What is the only natural source of lactose?

Milk is the only natural source of lactose, which is a disaccharide sugar composed of glucose and galactose. Lactose is primarily found in the milk of mammals, serving as a significant carbohydrate source for their young. When mammals produce milk, lactose is synthesized in the mammary glands, making it a unique characteristic of milk compared to other foods.

Eggs, honey, and cheese do not contain lactose in their natural forms. Eggs do not have any carbohydrates, including lactose. Honey, while a natural source of sugars, primarily contains fructose and glucose but not lactose. Cheese, although it is derived from milk, typically contains lower amounts of lactose due to the fermentation process that occurs during cheese-making, which breaks down lactose into lactic acid. Thus, milk stands out as the only food item that naturally contains lactose.