Truswell A S
Human Nutrition Unit, University of Sydney, Australia.
Eur J Clin Nutr. 2005 May;59(5):623-31. doi: 10.1038/sj.ejcn.1602104.
This review outlines a hypothesis that A1 one of the common variants of beta-casein, a major protein in cows milk could facilitate the immunological processes that lead to type I diabetes (DM-I). It was subsequently suggested that A1 beta-casein may also be a risk factor for coronary heart disease (CHD), based on between-country correlations of CHD mortality with estimated national consumption of A1 beta-casein in a selected number of developed countries. A company, A2 Corporation was set up in New Zealand in the late 1990s to test cows and market milk in several countries with only the A2 variant of beta-casein, which appeared not to have the disadvantages of A1 beta-casein. The second part of this review is a critique of the A1/A2 hypothesis. For both DM-I and CHD, the between-country correlation method is shown to be unreliable and negated by recalculation with more countries and by prospective studies in individuals. The animal experiments with diabetes-prone rodents that supported the hypothesis about diabetes were not confirmed by larger, better standardised multicentre experiments. The single animal experiment supporting an A1 beta-casein and CHD link was small, short, in an unsuitable animal model and had other design weaknesses. The A1/A2 milk hypothesis was ingenious. If the scientific evidence had worked out it would have required huge adjustments in the world's dairy industries. This review concludes, however, that there is no convincing or even probable evidence that the A1 beta-casein of cow milk has any adverse effect in humans. This review has been independent of examination of evidence related to A1 and A2 milk by the Australian and New Zealand food standard and food safety authorities, which have not published the evidence they have examined and the analysis of it. They stated in 2003 that no relationship has been established between A1 or A2 milk and diabetes, CHD or other diseases.
本综述概述了一种假说，即β-酪蛋白（牛奶中的一种主要蛋白质）的常见变体之一A1可能会促进导致I型糖尿病（DM-I）的免疫过程。随后有人提出，基于一些发达国家冠心病死亡率与估计的全国A1β-酪蛋白消费量之间的国家间相关性，A1β-酪蛋白也可能是冠心病（CHD）的一个风险因素。一家名为A2 Corporation的公司于20世纪90年代末在新西兰成立，旨在检测奶牛并在几个国家销售仅含β-酪蛋白A2变体的牛奶，该变体似乎没有A1β-酪蛋白的缺点。本综述的第二部分是对A1/A2假说的批判。对于DM-I和CHD，国家间相关性方法被证明是不可靠的，并且通过增加更多国家重新计算以及对个体进行前瞻性研究而被否定。支持糖尿病假说的对易患糖尿病啮齿动物的动物实验未得到更大规模、标准化程度更高的多中心实验的证实。支持A1β-酪蛋白与CHD之间联系的单一动物实验规模小、时间短，采用了不合适的动物模型，并且存在其他设计缺陷。A1/A2牛奶假说很巧妙。如果科学证据成立，这将需要全球乳制品行业进行巨大调整。然而，本综述得出结论，没有令人信服甚至可能的证据表明牛奶中的A1β-酪蛋白对人类有任何不良影响。本综述独立于澳大利亚和新西兰食品标准及食品安全当局对与A1和A2牛奶相关证据的审查，这些当局尚未公布他们审查的证据及其分析。他们在2003年表示，尚未确定A1或A2牛奶与糖尿病、CHD或其他疾病之间存在关联。
