It allows you to absorb vitamin B12

Normally, vitamin B12 is readily absorbed in the last part of the small intestine (ileum), which leads to the large intestine. However, to be absorbed, the vitamin must combine with intrinsic factor, a protein produced in the stomach. Your stomach is responsible for helping to release the crucial vitamin B12 [PDF] from the proteins you eat.

Hydrochloric acid and an enzyme called pepsin to break the locked B12 out of its protein so it can be absorbed into your bloodstream. “The metabolism of vitamin B starts in the stomach in the parietal cells,” Lisa Ganjhu, associate professor of gastroenterology and hepatology at NYU Langone Medical Center. Vitamin B “is one of the main vitamins in our body to help with metabolism and energy production,” she says.