SciTech

Making alternatives to milk to sidestep lactose intolerance

Credit: Eunice Oh/ Credit: Eunice Oh/

Ever since we were in kindergarten, we were told to drink milk to soak up calcium and keep our bones strong. However, a significant portion of the population can’t digest lactose. We all know where regular milk comes from (hopefully), but what about the milk substitutes made for our lactose-sensitive or vegan brethren? The processes behind soy, almond, and rice milk are intriguing, so let’s get to it.

As its name implies, rice milk is made by processing rice, usually brown rice. There are multiple methods that can even be done at home to process the rice. First, the rice is cooked normally on a stove top or rice cooker. Then, it is blended with water until it becomes liquefied. During the cooking process, the rice undergoes a natural enzymatic process. The carbohydrates in the rice are cleaved and become sugars, giving the rice milk a natural sweetness. After resting, one can pour the mixture over cheesecloth, a gauze-like cloth used for cheese-making and cooking. Rice milk has less fat than regular milk, but more carbohydrates. Furthermore, there are few natural nutrients in the milk, although most commercially-made rice milk is fortified with added calcium and vitamins.

Almond milk is made through a similar process. At-home methods include soaking the almonds for an extended period of time, blending with water, and then straining through a cheesecloth. Almond milk doesn’t have any cholesterol or lactose and has a lower fat content than cow’s milk. It provides much less protein than milk as well, although it still provides nutrients including calcium.

Soy milk is perhaps the most common milk substitute. Made from soybeans, soy milk has a long history with roots in Asia. Soybeans are soaked overnight and then go through a process called wet grinding to make a wet, pasty substance with the rehydrated beans. Boiling the purée enhances its flavor and sterilizes, while also improving the nutritional value. The liquid milk is then separated from the solids by filtering it through a cheesecloth. Finally, the collected soy milk must be boiled again.

So why are people lactose intolerant in the first place? It usually comes down to genetics and your ancestors’ evolutionary past.

Lactose is a disaccharide sugar made of galactose and glucose, and is found in milk. Lactose is digested by an enzyme known as lactase, which is encoded by the gene LCT in humans. Mutations in LCT itself are very rare and cause lactose intolerance beginning in infancy. Much more common adult-onset lactose intolerance is instead caused by a lack of expression of LCT post-infancy, which is dependent on other regions of DNA called regulatory elements. Scientists have found a nearby gene called MCM6 that controls the expression of LCT and, therefore, controls the production of lactase.

Some individuals have a variation of MCM6 that allows them to produce lactase all their lives, while others have variations that will stop working in childhood. Ancestry plays a great role in determining whether someone will be lactose-intolerant or not. Populations that historically raised cows and lived off milk for nutrition, such as northern Europeans, have about 95 percent lactose tolerance, according to the National Institutes of Health. Many East Asian populations, on the other hand, have 90 percent or greater lactose intolerance because there was no need for an active MCM6. In fact, around 65 percent of the population loses the ability to digest lactose post-infancy.

When we are unable to digest lactose, it builds up in the digestive system and acts as a food source for bacteria in the gut. The growth of bacteria is what causes the various gastrointestinal maladies lactose-intolerant individuals experience after consuming dairy products.

Whether your milk aversion is due to a non-functioning MCM6, a vegan lifestyle, or taste preferences, milk substitutes can be found in most grocery stores or made at home.