If you regularly pay 50 cents for soy or almond milk at Kerckhoff Coffee House to avoid the discomfort of consuming dairy products, you are not alone. In fact, compared to most of the world’s population, you’re in the majority.
Contrary to popular belief, and the particular naming of the term itself as a “disease,” lactose intolerance affects the majority of adults. Less than 40 percent of adults worldwide retain the ability to digest lactose, a sugar found in milk. Although all infants are born with the capability to digest lactose via the enzyme lactase, the ability to synthesize lactase declines as people develop into adults. From an evolutionary perspective, this makes sense, as the only source of lactose in societies that did not traditionally consume dairy food products is human breast milk.
Western scientists once believed most people retained lactase function, and thus ability to fully digest dairy products, into adulthood, but in most of the world population, retention of this function is far from the norm. In scientific parlance, researchers instead use the term lactase persistence to refer to the ability to digest milk into adulthood, a phenotype associated with genetic mutation found in certain genes. These mutations have high frequencies in populations originating in Europe, East Africa and parts of the Middle East, all of which arose independently as evolutionary strategies in response to a long history of dairy farming culture. The ability to consume dairy products without gastrointestinal distress into adulthood has not been the historical digestive norm, and an increasing inability to digest lactose sugars into adulthood remains the norm for most adults today.
In different studies done on lactase persistence in racial and ethnic groups within the U.S., 90 percent of Asian Americans, 53 percent of Mexican Americans, and 70 percent of African Americans were found to be lactose intolerant, or lactase non-persistent. At UCLA, these groups make up 56.6 percent of the undergraduate student population, not counting Native Americans, international students of various races and ethnicities, and additional U.S. students of European descent also unable to digest lactose. All in all, that means a sizable portion of the student population is lactase non-persistent.
Why aren’t more of us running to the bathroom after sipping on a café latte, then? The answer is the existence of intermediate phenotypes. Depending on your specific lactase genes, there may be some low level of lactase still being made in your body, decreasing the effects of severe lactose intolerance, or you may simply not be ingesting enough lactose to experience more severe symptoms such as diarrhea, nausea, growling stomach sounds and vomiting.
Degrees of severity of lactase non-persistence vary. People without noticeable symptoms may not even consider themselves lactose intolerant, though inability to digest lactose increases steadily with age, and thus many students, as young adults, may not be completely deprived of their juvenile lactase enzymes. Additionally, aside from milk and some other products, many common dairy products such as cheese and yogurt contain relatively little lactose and are unlikely to upset those only mildly intolerant of lactose.
Interestingly, the myth of ubiquitous lactase persistence continues to be perpetuated, even though 60 percent of the US population is lactase non-persistent. From a population-wide standpoint, it seems strange, then, that cow milk products within coffee drinks continue to be the norm and that the majority of the population is expected to pay extra for the privilege of experiencing a gastrointestinal-upset-free caffeine experience.
Frankly, it seems a little unfair for UCLA’s coffee shops to upcharge a sizable segment of the population for their enzyme deficiencies, though these prices follow from the coffee shop to the grocery store. A quick look at Instacart prices delivering to Westwood shows the cheapest 64 fluid ounce bottle of milk costs $3.09 and an identical volume of the cheapest soymilk costs $4.29.
What’s the source of this price discrepancy? One quick look at Google shows that the price difference for soy and cow milk seems to be linked to the U.S. government’s subsidizing of the dairy industry. Other answers point to the association of plant-based milks with fad diets and the health-conscious willing to spend extra in the name of “clean eating,” Paleo diets, and whatever dietary suggestions have been popular in the last few decades. Still others claim that since a demand for soy feeds into multiple products such as tofu as well as soymilk, prices must rise as a result.
The real answer is probably a mix of these, though it’s impossible to know for sure, as prices vary by location.
Though American food culture has long retained cow’s milk and other related products such as half and half as de rigeur coffee additives, plant-based milks have been rising in popularity, albeit for health trend-related reasons rather than an acknowledgement that a large segment of the population literally cannot successfully digest the normative coffee creamer. However, this popularity has not led to a fall in plant-milk prices equating to the heavily subsidized cow’s milk; almond milk, in particular, is expensive to produce, requiring lots of water, a fact of production most pertinent in drought-stricken California.
For the lactase non-persistent silent majority, it’s unlikely the biological reality will manifest in economic equity, and for those of a more extreme phenotype, we will continue to fork over a little extra to prevent a catastrophe of gastrointestinal proportions.