Lactase is a digestive enzyme that splits the milk sugar lactose in the small intestine into its two components, glucose and galactose, so that the body can absorb them. In many people, the body's own lactase production gradually declines after infancy, which can lead to what is known as lactose intolerance.
If there is not enough lactase, undigested lactose reaches the large intestine, where gut bacteria ferment it. This can cause bloating, abdominal pain or diarrhoea. The severity varies greatly from person to person, ranging from barely noticeable to clear symptoms after eating dairy foods.
Relevance for nutrition and sport
For athletes with lactose intolerance, the question often arises whether milk-based protein sources such as whey or casein are an option. Highly filtered forms such as whey isolate contain much less lactose than concentrate and are often better tolerated. Anyone who wants or needs to avoid lactose completely turns to specially lactose-free products or to plant-based protein sources.
Some people also take lactase as an enzyme supplement to tolerate dairy foods better. Whether this makes sense in an individual case depends on how pronounced the intolerance is. A detailed overview of suitable protein sources for lactose sensitivity is given in the guide lactose-free protein.
