One cup of white milk (250 ml) contains 12 grams of naturally-occurring sugar called lactose. It gives milk a slightly sweet taste. The body breaks lactose down into glucose and galactose (most of which is later converted to glucose). This process is important because glucose is the primary source of energy in the body and the sole energy source for the brain.
Determining if a food has naturally-occurring sugars or added sugars is important. As part of their nutrient-rich package, foods such as fruit, white milk and plain yogurt contain naturally-occurring sugars. These are all healthy foods to include in your diet. In contrast, added sugars are concentrated sources of calories with no nutritional benefit. Thus, limiting added sugars is wise since extra calories can lead to weight gain and increased risk for health problems.
Lactose, also known as milk sugar, makes up around 0-8 per cent of milk, by weight. Extracted from sweet or sour whey, lactose can be separated from milk, to create lactose free dairy products, and can be marketed and sold separately. Pure lactose is about 20 per cent the sweetness of cane sugar and is used in unique food applications and as a sweet addition to flavoured milk. Lactose is also a good way to support the growth of beneficial gut bacteria such as acidophilus.
Learn more about sugar in your diet here.