ARTICLE BY ILIANA ODOUARD, PHOTOS BY AKU ACQUAYE | SCIENCE ISSUE 2015
Most of you ice cream and cheese lovers out there probably haven’t thought twice about what happens to those creamy indulgences after you devour them. Or more specifically, what happens to the sugars, or lactose, found in that dairy. Culinarian writer Ili didn’t think about it either until her stomach forced her to. Unfortunately, many others like Ili are unable to digest lactose with the proper enzyme, lactase, and are diagnosed as lactose intolerant. Biologically speaking, it turns out that lactose intolerance isn’t uncommon at all, and may even be a more natural state for the human body.
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Babies are born with the ability to digest lactose since they only drink milk for the first few months of life. As they become older and grow teeth, their diet expands and lactose digestion becomes unnecessary. So, the ability goes away. Babies begin to stop producing more cells that contain lactase enzyme, losing their ability to break down lactose into its smaller sugar components, glucose and galactose. Why, then, can most of the human population in Western societies digest lactose as adults without a problem?
One single mutation in human DNA is responsible for the persistence of the lactase enzyme in the human small intestine. This means that in many societies, the production of lactase by the small intestine cells continues into adulthood, instead of fading after childhood. Though milk is a quintessential part of Western life, it’s actually quite strange that many of us are ingesting cow’s milk on a daily basis.
Why don’t we just drink human milk? No other animal goes around drinking other species’ milk. Other mammals cannot absorb lactose after they reach a certain age, which supports the idea that lactose “tolerance” is an abnormality that has spread widely through the human population. We see that lactose tolerance is not seen in every human population. Geographically, there are societies that are less lactose tolerant than the West. Asians, Africans, and many indigenous Americans are overall less likely to be able to digest lactose in adulthood. These societies tend to have less access to cows than Northern and Western Europe, which would explain why the need for lactase enzyme has dwindled with time.
Along with the scientific component, we see reasons for lactose tolerance when we look to the joint history between humans and cows. Obviously, before cows were domesticated, milk wasn’t available to anyone besides babies who obtained it from their mothers. Once human societies around the world realized the potential milky benefits of owning a few cows, a revolution began. In addition to being slaughtered for beef, cows began providing a major source of nutrition in the form of milk. And with that milk, people made cream, butter, cheese, and more dairy delicacies. When these products first appeared, they were seen as luxuries. As time went on, dairy products became more widespread and now we see them line the aisles of grocery stores around the world and feed millions. (That being said, a nice cheese will always be a luxury.)
Luckily, thanks to widely available, over-the-counter lactase enzyme pills, the lactose intolerant can still enjoy an ice cream every now and then. These pills are sold as Lactaid, and can be taken right before eating dairy products to make up for the lack of lactase in the small intestine. I was a pretty late bloomer with respect to the whole losing-your-lactase-enzyme thing considering that most lactose-intolerant kids show symptoms at a much earlier age; I only started shopping for Lactaid pills regularly about a year or two ago. Thank goodness they even exist, since my favorite food happens to be ice cream. Sick irony, right? I’m one of the lucky ones, though, since I can manage a bit of cheese or icing here and there without scrambling to pop a Lactaid pill.
Without the lactase enzyme present, bacteria in the colon digest lactose, which causes a lactose intolerant person to feel bloated, gassy, and potentially nauseous after ingesting dairy. A by-product of the bacteria’s lactose digestion is hydrogen gas, which can be detected in a person’s breath through a process called gas chromatography. This is often used to diagnose lactose intolerance. Doctors also use blood tests to verify whether or not a person is lactose intolerant. Since the lactase enzyme splits lactose into galactose and glucose, the blood of a person who has just consumed dairy would contain these molecules. However, a person who doesn’t produce lactase would not be able to cleave the lactose into its smaller components, and therefore would not show an elevated blood glucose or galactose level.
So, what does this mean? Are lactose intolerant people more “primitive” than lactose tolerant people? No! After all, it’s only a difference in one nucleotide of DNA that separates the tolerant from the intolerant. Luckily now, with non-dairy milks, ice creams, and cheeses on supermarket shelves alongside the dairy products, the lactose-free life can be quite glamorous (and convenient!). A lactose intolerant person might head down to Absolute Bagels and order a toasted bagel with herb Tofutti, a cream-cheese-like spread made from tofu, before heading over to Oren’s for a soy cappuccino. Both are sans lactose and beyond satisfying. Makes for a great Sunday morning, if you ask me.
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