A Fresh History of Lactose Intolerance

Six decades ago, Pedro Cuatrecasas, a fledgling resident at the Johns Hopkins School of Medicine, was studying the lives of impoverished residents of Baltimore when he noticed an unsettling trend. In interviews, a number of his Black patients would confess that they found milk repellent. The consistency of their laments alarmed Cuatrecasas. He suspected, after some digging, that they suffered from lactase deficiency, a condition that precludes one’s body from digesting fluid milk. Cuatrecasas corralled two of his colleagues to conduct a study that would measure the different responses Black and white subjects had to lactose, and the findings confirmed Cuatrecasas’s hunch: the majority of Black patients had trouble processing lactose, whereas the problem was far less pronounced within white test subjects. These Black patients even told Cuatrecasas that they often avoided milk altogether, for fear of the pain it would exact upon their bodies.

The findings of this study—published in the respected British medical journal The Lancet, in January, 1965—were monumental. Here was concrete evidence that the ability to digest lactose might be a genetic condition linked to one’s racial background. More studies over the following decades would draw similar conclusions about the difficulties that other communities of color—Native Americans, Asians—faced when trying to digest unfermented milk. A damning consensus began to form: the long-held belief that humans can drink fresh milk into adulthood applied almost exclusively to white patients with ancestral roots in northwest Europe. What this indicated, in plain terms, is that most people around the world probably couldn’t drink fresh milk without encountering some kind of physical anguish. One might naïvely imagine that this type of data would have prompted a wholesale reëvaluation of drinking milk’s supremacy in American diets. But this was not the case. Despite the consensus of these studies, little changed. Milk retained its pristine reputation as a bone-fortifying nutritional bulwark in the United States and beyond, thanks to such culprits as public-health officials, the dairy industry, and the American government.

The culinary historian Anne Mendelson relays this episode with slack-jawed befuddlement, and a dose of mild rage, in her latest book, “Spoiled: The Myth of Milk as Superfood” (Columbia University Press, 2023). As the subtitle intimates, this effort aims to question and dismantle the fallacy that what Mendelson refers to as “drinking-milk”—unfermented milk from an animal that does not undergo any alteration to become yogurt or cheese—is a nutritional necessity. She isn’t even convinced that those who are able to keep down milk really need it for their constitution, hazarding that medical authorities have overexaggerated its protein and calcium benefits. Humans certainly don’t require it to survive in the same way they do water, she reminds her readers. That fresh milk has been foisted upon so many Americans in the name of well-being strikes Mendelson as a grave injustice. To start, it has inconvenienced those in the country who, once they are weaned off their mothers’ breast milk, realize that their bodies aren’t wired to withstand unfermented milk; their experiences don’t correspond with prevailing societal logic about milk’s alleged magic.

Worse, Mendelson says, this haughty assumption about drinking milk’s remedial value has had ramifications beyond American borders. Countries around the world have embraced the beverage, even those whose populations may have trouble stomaching milk unless it’s fermented. Milk drinking is the locus of national campaigns in India, Mendelson notes, and China is now among the world’s most robust producers and importers of milk. India has long had sturdy culinary customs that do not involve drinking fresh milk but lean heavily on dairy in some other form: silken yogurts such as curd, commonly known as dahi, and tangy cheeses such as chhena have been bedrocks of cuisines within the country. (India’s movement to empower dairy farmers gained ground in 1970, setting the stage for milk drinking to become a fashionable activity in the years that followed.) And nations like China, Mendelson points out, even made milk drinking into a patriotic pursuit in recent decades as a bid to compete with the global might of the United States.

Histories of this nature are Mendelson’s métier: her past output has included “Stand Facing the Stove” (Henry Holt, 1996), a joint biography of the mother-daughter duo behind the beloved American cooking tome “Joy of Cooking,” and “Chow Chop Suey” (Columbia University Press, 2016), which chronicles the proliferation of Chinese cooking in the United States. She has also fused her historical inquiry with recipe writing, most notably in “Milk: The Surprising Story of Milk Through the Ages” (Knopf, 2008), an encomium to the titular ingredient that cruises through its history before exploring its many possible forms, whether clotted cream or paneer.

The existence of “Milk” may make “Spoiled” seem like an abrupt reversal for Mendelson. But this latest book is not so much an excoriation of fresh milk as it is a provocation, one that urges readers to question fresh milk’s hegemonic grip over the American mind. Though Mendelson admits that she is not the first to tread this ground—she is openly working within the scholarly tradition of such predecessors as Andrea S. Wiley’s ​​“Re-imagining Milk” (Routledge, 2010), Deborah Valenze’s “Milk” (Yale University Press, 2011), and Mark Kurlansky’s “Milk!” (Bloomsbury, 2018)—she positions her book as sui generis. “No previous history of drinking-milk as a major modern industry has examined the ramifications of what is now known about lactase persistence or nonpersistence—often popularly called lactose tolerance or intolerance—in either the remote past or the present,” she writes.

​The moment feels ripe for an undertaking as ambitious as Mendelson’s. For Americans of a certain age, “Got Milk?” advertisements, featuring celebrities whose upper lips bore pasty milk mustaches, were abiding presences on television or in magazines, propagating the belief that milk was a nonpareil elixir of calcium. Even still, Americans were routinely assailed with a dizzying catalogue of fresh-milk variants in coffee shops and grocery stores: whole, reduced fat, low fat, skim. The very definition of “milk” has only recently become a site of semantic litigation, as plant-based alternatives to dairy—made from almonds or oats, pistachios or potatoes—sprout on supermarket shelves, offering accommodations to lactose-intolerant consumers. The past few years have likewise brought increasing cultural awareness that the American dairy industry, in its current formulation, is sustainable for few: farmers struggle to turn a profit, increasingly contending with depression, even suicide. Cows themselves suffer maltreatment, pressured to bear the highest possible yield. Americans who drink milk may receive a product that scarcely resembles what emerged from the animal; those who can’t tolerate milk might be left to tend to their own discomfort, resorting to Lactaid pills to ease their irritations. This makes a project like Mendelson’s unquestionably well timed, the premise she teases in her opening pages intriguing: How did a practice as absurd as drinking milk become such a sworn article of faith in the United States and beyond?

What follows are three hundred pages dense with scrupulous research, amounting to a largely persuasive attempt on Mendelson’s part to engage the layperson in sharing her anger at this state of affairs. Mendelson whizzes through centuries of history as she charts the gradual spread of “dairying,” from its origins in the prehistoric Near East and Western Asia, where milk carried associations with goddesses, to its prevalence in northern Europe. Settlers to that area developed a genetic attribute that allowed them to digest fresh milk as adults somewhere along their journey from the Fertile Crescent. (Mendelson triangulates that this may have happened between 5,500 B.C. and 2,300 B.C.) That very trait spread through the population of northern Europe. Thousands of years later, Britain, one of the stations where this genetic quirk was especially prominent, would become a dominant global power, colonizing diffuse corners of the world while it, along with the United States later on, developed the influence to govern scientific dogma internationally.

This set of conditions thus made it easier for milk drinking to become the worldwide phenomenon it is today. It was around the late eighteenth and early nineteenth centuries that medical authorities codified the misguided principle that all humans, regardless of racial provenance, could digest unfermented drinking milk without issue. After the Second World War, medical experts from former imperial countries sought to “modernize” the diets of once colonized territories, whose people trustingly accepted myopic medical advice about milk’s palliative qualities.