What is the function of vitamin B-12 in the body?

Vitamin B-12 plays a crucial role in the body's ability to produce new cells, particularly red blood cells. It is essential for DNA synthesis and the proper functioning of nerve cells, which also ties into its role in preventing certain types of anemia that can occur due to insufficient red blood cell formation. Without adequate vitamin B-12, the process of cell division slows down, leading to potential health issues, including fatigue and cognitive disturbances. This key function emphasizes the importance of vitamin B-12 in overall health and cellular maintenance.

The other options focus on functions that are not directly associated with vitamin B-12, such as fat digestion, blood sugar regulation, or skin health, which are primarily influenced by other nutrients and vitamins in the body.