Which vitamin is necessary for DNA synthesis and is commonly found in meat, poultry, fish, eggs, and milk?

• A. Vitamin A
• B. Vitamin C
• C. Vitamin B12
• D. Vitamin E

Answer: (C)

DNA synthesis depends on a form of B vitamins, with vitamin B12 playing a key role as a cofactor in reactions that help regenerate molecules needed to make DNA. Specifically, B12 is involved in converting homocysteine to methionine, which in turn supports the cycle that provides thymidine, a building block of DNA. Without enough B12, this process slows down, hindering DNA replication.

Vitamin B12 is found primarily in animal-based foods—meat, poultry, fish, eggs, and milk—so these sources are important for maintaining adequate B12 levels. The other vitamins listed don’t directly drive the DNA synthesis pathway: vitamin A supports vision and immunity; vitamin C aids collagen formation and antioxidant protection; vitamin E serves as an antioxidant. Hence, vitamin B12 is the nutrient most closely linked to DNA synthesis and matches the described food sources.