Lactose

Definition

Lactose is a disaccharide sugar composed of two monosaccharides, glucose and galactose. It is primarily found in milk and dairy products, serving as a significant energy source for many mammals during infancy. Lactose plays an important role in nutrition but also requires the enzyme lactase for its digestion, which can lead to intolerance in some individuals who lack sufficient lactase production.

5 Must Know Facts For Your Next Test

1. Lactose accounts for about 2-8% of the total solids in milk, varying between species.
2. The ability to digest lactose beyond infancy is due to genetic adaptations and varies widely among populations, leading to lactose tolerance or intolerance.
3. Lactose can be fermented by bacteria in the gut, producing lactic acid and gas, which is often responsible for symptoms of lactose intolerance.
4. In dairy processing, lactose can be removed or broken down to make lactose-free products for those with intolerance.
5. High levels of unabsorbed lactose in the intestines can lead to osmotic diarrhea, as water is drawn into the gut lumen.

Review Questions

• How does the composition of lactose relate to its function in nutrition?
  • Lactose's composition as a disaccharide made of glucose and galactose allows it to serve as an important energy source, particularly for infants who rely on milk. The presence of these monosaccharides means that upon digestion, lactose provides readily available energy needed for growth and development. This dual structure highlights its essential role in mammalian diets, especially during early life stages.
• Discuss the implications of lactose intolerance on dietary choices and health.
  • Lactose intolerance can significantly impact an individual's dietary choices, as they may need to avoid traditional dairy products that contain high levels of lactose. This condition arises when there is insufficient lactase enzyme to digest lactose effectively. Consequently, those affected might seek out lactose-free alternatives or incorporate non-dairy sources of calcium and vitamin D into their diets to maintain nutritional balance while avoiding discomfort.
• Evaluate the role of genetic variations in lactase persistence and how they influence human populations.
  • Genetic variations leading to lactase persistence allow certain populations to continue digesting lactose into adulthood. This trait has evolved in cultures with a long history of dairy consumption, providing a nutritional advantage through access to a stable food source. Conversely, populations without this adaptation often experience higher rates of lactose intolerance. Understanding these genetic differences highlights the interplay between culture, diet, and evolution within human populations.

Related terms

glucose:

A simple sugar that is an important energy source for living organisms and a key component of many carbohydrates.

galactose: A monosaccharide that combines with glucose to form lactose, playing a vital role in the metabolism of certain sugars.

lactase: An enzyme produced in the small intestine that breaks down lactose into glucose and galactose, facilitating its absorption into the bloodstream.