Lactose

Beta-D-Lactose.svg

Lactose is a disaccharide sugar composed of glucose and galactose that is found in milk and other dairy products. It is a significant carbohydrate in the diet of many mammals, including humans. Lactose is broken down by the enzyme lactase into its constituent sugars, which can then be absorbed into the bloodstream.

Structure and Composition

Lactose is a disaccharide, meaning it is made up of two monosaccharides: glucose and galactose. The chemical formula for lactose is C₁₂H₂₂O₁₁. The bond between the glucose and galactose molecules is a β(1→4) glycosidic bond.

Digestion and Absorption

The digestion of lactose occurs in the small intestine, where the enzyme lactase hydrolyzes lactose into glucose and galactose. These monosaccharides are then absorbed through the intestinal lining into the bloodstream. In individuals with lactose intolerance, the production of lactase is insufficient, leading to symptoms such as bloating, diarrhea, and abdominal pain when lactose-containing foods are consumed.

Lactose Intolerance

Lactose intolerance is a common condition where individuals are unable to fully digest lactose due to a deficiency in lactase. This condition can be diagnosed through various tests, including the hydrogen breath test and lactose tolerance test. Management of lactose intolerance typically involves dietary modifications to limit or avoid lactose-containing foods.

Sources of Lactose

Lactose is primarily found in milk and dairy products such as cheese, yogurt, and butter. It is also present in some processed foods and medications as an additive. The concentration of lactose varies among different dairy products, with milk containing approximately 4-5% lactose by weight.

Industrial Uses

Lactose is used in the food industry as a sweetener and stabilizer. It is also utilized in the pharmaceutical industry as an excipient in tablets and capsules. Additionally, lactose is used in the production of lactic acid and other fermentation products.

Health Implications

While lactose is a valuable source of energy and nutrients for many individuals, those with lactose intolerance or a milk allergy must manage their intake carefully. Alternatives such as lactose-free dairy products and plant-based milk substitutes are available for those who need to avoid lactose.

See Also

• Lactase
• Lactose intolerance
• Disaccharide
• Glucose
• Galactose
• Milk
• Dairy product