Title: The Science Behind Lactose Intolerance
Headings: The Science Behind Lactose Intolerance
Biotechnology
The Science Behind Lactose Intolerance
Elizabeth Paine, PhD
Lactose intolerance
What causes lactose intolerance symptoms?
Lactose intolerance is the original phenotype
What is the evolutionary advantage of being able to produce lactase as an adult?
References

Content: The optimal pH for human lactase is 6.0. At pH 8 to 9, it exhibits 50% of its maximum activity and has little activity below pH 3. In most people, lactase expression diminishes between the ages of 2 and 12. As most people mature to adulthood, the cells that produce lactase are programmed to stop making significant amounts of the enzyme. The lactase gene is still intact, but is no longer expressed or is expressed only at very low levels. Once people stop producing lactase, they become lactose intolerant. They cannot comfortably digest dairy products that contain lactose, or are limited in the amount of dairy they can comfortably consume. People can also become lactose intolerant because they have a condition that damages the lactase-producing cells in their intestines. For example, people with celiac disease have an immune reaction to the gluten protein found in some grain. Over time, this immune reaction damages the intestinal lining to the point that it no longer produces lactase.