Nestlé Research Center Lausanne, BioAnalytical Science Department, Food and Health Microbiology, CH-1000, Lausanne, 26, Switzerland.
Environ Microbiol. 2013 Aug;15(8):2154-61. doi: 10.1111/1462-2920.12117. Epub 2013 Apr 9.
Food and nutrition have played a crucial role in biological evolution. Lactation in mammals was one key invention. A central role in milk is played by lactose, otherwise an exotic sugar in nature. Lactose digestion needs the induction of specialized gut enzymes. This enzyme is shut off in a precisely timed developmental step leading to lactose malabsorption promoting weaning in the young and ovulation in the mother. The lactose-lactase system could thus regulate optimal birth spacing in land mammals. The domestication of cattle promoted milk as a food item also for adult nutrition. This was only possible by two further key inventions: the concomitant domestication of lactic acid bacteria which ferment the non-digestible lactose to the easily absorbed lactic acid and the mutation to lactase persistence (LP) in adults from dairy societies. This mutation represents one of the strongest selected loci of the human genome. Since no crucial nutritional selective advantage is conferred by LP, its dominance might be the result of indirect effects like the spread of cattle pathogens into humans. Lactase is also temporarily lost in rotavirus and Escherichia coli childhood diarrhoea and persistent diarrhoea is consequently best treated with lactose-free diets.
食物和营养在生物进化中起着至关重要的作用。哺乳动物的哺乳是一项关键发明。乳糖在牛奶中起着核心作用，否则它在自然界中是一种外来的糖。乳糖消化需要诱导专门的肠道酶。这种酶在一个精确的时间发育步骤中关闭，导致乳糖吸收不良，促进幼崽断奶和母亲排卵。因此，乳糖酶系统可以调节陆地哺乳动物的最佳生育间隔。牛的驯化促进了牛奶作为一种食物，也促进了成年人的营养。这只有通过另外两个关键发明才能实现：同时驯化乳酸菌，将不可消化的乳糖发酵成易吸收的乳酸，以及从乳制品社会的成年人中发生的乳糖酶持续存在（LP）突变。这种突变代表了人类基因组中最强的选择基因座之一。由于 LP 没有赋予关键的营养选择性优势，它的优势可能是间接影响的结果，例如牛病原体传播到人类。轮状病毒和大肠杆菌引起的儿童腹泻也会暂时失去乳糖酶，因此持续腹泻最好用无乳糖饮食治疗。
