1 β-酪蛋白的牛奶不耐受。
BACKGROUND/OBJECTIVES: At present, there is debate about the gastrointestinal effects of A1-type beta-casein protein in cows' milk compared with the progenitor A2 type. In vitro and animal studies suggest that digestion of A1 but not A2 beta-casein affects gastrointestinal motility and inflammation through the release of beta-casomorphin-7. We aimed to evaluate differences in gastrointestinal effects in a human adult population between milk containing A1 versus A2 beta-casein.SUBJECTS/METHODS: Forty-one females and males were recruited into this double-blinded, randomised 8-week cross-over study. Participants underwent a 2-week dairy washout (rice milk replaced dairy), followed by 2 weeks of milk (750 ml/day) that contained beta-casein of either A1 or A2 type before undergoing a second washout followed by a final 2 weeks of the alternative A1 or A2 type milk.RESULTS: The Al beta-casein milk led to significantly higher stool consistency values (Bristol Stool Scale) compared with the A2 beta-casein milk. There was also a significant positive association between abdominal pain and stool consistency on the A1 diet (r = 0.520, P = 0.001), but not the A2 diet (r = -0.13, P = 0.43). The difference between these two correlations (0.52 versus -0.13) was highly significant (P < 0.001). Furthermore, some individuals may be susceptible to A1 beta-casein, as evidenced by higher faecal calprotectin values and associated intolerance measures.CONCLUSIONS: These preliminary results suggest differences in gastrointestinal responses in some adult humans consuming milk containing beta-casein of either the A1 or the A2 beta-casein type, but require confirmation in a larger study of participants with perceived intolerance to ordinary A1 beta-casein-containing milk.