The globalization of cow's milk production and consumption: Biocultural perspectives

Cow's milk consumption has been relatively rare in human history, largely confined to populations with genetic adaptations for continued production of lactase, the enzyme that breaks down the unique milk sugar lactose. But in the last forty years, both the production and consumption of cow's milk have spread around the world, and trade in milk products has likewise increased. Populations with no history of milk drinking have embraced this new beverage, and governments promote its consumption in their food-based dietary guidelines and school milk programs. China is a particularly good example of this trend. There the dairy industry is growing rapidly and milk consumption has become increasingly common in urban areas. Milk is viewed as especially appropriate for children, with growth-promoting properties; the larger size and athletic success of western athletes is often attributed to their greater milk consumption. Milk is a very unusual food insofar as it is uniquely produced by mammals to support the growth, maturation, and health of nursing infants. Furthermore, there is variation among human populations with respect to the production of lactase in adulthood (lactase persistence/impersistence); consumption of lactose, which is only found in milk, beyond the traditional nursing period can result in the gastrointestinal symptoms of lactose intolerance. Thus the surge in consumption among lactase impersistent populations is likely to be accompanied by increases in digestive complaints. With regard to the purported positive relationship between milk and growth, the current evidence is not compelling that milk consumption in childhood results in significant gains in height.