Vitamin deficiency in the united states is not common. however, inadequate gastric acid secretion secondary to gastric resection, use of medications that suppress gastric acid, or gastric infection with helicobacter pylori is the most common cause of which of the following?
select one:
a. thiamine deficiency
b. riboflavin deficiency
c. vitamin b12 deficiency
d. folic acid deficiency

c. Vitamin B12 deficiency

Explanation:

Vitamin B12 deficiency is the cause of many diseases, from anemia to thrombosis. This deficiency is not common in the US, however, it is easily caused by inadequate gastric acid secretion secondary to gastric resection, use of drugs that suppress gastric acid, or gastric infection by Helicobacter pylori.

Vitamin B12 is essential for red blood cell formation, integrity and maturation. In their absence, they increase in volume. In the bone marrow - where they are produced - the number of cells increases so much that the appearance simulates that of leukemias.

It is a necessary vitamin for the development and maintenance of nervous system functions. Without it, the myelin that covers the nerves (as the protective cap does with the electrical wires) suffers wear that is called demyelination, a process that occurs in both peripheral nerve neurons and those in the white matter of the brain.

The main source of B12 is in animal foods. But to absorb it, the digestive tract depends on intrinsic factors present in a special group of stomach cells (parietal cells) and receptors located in the ileum.