Lactose is a natural sugar found in milk. It is also known as milk sugar. As well as being a good source of energy, lactose helps the body to absorb a number of minerals, such as calcium and magnesium.
In order for lactose to work effectively, it first has to be broken down into two simpler sugars, glucose and galactose. Once lactose has been broken down, it can pass from the gut into the bloodstream.
Lactose is found in the milk of mammals, and it is also added to many foods including:
- dairy products, such as cream, cheese and yoghurt,
- ice cream,
- salad cream and mayonnaise,
- biscuits,
- chocolate,
- boiled sweets,
- cakes, and
- peanut butter.
Lactose intolerance
Lactose intolerance is when the body is unable to break down lactose. The problem is usually caused by the lack of a substance known as lactase. Lactase is an enzyme (a protein that causes a chemical reaction to occur) that is normally produced in your small intestine. The lactase breaks down lactose into glucose and galactose.
If your body produces very little, or no, lactase it will be unable to break down the lactose in your system. The unabsorbed lactose passes through your stomach and into your large bowel. Bacteria in your large bowel ferment (react to) the lactose, producing fatty acids, such as acetate, and gases, such as hydrogen and methane. This can cause symptoms such as stomach bloating and flatulence (wind).
