Many Americans experience discomfort after consuming dairy because they have lactose intolerance, meaning they cannot properly digest lactose, the main sugar in milk. This happens because their small intestine doesn’t produce enough of an enzyme called lactase. Without sufficient lactase, the lactose travels undigested to the colon, leading to gastrointestinal issues. Addressing this common problem, USDA chemist Virginia Harris Holsinger pioneered a solution in the 1980s. She discovered that adding lactase enzyme sourced from non-human origins, such as fungi, directly into milk could effectively break down the problematic lactose.  

Holsinger’s method works because the added lactase enzyme pre-digests the milk sugar, breaking the lactose down into simpler, easily digestible sugars: glucose and galactose. The resulting milk tastes slightly sweeter than regular milk but provides a way for lactose-intolerant individuals to enjoy dairy without negative symptoms. Her research was successfully commercialized by the company Lactaid. They introduced lactose-free milk to the market and later expanded the concept to offer a variety of other popular dairy products, including ice cream, cottage cheese, sour cream, and even eggnog, suitable for those with lactose intolerance.