Which protein source contains lactose?
a. Egg
b. Pea
c. Soy
d. Casein
The correct answer and explanation is:
Correct Answer: d. Casein
Explanation:
Lactose is a natural sugar found in milk and dairy products. It is composed of two smaller sugar molecules, glucose and galactose, which are broken down by the enzyme lactase in the human digestive system. Among the options listed, only casein contains lactose because it is a protein derived from milk.
Understanding the Options:
- Egg (a):
Eggs are a highly nutritious source of protein but do not contain lactose. Lactose is exclusive to milk and dairy products, and eggs come from birds, not mammals. Therefore, they are safe for individuals who are lactose intolerant. - Pea (b):
Pea protein is plant-based and derived from yellow split peas. It is free of lactose and suitable for people avoiding dairy or lactose due to intolerance or dietary preferences. - Soy (c):
Soy protein is also plant-based and derived from soybeans. Like pea protein, it does not contain lactose and is widely used as a dairy-free protein source. - Casein (d):
Casein is the primary protein in milk and is separated during the cheese-making process. Because it is extracted from milk, it contains lactose unless specifically processed to remove it. Casein-rich foods such as some cheese and dairy products are not suitable for individuals with lactose intolerance unless they are labeled as lactose-free.
Lactose Intolerance and Casein:
Lactose intolerance occurs when the body produces insufficient lactase enzyme to digest lactose. Consuming lactose-containing products like casein can lead to symptoms such as bloating, gas, diarrhea, and abdominal discomfort. However, there are lactose-free casein products available for those with intolerance.
In summary, while eggs, pea protein, and soy protein are lactose-free, casein contains lactose because it originates from milk. This distinction is essential for dietary planning, especially for those avoiding lactose.